I collected the most interesting sway bar specs that can be used on both
Mk.V and Mk.VI GTI (FWD) and R32/R (4-motion):
car model/manufacturer, front bar dia x wall thickness, rear bar x wall thickness
stock (most are hollow, see wall thickness):
standard Golf/TDI/A3: 21.7x3.0 or 22.5x.3.5 / 18.5x2.5 or 19.6x2.6 or 20.7x2.8
Scirocco: 21.7x3.0 or 22.5x.3.5 / 20.7x2.8 or 21.7x3.0
TT-RS quattro: 22 mm solid / 18.5 x 2.5 mm
A3 Ambition/S-Line: 22,5 x 3,5 / 20,7 x 2,8 (FWD)
Golf V GTI: 23,6 x 3,5 / 21,7 x 3,0
Golf V R32: 22,0 solid / 21,7 x 3,0 (4-motion)
Golf VI GTI: 23,6 x 3,5 / 21,7 x 3,0 PR-0BF or 21,7 x 3,6 PR-0BM (DCC?)
Golf VI R: 22,0 solid / 21,7 x 3,6 (4-motion)
Scirocco R: 23,6 x 3,5 / 21,7 x 3,6
Touran 170 PS: 23,0 solid / 21,7 x 3,0
Passat R36: 23,6 solid / 21,7 x 3,6 (4-motion)
Sharan 2011 on: 24.0 mm solid / 20.0 mm solid
after market (almost all are solid):
H&R TT Quattro: 24 / 22 mm incl. TT-RS
H&R 'small': 26 / 22 mm
Eibach AntiRoll: 26 / 23 mm
KW clubsport: 26 / 23 mm (made by Eibach)
VW Racing: 26 / 23 mm (made by Eibach, discontinued)
ECS: 26 / 23 mm
H&R 'big': 28 / 24 mm (AWE used to sell also a H&R 28 mm rear bar)
H&R 4-motion/Quattro: 24 / 26 mm
034Motorsport: 25.4 mm rear only
Autotech: 25 / 25 mm (tube/hollow; reliability issues)
Whiteline: 24 / 24 mm (3-way adjustable)
Neuspeed: 25 / 25 mm (tube/hollow; also 28 mm rear avail.; reliability issues)
BFI/Stabila: -- / 25 mm rear only (different version for FWD and AWD)
Hotchkis: 27 / 27 mm (tube/hollow)
APR: 27 / 27 mm (tube/hollow; made by Hotchkis)
BSH: -- / 27 mm (3-way) rear only
I don't know if Autotech and Neuspeed do come from the same manufacturer.
Suspiciously both share the same dimensions and similar reliability probs.
I also compared several arm length ratios:
Eibach front 26 mm: 190 and 210 mm
Eibach rear 23 mm: 160 and 175 mm
H&R front 28 mm: 198 and 218 mm
H&R rear 24 mm: 140 and 160 mm
Whiteline front 24 mm: 199, 217 and 235 mm
Whiteline rear 24 mm: 205, 215 and 225 mm
There are some differences, particularly on rear. The H&R are shortest, Whiteline are longest.
Keep in mind H&R kits come with a bigger front bar, so this matches the different arm lengths.
Last not least, an example of sway bar rates:
This is the sway bar stiffness in N/mm.
short arm vs. long arm
- stock front sway bar Mk.V/VI GTI, diameter 23,6 x 3,5 mm - tube:
c = 65,6 N/mm
- H&R front sway bar, diameter 28 mm - solid:
c = 172 N/mm center (~ 156 N/mm long and 188 N/mm short arm)
- stock rear sway bar Mk.V/VI GTI, dia 21,7 x 3 mm - tube:
c = 59,5 N/mm
- H&R rear sway bar, diameter. 24 mm - solid:
c = 122,7 N/mm center (~ 109 N/mm long and 139 N/mm short arm)
Obviously the rear H&R doubles the torsional resistance, the front H&R even is 2.5 to
almost 3 times stiffer.
Used together with common coilovers body roll should be only half as much compared
to stock at the same cornering speed.
Stiffness Specs of 2013 VWR sway bars (but still no proved data on diameter):
1. 56.4N/mm; +32%
2. 69.1N/mm; +44%
3. 86.5N/mm; +55%
1. 50.2N/mm; +9%
2. 66.9N/mm; +31%
3. 93.4N/mm; +51%
1. 88.2N/mm; +46%
2. 116.9N/mm; +59%
3. 161.7N/mm; +70%
The % seem a little bit confusing when proved data states the stock GTI sways
already are 65,6 N/mm front and 59,5 N/mm rear.
Uprated sway bares used together with common coilovers, body roll
should be only half as much compared to stock at the same cornering
Why I don't recommend fitting a bigger rear sway while leaving the front
Bear in mind a GTI's sway bar rates are 65,6 N/mm front and 59,5 N/mm
rear, which equals a 52:48 % ratio, while the weight distribution is 60:40.
In some way we could conclude stock sways already are rear biased !!!
Ok, this is just half the truth. While the GTI's rear sway bar ist still stiffer in
relation to the weight, this isn't necessarily true for roll stiffness, as the roll
center ist also an equally significiant factor. And yes, roll centers aren't same
height front and rear. Unfortunately reliable data is hard to obtain.
However, while a too-stiff rear sway might give you funny turning at lower
speeds and narrow corners, it will also cause dangerous high-speed oversteer.
DO NOT TAKE ANY RISK - THIS IS NO JOKE, DUDES !!!!