chassis & suspension tweaking - Audi A3 & TT parts using on Mk.VII Golf/GTI/R

the bruce

Go Kart Champion
Golf GTI Mk.V 2008
chassis & suspension tweaking:
Audi A3 (8V) & TT (8S) parts using on Mk.VII Golf/GTI/R

important: I'm not responsible to any damage and consequences you make to your car.
Bear in mind, any changes to your car affect warranty. Even more, suspension is a a
major safety relevant part of the car. Do not do any changes if you're not 100 % sure to
do things right. Mistakes may cause serious accidents !!

Hello all,

Some of you who had a Mk.V or Mk.VI before might remember, I started similar threads on
the M.V and Mk.VI forums some years before.


For a reason. I did find out, that on the former "PQ35" platform (Mk.V/VI Golf/GTI/R/R32,
A3/S3/RS3 8P, TT/TTS/TT-RS 8J, Passat/CC 3C, Leon 1P, Tiguan, Octavia 1Z etc.) the very
most chassis and suspension parts have been interchangeable/compatible.
The point is, for performance reasons, it did make sense to fit front axle componentry like
Audi S3 and Passat or even Audi TT swivels + control arms to a Golf/GTI/R.
Contrary to the Golf variants, these swivels/hubs and control arms are made from forged
aluminium instead of steel, and there are some specific changes to geometry. Even more,
the S3 and TT control arms also came with solid rubber bushings, which are more reliable
and improve steering response.
For example, Audi S3 (= Passat) aluminium swivels, while shving some made compared to
the cast steel Golf ones, gave a slight change in steering ratio, lessening steering (angle)
effort. As mentioned, the stiffer and lighter alu control arms helped steering precision.
And the very biggest effect is gained by the use of Audi TT control arms, as they're slightly
longer and come with adjustable ball joint, giving camber adjustment. Remember, you
cannot adjust front axle camber on a stock Golf, and camber is of huge importance to
cornering performance. Any lack of front camber will cause understeer.

Well, why do I write this on a Mk.VII forum?

All the above similarly applies to the current "MQB" (Mk.VII) platform.

There are differences though. Firstly, most Mk.V/VI part do not fit to the Mk.VII.
I didn't try any yet though. Let's collect some facts (hope to be as correct as I'm able to
- remember, this is pioneer country).
Secondly, all Mk.VII GTI and R already come with aluminium swivels on front. Most likely,
also the GTD does. If in doubt, turn steering and have a look into your wheel well -
aluminium is silver, while the steel parts are painted black with some rust (after one salty
Next, all Golf/GTI/R and Audi A3 8V share the same sheet steel control arms, while both
the new Passat and the Audi TT come with aluminium control arms. The new Audi TT (8S
= 3rd gen) control arms again come with adjustable ball joints (same part numbers as
8J/2nd gen), so they're camber adjustable again.
As on the former PQ35 platform, rear axle parts are the same throughout several models.
No gain here. It's just Audi TT and Passat come with different rear aluminium hubs
for increased track width. Guess most of us don't want to pull rear fenders, so this
is no option.

However, there is one more thing worth looking on the MQB/Mk.VII. ;)

While all the PQ35 Mk.V/VI variants came with a exceptionally solid and corrosion resistant
aluminium subframe, the use of this (expensive to manufacture) cast aluminium part on
the new MQB is limited to Passat, Audi A3/S3 and TT. Unfortunately, the Golf incl. GTI and R
just come with a cheaper sheet steel subframe, similar to the old Mk.IV. Obviously, it will
rust, as it's exposed to gravel, stones and salt, and not covered by plastic trim, as
most of the underbottom:

Fortunately, the Audi A3/S3 (8V) solid aluminium subframe seems to fit the Mk.VII Golf/GTI/R.
All other chassis parts share the same parts numbers. So I'd bet, it'll fit nicely.

This is the subframe's part number: [FONT=&quot]5Q0 199 369 G[/FONT]

In Europe it's about 300 €, while ECS sell it for 393 $:

Just google the partnumber. ;)

And it looks like this:

As I couldn't obtain any good photos of the A3 underbody, this is the way the aluminium
subframe looks on the former PQ35 (Mk.V/VI) platform (seems to be a Mk.V R32) with
heavy cast steel control arms, but neat subframe:

This is the 8V A3 quattro and S3 birdview; see alu subframe and steel control arms on the right:


So, what to do now? When I have my Mk.VII GTI, I will most probably go for the mentioned
A3/S3 (8V) subframe and the Audi TT (8S) front control arms.
Subframe for beauty and reliability, control arms for beauty and camber. If I will be able to
get about -1°30' front camber with them, the increase in cornering performance will
be noticeable.

Needless to say, I'd be happy if someone will try it out as sonn as possible.



Go Kart Champion
Saint Cloud, FL
Bruce, any idea on the weight difference between the cast steel vs. aluminum subframe, and the weight difference between the cast steel vs. aluminum control arms?

I like the idea of changing out the subframe and control arms as the cast steel one will eventually rust.

In regards to your comment about the aluminum rear hubs on the Passat and TT, I assume having wider rear tires will aid in overall track performance, more tire contact on pavement = more grip, yes? How wide of a tire can you get with the aluminum rear hubs? (235,245,etc.)

the bruce

Go Kart Champion
Golf GTI Mk.V 2008
Teck, to be honest, weight saving isn't dramatic, so can't be the main reason to
swap parts.
Both the Mk.VII and A3/S3 come with fairly light pressed sheet steel arms, which
aren't that heavy as the Mk.V GTI & R32's and the Mk.VI R's cast steel arms. The
main point here is, the TT 8S arms are more reliable and offer camber adjustment.
Similar with the subframe - it's way more solid and won't rust. The weight saving
is a bonus, I'd say.

Searching the web is quite irritating, as you'll find different numbers. Somewhere
I've read about the Alu subframe to be 3 kg lighter, while Audi claims -1.5 kg here
(probably Audi claims 1.5 kg less weight compared to the former 3-piece alu frame
of the former A3 8P? - this isn't clear). I think, if someone say "less" he should also
say "compared to what"):

Weight saving of Alu swivel is more, but any Mk.VII GTI and R does already come with
them, which is the good news here. The bad news being the cheap steel subframe.

Anyone, feel free to compare part numbers online. These are all the available A3/S3
part numbers:

You'll notice, all parts being relevant for physical fitment, do come with Mk.VII (5Q0)
part numbers, commonly indicating fitment (on the Golf).

Regarding TT rear hubs and track width: Wider tires on rear wont help on track with
a FWD car. I won't even help on an AWD R, as I can say from experience, you even
want to lessen rear grip (by increasing rear tire pressure). It's the front tires which
lack grip on our cars. Remember Audi offered wider front tires as an option to the
former RS3 8P. I'd alswys put same tires on all four corners, as this is the only way
to swap fronts and rears frequently.
Feel free to compare Golf/S3 and TT track width data. Take wheel offset into concern.

On track you need to adress three points mainly: tires, front camber, brake ventilation.
This is a bit off topic though. If there's interest, we could add a "track day technical"
topic later. Don't get confused - the mentioned Audi A3 and TT parts are intended for
both street driven cars and occasional track use. Bear in mind, any A3 comes with the
alu subframe, and any TT with both aluminium subframe and adjustable camber.


Go Kart Champion
let's talk sway bars! I believe that I've read somewhere that the Mk7 GTI stock sway bars are roughly 24mm front and 21mm rear. Given that VW went with a stronger front this time would only upgrading the rear bar to say 24 or 25mm successfully dial out most understeer? I ran 24mm front/25mm rear solid steel Whiteline sway bars on my mk6 GTI with very good feel and results.

Does anyone really need to replace both stock sway bars on this car given the stronger stock front bar?

the bruce

Go Kart Champion
Golf GTI Mk.V 2008
Not a bad idea at all.
I'll definitely start a dedicated thread on sway bars as soon I've collected some
interesting data. Without this it'll be hard to have a valuable discussion.
I'd do both sways as a matched pair, and prefer to adjust under-/oversteer by
altering camber, toe and tire pressures, as I find a huge rear bar doesn't give
the desired results on a front heavy Golf. I still prefer H&R sway bars, as their
built quality is top notch and unrivalled. However, you could do the rear first,
then the front sway at the same time while you swap the subframe (if you do).

For basics have a read on what I started on the Mk.V and Mk.VI forums a couple
of years ago (perhaps you already know this):


Go Kart Champion
Thanks Bruce, you helped me a ton on my mk6 suspension decisions. My point with the Mk7 is that if stock front is 24mm maybe I can get away with a 24-26mm rear? A 24mm would match.

the bruce

Go Kart Champion
Golf GTI Mk.V 2008
Give it a try and write a review. :D

If it doesn't give the expected results you could always swap the front sway
later. That way you won't loose any money compared to fitting both at the
same time. On the Mk.V I purchased them both at the same time, but fitted
the rear first to have some testing for one week. I found the rear too unstable,
and couldn't drive quick with the ESC on - too many interventions, even with
the sway bar set to soft. While I use to disable ESC on track or AX, it has been
annoying even on street.

Generally: You get issues, when you work against a car's nature. ;)


Go Kart Champion
I'd bet adding a 24mm rear would be great if stock front is already 24mm

the bruce

Go Kart Champion
Golf GTI Mk.V 2008
Bear in mind it isn't a solid bar. Almost all stock sways are hollow for weight saving reasons, thus less stiff.
Even the stock rear sway is stiff enough to lift one rear wheel on hard cornering, at least with proper summers.
A sway bar cannot do anthing more than lifting the inner wheel, it doesn't matter if it lift by one or two inch.

the bruce

Go Kart Champion
Golf GTI Mk.V 2008
Yes, and I already mentioned them on the forum (e.g. Bilstein, H&R and KW Clubsports + VWR
and ST), but I don't want to drive camber plates on a street driven GTI, as it's quite annoying.

Audi TT arms don't increase NVH at all. The only point worth mentioning is increased track width,
which affects lower offset wheel fitment. No issue with either stock wheels or the OZ Allegeritas
(8x17 or 8x18 ET48), I'm looking at, though.



Ready to race!
I just came from a mk1 Quattro TT. The upgraded suspension components made quite a difference compared to my 2003 GTI. It was nice being able to lower it and align it properly.
I've got a TDI now, and it handles better than expected with the solid rear beam. I've seen a mk6 Jetta do a rear beam to independent rear suspension setup and it pretty much bolted right in. I'm hoping once the A3 TDI comes to the us this will becoming a possibility. I think the only issue is the ad blue tank being to large. I've yet to look under the car; wouldn't surprise me it there are no packaging constraints and it fits as is.

the bruce

Go Kart Champion
Golf GTI Mk.V 2008
Quite interesting question. If you ever to this I very much appreciate to see pics of it.
Do you have link to the Jetta guy? The biggest issue I'd see, is to pick up the parts at
an acceptable price. Best to find a (front-) crashed GTI or A3.