# Hi from the UK - First Post on here, Making my TT lighter



## TT_CS (Nov 26, 2013)

*TT_CS - build thread focused on weight saving*

Hi there,

My first post here, I live in the UK, pretty well in the middle (Midlands)

I own a TT - 2003 facelift 225 Quattro Coupe, light metallic silver, totally standard

I have owned it for 2 years and driven 35,000 miles coming to a total now of 75,000 miles.



It's a little rough around the edges bodywork wise and the wheels are an embarrassment as far as peeling paint goes, but relegated to winter use now, but seems OK mechanically

My plans are to reduce the weight as far as possible and still be a daily driver, it is currently at 1360 Kg (3000 lbs ish), unladen without fuel or driver, as far as obvious visual changes it has had the rear seats deleted but other than that the weight loss has been 'under the skin' 

I'd like to get below 1300 Kg / 2867 Lbs and take it from there, that is my plan...

I can update with what I have done so far to get to this weight, but it's all pretty run of the mill

Cheers


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## warranty225cpe (Dec 3, 2008)

Welcome :wave:

When you get a chance, introduce yourself here.

http://forums.vwvortex.com/showthread.php?5896573-quot-The-TT-Roll-call-thread-quot


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## Converted2VW (Apr 8, 2009)

Welcome!

Weight reduction is underrated but one of the main things you can do for performance in a TT.
Please do share what you have done so far.


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## TT_CS (Nov 26, 2013)

*The weight loss begins...*

Thank you for the welcome,

I'll add myself to the 'roll call' thread when I can find a photo suitable for human consumption 

My background is chassis engineering in both the Automotive road car area and Motorsport for the last 3 decades and including the TT I have 3 projects currently active / inactive, a 200 - 275 Hp (Still deciding between NA & Turbo) / 600 Kg Classic Mini and a Chrome bumper MG Midget which also is having an engine swap / chassis 'update'.

My interest is mainly Classic / older cars with a retro race / rally feel, the three projects I have are deliberately FWD, RWD and 4WD.

IMHO the TT is now in a position were it's purchase price has fallen drastically in the last few years (well in the UK anyway) and we are starting to see quite a few cars disappear as relatively minor accident damage exceeds an Insurance companies value. A lot of recent purchasers / owners aren't prepared for the cost to maintain and repair what was a relatively expensive car from new but are now readily available for £3500 - £4500 GBP in good cosmetic condition but can be pretty expensive to fix (if your not willing or able to work on the car yourself), which has also lead to an increasing number of TT's being broken for spares.

So considering the above I thought long and hard about starting these modficiations particularly with a view to what could easily be returned to standard if I didn't like the new compromise, but with the boom in second hand spare parts (especially if your willing to get your hands dirty) and the relatively low residual value of my car I quickly decided that anything goes.

The weight loss story begins;

The rear 'ballast':

I don't like to use the term ballast for the 15 / 16 kg lump attached to the rear body of the TT as this seems to suggest it's there purely for weight distrbution / Yaw inertia reasons - IMO (My opinion - NOT fact) it isn't, it's a dynamic absorber / mass damper which can be rigidly or flexibly mounted, obviously in this instance it is seemingly rigidly mounted - but the bodywork it is attached to still has a 'spring rate'. Of course it has a weight distribution / inertia effect that cannot be denied but I think this is secondary function if at all.

A wikipedia image of what a 'tuned' mass damper / dynamic absorber can do:



This very simple system shows the original blue curve which has a peak amplitude at around 9Hz, the addition of a mass damper adds another 'mode' or curve to the system which is added to the original 'mode' and results in the new bi-modal curve, we now have two frequency peaks but importantly the peak amplitude is reduced and the percieved 'vibration' will be reduced. 

Anyways I removed it, drove it and lived to tell the tale  But seriously though I am in no way either recommending or endorsing doing this to your TT, i'm just reporting what I found with my car / driving style / road conditions, your findings may be entirely different. I didn't notice a ride height change - although my car has had the rear springs replaced with non OEM springs (Probably not facelift ride height) so the rear is too high already which may disguise if there was a subtle change.

Under normal road driving and attempts to push a little harder I didn't notice any ill effects, the rear didn't feel light or 'loose', I also didn't feel any additional resonances (secondary ride) associated with it's removal. So over a period of a few weeks driving like this I decided to leave it off permanently knowing it can be easily reinstated if I find a road or handling condition which is worse than before. I haven't tested at every limit handling condition so cannot pretend it will behave the same for all of these but anyone who changes to aftemarket springs / dampers / aero / ARBs etc... is subject to the same level of uncertainty 

At the same time as removing the 'ballast' I removed the rear towing eye and all associated bolts for both items came to 18.3 Kg, so any comments refer to both items. 

Sorry it ended up a lot more 'wordy' than I intended

Cheers


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## TT_CS (Nov 26, 2013)

*Latest weight saving*

Currently at 1350 kg (2977 lbs) with interior back in (Std heated seats, rep RS4 alloys, stereo with 6 speakers, tool kit and clamp in spare wheel well, AC / PAS / EW / EM all still in place 

Steering wheel is the latest change

It's 335mm CF centre and CF hollow rim, CF but no bling, the carbon is bare finish - no lacquer, Momo collapsible adapter (Modified to suit PCD of bespoke wheel) 





Still need to sort a momentary push button for the horn. The wheel is a bit tatty some of the suede is shiny where it has been used, I will try to renovate it but ultimately I think it will need re-covering




I used 10.9 M6 countersunk bolts with K nuts to prevent anything coming loose, this unmarked M5 bolts that came with the Momo adapter are on the left




The std steering wheel body - 1.376 kg




The air bag - 1.570 kg


The Carbon wheel and adaptor comes in at just over 1.0 kg so roughly 2.0 kg saved over the 3.0 kg std unit.




This was taken before the interior went back in, all sound deadening and sound proofing removed, also all brackets & bosses that are not required have been moved.




J143 Xenon leveling control unit has been relocated to the left rear quarter out of harms way




Interior back in but still haven't decided how to deal with rear seat delete, current plans include just carpeting directly over it.

Next step are the Aliens, although strictly speaking they are required for a UK MOT (As is the steering wheel airbag)

Cheers


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## PLAYED TT (Oct 17, 2010)

Welcome! 
What about replacing the seats with lighter ones? Also lighter wheels? If you can delete the evap and sai pump that saves some as well as adding a lighter battery. Not sure of the laws over there


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## TT_CS (Nov 26, 2013)

Hi Played TT,

Yes I already have a CF FIA race seat (6 kg), sorting mounts out for it but it might be a bit too narrow, in which case it will almost certainly be Recaro PP's

This is the CF seat:







It will be on fixed mounts so should be no more than 8 kg (17.5 lbs) total 

Wheel wise I am still deciding between 

Fat Fives (Competition forged OEM) @ <10kg - So not especially light but 3.5kg lighter than what I currently have so 14 kg (31 lbs) saving, fairly cheap and 'stealth' as OEM

OZ UltraLegerra - 23 kg saving
OZ Alleggeretta - 24 kig saving

Battery is waiting to go in, Odyssey PC950 - 9 kg (3 kg saving) I will fit it to the front initially for ease, but if it copes OK I will transfer to the spare wheel well (heavier due to battery cable run but better for weight distribution)

Here is a mock up with a Varley RT40 that I have from another project (the PC950 is the same dimensions except for its height)





I have been looking into what can be removed from the engine bay - what if any are the downsides of the evap / sai deletes

Cheers


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## Converted2VW (Apr 8, 2009)

Looks like you are making some progress!

TT's are so fat...I'd like to go this route at some point.


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## TT_CS (Nov 26, 2013)

*What's gone / been lightened / replaced so far...*

Thanks converted2vw,

All the stuff which is gone / lightened / replaced:

Rear seats and all associated brackets > Still need to carpet / cover area as light as possible
Rear towing eye
Rear mass damper / ballast
CD Changer
Bose amplifier
All wiring from OEM stereo installation (1.5 kg)
Pioneer mechless head unit replaces OEM (0.8 kg lighter)
Dash centre speaker
All bitumen sound deadening (not any from front bulkhead yet)
Rear parcel shelf
Space saver
Warning triangle
All engine covers that are just for decoration
Oil filler cap extension tube
Ducting for centre dash vents (all air directed to screen demisting)
Footwell mats

Lightened items:

Body control unit mount
All interior trim panels
Glovebox
Carpet
Foot rest frame
Drivers side under dash
brackets for dash mounting
Centre console mtg bracket

Project started at 1467 kg
Currently at 1350 kg

117 kg (258 lbs) saved so far

Pretty sure I can get below 1300 kg (2867 lbs) with AC and interior still intact

Cheers


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## racin2redline (Sep 25, 2008)

Nice build ..or dismantle so far!  curious to see the total without a/c and related components


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## 20v master (May 7, 2009)

What is this car going to be used for?


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## LF_gottron (Jan 24, 2013)

i have a planted passenger seat bracket for sale if interested


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## TT_CS (Nov 26, 2013)

Thanks for the comments,

The plan at the moment is to leave the AC as it will still be used on the road as well as sprints, hillclimbs and trackdays (Not sure if sprints and hillclimbs have the same meaning / event type in the US?) In the UK I tend to use the AC more for demisting than keeping cool 

The car will be run with harnesses as a requirement for the track stuff but will make the road use a little more difficult but I have used them on several road cars before so I am ready for the compromise, as mentioned if my specific bucket seat / shell is too hard core for road use then I am pretty certain the Recaro PP as used in the UK spec Quattro Sport will be a better (and better looking) option, from measurements I have been given it is around 20 - 40mm wider across the hip area than this seat.

Pretty well all of the cars I have owned over the last few decades have either been 'classic' cars or stripped out versions such as the 911 Club Sport etc so I am used to the noise levels & compromises they provide. I use my partners Mini Clubman Cooper D if I really need to be sensible. I do however feel that the Porsche compromise for say the RS's and GT3's is too stiff (The 1987/8 Club Sport was for me the best compromise) - a lot from the low speed damping and the resultant steering feedback can be become tiresome rather than beneficial (just my opinion from having owned or driven a few now) 

The side impact bars / structure is shown removed as they are being used as templates for a bespoke T45 rear roll hoop which may or may not utilise these fixing points, 

I have ordered a 19mm FARB to test versus the 20mm fitted and I plan to have some springs made to try and counter the ever increasing ride height as I lose more weight, the current ride frequencies are around 15% higher at the rear and 5% at the front which reflect where the relative weight loss has been made. I need to test the spring rates of the OEM springs and damper force / velocity first though - does anyone know the OEM spring rates or F/V curves for a 225 Facelift Quattro? 

I don't just want to fit aftermarket springs / dampers as most vendors I have contacted just quote a percentage rate increase over standard (some couldn't even tell me that) also without being able to comment on the available spring travel that aftermarket springs give.

At the moment solely due to the mass reduction (once ride heights are fixed) the roll moment distribution and lateral load transfer distribution will mean there is effectively less understeer due to the rear being proportionally stiffer than the front so I want to see how it behaves in this guise before I delve any deeper into a stiffer RARB and revised coil & damper rates.

Most if not all of the changes have been and will be done incrementally to see how the refinement / weight saving / handling behaviour compromise stacks up and therefore I can either revert back if the impact of any specific change is too far for road use - or I will reconsider the ratio of track use versus road use if it becomes more track focussed. Also most of the modified road car sprint / hillclimb classes require that most if not all of what looks like a standard interior is retained.

One good example so far of assessing each of the 'delete' / changes is the sound deadening / sound insulation in the doors of the Coupe, I have removed both the 'bitumen' deadening material to the inside of the door skin and the foam layer which come to around 400 grams (per door), now I want to save weight wherever possible so every gram counts, but, if you want to retain the reassuring thud that your TT door currently makes then DON'T remove these as it will sound like a Transit van (I guess panel van in the US?) so the bitumen (150 g) will be going back in to see if this alone prevents the hollow 'ringing' sound it currently has  

LF Gottron - Thanks for the offer, I have a few sets of seat brackets I am hoping to use depending on how they workout, although I suspect shipping costs my make it uneconomic for me 

Cheers


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## TT_CS (Nov 26, 2013)

*1326 Kg at the latest weigh in...*

So I needed to get it on the cornerweight scales again just to confirm where I am - 1326 Kg (2925 lbs) as weighed

I keep a spreadsheet of the changes made since the last time it was weighed but dropping it on the scales removes any doubt



As you can see I am spending more time saving weight than cleaning it at the moment

The ride height is off road spec but not quite as bad as shown in the photo, the car has just been lowered onto the cornerweight scales so hasn't settled, the scales aren't properly levelled as I am just interested in the overall weight and not accurate actual corner weights. The scales have just been calibrated. 

So the spec as it stands is:

Heated leather recaro airbag seats
AC still fitted
Replica 18" wheels with winter tyres
All interior still fitted except for rear seats - most of interior has been lightened 
Aliens deleted
Nearly empty of fuel
Washer bottle full
Standard battery
Tool kit in polystyrene tray in spare wheel well
Lightweight mechless HU with OEM 6 speakers system
No parcel shelf
Carbon fibre steering wheel
Space saver removed
Standard exhaust system

I think I am at the point where most of the easy items to delete or lighten are done

Battery is next:



This will save around 4 kg on top of what's been found so far

Sub 1300 kg (2867 lbs) looks easy whilst still retain pretty standard appearance

The next steps are getting a little more expensive:

OZ Alleggretta
Recaro PP
Lightweight exhaust silencer / system
T45 Tubular subframes - bespoke - Need to buy some spare subframes to see what can be done
Adjustable platform springs to compensate for the weight loss effect on ride height
Tempted to remove and weigh the AC components just to see what it comes to

Cheers


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## warranty225cpe (Dec 3, 2008)

Nice progress! BTW, car washes are overrated.


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## taverncustoms (Feb 18, 2011)

I see you got rid of the glove box. the lower dash pad on the drivers side is cast aluminum as well and its only purpose is to hold the light switch. and the carpet pad weighs a ton.


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## carsluTT (Dec 31, 2004)

fun stuff, its nice to see solid data on how much the bits able to be removed actually weigh. keep at it!


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## TT_CS (Nov 26, 2013)

Thanks for the comments,

All comments / weights below relate to a UK spec car (Euro) as there seems to be some trim weight differences between the values I have seen for US spec cars / parts and that I have weighed from my car.

The Glove box is fitted and included in this 1326 kg weight, it was removed in an earlier photo as I was waiting for a new ESP switch and working on a HU area squeak / rattle, as standard the Glovebox is 2.3 kg, current weight is 1.8 kg

The drivers side lower dash panel is just over 1.4 kg as standard (UK car - Euro spec panel - not the cast ally one as in the US) - this has been lightened and is now about 1.1 kg

The standard 'moulded' carpet (I assume you mean this by 'pad'?) is 11 kg - I am at around 4 kg for the carpet which is currently fitted to the car. 

The plan at the moment is to try and keep all 'visible' interior trim panels fitted so that the interior looks standard except where parts have obviously been replaced such as steering wheel and seats when I change them.

If I wanted to completely gut it and removed the interior trim / carpets / Stereo from what I have it would save another 28 kg (Not including headlining, door cards, tailgate trim or AC)

Made up of: (Weights are for current lightened parts not standard)

Carpet 4 kg
Boot area fibreboard liner 4 kg
Rearmost boot trim panel 1.1 kg
Boot area side trim panels x2 1.7 kg
Rear quarter side trim panels x2 2.8 kg
Carpet to sill area trim covers x2 1.0 kg
Glove box 1.8 kg
Drivers side lower dash 1.1 kg 
Footwell side trims x2 0.5 kg
Ally 'triangles' x2 (8N0 857 645) 1.9 kg
Knee pads x2 0.2 kg 
Chrome Cargo eyelets x4 0.5 kg 
Head unit (Mechless) 0.7 kg 
Door speakers x4 1.5 kg
Rear speakers x2 1.6 kg
Tool tray 3.0 kg

So 28 kg ish

Which would exceed my 1300 kg (2867 lbs) target but I want to hit this target with what appears to be a full interior albeit with a rear seat delete.

From the 1467 kg (3235 lbs) weight it left the factory to the 1326 kg (2924 lbs) with interior it is now, it is 141 kg (311 lbs) lighter so far

Cheers


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## Converted2VW (Apr 8, 2009)

Awesome stuff! Keep it up!


Sent from my iPhone using Tapatalk


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## TheDeckMan (Sep 26, 2004)

Love it!

Car weight with the spare out, full tank of gas, a light exhaust system and some weight reduction was 3062 lbs (LF:927 RF:959 LR:547 RR:602). Ballast, stock seats, AC, stereo and pretty much everything still else in the car. 

With me in the car 3197lbs (LF:978 RF:981 LR:617 RR:621)

:thumbup:


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## TT_CS (Nov 26, 2013)

Cheers DeckManDubs,

So yours weighs 3035 lbs (1376 kg) full of fuel, which according to UK specs is 62L capacity....

62L @ 0.73 kg / litre (at room temp 13 deg C) = 45 kg (100 lbs)

Which makes it 2935 lbs - 1331 Kg 'dry' of fuel

You still have the rear ballast which I weigh at 16 kg

So without the 'ballast' you are 1315 kg, 2900 lbs!!

Surely you have done more than a 'bit' of lightening? 

As that's 14 kg lighter than me and other than the things I have mentioned (wheels, seats, exhaust sys, battery)

I am not going to be able to lose any more weight easily and still retain an interior and AC?

Do you still have:

All airbags, air bag steering wheel
Front and rear bumper crash bars
Rear towing eye / bracket
Rear seats
Full interior / carpet / glovebox / boot 'fibreboard' cover etc...
Sound deadening / insulation
Full glass
Engine bay trim covers
Std bodywork not FG / CF panels?
Stock battery

What spec / weight wheels & tyres

Sorry for all the questions just eager to learn from what you've done

If yours is a 'Street' car then I think it's the lightest I've seen figures for I don't think I could get to that weight with the rear ballast still in place

Well done, I still have a good deal more to find then! :screwy:

Any pics of your car, especially interior / engine bay

Cheers


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## PLAYED TT (Oct 17, 2010)

TT_CS said:


> Cheers DeckManDubs,


You and Noah are about to become good friends....he lives for this :laugh:


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## TheDeckMan (Sep 26, 2004)

PLAYED TT said:


> You and Noah are about to become good friends....he lives for this :laugh:







TT_CS said:


> Cheers DeckManDubs,
> 
> So yours weighs 3035 lbs (1376 kg) full of fuel, which according to UK specs is 62L capacity....
> 
> ...



My thread is right here, lots of pictures and info.
http://forums.vwvortex.com/showthread.php?5533521-Aviator-225-Refinement

I am finishing up on upgrading the brakes using Titanium brackets for the Boxster calipers and putting in my UK GT3 seats which should yield around 70-80 lbs in savings. The ballast and rear seats are slated to come out with some other odds and ends. The A/C will most likely be ditched this year as well. I am personally shooting for 2850 wet, to put me @ 3000 lbs with me in the car.

-Noah


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## TT_CS (Nov 26, 2013)

*I still have a long way to go...*

Hi Noah,

Thanks for answering my questions, so, I think I have to do some serious head scratching and look harder as to where I can save more weight

I have a 'Mass and Inertia' spreadsheet for my car which sort of tracks what I have changed and where it should be with the intended future mods, so I took the liberty of trying to put our car specs in a similar place to try and understand the weight differences, so:

My estimate of your car (AG) in various specs to try and compare with where I am at, all changes are cumulative (and use my weights for what has been removed)


AG - As per supplied cornerweight data = 1376 kg (3035 lbs) 62.1% front
AG - No fuel estimate = 1331 kg (2935 lbs) 
AG - Rear ballast removed = 1315 kg (2900 lbs)
AG - Rear seat delete = 1292 kg (2849 lbs)
AG - Sound insulation removed = 1286 kg (2836 lbs)
AG - Rear towing eye removed = 1284 kg (2832 lbs)
AG - Non airbag steering wheel = 1282 kg (2827 lbs)

My car (CS)

CS - Current spec - full fuel = 1372 kg (3026 lbs) 61.7 % front
CS - Current spec - no fuel = 1329 kg (2929 lbs) - My car already has rear seat delete, rear ballast delete, rear towing eye delete, non airbag steering wheel, sound insulation removed, alien delete (1 kg), no rear parcel shelf (1.3 kg) etc....
CS - With 18lb wheels as per AG = 1307 kg (2881 lbs)

So in a comparable spec to mine you are at least 24 kg (54 lbs) lighter with whatever lightweight mods you have made, plus I have lightened pretty well every piece of interior, I haven't put any material back in to tidy up the the rear seat delete so my guess you are more like 30 kg lighter in a comparable spec - so I need to look back a bit closer through your build thread as assuming the build spec for US cars is similar to UK (I always guessed US cars would be heavier with things like the drivers side ally lower dash frame).

Any other areas where you have saved weight but not included in your build thread which you care to share? 

On the first page of your car service book do you have the unladen weight it left the factory at? Its on the sticker that they put on the first page in the bottom LH corner - just interested to see if there is much base vehicle spec difference US <> UK

My engine bay is very similar to yours in terms of the plastic covers being discarded - you even removed the metal piece which the 6 torx screws holding the bumper / grille area to the slam panel as I did, I haven't removed any engine pipework, N249 / Cannister etc and my BAM doesn't have SAI? As far as I know if I did a VVT delete there is no weight saving? 

Seriously though thanks for your info as it has shown I need to dig a little deeper instead of just relying on the weight saving coming from the lighter seats, wheels, battery and exhaust system (Any idea how much weight your exhaust saved?)

I'm going to have to spend less time on my other projects and focus a little more :laugh exhaust

Cheers


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## TheDeckMan (Sep 26, 2004)

All EVAP components are gone, SAI is gone. Between the 3" down pipe and test pipe ~ 15lbs in saving or so. The exhaust is about 15-20 lbs lighter than the stock unit.


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## TT_CS (Nov 26, 2013)

Hi Noah,

So that's 15 > 20 lbs total saved with the exh system and the DP or is it 15 lbs + 15 to 20 lbs so 30 > 35 lbs total saved?

Goes part way to explain the differences I guess, any other tips? 

Cheers


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## Marcus_Aurelius (Mar 1, 2012)

Hi, welcome aboard! I like where you're taking this, I've done quite a bit of weight reduction myself on my tracked roadster. My car was heavier being a convertible, but I got it down to 2790 lbs now at race weight (a bit under 1/2 a tank of gas). Since I've gone farther than you guys with the weight loss, I'll share the weight of some parts you guys haven't done (I'll only list the coupe/roadster interchangeable pieces and things that will keep the car somewhat streetable).

Weight reduction list:


A/C 25 lbs
Bumpers 17 lbs
Glove box 10 lbs
Lower dash panel 6 lbs
Carpet 25 lbs
Sun visors 3 lbs
Trunk spoiler 13 lbs
Evap pump 5 lbs
Sound deadening 7.x lbs (so far, I haven't done all of it)
Under belly panels 6 lbs


Other things that IMO can be done that I didn't list are the plastic panels in the wheel arches. I had them removed a long time ago and didn't care to weigh them at the time. They were quite heavy overall (especially the rear ones) and that's a good way to ditch 10+ lbs.


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## TheDeckMan (Sep 26, 2004)

TT_CS said:


> Hi Noah,
> 
> So that's 15 > 20 lbs total saved with the exh system and the DP or is it 15 lbs + 15 to 20 lbs so 30 > 35 lbs total saved?
> 
> ...


30-35lbs in the whole exhaust using stainless steel. Now if you go with some Inconel 625, the wall thickness can be cut in half ~ save another 10lbs or so.


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## TT_CS (Nov 26, 2013)

Yeah Inconel 625.... 

I am having a Turbo manifold made for my other project for an IHI Twin scroll VF42, I discussed Inconel for about 30 seconds but stuck with good ol' 304 SS, just a bit too rich for wallet at 3 1/2 times normal SS. The guy making the manifold has used Inconel for years on the race manifolds he has made. I have a few Inconel bends I have accumulated but doubt I will ever use them. 

Ok cheers, 30 - 35 lbs saved on the whole exhaust that probably accounts for half the difference, your test pipe (I assume this means no cat?) I will run a sports cat so not able to get quite as light but I'm still looking



Thanks for the information Marcus,

So it's 25 lbs for the AC delete, that's everything - the compressor, hoses, evaporator? If it does eventually go it will probably as a last resort as I find it useful

When you say 17 lbs for bumpers? You have FG / CF replacements or something else?

I have considered the wheel arch liners but was concerned that I would just hear the never ending sound of stones being thrown up at the inner arches, also worried the SMIC would be vulnerable, but like all of the other sound insulation or trim removals I have done I could try them and see how bad it sounds. Back in the day I had a '88 911 Club Sport which had no sound insulation or wheel arch liners and the front fenders had lots of tiny little dents where stones had been thrown against them and just the constant sound of debris against the inner arches.

Wow rear spoiler 15 lbs, how did they manage to make it that heavy? Maybe a mould and FG part is called for? 

I'm really leaning towards getting the DP done as anything up front is at the top of my list and so little can be done in this area (AC aside) 

Marcus, OT, but any idea what the TT standard rear spring rate is? My guess is circa 60 N/mm as this would give a ride frequency of about 1.6 Hz at the lower end of 'sporty' but it feels at this sort of level

Cheers guys


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## Marcus_Aurelius (Mar 1, 2012)

Yes, the weight for the A/C included the compressor, evaporator, lines, etc. The numbers listed under bumpers are for the 5 mph crash bars that some people remove in the front when using a FMIC. 

The rocks and debris noise is not bad in the TT, which has a cabin with very good "outside noise" insulation. I've done the same thing in my Evo before with thin aluminum front fenders and built with a lot less care for cabin comfort, I can tell you it was very pronounced compare to how it is in the TT. 

As far as the spring rates, I believe they are around 250/290 lbs/in (front to back). Times 0.175 to get your Newton/mm conversion, and that leaves us with about 44/50 N/mm. This gave me approximately 1.7 Hz front and 1.5 Hz rear. So, definitely at the lower end of sporty with only 1.5 Hz in the rear. As a reference, my wife daily drove the roadster until she was half way through her first pregnancy with 1300 lbs rear springs (227 N/mm) and rear NF around 3Hz.


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## TT_CS (Nov 26, 2013)

OK Cheers,

With those spring rates I get F 1.6 Hz / R 1.52 Hz, obviously affected by the sprung / unsprung mass and parasitic rates etc we are both using, but close enough for me. I will be measuring the rears soon as I have some Eibach springs with adjustable platforms coming soon

With ride frequencies that low it surprises me how bad (IMO the worst feature of my TT) and how 'fidgety' and disturbed it gets over poor surfaces as though its too stiff, I have plenty of suspension travel as my car is way too high due to the weight reduction - so it's not bottoming out or getting into the bump rubbers earlier than a standard car, I was already planning to get 17" wheels / tyres as part of the track / lightweight set up but this feels like another argument for me to go this way.

Wow 3Hz ! Most of the circuit race cars I have run have been below that.

My suspension plan is:

Rate the Eibach rear springs when they arrive

Fit the rear Eibach springs and hopefully get a little lower than a standard facelift car ride height using the adjustable platforms

Rate the standard OEM rear springs when they are taken off 

Assess the Eibach rear springs > Decide if I need to go stiffer / softer / no change > Get some springs made if nece

Rate the rear dampers (I don't know the rear damper motion ratio though to make real sense of the data yet)

Probably get some Bilsteins valved to suit my spring choice (If any tuners / suppliers had Force / Velocity data for their dampers / coil overs I could chose from what's available aftermarket but no one ever seems to have or want to share the data, and I'm not buying them blind) 

Fit a 19mm OEM FARB and new bushes (I was going to disconnect the FARB a long time ago just to see how much it does but never got around to it) - really interested in how either of these feel, not convinced by the massive ARB's which some supply as a FARB 'upgrade' in a car which already understeers - but obviously needs to be considered as a 'package' really and not one end of the car at a time.

Fit pre recall front wishbone bushes at some point > See what this does to the lateral compliance understeer / steering feel

I didn't want to start the suspension tuning project until most of the weight saving was done as I think I could end up ~ 200 Kg lighter than when I started, especially the rear weight reduction, but I think I am close enough now especially as a large chunk of the remainder I will save is unsprung.

Cheers


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## 20v master (May 7, 2009)

TT_CS said:


> (I don't know the rear damper motion ratio though to make real sense of the data yet)


Before Max replies, rear motion ratio is 0.63. Skip the upgrade FARB or sway bar as we call them here. No need with proper spring rates and matched dampers. Max uses extensions to decrease the spring rate of the front bar. I've ran with no front bar and a big rear bar, on stock suspension and Bilstein PSS's, and it definitely makes the car more twitchy at the limits. I've gone back to stock bars in both spots and the handling is much more predictable and controllable at the limits. 

While removing the deflection of the larger front control arm bushings is good, don't expect much improvement in reducing understeer from them. The improvements are more in terms of steering response and removing slop there, than in overall handling benefits. :beer:


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## TT_CS (Nov 26, 2013)

Thanks 20v Master,

I had done some rough measurements of wheel / spring travel to get a MR just over 0.6, so close to the figure you have quoted of 0.63

But as far as the rear damper motion ratio goes? Are you sure it's the same as the spring MR my initial measurements (which I gave up on and need to repeat the exercise) weren't near the same as the spring MR? I guess I need to repeat but also it looks horribly falling rate as well?

Cheers


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## Marcus_Aurelius (Mar 1, 2012)

TT_CS said:


> OK Cheers,
> 
> With those spring rates I get F 1.6 Hz / R 1.52 Hz, obviously affected by the sprung / unsprung mass and parasitic rates etc we are both using, but close enough for me. I will be measuring the rears soon as I have some Eibach springs with adjustable platforms coming soon
> 
> ...



One thing that caught my attention as well with the stock suspension was how easily unsettled it gets in the back over rough surfaces. Knowing how low the spring rates and resulting Natural Frequencies are, only two possible things are making this happen (maybe it's a combination of both): 

a) The valving on the dampers, specifically what's controlling the high velocity forces (commonly referred to as high speed valving). Whenever I had a damper (although all my experience is in motorsport conditions) that struggled to properly control rough surfaces, it always was a result of overdamping of the high speed valving for the specific Natural Frequency used. Fixing this region of the valving always took care of this problem for me and I'm sure plays a role in what is happening with the TT's odd behavior in stock form. Generally, staying under 0.5 critically damped above 4 in/sec of shock velocity is a good place to start. 



20v master said:


> Before Max replies, rear motion ratio is 0.63. Skip the upgrade FARB or sway bar as we call them here. No need with proper spring rates and matched dampers. Max uses extensions to decrease the spring rate of the front bar. I've ran with no front bar and a big rear bar, on stock suspension and Bilstein PSS's, and it definitely makes the car more twitchy at the limits. I've gone back to stock bars in both spots and the handling is much more predictable and controllable at the limits.
> 
> While removing the deflection of the larger front control arm bushings is good, don't expect much improvement in reducing understeer from them. The improvements are more in terms of steering response and removing slop there, than in overall handling benefits. :beer:


Totally agree here. Sans-swaybar or reducing the rate of the front bar goes a long way in getting rid of the understeer behavior that plagues the car. However, as mentioned by Adam, proper spring rates is needed or poor roll control and operating in the red region of the camber curve will come as a result. If the spring rates are allowed to totally limit the amount chassis lean, the front swaybar is no longer a necessary evil and should be deleted from the equation. 




TT_CS said:


> Thanks 20v Master,
> 
> I had done some rough measurements of wheel / spring travel to get a MR just over 0.6, so close to the figure you have quoted of 0.63
> 
> ...


Damper motion ratio is going to vary depending on the on the one that is used. That's why it is mostly left out in general suspension tuning as it's a constant variable. Imo, there is no need to calculate or even worry about it at this level, just make sure the dampers are critically damped and valved properly for the intended use and chosen spring rates. 

PS: why do I feel that we should be discussing all this in the dedicated TT suspension thread so it could be properly archived and searchable


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## TT_CS (Nov 26, 2013)

So this was my attempt at keeping a stereo but trying to reduce weight, Mechless seemed the obvious way to go...

It's not difficult to see how these mechless head units are so light:



However in the photo the black lead you can see is a USB output to the rear of the head unit that I have added because I can't bear having wires everywhere coming out of the dash area such as when you have a sat nav connected, so...

I have 'belled out' the wiring of the front mounted USB connection of the HU and soldered what is essentially a cut down USB extension lead coming out via the rear, the plan is to feed this under the centre console and will come out near the handbrake SO I can attach an Ipod here.

I have added a grommet to pass through the HU chassis and a few bits of Raychem heat shrink to act as strain relief as the wires are soldered directly to the PCB so need a little protection.

 

Whilst modifying the HU I decided to save a few more grams and added some swaged lightening holes which means I am down to 750 grams total now for the HU and supporting items.



No doubt a little OTT / OCD but it becomes a little obsessive trying to save weight.

And as it finished (well before I covered the swaged holes with ally tape) :



The three swaged holes did make a useful handle like a bowling ball

As a reference the Chorus HU weighed 1.45 Kg
The CD changer removed was - 2.85 kg
The Bose Amp - 1.53 kg
Removed wiring - 1.5
Dash centre speaker - 0.15 kg

So in total with a few other brackets and plastic cable guides a total of 6.8 kg was saved but still retain the other 6 speakers

And this is what your ride height will look like if you save 140 kg and you don't correct the spring lengths...



Cheers


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## TheDeckMan (Sep 26, 2004)

Speed holes FTW!


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## TT_CS (Nov 26, 2013)

Cheers Noah,

I was looking at your build thread again which reminded me of your 'speed holes' in the 'Ally triangles' which support the dash to the centre console... (Still trying to figure out where you stealth-ed your extra weight saving away!)

I must take mine out to show what I did as I had essentially the same idea but a little more stealth (but probably saved a little less weight as a result)

Cheers


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## TT_CS (Nov 26, 2013)

More of my 'speed holes' all very minimal on thier own...

Dash supports:



Regulators:



Body controller mount:


Another dash support:


But it's all adding up (need to get out more)

Cheers


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## TT_CS (Nov 26, 2013)

*Speed Holes are so last year *

So I dug out the photos from when I lightened the dash support triangles, basically I milled pockets in the rear face of the supports so that the 'styling' surface is as standard:



The knee pads fit the same as before



Once fitted to the car with the knee pads attached there is only a very small area visible where the back of the supports have been pocketed out.

When you start to strip out the car and weigh the various bits these supports stood out as subjectively feeling very heavy for the function they provide but I wanted to keep them as part of the interior as they are part of what makes the TT interior IMO

Not getting much else done as the weather is pretty grim with rain most days and having to currently work outside

Cheers


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## carsluTT (Dec 31, 2004)

great work digging into the inner workings of the car to shave weight. i would of done the pocketing on the dash supports on the outer side, it adds a little something to the look of them but not so much it would take away from the look of the interior. i like the pocketing so much ill have to find an extra set of dash supports so i an get that done for my car :laugh:

:beer:


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## TheDeckMan (Sep 26, 2004)

About time you lightened those suckers up!


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## TT_CS (Nov 26, 2013)

Cheers CarsluTT,

I think you might be right there I have been so preoccupied with trying to hide anything that I have lightened, or at least try not to make it obvious that the pockets might have looked OK visible. But I am better an engineering than aesthetics so I should probably stick to what I know 

Noah,

I wish I had just lightened them because that would mean I had reduced the weight further since it was last on the scales but sadly not they were done in early Dec, time and weather currently against me.

I need to dig deeper behind the dash and all the wiring / heater stuff and also look more closely in the engine bay, plus I am going to try removing the wheel arch liners at least 

Because at the moment most of my current options (Wheels / seats / zorst) all involve spending a fair bit of money, pretty well all of my options work out to about £40 GBP / Kg saved, or $30 USD / lbs saved (If I have done the conversion correctly)

Cheers


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## TT_CS (Nov 26, 2013)

So My Eibach rear springs and adjustable platforms are in the UK now so I should get them in the next few days, so I have made a start on some adjustable length rear lateral links to adjust the camber / track width.

They are made from T45 tube and S514 plate (S514 is essentially T45 in sheet / plate form)



The ends of the T45 tubes are 'fish mouthed' and drilled to allow 'rose' welding - both done to increase the effective weld area

I want to keep them as light and as stiff as possible, it's not clear to see yet but the 'outer' end of the lateral link is bolted / ring dowelled to the lateral link meaning that neither the shank of the through bolt nor the root of the thread of the through bolt is the minimum section thickness in the assembled link. 



The through bolt is 12.9 / EN24 Spec



Next to the lateral links you can see the S514 outer end part way through being folded up and fabricated, this will have an EN14 bush welded in to it which is a properly toleranced fit, they will not be on car adjustable, the outer end is removable and the overall length is altered using spacers



This shows the outer removable part of the link before it was folded into its near final shape as shown above

I will hopefully trial fit them this week along with the Eibach springs before I send them off to get Kephos lightweight coated, this is a thin durable coating which has the main benefit of allowing proper crack checking during the service life of the part, powder / epoxy type coatings do not allow this.

Cheers


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## Marcus_Aurelius (Mar 1, 2012)

Looking good! I took some measurements for you yesterday (got a break with the weather) on the rear shock/wheel travel ratio. I'll put everything together and post them in the suspension discussion so I don't litter your build thread. :beer:


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## TT_CS (Nov 26, 2013)

Hi Marcus,

That's great, be really interested to see how it came out falling ratio etc... also interested to see what the percentage critical damping looks like when I have FV for the OEM rear damper using your damper MR

I am getting my rear Eibach springs rate measured (They quote OEM +25%) so I am clear what I have got and once I have fitted them I will get the OEM springs measured

Feels like it's coming together now

Cheers!


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## 180dan (Apr 4, 2011)

I was able to drop 20lbs by switching tires from Bridgestones to Conti Extreme Contact DWS. The Contis are about 4-5lbs lighter per corner than most tires(21lbs). This is weight at the outer edges of the wheel so it has an even greater effect. It seems like most of the weight reduction is coming from the back of the vehicle. The car's front heavy as it is. I'm wondering to what extent this is reducing handling performance. I think a battery relocation to the trunk would especially help cars that have gone on a diet.


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## TT_CS (Nov 26, 2013)

Hi Dan,

Yes I have looked at quite a few tyre types, with the emergence of 'efficient dynamics' (BMW) and various other OEMs making lighter vehicles, quite a few of the tyre OEMs are making genuinely lighter tyres but not sure how well it translates in terms tyre grip / performance for all the tyres available. The tyres I have narrowed my choice down to are also 4 - 5 lbs lighter per tyre than what I currently have

My car is now about 150 kg (330 lbs) lighter than standard and for all the road driving I have done in this configuration it feels more responsive both in terms of steering and acceleration with no noticeable increase in turn in understeer - which is where increased front weight bias usually hurts most. Don't get me wrong if I could reduce the front weight bias further I would, all else being equal I wouldn't set out to increase it, I just think the lighter car will overall be quicker to varying degrees depending on circuit / course type. 

Moving a lighter battery to the rear helps by around 1% in weight distribution (I was suprised by the amount but bear in mind you lose front weight as well as gain rear) but adds about 1.5 kg overall (mainly cable weight and mountings).

The good thing about being lighter weight is that you can test adding ballast to the rear during a test session to see if any handling improvement is offset by the accel / decel / steady state gains the lighter car may have and by adding any ballast as low as possible you lower the CofG compared to the original car. 

So the adjustable rear lateral links are done, there not coated yet but I have a bit more to do first - establish the length required within a likely range of ride heights and add the headlight leveling bracket (if nece)

The outer end (the 'U' section) of the standard OEM link feels especially flimsy but I am not so sure this is a big problem as the main load direction is axial for the link, but the replacements in S514 feel much more rigid.



You can see the 'fish mouthing' and the 'rose' welds more clearly here



As this still has to function as a road car I am still using the OEM metallastic bushes, never had good experience with poly bushes either





This is end fixing, most of the race cars (If not all) have the same method of adjustment in that shims or spacers are used to set lengths and tend not to be on car adjustable, slower to set up but stiff and lighter 

 

I will use 0.6 - 1.2mm shims / washers initially and then depending on the final thickness of the required spacer get a single one turned up.



The Eibach springs are being rate tested today, so I should be able to try these out in the next few weeks





Cheers


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## Marcus_Aurelius (Mar 1, 2012)

The links came out good! 

The only thing that worries me is the pic next to OEM ones. It seems to be of the same length (meaning you can only add shims to extend it and make it longer). This restricts you to using these in the upper position in order to correct excess negative camber from lowering. That normally wouldn't be a big deal (except for maybe complicating install/removal being into the upper position), but adjustable links in the upper position have more bearing on changing toe due to the pick up points position in relation to the center of the hub. Running them longer than stock, and in the upper position, still allows some camber adjustment but with a lot of crosstalk to the toe setting - that's why it's better to run shorter links at the bottom to fix camber (which will be way more neagative than desired with lowering), and longer at the top to dial the toe. 

If you want, PM me and I'll give you the measurements needed to make short ones that can be extended to give acceptable camber throughout the range of possible static height (making over 300 of those gave me a bit of experience ).


PS: also from experience, it's good that you got the yoke end beefier than OEM. Beefier is definitely better there because all the failures (not coming from crashes) I've seen are from the yoke end snapping from lack of articulation on the hub rose-joint or bushing. It is definitely the weakest or most stressed point in our rear links through the range of motion that, besides the axial loads, involves quite a bit of twisting of radial force as well (I went to great lengths to make my U-section/yoke super strong and beefy knowing this). :beer:


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## TT_CS (Nov 26, 2013)

Hi Max,

It's not clear from the photos but I made them 10mm shorter than OEM (bolt centre to bolt centre) and there is more which can be turned off the 'links' if necessary.







I was planning on using them as lower links and had done some rough calcs on how much to take off but I will take you up on your kind offer an PM you on what range of lengths you have used as this will help for a start point

I might measure the bump steer and track width increase before and after to see what effects it has - just a question if I can adapt the bumpsteer measurement kit I have to fit the TT drive flange

Cheers


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## 3.1415 (Jun 15, 2009)

Cool stuff. Nice looking work.


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## TheDeckMan (Sep 26, 2004)

:thumbup::thumbup:


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## Converted2VW (Apr 8, 2009)

Great work!!! I need to start some degree of this as well


Sent from my iPhone using Tapatalk


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## TT_CS (Nov 26, 2013)

*Finally below 1300 Kg....*

Cheers guys,

Been a little busy with my other projects - Turbo install on my little Mini see below  but back on the TT for the time being



So finally I have broken the 1300kg barrier! 1299kg to be precise.

I was at 1380 Kg when I started this thread in Nov 2013

I have been chipping away at a few thing but it is mainly thanks to Mr Alleggerita HLT - OZ



They are individually tagged at 7.255 Kg





They are made using OZ's HLT process "High Light Technology" which seems to be a low pressure casting / flow forming process which allows the stiffness of the wheels made to approach that of a forged wheel but still remain relatively lightweight.



I also did quite a lot of research into tyres and specifically tyres which still perform well but again at a sensible weight which has resulted in a total fitted unit weight of 16.48 Kg



Compared to the units I took of at 23.56 Kg !



Which is a total saving of just over 28 Kg or 63 lbs 

Even just fitting them to the car the weight difference feels ridiculous, the RS4's required the use of both hands and a knee to support them whilst trying to fit the wheel bolts but the new units are easily offered up with one hand to line it up with the hub while the other hand fits the bolts.

Still running them in at the moment but the car does feel more free to accelerate but it could just as easily be wishful thinking.

With the lightweight battery and replacing the seats I should get to about 1250 Kg with a full interior, AC, Stereo with 6 speakers, tool kit etc but then it starts to get a bit tricky to make any significant steps

Cheers


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## Converted2VW (Apr 8, 2009)

Good work!

Would you mind sharing which tires you used?


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## TT_CS (Nov 26, 2013)

Cheers Luis,

I got Dunlop SportMaxx RT

I got the 'AO' (Audi) specific versions as they were available so thought why not

Feel good so far, but the labels are barely off them yet

I am much happier with the ride over uneven surfaces with 17" as it gets much less unsettled, the taller sidewall looks a little more retro 

I'll take some photos when the ride height is sorted out but still waiting on Eibach lower spring platforms which were missing from the rear kit

Cheers


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## TToxic (Nov 15, 2008)

180dan said:


> I was able to drop 20lbs by switching tires from Bridgestones to Conti Extreme Contact DWS. The Contis are about 4-5lbs lighter per corner than most tires(21lbs). This is weight at the outer edges of the wheel so it has an even greater effect. It seems like most of the weight reduction is coming from the back of the vehicle. The car's front heavy as it is. I'm wondering to what extent this is reducing handling performance. I think a battery relocation to the trunk would especially help cars that have gone on a diet.


Moving battery in the back transfers approx. 30 lbs. weight but the cable adds weight, I used 1 gauge. Re-thinking it I ought to have simply purchased a small light weight battery. Unless you need the extra room up front IMO - I no longer think its worth relocating battery.


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