Rear anti-roll/sway bar size?

[NickZag]

My A4 is equiped with the Sport Package which comes the 22mm anti-roll bar in the rear. All the aftermarket ones I've seen are 28mm, which I was told is the same as the S4's. Does anyone know if the S4 anti-roll bar is a straight bolt on for the A4? I'm thinking it is as there aren't too many chasis difference between the cars minus larger brakes and slightly stiffer dampening and springs.

[hoppy6698]

My A4 is equiped with the Sport Package which comes the 22mm anti-roll bar in the rear. All the aftermarket ones I've seen are 28mm, which I was told is the same as the S4's. Does anyone know if the S4 anti-roll bar is a straight bolt on for the A4? I'm thinking it is as there aren't too many chasis difference between the cars minus larger brakes and slightly stiffer dampening and springs.

H&R RSB is 24mm, not 28mm. I believe someone put on the S4 version, but complained it made the car really stiff.

[Alkivar]

OEM S4 bar is 21.7mm according to ETKA.

H&R B8 RSB is 24mm... there is no 28mm bar from H&R. The only 28mm bar I know of for B8 cars is the STaSIS A5/S5 rear bar.

H&R's bar is the same whether the car is A4/S4/A5/S5... we all use the same bar.

[johnnythepie]

Correct....S4 rear sway bar is same as sline at 21.7mm.I have eibach front and rears, the rear measuring 23mm and the front 28mm.Makes a real differance, but is massively dependant on the tyres you are riding on.A soft sidewalled tyre defeats the object as I have found to my cost!!!

[NickZag]

My tires are fairly decent (Pzero Nero) but I do tend to get some understeer on the track which I believe would be corrected with a larger rear anti-roll bar. Your call correct, I called my dealership and they said the S4's anti-roll bar is the same size as the one on my Sports Package. Do you guys think the 28mm Stasis is overkill compaired to the H&R?

[hoppy6698]

My tires are fairly decent (Pzero Nero) but I do tend to get some understeer on the track which I believe would be corrected with a larger rear anti-roll bar. Your call correct, I called my dealership and they said the S4's anti-roll bar is the same size as the one on my Sports Package. Do you guys think the 28mm Stasis is overkill compaired to the H&R?

If you are tracking regularly, the RSB will help eliminate the turn-to-turn shift of weight, but does almost nothing for understeer. You need better tires and/or tighter springs to compensate for the heavier bias of the A4 in the front. My stock tires gave up more quickly than true track tires, but with better tires, I know (and instructor noted) that the understeer would be drastically reduced.

Also, if you are tracking on 19s over 18s, you may want to go back down a notch to allow more roll in the tires on corners. Those with less sidewall have almost 0 tolerance before breaking loose from the pavement. I saw it a number of times at our event, including a Porsche GT3RS running on 19s (he is having 18s fabricated for his car for better grip (and they are cheaper)).

[Alkivar]

My tires are fairly decent (Pzero Nero) but I do tend to get some understeer on the track which I believe would be corrected with a larger rear anti-roll bar. Your call correct, I called my dealership and they said the S4's anti-roll bar is the same size as the one on my Sports Package. Do you guys think the 28mm Stasis is overkill compaired to the H&R?

you cant buy the stasis bar by itself anymore... only with a suspension package... so the H&R bars is probably a better option if you already have an upgraded suspension.

[NickZag]

If you are tracking regularly, the RSB will help eliminate the turn-to-turn shift of weight, but does almost nothing for understeer. You need better tires and/or tighter springs to compensate for the heavier bias of the A4 in the front. My stock tires gave up more quickly than true track tires, but with better tires, I know (and instructor noted) that the understeer would be drastically reduced.

Also, if you are tracking on 19s over 18s, you may want to go back down a notch to allow more roll in the tires on corners. Those with less sidewall have almost 0 tolerance before breaking loose from the pavement. I saw it a number of times at our event, including a Porsche GT3RS running on 19s (he is having 18s fabricated for his car for better grip (and they are cheaper)).

I'm working on a set of 18x8.5 and track tires (probably Nitto NT05's) right now. I agree with the sidewall tolerance 100%. People think a lower profile tire means more performance which obviously is not the case. I have 19's on my C63 Mercedes which I switch to 18's on track days. I'm trying to keep the ride comfortable as this is my daily driver so a stiffer set of springs isn't my first choice to tighten up the handling. Maybe later on but for now I'm to keep it comfortable.

Your right about the stasis sway bar. I've found a few smaller shops that still have them on the shelves though.