# Has any TT-RS owner installed the Haldex 'Race' Controller?



## LongviewTx (Dec 26, 1999)

I keep watching the other thread for s review specific to the TT-RS. I wonder if it would provide a $900 handeling improvement on the track? Just have never seen any confirmations that this will improve what the car all ready has "out-of-the-box".

Any one?


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## DesertTTRS (Dec 17, 2011)

*Installed race controller*

Big difference in power delivery under braking - love it and worth every penny. I did the RF switched version. If I did it over I'd just do the race only.


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## JohnLZ7W (Nov 23, 2003)

DesertTTRS said:


> Big difference in power delivery under braking - love it and worth every penny. I did the RF switched version. If I did it over I'd just do the race only.


I don't understand, do you mean while left-foot braking?


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## - Jeremy - (Feb 23, 2006)

JohnLZ7W said:


> I don't understand, do you mean while left-foot braking?


No. The Haldex controller in sport mode disengages the AWD clutch under braking and re-engages it on acceleration. In race mode, it's always engaged. Even under braking. Most people say it feels much more consistent and in control when in race mode. But it uses more fuel in daily use, etc.

- Jeremy -


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## JohnLZ7W (Nov 23, 2003)

- Jeremy - said:


> No. The Haldex controller in sport mode disengages the AWD clutch under braking and re-engages it on acceleration. In race mode, it's always engaged. Even under braking. Most people say it feels much more consistent and in control when in race mode. But it uses more fuel in daily use, etc.
> 
> - Jeremy -


I was confused by the "power delivery while braking" comment. Unless someone left foot brakes there shouldn't be any power delivery occurring under braking. I am very interested in feeling the difference with the haldex engaged under braking though. Is it really that noticeable?


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## DrDomm (Feb 16, 2003)

JohnLZ7W said:


> I was confused by the "power delivery while braking" comment. Unless someone left foot brakes there shouldn't be any power delivery occurring under braking. I am very interested in feeling the difference with the haldex engaged under braking though. Is it really that noticeable?


I haven't tracked my RS, but I deliver power under braking everyday. And I don't left foot brake. I heel 'n toe as I downshift through the gears. I don't have the "Race" controller, and didn't realize what the "Sport" controller did under braking. Very interesting.


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## LongviewTx (Dec 26, 1999)

- Jeremy - said:


> No. The Haldex controller in sport mode disengages the AWD clutch under braking and re-engages it on acceleration. In race mode, it's always engaged. Even under braking. Most people say it feels much more consistent and in control when in race mode. But it uses more fuel in daily use, etc.
> 
> - Jeremy -


Thanks, great food for thought. I consdier my car a touring car, albiet sporty, but I am currently generating a track addiction. Either way, she is not my daily driver. I guess I'll wait until more specific pro vs cons are established.

*If installation is easy enough, maybe just switch back and forth when arriving at said track event?*


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## JohnLZ7W (Nov 23, 2003)

DrDomm said:


> I haven't tracked my RS, but I deliver power under braking everyday. And I don't left foot brake. I heel 'n toe as I downshift through the gears. I don't have the "Race" controller, and didn't realize what the "Sport" controller did under braking. Very interesting.


heel-toe doesn't really deliver power either, the engine blip is done with the car in neutral so having the haldex engaged shouldn't affect the feel at all.


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## Marty (Jul 14, 2000)

I would guess that any "feel" differences for swapping in a Race controller on a TT-RS would be placebo. On the track, if you're flying all over the place, I have to imagine that the stock rear power delivery adjustment takes over and mimics the Race controller settings.


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## DrDomm (Feb 16, 2003)

JohnLZ7W said:


> heel-toe doesn't really deliver power either, the engine blip is done with the car in neutral so having the haldex engaged shouldn't affect the feel at all.


I guess it's a matter of semantics, but if you apply throttle while your braking, you're increasing power output. Unless you have a perfect rev match as you engage the clutch, some of that power is going to get through to the "driven" wheels. With the "sport/stock" controller, that power is transmitted to only one pair of wheels (front or rear, I don't even know). With the "race" controller, that power (as you engage the clutch) is transmitted to all 4 wheels (apparently). I assumed this difference was what DesertTTRS was referring to when he said "power delivery under braking".


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## [email protected] (Mar 9, 2007)

Marty said:


> On the track, if you're flying all over the place, I have to imagine that the stock rear power delivery adjustment takes over and mimics the Race controller settings.


I am not professing to be an expert here, but:










This graph was generated on a Golf R, which uses the same Gen.4 Haldex as the TT-RS...there is a significant increase in pwer delivery in race mode.

Have any of you seen what our latest offering is?

Haldex Gen.4 Competition Controller 

From the post:

_The HPA Gen.4 Competition Controller is calibrated similar to the "Race mode" setting used in the standard Gen.4 Performance Controllers, but has the additional feature of increasing the clutch torque when braking. By doing so, wheel brake torque is now transferred rearwards through the AWD clutch, offering a far more aggressive deceleration capability. Additionally, the Competition controller will support left foot braking without disengaging the 4-motion clutch while out on the track. _


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## Marty (Jul 14, 2000)

[email protected] said:


> I am not professing to be an expert here, but:
> 
> 
> 
> ...


How should I interpret that plot? The x-axis isn't even labelled. And how do we know how the TT-RS behaves? It's not a Golf R, and I'd imagine that there is more customizability built in to the system than "all gen4 haldex cars must behave identically).


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## [email protected] (Jul 3, 2007)

Marty said:


> How should I interpret that plot? The x-axis isn't even labelled. And how do we know how the TT-RS behaves? It's not a Golf R, and I'd imagine that there is more customizability built in to the system than "all gen4 haldex cars must behave identically).


Nope.


That graph is kind of hard to read, this one makes it simpler. 











All Gen 4 systems do behave identically, ( TT-S, TT-RS, Golf R, all use the *SAME* controller ) The stock Gen 4 controller is NOTHING like the switchable controller in Race mode, and certainly no where near the competition.

With the stock or the switchable controller under braking ( ie as soon as you touch the brake pedal ) you have no more rear wheel mechanical braking, meaning now all the mechanical braking ( even if you just touched it ) is now 100% being done by the front wheels. So going into a corner your now having a fairly decent weight shift to the front axles, and unloading the rear.

Comment from Golf R owner Dummy:

"On another note, yesterday's accomplishments:

HPA Gen4 Haldex controller & dog bone mount installed (complete with pre and post AWD dyno runs...they'll be posting the runs on monday or tuesday, but i'll post one of them below) all i can say is even though it is supposed to really only help on the track HOLY $H!T it takes the stage one and makes it feel like you've been kicked in the back when you floor it. the new Haldex programming puts power to the ground WAY better than the stock system. as you can see, the controller balances the power to be almost 50/50 and you don't have the torque loss in the lower RPMS like with the stock system which means more HP to the ground... "


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## Marty (Jul 14, 2000)

Thanks for chiming in! Would love to hear some more technical details about your product.



[email protected] said:


> Nope.
> 
> 
> That graph is kind of hard to read, this one makes it simpler.


Sorry, but what are you trying to show with that plot? If I'm interpreting the plot correctly (you didn't provide any insight in to what I should be looking for on the plot), then the stock Haldex in at least one specific operating condition on the dyno has ~25 hp of difference between the front and rear wheels, vs. ~10 hp of difference. At ~5000 RPM on the plot you shared, that's equivalent to a F/R split of 55%/45% stock vs. 52%/48% (so only a ~3% absolute difference). That doesn't sound like much to me...



[email protected] said:


> All Gen 4 systems do behave identically, ( TT-S, TT-RS, Golf R, all use the *SAME* controller ) The stock Gen 4 controller is NOTHING like the switchable controller in Race mode, and certainly no where near the competition.


Does the car's ECU have any input to the controller to change its behavior dynamically or per car? Sure, the same controller is used, but are there any settings changed on it for a TT-RS vs. Golf R? 

Also, is the TT-S really gen4? I thought gen4 was new for the TT's on the TT-RS only.



[email protected] said:


> With the stock or the switchable controller under braking ( ie as soon as you touch the brake pedal ) you have no more rear wheel mechanical braking, meaning now all the mechanical braking ( even if you just touched it ) is now 100% being done by the front wheels. So going into a corner your now having a fairly decent weight shift to the front axles, and unloading the rear.


Assuming you haven't lost traction, changing the distribution of braking force between the rear and front tires does nothing to the "weight shift" (the vertical reaction forces on the tires as a result of the torque on the chassis created by the deceleration of the vehicle mass). Either way, the torque about the center of mass of the car is the same (since the vertical distance from the center of mass to the force application point at the tire patch is the same). Draw a free body diagram of the car and calculate the forces if you don't believe me.

So the total weight on the rear does NOT change as a result of this mechanical switching from the stock Haldex during braking. Just wanted to point that out.



[email protected] said:


> Comment from Golf R owner Dummy:
> 
> "On another note, yesterday's accomplishments:
> 
> HPA Gen4 Haldex controller & dog bone mount installed (complete with pre and post AWD dyno runs...they'll be posting the runs on monday or tuesday, but i'll post one of them below) all i can say is even though it is supposed to really only help on the track HOLY $H!T it takes the stage one and makes it feel like you've been kicked in the back when you floor it. the new Haldex programming puts power to the ground WAY better than the stock system. as you can see, the controller balances the power to be almost 50/50 and you don't have the torque loss in the lower RPMS like with the stock system which means more HP to the ground... "


It's great that people like it. Placebo is also a powerful thing. I'm not claiming that your Haldex race controller doesn't provide a lot of benefit (nor am I claiming that it does), but I am claiming that subjective reviews from folks that just spent a lot of money on one aren't the most reliable sources for unbiased information.


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## YYC Dubber (Jun 23, 2011)

[email protected] said:


> Nope.
> 
> 
> Comment from Golf R owner Dummy:
> ...



hmmmm, starting to think this version might be worth the install.... its once thing I keep hearing is that quite a few people are finding the car a bit unpredicatable at the limit when the power gets applied again.... maybe this will prove a good solution.... hoping to hear from anyone who has tried this COMPETITION MODE on their car 

Probably best solution is for someone who owns a stock one to drive someone else's race haldex equipped RS at a meet n greet.


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## Dr. Bill (May 15, 2011)

[email protected] said:


> With the stock or the switchable controller under braking ( ie as soon as you touch the brake pedal ) you have no more rear wheel mechanical braking, meaning now all the mechanical braking ( even if you just touched it ) is now 100% being done by the front wheels. So going into a corner your now having a fairly decent weight shift to the front axles, and unloading the rear.


Does that mean it takes a front-wheel biased all wheel drive system and changes it to a front wheel drive system under braking? Wouldn't that make the understeer more severe? Or would it cause oversteer?

It's all so confusing! :what:


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## [email protected] (Jul 3, 2007)

Dr. Bill said:


> Does that mean it takes a front-wheel biased all wheel drive system and changes it to a front wheel drive system under braking? Wouldn't that make the understeer more severe? Or would it cause oversteer?
> 
> It's all so confusing! :what:


The stock controller and the switchable both do de-couple the rear end, making your AWD car FWD under deceleration.

Marty, Thank you for the technical brief but I'm not sure what I can do to aid you in your purchase, those that are going to review it will have purchased it!


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## Marty (Jul 14, 2000)

[email protected] said:


> Marty, Thank you for the technical brief but I'm not sure what I can do to aid you in your purchase, those that are going to review it will have purchased it!


No problem. I'm still just trying to understand what you guys are trying to show with the plots that you're referencing.


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## 996cab (Aug 13, 2011)

LongviewTx said:


> I keep watching the other thread for s review specific to the TT-RS. I wonder if it would provide a $900 handeling improvement on the track? * Just have never seen any confirmations that this will improve what the car all ready has "out-of-the-box".*
> 
> Any one?


Hi,
to answer your specific question for track use the simple answer is yes and also on a wet track or streets the simple answer is yes.

Otherwise you will not notice any difference.

I have had the race only version for over 18-mths. I track the car once a month or 10 times per annum. The Haldex Race Controller only comes in to full use on track where it does maintain traction on all 4 speicifcally in to and out of bends. That is its main and only strength to me over the oem haldex which had a tendency to make the nose push out wide.

This is the key point...I have now done many other handling changes to the car and IF I were modding a new TT-RS from start today, I *WILL NOT* fit the upgraded Haldex unit...I will leave the OEM in situ and instead make changes elsewhere...simply because I now know how to get the car to my liking without the Haldex upgrade.

BTW, the Haldex Race Controller by itself will not entirely cure the nose pushing out wide...you will also need an ARBs upgrade...those two go hand-in-hand IMO.

WB


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## Stevelev (Mar 4, 2004)

^ Interesting info regarding doing suspension work instead of Haldex upgrade. I do agree that inclement weather is where the true benefits are felt.

Although I have the "lowly" TTS, I upgraded the Haldex along with a beefier rear sway and there is a noticeable benefit with respect to understeer. Although I had the Neuspeed bar installed first, it wasn't until the Haldex went in that I found, in slippery weather, the car had far better manners (i.e.: neutral handling). I would suggest that the Haldex transformed the TTS from a FWD bias to a more similar feel of my previous car (RS4).

edit: Car hasn't been to the track but is booked to go in May


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## DjSherif (Apr 27, 2005)

Marty said:


> Also, is the TT-S really gen4? I thought gen4 was new for the TT's on the TT-RS only.


Not only do 2010 and newer TT's have Gen 4 but so do A3's from 2010 on.


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## 996cab (Aug 13, 2011)

To comment further on the Haldex Race Controller...;

At present I can feel the 4 corners pushing the car along - with the OEM controller unit in place car felt more FWD.

Whilst the Haldex Race Controller is great in the wet/exit of corners as I can get on power earlier...those are the only two occasions that it has benefits which I can feel from the driver’s seat. All other occasion it simply feels like all 4 wheels are transferring power to the road...now, that can be a good thing or a bad thing depending on how you want the car to behave.

Over time, I have come to want the rear axle to 'slide' round corners - oversteer - in a way that allows me to moderate power...the Haldex Race Controller had been stopping me doing so by design until I made the following changes...;

1) stiffer rear springs - upped the spring rate from linear 44N/mm to progressive (22N/mm >46N/mm > 88N/mm)...I will explain more on this below as we have also added rebound capability with the springs changes here...this was unintentional however has proven very effective on handling.

2) softer front springs (in relation to rears) - now at 48.95N/mm

So as I note above, the Haldex Race Controller for me is now a bad thing as am making changes to counter its key operation certainly on a dry tarmac. I have setup my car to mildly oversteer in the dry on the limit by driving in lower gear at higher RPMs...the way you would drive a N/A engine like a 911 as an example. Offcourse, in the wet I am happy to have it as I can revert to rely upon it by not driving in lower gears at higher RPM.

*REBOUND CAPABILITY*

Background...;

I bought the TT-RS back in 2009 to replace a couple of Italian V8s which were hardly used. Initially, I was very impressed by the TT-RS. 

Over time I decided on changes as I felt these would make for a better car especially on B-roads – see http://www.youtube.com/watch?v=B38h7405h3Q and on track – see http://www.youtube.com/watch?v=tjqAjucTYfY. I guess the question could be asked of me...why not buy a track focused car that is also capable on B-roads...fair question however I felt the TT-RS was a good base to start from.

*TRIPLE STACKED SPRINGS*.
I wanted to touch on this the way I am experiencing it at present having designed a rear spring system that is just working great for me. 

*POINT TO NOTE*: A single linear spring relies on the damper to control rebound during its operation...which is by design and works fine provided the damper is matched to the single linear spring. The main issue I had on the TT-RS in regards to handling is that the fronts leaned too much in corners and MagneRide was not capable of applying enough rebound (on fronts) or compression (on rears) to counter the leaning / squatting. Help was required and I was determined to keep the MagneRide operation thus Coilover kit was a not an option – I have not got the time to get under the damn car to fiddle with knobs to get more compression or rebound...! I prefer the one touch offered by MagneRide via the Sports button.

I traced the issue to the rears squatting during the 3 corner phases – entry ; mid; exit whilst on a trackday at Goodwood Motor Circuit. “How did you do this?” you asked...well, I got a photographer friend of mine to stand at the end of the Lavant straight and at the last chicane before the main pit straight to photograph the car in motion during the critical corner 3-phases (entry; mid; exit). What we noted upon viewing the images was how the rear of the car was in a permanent state of squat thus the fronts (left or right) wheels were barely making contact with the tarmac.

That series of images set me off to undertake a crash course in suspension set-up and through weeks of NET research and speaking with BWI (they make the MagneRide dampers for Audi however Audi apply their own algorithm – which is actually very good to be fair). I settled upon stacked springs as a good friend and also a current 997 Gen2 GT3RS owner had these on his car though he had dual rate spring system (the norm for most C/O kit) I went one step further and installed triple rate springs made up of a progressive tender and linear main spring.

What we (btw the 'we' are...a very good GT3RS owner friend and my VAG Indi tuner) found was that due to the natural operation of stacked springs, there is always going to be a counter motion depending on the amount of load being applied. Thus, the following and a variation off is the norm under operation...this assumes a triple stacked spring system as I have on my car;

1)	*APPLIES TO COMPRESSION*: When spring #1 compresses under load, spring #2 and spring #3 resist compression until the applied load exceeds the load capability of spring #1. At this point spring #2 starts compressing until the load exceeds its load carrying capability then spring #3 starts compressing until all 3 springs compress completely (termed as spring is ‘blocked’). 

2)	*APPLIES TO REBOUND*: Can you guess what happens under rebound when load is being lightened? Well, the reverse occurs...thus when the applied load that spring #1 can handle is taken off (often would be the case naturally) until it is uncompressed it then acts as a resistant force for spring #2 when it is uncompressing once the applied load that it can handle is taken off. Same applies to spring #3. So, there you get the rebound capability from the stacked springs. The key point to note here is that these rebound capability means that the dampers rebound force can be dialled low which takes ages to get right however – and this is the key benefit of a semi-active damper like MagneRide or PASM – they do that ‘fine’ tuning on the amount of rebound the dampers needs to apply. 

The net effect of the stacked springs having rebound capability is that the ride is more comfortable and the car remains stable during the 3 cornering phases...gone will be any sudden jolt or camber upsetting the car...S I M P L E S! 

The effects has to be sampled to understand how well stacked springs fares when mated with a semi-active damper.

In short, a semi-active damper operates very well with stacked springs as it has less work to do being that the springs natural operation described above helps with rebound as well as compression offcourse – we always think of stiffer springs for compression duties...that is the main issue using linear single springs...the damper has to work overtime on rebound...hence it takes ages to set this up right on non-active dampers...!

I have had mine on the car for 4-mths now and have completed 2 trackdays plus countless street bouts and it just amazes me in the dry and wet how I am able to easily and controllable get the car to oversteer...making this old fool here look good at the helm...:laugh:


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## pal (Aug 16, 2000)

996cab- thanks for that detailed explanation. I am trying to picture the rebound case and I am imagining spring #1 fully unloaded and spring #2 starting to unload. Is spring #1 now resisting the unloading of spring #2 as its being compressed from below (assuming that #1 sits on top, #2 below it and #3 at the bottom)? And hence acting as a damper and assisting in rebound?

Also, does the MagneRide damper not need to have additional damping to counter the stiffest spring (#3 in this example) compared to stock? And if that spring rate is much higher than stock cause premature wear on the damper? I am assuming you have not felt under damping (bouncy car) on the street or track ao far with your current setup.

I ask because a couple of shops recommended against using different spring rates with the stock MagneRide damper on my 3.2 TTC for fear of "blowing" them up sooner- aka they fail/start to leak. One of them cited a customer car as an example.


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## 996cab (Aug 13, 2011)

pal said:


> 996cab- thanks for that detailed explanation. I am trying to picture the rebound case and I am imagining spring #1 fully unloaded and spring #2 starting to unload. Is spring #1 now resisting the unloading of spring #2 as its being compressed from below (assuming that #1 sits on top, #2 below it and #3 at the bottom)? And hence acting as a damper and assisting in rebound?.


Correct - spring #1 is now resisting thus acting at the point spring #2 rebounds which aids ride comfort. If you really think about it and assuming you have the travel/space, you could easily have a quad rated spring system...!





pal said:


> Also, does the MagneRide damper not need to have additional damping to counter the stiffest spring (#3 in this example) compared to stock? And if that spring rate is much higher than stock cause premature wear on the damper? I am assuming you have not felt under damping (bouncy car) on the street or track ao far with your current setup.
> 
> I ask because a couple of shops recommended against using different spring rates with the stock MagneRide damper on my 3.2 TTC for fear of "blowing" them up sooner- aka they fail/start to leak. One of them cited a customer car as an example.


So little is known about the MagneRide implementation on the VAG cars – unless you worked directly in the project implementing the algorithm - that I would not bother speaking to those who think they 'know'...just contact BWI and speak to a chap called Olivier Raynauld...he is a rather busy man however persistence will pay off. The info I have had from him to date makes me laugh when others make unfounded claims about the operation or reliability of MagneRide. 

Just remember a simple fact about MagneRide...it is a pro-active system...give it soft springs and it will be working overtime to stiffen the dampers to ensure car does not kangaroo down the road...give it stiffer springs and it will have less to do. 

Getting a *'spring system'* to match MagneRide is the real key here. To achieve this, I sent Olivier all my calculations and theories made in relation to which springs would work best with MagneRide and the rebound theory is one he particularly liked...the implementation worked a treat as per the theory and countless calculations. 

The principle is simple enough – we are using springs in an arrangement that reduces the work rate of the dampers...S I M P L E S...!


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## Marty (Jul 14, 2000)

Huh? 996cab, I think the understanding of springs is off. A stack of springs can change effective spring constant (F = -k*x, where F is the force in the opposite direction as the displacement, hence the negative sign) as a function of the displacement itself (so k is actually k(x)).

But unlike dampers, the force is always in the direction towards the uncompressed natural state. In compression, their force will always be in the same direction.

So that being said, I have no idea what you mean in your description of the rebound benefits of triple springs allowing you to do anything different with the damper settings. Even in rebound, the force from the springs is still trying to push th chassis away from the control arm. And at every point in the rebel, the effect rebound and compression spring constant is the same (for small displacements).


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## 996cab (Aug 13, 2011)

Marty said:


> Huh? 996cab, I think the understanding of springs is off. *A stack of springs can change effective spring constant* (F = -k*x, where F is the force in the opposite direction as the displacement, hence the negative sign) as a function of the displacement itself (so k is actually k(x)).
> 
> But unlike dampers, the force is always in the direction towards the uncompressed natural state. *In compression, their force will always be in the same direction.*
> 
> So that being said, I have no idea what you mean in your description of the rebound benefits of triple springs allowing you to do anything different with the damper settings. Even in rebound, the force from the springs is still trying to push th chassis away from the control arm. And at every point in the rebel, the effect rebound and compression spring constant is the same (for small displacements).


Marty,
your comment in bold makes sense as written and read in relation to compression. 

In relation to the springs uncompressing, your statement in red text does not make sense to me. Can you elaborate further. Am always keen to learn.

I have also re-edited my response on post #24 for clarity. I think that may be the source of your query.

Essentially in test, I upped the rear linear springs rate from 43.43N/mm to 50.99N/mm to stop the rears from squatting - a major reason for the handling issues I was having on the car. The car was fine on smooth tarmac. However, when I hit any road bumps the jolt unsettled the rears to the point that the car skipped. The car felt like it was permanently on the bumpstop...the ride was very harsh. MagneRide was not able to apply enough rebound force hence the 'bumpstop' feeling. Also the car was not able to soak up any bumps due to the higher linear spring rate of 50.99N/mm.

The solution was the stacked springs and as you rightly point out, the effective initial rate of a stacked spring is lower though the blocked rate will remain that of the higher load in the stack. The arrangement of the springs is irrelevant to which spring blocks first...the first spring to block will be the one with the lowest *load* ratings and so on - am sure you are aware of that. As I pointed out, the stacked spring I designed & fitted starts from 22N/[email protected] of load > 46N/[email protected] of load and blocks at 88N/[email protected] of load.

The * ‘rebound capability’* I note here is simply due to the way each spring will uncompress at a different load rate *DUE* to the fact that each spring used in the stacked arrangement has different *Load *and *Spring *rate.

Hope above explanation is clearer as my earlier attempt at post #22 & #24 was not.

Final point before I join the kids playing WII downstairs - *the stacked springs will not all uncompress at the same time* assuming they were all blocked due to high load as would be the case during high speed cornering...it is an important point to note...I made the assumption that all the stacked springs will uncompress at the same time as I could not comprehend why they would not however once load rating is understood then it all made sense to me during my research...took a few goes though...!!!


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## Marty (Jul 14, 2000)

996cab said:


> Marty,
> your comment in bold makes sense as written and read in relation to compression.
> 
> In relation to the springs uncompressing, your statement in red text does not make sense to me. Can you elaborate further. Am always keen to learn.
> ...


Sorry I'll try to be more clear... admittedly this would be much easier to explain with a few sketches and a graph or two.

Here's a simple summary: at a high level, stacked springs behave exactly like a single spring with a varying spring constant. Their spring constant changes deterministically as a function of the amount of compression of the spring (not the instantaneous direction of travel of the spring). 

The springs when installed in the car are always operating in compression. That is, they're always pushing against their perches at all times when driving the car. So when part of your suspension is in "rebound", while the shocks and springs have reversed direction of travel, the springs are just going from one compression level to another compression level, and the spring force is changing in the process according to the spring constants. As springs always exerts the same deterministic force at a given position, regardless of whether it got to that position during a "rebound" event from one direction or a "compression" event from another direction. 

Dampers (shocks) are different, since they always apply force that resists the direction of travel at any position, and the force they exert is a function of the _rate_ of compression (or tension) of the damper, not the position.


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## Audi RS3 (Apr 20, 2011)

[email protected], do you have the correct version of the Haldex Controller to the Audi RS3? And is the wireless version best?


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## YYC Dubber (Jun 23, 2011)

*996cab*,

I must say your presence on the forums and your persistence and attention to detail in your suspension mods deserves to be applauded. 

The biggest complaint hardcore performance magazines had with the TTRS was its lack of driver feedback, tossability, and inability to induce enough oversteer to aid times and lines on the track. It seems you have licked this problem... would love to see EVO magazine test drive your car and remark on how the improvements have enhanced the character of the car

CHEERS to you sir!:beer:


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## 996cab (Aug 13, 2011)

Marty said:


> Sorry I'll try to be more clear... admittedly this would be much easier to explain with a few sketches and a graph or two.
> 
> *Here's a simple summary: at a high level, stacked springs behave exactly like a single spring with a varying spring constant. Their spring constant changes deterministically as a function of the amount of compression of the spring (not the instantaneous direction of travel of the spring). *
> 
> ...


Marty,
in short I think you are where we were when we were attempting to apply logic in regards to MagneRide - that is the unknown quantity. 

Anyway, the single Linear spring does not operate as a stacked spring - one acts as linear the other acts as progressive (the stacked spring)...big difference. The other difference between operartion of the two types of springs is the counter-action of stacked springs whilst linear springs....well, moves in one direction only per time. 

Am off to work however I will find a Youtube vid and send you a link on the operation of stacked springs...the counteraction point is one to take note...

No, am not an expert...far from it however the little I cared to read about through research got me to make a change that whenever I bring up on forums tends to stir counter arguments...which is interesting because the issue I set out to resolve and still keep MagneRide has been resolved. Ohh, and I tried pretty much everything else to solve the said issue.

Anyway, as I said...am happy to add to my knowlegde so do throw more thoughts across. Thus far nowt new discussed.


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## 996cab (Aug 13, 2011)

YYC Dubber said:


> *996cab*,
> 
> I must say your presence on the forums and your persistence and attention to detail in your suspension mods deserves to be applauded.
> 
> ...


Thx.
I will be seeing Jeremy at the 'Ring at end of June - assuming the weather holds out. Jeremy can give a feedback on the car as I hope he will take it round the 'Ring for a 'few' laps. We will be there for an entire day.


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## - Jeremy - (Feb 23, 2006)

996cab said:


> Thx.
> I will be seeing Jeremy at the 'Ring at end of June - assuming the weather holds out. Jeremy can give a feedback on the car as I hope he will take it round the 'Ring for a 'few' laps. We will be there for an entire day.


Are you sure you trust me with that thing? Did I forget to mention that I only have one arm and cataracts? 

- Jeremy -


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## 996cab (Aug 13, 2011)

- Jeremy - said:


> Are you sure you trust me with that thing? Did I forget to mention that I only have one arm and cataracts?
> 
> - Jeremy -


 Well, you are doing better than me then...I have two left feet and driving skills not to be admired...Ohh, and am blind in both eyes...well, I might as well be as I keep missing the apex (whatever those things are...haha) on tracks.

Jeremy, you will be fine...just drive it like you stole it...I do...!!!


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## 996cab (Aug 13, 2011)

Marty said:


> Sorry I'll try to be more clear... admittedly this would be much easier to explain with a few sketches and a graph or two.
> 
> Here's a simple summary: at a high level, stacked springs behave exactly like a single spring with a varying spring constant. Their spring constant changes deterministically as a function of the amount of compression of the spring (not the instantaneous direction of travel of the spring).
> 
> ...


Marty, 
hope you got time to go through this...this thread - see http://forums.rennlist.com/rennforu...sign-your-own-dual-spring-rate-coilovers.html - set me off to look at the rebound capability of the stacked springs, read post #1 2nd point paragraph 4 and 5.

The poster makes references to dialling down rebound and using well matched higher rate springs...I had already made an educated guess that the single stiffer spring was not suited to MagneRide due to lack of rebound control of MagneRide when using stiffer spring required for track use as in my case. 

The points in paragraph 4 and 5 got me thinking during the many calculations I used and the theories I had. In essence, a dual stacked spring in the case of the poster in the link provided aided rebound as he - like I did - tried a higher spring rate (thus stiffer) single linear spring which was not suited even when he played around with the rebound settings on his Koni damper. The poster goes through detailed calcs which I had already done anyway...the difference between his damper and mine is that he could control bump and rebound...mine is controlled by the pre-defined - and well defined as previously noted - Audi algorithm.

What I can tell you is that Eibach UK were extremely helpful in allowing me to order over 10 sets of springs to conduct extensive load tests to understand the behaviour of stacked springs...I could not fit these springs to the car and test drive else I would have been there forever thus we did manual static load and unload tests to see how the springs behaved and it was during these tests that I noted the counter-active action...ahh, I thought...rebound...! ...or something to that effect.

Offcourse not being an expert I then contacted various personals to verify my findings and also did lots of research on the NET including the post above and that gave me confidence that I was on the right track with the rebound theory. 

Anyway I setteld on two sets of springs as follows;
*SET ONE *- a 600/1300Ib progressive tender stacked on top of a 350Ib linear main spring...my calcs indicated that this was 'OK' ... I will go in to more details why if you wish...just let me know.

*SET TWO *- a 250/550Ib progressive tender stacked on top of a 500Ib linear main spring...my calcs indicated that this was also 'OK' ... I will go in to more details why if you wish...just let me know.

I went for *SET TWO* because the car would ride at a lower spring rate before going in to the higher rate on high load compared to *SET ONE*.

If you want a more definitive evidence of a dual stacked spring in action working in counter-active mode then I will dig out the YouTube vid and post here...just let me know.

Happy to learn something new from you if you can spot a gap in what I have designed.


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## 996cab (Aug 13, 2011)

Marty,
I found the vid in question - see http://www.youtube.com/watch?v=FEEFGqTq99g&feature=related. Pause at 2:03. You will not that the tender is now fully extended...play the vid and you note how that now acts in resistance to the main spring.

Also note how the tender (rated at 500Ib) is doing most of the work in compression and rebound. The main spring (rated at 600Ib) is hardly being called in to action...this is exactly how mine works...offcourse, at high load the tender is fully compressed - termed 'block' - and the main spring then comes in to play. The counter-action clearly shown all through the vid and at 2:03 is the only evidence I needed that the stacked springs can aid rebound thus the damper has less work to do.

This vid also gave me the confidence to go through with my calcs and turn the theory in to reality...it works so well that I wish I knew this earlier before spending over $5k in handling related fixes...non of which solved the issue. 

The stacked spring solution cost less than $1k...and works.

Those who know me would tell you that I am a terrible tinker however since the stacked spring fitment, I cannot find a fault with it to warrant further tinkering...and best of all, I get to keep MagneRide so I can have smooth ride on streets and firm ride for track all from a press of a button...S I M P L E S!

Couple the above fitment with front camber only change (I have managed to get -1.45 due to lowered springs and the SuperPro bushes) and the suspension is ready to go.


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## Marty (Jul 14, 2000)

996cab said:


> Marty,
> I found the vid in question - see http://www.youtube.com/watch?v=FEEFGqTq99g&feature=related. Pause at 2:03. You will not that the tender is now fully extended...play the vid and you note how that now acts in resistance to the main tender.
> 
> Also note how the tender (rated at 500Ib) is doing most of the work in compression and rebound. The main spring (rated at 600Ib) is hardly being called in to action...this is exactly how mine works...offcourse, at high load the tender is fully compressed - termed 'block' - and the main spring then comes in to play. The counter-action clearly shown all through the vid and at 2:03 is the only evidence I needed that the stacked springs can aid rebound thus the damper has less work to do.
> ...


Thanks for all the links. I read through them all, and I still don't see anything inconsistent with what was mentioned previously: stacked springs behave exactly like single springs, but with spring constants that vary as a function of the compression (you can call them "progressive" if you want).

Try to visually ignore the behavior that your eye is drawn to in the YouTube video, and just visualize the total length of the "effective spring" between the outer perches. The two springs in this case are just behaving like a single spring whose spring constant is initially one value up until a certain level of compression, at which point it increases to a higher value for the remainder of compression.

There is nothing magical about the "rebound" when the spring uncompresses in one direction that is any different in how it behaves while it is compressing in the opposite direction. It always just behaves like a spring with a certain spring constant (and that spring constant depends on the level of compression).



996cab said:


> Marty,
> hope you got time to go through this...this thread - see http://forums.rennlist.com/rennforu...sign-your-own-dual-spring-rate-coilovers.html - set me off to look at the rebound capability of the stacked springs, read post #1 2nd point paragraph 4 and 5.


This Rennlist post is just saying that with a dual-spring stack, you can have a low initial spring constant (which is just in effect up to a certain level of compression), which allows you to then have a lesser amount of damping to critically damp the mass-spring-damper system of your car, enabling a more comfortable ride on the street. But then when you turn hard and compress the springs enough to enable the higher spring constant, you then get that "stiff suspension" behavior for spirited driving. 

So again, the only functional benefit (that I can see) for stacked springs is the ability to tune the springs constants at different levels of compression. You could achieve this with a single custom-wound progressive spring (which would be harder to manufacture, but could behave identically). As the Rennlist post points out, this can enable you to adjust your damper settings to have a more comfortable ride on the street, while still having a very high effective spring constant at high lateral loads (hard cornering).


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## 996cab (Aug 13, 2011)

Marty said:


> So again, the only functional benefit (that I can see) for stacked springs is the ability to tune the springs constants at different levels of compression. *You could achieve this with a single custom-wound progressive spring (which would be harder to manufacture, but could behave identically*). As the Rennlist post points out, this can enable you to adjust your damper settings to have a more comfortable ride on the street, while still having a very high effective spring constant at high lateral loads (hard cornering).


Marty, 
thx for taking the time and good to walk through all of this with someone else who shows an interest.

I agree with the above statement above - inparticular the point highligted.

Yes, I made enquiries in regards to 'true' progressive springs...the difficulties pointed out to me here was that the rate of progression required for MagneRide to function as desired was an unknown quantity...that was something we could not find out...the car would have had to be sent to a 'recepetive' spring manufacturer for R&D...not an option given some of the figures I was being quoted for their time.


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## 996cab (Aug 13, 2011)

So, in regards to semi-active dampers...would you 2nd the view that stacked springs (or true progressive springs could also be an option) is an alternative to going Coilover. That is now firmly my view having sampled a coilover car (KW v3 equipped) and offcourse what I have. I would personally advise against lowering using linear springs...it is simply to crude in operation and offers looks not function IMO.

The key benefit with the rear ONLY change as I have made is that the car soaks up bumps with much more poise than in stock mode with MagneRide in soft or firm settings...something am still amazed about till today.


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## Marty (Jul 14, 2000)

996cab said:


> Marty,
> thx for taking the time and good to walk through all of this with someone else who shows an interest.
> 
> I agree with the above statement above - inparticular the point highligted.
> ...


No problem. Could you help provide some more insight in to what makes the stacked springs so great with the magride? Is it just that you can achieve great handling with progressive springs with the low damping ratio in non-sport mode? Also, it sounded like you wanted to add some stiffness to the rear springs to change the suspension dynamics in cornering? Just trying to understanding specifically what was great about the stacked spring approach for this application. From my understanding, it's really the ability to hit a high spring rate and still have comfort.


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## Marty (Jul 14, 2000)

996cab said:


> So, in regards to semi-active dampers...would you 2nd the view that stacked springs (or true progressive springs could also be an option) is an alternative to going Coilover. That is now firmly my view having sampled a coilover car (KW v3 equipped) and offcourse what I have. I would personally advise against lowering using linear springs...it is simply to crude in operation and offers looks not function IMO.
> 
> The key benefit with the rear ONLY change as I have made is that the car soaks up bumps with much more poise than in stock mode with MagneRide in soft or firm settings...something am still amazed about till today.


IMO, the benefit of coilovers is simply the adjustable perches to tweak ride height (in exchange for working range of the suspension). Fundamentally suspension-wise, there is nothing that a coilover can achieve that a traditional shock and spring can't (other than height adjustability).


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## 996cab (Aug 13, 2011)

Marty said:


> No problem. Could you help provide some more insight in to what makes the stacked springs so great with the magride? Is it just that you can achieve great handling with progressive springs with the low damping ratio in non-sport mode? Also, it sounded like you wanted to add some stiffness to the rear springs to change the suspension dynamics in cornering? Just trying to understanding specifically what was great about the stacked spring approach for this application. From my understanding,* it's really the ability to hit a high spring rate and still have comfort*.


Marty,
response in bold is the key reason for me...high spring rate reduces squatting on the rears and helps the fronts retain grip during high speed cornering. Below is other reasons and link gives more details.

I have been giving the GT3/RS boys at rennlist a feedback on forum and on PMs. Recent benefit is here - see http://forums.rennlist.com/rennforu...tracks-sebring-suspension-upgrades-etc-7.html. A handful are heading down same route with their GT3 and GT3RS as opposed to revalving their dampers or going for C/O.

Below is the summary of the benefit...in simple terms, if you have MagneRide (Aston Martin; Audi; Ferrari; to name but a few) or PASM (Porsche) you do not have to take that off for C/O just to get adjustability of ride height and a better handling/composed car for track use or a car that ride so well on rough roads as well as firms up for some 'competitive' action on track. You can opt for what I did. 

I used Eibach springs because they were the only manufacturer willing to go on the 'journey' with me. There are other springs to use...Swift; KW and many less known brands...

*BENEFIT*
The main benefit I have found with the triple-rated dual stacked spring system designed and now fitted to the car is that the car as a whole is more composed on streets or track as the semi-active dampers combined with the stacked springs are now doing what the suspension is designed to do best and that is to soak up bumps. That simple ability to soak up bumps helps stabilise the car during cornering or on a cambered road or track.

I have also firmed the front spring rate up thus I now have a more composed and firmed up suspension system as a result. The key point to note here is that stacking springs by carefull selection yields benefits specifically on a semi-active suspension system which is so impressive that it really changes the car in to an entirely sports focused yet comfort retained vehicle that is much more of a joy to jump in and have a go…Amen indeed…!


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## YYC Dubber (Jun 23, 2011)

Any chance of getting your photog buddy to video a few trackside scenes demonstrating the new willingness of the car to allow controlled oversteer?opcorn:


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## 996cab (Aug 13, 2011)

YYC Dubber said:


> Any chance of getting your photog buddy to video a few trackside scenes demonstrating the new willingness of the car to allow controlled oversteer?opcorn:


Will do.


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## GBXRS (Sep 1, 2015)

*stacked springs for TT RS*



996cab said:


> Marty,
> hope you got time to go through this...this thread - see http://forums.rennlist.com/rennforu...sign-your-own-dual-spring-rate-coilovers.html - set me off to look at the rebound capability of the stacked springs, read post #1 2nd point paragraph 4 and 5.
> 
> The poster makes references to dialling down rebound and using well matched higher rate springs...I had already made an educated guess that the single stiffer spring was not suited to MagneRide due to lack of rebound control of MagneRide when using stiffer spring required for track use as in my case.
> ...


I have been working through the process of getting my 2010 TT RS to handle well. (I'm comparing it to my Lancer EVO X RS tarmac rally car that has full time AWD, 3 way coilovers etc).

Your experience sounds like it might save me a lot of time. I have H&R sway bars installed & the SuperPro bushes and I have a Haldex competition controller. I have been doing a lot of testing at the track and the car is definitely getting better. It still has corner exit power on understeer, though not as much as when I started.

Your testing with the Magride and stacked springs appeals to me.

Am I correct that you settled on:
a 250/550Ib progressive tender stacked on top of a 500Ib linear main spring?

Can you tell me the Eibach part numbers so I can order a set, please?

Cheers
Greg


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## croman44 (Jan 9, 2013)

GBXRS said:


> I have been working through the process of getting my 2010 TT RS to handle well. (I'm comparing it to my Lancer EVO X RS tarmac rally car that has full time AWD, 3 way coilovers etc).
> 
> Your experience sounds like it might save me a lot of time. I have H&R sway bars installed & the SuperPro bushes and I have a Haldex competition controller. I have been doing a lot of testing at the track and the car is definitely getting better. It still has corner exit power on understeer, though not as much as when I started.
> 
> ...


This is the result of all of his hard work, and what a fantastic result it is

http://www.msskits.com/

Search the forums and you will find lots of reviews for the kit and I do not think you will find a negative one among them. I personally own the Fully Adjustable Sport Kit and its the best mod on my car


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## ZPrime (Mar 7, 2006)

*FV-QR*

Wow, this thread got necro'd...

To comment on the original topic though - when HPA is talking about the Haldex controller being the same between Golf R and TTRS -- they are accurate that the _hardware_ is identical. 

The _software_ most definitely is not. The stock/OEM software on a TTRS Haldex (gen4) controller is different from what's on the Golf R's controller. I was given this information by another tuner who is capable of reading / writing to the OEM Haldex controller, they have dumped the modules from both cars and have mentioned there are differences. I was not privy to the exact details of the differences, just that the code *isn't* the same.

As such, I'm not sold on the HPA upgrade being as much of a benefit for a TTRS. The only thing that would interest me is keeping it engaged under braking during track conditions. I suspect that the rearward power engagement is already higher with a TTRS controller than with a Golf R - look at how hard the TTRS rears back on a launch! VAG would have to be stupid to not specify increased rear power transfer to help with this.


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