Uprdated ARBs

[xxx_mojo_xxx]

Can anyone tell me what the radius/thickness of the standard anti-roll bars (ARBs) are for the front and back please? Also, are they solid or hollow?

Looking to hear from people who have after-market ones installed and general recommendations.

Thanks

[999pooch]

Strangely I have been thinking of this mod over the last 2 days. I have done a few google searches, but came here to see if I could see any further info

Can't help you much as I too will be watching this thread.

What I have learnt is that cars with full ADS have smaller RARBs. So need to be sure you compare the right one

[xxx_mojo_xxx]

What I have learnt is that cars with full ADS have smaller RARBs. So need to be sure you compare the right one

Why on earth is that?

[xxx_mojo_xxx]

My googling has found the following potential options:

Front: 35mm, Rear: 22mm
http://www.hotchkis.net/0911_audi_a4_sp ... black.html

Front: 30mm, Rear: 24mm
http://www.hrsprings.com/application/se ... 1225/2009/

I'm pretty sure eibach will do a set just cant find the link on the web.

From surfing the net it appears that there is potentially limited value upgrading ARBs if you have the sports differential as this counters any need. The standard ARBs are 24mm.

[999pooch]

What I have learnt is that cars with full ADS have smaller RARBs. So need to be sure you compare the right one

Why on earth is that?

Its buried in this thread -

http://www.audizine.com/forum/showthrea ... -Sway-Bars

Basically the ADS cars use the struts to prevent body roll.

However I am just requoting info so can't be 100% on this info.

[xxx_mojo_xxx]

A little summary (copied from Audizine http://www.audizine.com/forum/showthrea ... ble-for-S4)-

OEM/Stock Without ADS:
Non-adjustable Front (25.9mm) and non-adjustable Rear (22.0mm)

OEM/Stock With ADS:
Non-adjustable Front (25.9mm) and non-adjustable Rear (16.0mm)

Hotchkis :
2-way adjustable (45%, 75% stiffer than stock) Front (32.0mm) and non-adjustable Rear (25.5mm) - $510.95

H&R:
Adjustable Front (30.0mm) and non-adjustable Rear (24.0mm) - $524.90

GMG:
2-way adjustable (35%, 85% stiffer than stock) Front (28.6mm) and 2-way adjustable (83%, 120% stiffer than stock) Rear (25.5mm) - $595.00

No real info available for the Stasis.

*Sway bar FAQ: Sway bar rigidity or stiffness is not determined by sway bar thickness alone. Grade of material (tensile strength of steel) and design of sway bar are more important then the overall diameter.

[xxx_mojo_xxx]

Looks like its not so straight-forward if you have sports diff and ADS

I'm not sure if its a good idea to upgrade the ARBs now. I need to understand why Audi reduced the size of the rears...there must be a reason...how do I go about finding out?

[Doug_S2]

H&R are stiffer and good in the dry - but with sports diff in the wet you could do with softer as it is so tail happy. To compensate for lack of feel from the steering we set the front to stiff on H&R and that makes it more precise/sharp in turn in. The roll bars are good in the dry but make its more skittish in the wet.

[adsgreen]

Looks like its not so straight-forward if you have sports diff and ADS

I'm not sure if its a good idea to upgrade the ARBs now. I need to understand why Audi reduced the size of the rears...there must be a reason...how do I go about finding out?

I would imagine that it is down one or more of:
- ADS may be able to individually increase damping on a per wheel basis to counter roll. As such a mechanical ARB would not be as important.
- With non ADS the suspension has to cover a set of wide operating conditions with fixed settings. In this cases the damping would be on average softer than what ADS could provide so need to setup with the harder ARB to compensate.
- Does ADS come with the sport diff as standard?

Whatever the reason it's an interesting choice - assuming the same material etc then the small rear ARB will increase understeer and make the rear less tail happy.
My gut feel is that this has been done for balance in the the scope of adjustability from the ADS is such that it can adapt to more scanarios so having a weaker rear ARB allows more controllability in this. If ADS cars don't appear to undesteer then this means the ADS is coping with the tweak.

[xxx_mojo_xxx]

ADS does not come with sports diff as standard. I had to select the two options separately.

[StandFreeRS4]

I've got myself confused with the whole ARB thing. I'm looking to get the H&R ones for my B8 S4 and I have ADS but not sports diff.

H&R only seem to stock a front 30mm adjustable and rear 24mm non-adjustable set.

http://www.hrsprings.com/application/se ... /1225/2012

Will this work with my current setup?

Can anyone comment on the improvement this will make i.e. near to a sports diff car or even better? So annoyed I didn't spec that up with the car.

Cheers

[StandFreeRS4]

Forgot about this so bumping it!

If the OEM bars on an ADS fitted car are Front 25.9 and Rear 16; I can understand the H&R front fitting as it's adjustable but the rear is not adjustable and is 24.

Any help much appreciated!

[adsgreen]

As above - need to test the material. Quick n dirty (although tricky to achieve) would be to weigh them. Not totally accurate but a good start.

What problem are you trying to fix?