# 2004 TT Quattro EV swap - Re: Haldex



## DirefulEvolution (Apr 17, 2019)

Good afternoon!
My name is Olivia and this is my first post on VWV.

I'm in the planning stages of converting my 2004 Audi TT Quattro to electric! I've done so much research that my head is spinning and I've decided I'm going to be using the Netgain WarP11HV motor. These motors have interpoles which allows them to take incredible amounts of voltage- this is important because RPM scales almost linearly with voltage in these motors, and horsepower can be calculated using proportions of voltage vs. amperage, divided by 746 and multiplied by approximate drivetrain loss. With modern battery technology (thank you based Elon Musk) electric vehicles have never been more capable of extreme speed, long range, and rapid charging. In the eyes of this aspiring electrical engineer and IT professional, the ICE is rapidly becoming obsolete! In the face of the oncoming climate catastrophe, this is especially important for I am a treehugger with a lead foot.

I must emphasize that this thread has absolutely nothing to do with getting the motor in and running. Several companies make anything from adapter plates to mate the motor to the stock transmission, to utilizing a modified input for a Chevy EV transmission, all the way to gutting and rebuilding VW/Porsche/Audi transaxles with significantly strengthened, 2-speed configurations! It's absolutely magnificent!

My question pertains to Haldex. The Quattro in the equation is essential to me utilizing this car for this swap. Because this is relatively uncharted territory for this specific car, I'm not sure how to get the Haldex to work properly.

From my searching on this forum, I understand that the controller talks to canbus to get input such as wheel speed (comparing front to rear speeds to detect slip), throttle position, braking, RPM, and a couple other parameters. Complex stuff!

Obviously, the stock ECU and honestly a vast majority of the stock electronics are getting binned. Even if they could be retained, 300+ volts and 1000+ amps would ****ing vaporize the thin stock wiring. I'm not trying to have a car full of plasma and molten copper. However, I'm stumped on how to control the haldex without retaining the stock canbus system? I see that there are aftermarket controllers but are these standalone? Could I theoretically directly wire a 12v signal to the stepper motor to pressurize the haldex, and splice the wiring to the ABS module to use wheel slip as a parameter to engage the clutch packs? How would I make ABS work without the stock ECU, though...? There are tech sensors you can buy for these motors that connect directly to the output shaft.. could I use this signal to control it?

What about mechanically locking it 50/50 at all times? Wouldn't that annihilate the clutch packs? I can configure an oil cooler to keep it cold but these motors are capable of hundreds if not thousands of lb/ft from >literally< 0RPM to about 4500RPM. Higher still with better quality brushes (essentially a chunk of doped carbon that passes current to the commutator to spin the rotor) and a controller that can handle the demanded current. Are there upgrades to the clutch packs in the event that they would slip and/or shear?

I also see there are standalone Haldex controllers for sale, from USP Motorsports and others. Their websites give me woefully little information about how these systems actually function. If they rely on talking to an ECU of any fashion to work, it would be useless to me, because no ECU would be able to talk to my electric motor. Nothing about a direct current motor can be translated to an ICE, except for very basic physics principles like RPM, which is a system that will be handled separately anyway. All gauges, all commodities (power steering, A/C, radio) will be independently integrated using a DC/DC controller; think about the transformers you see on electric poles, just extremely miniaturized. They use semiconductors to bring high voltage down to up to 12v. Hence, pretty much nothing from the factory electronics will be retained. 

I'm sorry for the barrage of questions but each one is individually important to this huge project. Realistically, any single factor not being addressable would cripple my ability to use this car for a conversion. Light weight and AWD are the two precise reasons why I want to utilize this car for an EV swap. Without AWD integration, I'll likely move onto something simpler, like a mechanical AWD car or something RWD like a classic rice rocket or maybe a genesis coupe. I LOVE my TT but AWD is >essential< to my vision. I will not drive a FWD car with this much instant torque. That's asking to plow into a median or another car by looking at the throttle slightly too hard.

Thank you for any insight you could provide!

P.S.: This conversion will be utilizing a Hall Effect accelerator most likely. I don't understand the mechanisms enough to explain it to you because it's electromagnetic wizardry, but essentially it's a fancy potentiometer. I read in another thread somewhere that someone suggested using a potentiometer to get a Haldex >swap< into an older gen Jetta(?) to not only work, but work dynamically based on throttle position. Thanks again!


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## DirefulEvolution (Apr 17, 2019)

Erm.. sorry for the double post, but I'm posting using my phone and from my perspective this post looks like a giant wall of text!! 😖😖 Does it appear in broken up paragraphs to you folks? Or did I **** something up??


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## asiwa (Dec 18, 2014)

Interesting topic. Before EVs came into the public eye in a big way I was really into conversions like this, so props to you!

I feel that the most straightforward and efficient solution to your problem would simply be to use a different vehicle with a mechanical center differential or transfer case. An A4, Impreza/legacy/etc or something similar would be far easier to work with than a TT.

We talk about the Haldex in a way that makes it seem simplistic - it's based primarily on wheel speed sensor data and sends torque to the rear wheels when a certain amount of slip/speed difference is detected.

In reality the Haldex's operation is tied into many of the car's primary systems just like you mentioned, including the ABS and ESP systems on your later-year car. Throttle position and status of the e-brake sensor is also tied in. The controller makes decisions based off of data it receives from the CANBUS but take away that system and it doesn't really have anything to operate from.

There have been several solutions created over the years to modify or improve the controller functionality but all of them piggyback off the original hardware or software and are not capable of operating independently of the car's primary ECU. This includes the UM flash, HPA TouchMotion and the older blue/orange/silver controllers which are impossible to locate and by today's standards are not worth the money people ask for them. 

There are a select few threads floating around on different forums of people who essentially tried to create their own controllers through time-intensive reverse engineering and programming but these endeavors seldom led to any actual product and at the end of the day the ones that did really didn't operate much differently than the stock one and still required certain signals from the ECU.

The only out-of-box solution that would solve your problem would be the SQS Haldex regulator which can be found here:
http://www.sqsracing.com/produkt/314:406:haldex-regulator-controler-valve 

This valve locks the clutches based on the position of a knob, but as you stated the effects of that locking on the clutch pack with such immediate and high torque output would be completely unknown territory and could easily lead to a ruined Haldex coupling in a short amount of time.

I hate to be a debbie downer about it since an EV-converted TT would be awesome, but the time, money and research investment into making the stock system work would be excessive. You would have to design an entire system and program it to receive signals from existing sensors and coordinate them with the existing programming in the controller. Not saying it can't be done by any stretch - it would just be far more trouble than it's worth in the end. 

Regardless of what you end up doing, please keep us in the loop! I'm excited to see where your project goes!

Sent from my Pixel 2 XL using Tapatalk


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## DirefulEvolution (Apr 17, 2019)

Damn! That's precisely the answer I was simultaneously expecting and dreading. The TT would have been such a phenomenal car to do this with.

Idea: what about a direct drive setup? Is it possible to delete the Haldex entirely and connect a motor directly to the differential?

That's how a lot of race EV's work. The motor is connected directly to the diff using custom gear reduction. The Tesla swapped Audi S5 (Google Polykup) uses a custom 9.5:1 gearing. 

Or... what about adapting a mechanical rear diff to fit the TT rear end, if Haldex cannot be unmated from it? I bet an RS(x) or R8 TorSen rear end could handle it. You wouldn't need a custom driveshaft or center diff because you can buy these motors with double-ended output shafts.


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## DirefulEvolution (Apr 17, 2019)

A follow-up thought: you mentioned an A4 for a candidate since it has a mechanical torsen style AWD system, but I want a 2 door dammit!

It got me thinking... what about an Audi A5?

I could put RS5 supporting pieces onto it for easy OEM upgrades, such as brakes and sway bars and limited slip diffs and axles, but with the used A5 price! I wouldn't need the V8 because the motor is coming out anyway. Weight reduction could bring me not quite to TT level weights but closer, and with a stiffened suspension it could definitely be a track monster.

Hell, I bet I could fit a dual motor into it since it's mounted longitudinally. Basically, some folks in the EV racing community use adapter plates to stick 2 motors together, effectively doubling the output at the same amount of work for each motor, stressing one single motor out less. That's how a record-setting 3 series convert was setup!


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## DirefulEvolution (Apr 17, 2019)

WAIT. I MAY HAVE GENIUSED.

The TT shares a common platform with the B5 A/S4, which is a torsen style AWD system.

Theoretically, could one use the front and rear subframe from the torsen car to mount a center and rear diff to a TT? Transmission comparability and longitudinal vs transverse doesn't matter because direct current motors are comparatively tiny to ICE's and would absolutely 100% fit long ways inside the TT engine bay, and you can use the special power glide 2 speed transmission sold by EV West and the appropriate rack and pinion to fit it to the front diff. The rest is mechanical and wouldn't need a controller to work properly.


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## DirefulEvolution (Apr 17, 2019)

...but then there is the problem of fitting the center diff in the car without butchering the **** out of it. Damn!! :headwall:


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## B1-16V (Aug 5, 2002)

I might be over-simplifying this, but to me it sounds very simple.

You mentioned that you would have a system in place that steps down voltage to ~12V to run the existing systems. To me, that's the key.

The systems in the car don't care what is spinning the transmission. Whether it's an electric motor, ICE, or a superhuman dude spinning a crank, the transmission just needs to spin, and all the other existing stuff needs 12V of electricity. 

The point I'm getting at is the electric motor just needs to be a "standalone" system from the rest of the car.
You mentioned that all the electronic stuff would be "binned". I personally think that's the biggest mistake in this project. 
Keep everything. Change ONLY what makes the tranny spin.

You just need to figure out where the Haldex is getting it's throttle position input from, and give it the same signal. Since the car is Drive By Wire already, this should seem easy to someone already going to this type of project.


The other option would be to eliminate the transmission completely, and go RWD only. Tie the Electric Motor to the driveshaft and be done with the sensors of the Haldex. Lock the Haldex Controller in the up position and be done with it.


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## DirefulEvolution (Apr 17, 2019)

B1-16V said:


> I might be over-simplifying this, but to me it sounds very simple.
> 
> You mentioned that you would have a system in place that steps down voltage to ~12V to run the existing systems. To me, that's the key.
> 
> ...


The issue is that the DBW system wouldn't be remotely relevant in this conversion, because EV motors have devices known as "potentiometers" which, if I understand correctly, compare voltages going in and out of the controller to determine for the controller how much energy the motor needs in order to function. It doesn't work at all like an ICE gas pedal, especially if you're using the "Hall Effect" to do this.

Here's a reading on the hall effect: https://en.wikipedia.org/wiki/Hall_effect

Using that SQS device to permanently lock the haldex clutch pack into "on", for a permanent even 50/50 torque split, would bypass the electronic sensor hoopla required to make the haldex controller function properly. This is absolutely a solution!

My only concern, is how much wear those clutch packs can take. I know that they can handle drag racers pushing 800+whp through them for short stints, as evidenced by this video: https://www.youtube.com/watch?v=EpZZWy3dU7c

However, direct current motors are completely different beasts. All of the torque the motor can generate is available instantaneously from a standstill, all the way to about 4000RPM. I'm worried about obliterating the clutch packs, even with my modest goal of a daily-driven 400whp.

A cool thing about these motors is like you said, you can bolt them directly to a differential and be done with it. Theoretically, if they would fit, I could have two motors independently controlling both my front and rear differential, deleting the haldex controller and transmission altogether. Lots of drag racers do this. I'm unsure if it would fit in the driveshaft tunnel though; I would have to jack my car up and take measurements, or find some measurements online. 

The Warp11HV is 11" in diameter, as its name implies, and I want to say a bit over 2' in length. For any Euro folks looking at this, that's 27.94cm diameter, and 60.96cm in length.

Hypothetically, let's say that those clutch packs are way more durable than I'm giving them credit for, and they could take the axle-snapping torque of a high-voltage direct current motor. That's brilliant news! Because then the only thing I would have to figure out would be heat dissipation for the gear oil, because surely the friction of having it locked in permanent 50/50 would cause constant overheating and thermal wear. If wiring a 12v signal to the stepper motor to get the oil pressure flowing in the controller is all that's needed to "arm" the device, and a manual valve mechanism is needed to actuate that pressure into clamping force on the clutch packs... Theoretically I could tap the oil galleries that are used for pressure relief (to prevent too much pressure in the system) and wire another in-line stepper motor oil pump to circulate the oil to an auxiliary oil cooler, and then feed it back into it in a closed loop fashion, thereby retaining the required mechanical pressure needed to actually make it work. 

It would be a lot of complex electronics, but hell, that's the idea behind this whole project, isn't it?

The big question to me, then, is whether or not the clutch packs could survive, assuming that I would devise a system to cool the hydraulics.


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## DirefulEvolution (Apr 17, 2019)

In the meantime, I'm researching used Audi A5's. :laugh: I really want to retain the AWD part of a car, even though a RWD car would be a lot easier to do this with. The mechanical torsen AWD would absolutely be able to handle this kind of power, and with aftermarket limited slip differentials in all 3 spots, putting the power to the ground would be a thing of beauty.

It would just make me sad... I really fell in love with this TT. It handles brilliantly and it's such a pretty car... At least I'm trying to stay in the VW family?!


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## B1-16V (Aug 5, 2002)

Many here can assure you, you will NOT want permanent 50/50 AWD. Fine for a drag car, very hard to live with on a daily driven car.


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## DirefulEvolution (Apr 17, 2019)

B1-16V said:


> Many here can assure you, you will NOT want permanent 50/50 AWD. Fine for a drag car, very hard to live with on a daily driven car.


Fair... I just hearken back to my STi, with its driver controlled center differential. Pretty cool stuff.

But alas, I think, at least for the TT specifically, this is a project that would fundamentally change characteristics of the car that I'm not comfortable changing. I would like to turn this project into a business, so I need a proof of concept that the everyday person could live with- even if my own personal iteration is completely bonkers. :screwy:

Thank you for the help mulling through all these thoughts! I think I'm going to jump into the used market for an A5, and see what I can do with that. Slightly heavier but I think de-ICE-ing the vehicle and replacing heavy stock pieces (like the seats and wheels) with lightweight performance variants will bridge the gap considerably. Apparently, the A5 platform was used in two successful racing campaigns, which gives me a lot of hope.

Stay tuned on the forums, because I'll certainly be posting a build thread up here when I have the funding to get this underway! Thank you again for all your assistance. Sometimes, the best help I can get is just gentle guiding through my own thought processes. :heart::heart::heart::heart:


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## Donal-Ireland (Apr 10, 2021)

DirefulEvolution said:


> ...but then there is the problem of fitting the center diff in the car without butchering the **** out of it. Damn!! :headwall:


Hi DirefulEvolution,

I came across this post while doing some initial research on converting a 2000 Audi TT Quattro to EV. 

Background: I have recently taken possession / ownership of a very clean / original 2000 Audi TT Quattro ( 70k miles / one owner / fully Audi service history with OEM parts ) I did this as favour to a good friend as it was his fathers car and he didn't want to fully 'let it go'. I already have my 2 seater fun car ( a 1978 MGB Roadster V8 ) so don't really have the desire to keep the TT as is. Although the TT is in great condition for its age, If I was going to keep it, I would probably spend a few thousand on bringing it back to 'mint' ... as its 21 years old, it needs some of the usual stuff done ( shocks, breaks, bearings, bodywork etc ) 

I have always wanted to do EV conversion project and would love to use the TT. 

My questions : 

Did you start / finish the TT conversion project ? 

Do you think the a 2000 TT is a suitable car to convert ? 

Any help would be really appreciated. 

Cheers,
Don


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## TT- EV project (Aug 14, 2021)

B1-16V said:


> I might be over-simplifying this, but to me it sounds very simple.
> 
> You mentioned that you would have a system in place that steps down voltage to ~12V to run the existing systems. To me, that's the key.
> 
> ...


AUDI TT -00 Roadster to EV.
I notice its an old line of discussion. 
Today I talked to a person that handles the registration of rebuilt cars in Sweden.

The idea is to do my Audi TT -00 Roadster to EV. His suggestion was to buy the rear axle and drive train from a 4WD Audi Quattro and then connect and mount it in my Audi TT and then mounting a used Tesla rear motor on the differential.
Does anybody have any information of such a suggestion?


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## daczone (May 7, 2015)

Sounds like an interesting project. Only issue I see is the TT is so small and where to put the batteries? I would opt for a dual motor setup like the Model 3. I own both, the acceleration has to be felt to realize how fast it is. I love taking people for a ride. I still like my TT but it's just not fast anymore.


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## TT- EV project (Aug 14, 2021)

daczone said:


> Sounds like an interesting project. Only issue I see is the TT is so small and where to put the batteries? I would opt for a dual motor setup like the Model 3. I own both, the acceleration has to be felt to realize how fast it is. I love taking people for a ride. I still like my TT but it's just not fast anymore.


Hello,
I have actually never driven a Tesla, just heard that the acceleration is impressive. Battery will probably be a challenge. That solution with 3 motors would be something but that is above my knowledge and ambition. I understand that the TT must feel slow, but I like the design and also the Roadster. But you cannot get everything! We will see if some smart idea of solution comes up that could be handled by a non professional.


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