Whats the best size ant-sway bar i should get for the front and rear for my 01 TT quattro? I don't care about smoothness for my ride I'm all about performance.

 

I put the 25mm front and 21 mm rear in my car. Really like the upgraded handling.

Audi TT MKI Quattro 225HP > Suspension > Sway Bar > ES#5475 Sway Bar Set - 7031271312

 

Adjustable ones are always useful to dial it in. Also may want bars from the same brand so they work the best together

 

Where can i get adjustable one at???

 

The H&R set I linked to above are "adjustable". They have two separate attachment points that adjust the stiffness of the sway bar.

 

Ecstuning usually has them.

 

The best size anti-sway bar is stock or maybe even softer in rate than OEM. Anti-roll bars, to begin with, should be looked at in rate and not size (construction material and design all play a role in the bar's final rate). for example, a hollow 25mm bar from company X is not going to have the same rate as brand Z's conventional 25mm bar.

Now, before anyone jumps on the guy with only 1 post, going against the "bigger swaybar bandwagon", I'll make an attempt to explain why in layman's terms. Swaybars are only a piece of a chain that determines the final wheel rate (total rate in lbs measured at the wheels); the springs+swaybars and taking into account the motion ratios gives the wheel rate. The swaybars works by resisting the twisting forces applied by the suspension's load transfer but it is also linking both sides and removes independance from side to side (removes grip on one side to help the other side but total grip isn't increased).

Audi's infamous early recall can illustrate what I'm saying, in order to tame the car and turn it into a numb pig that is prone to understeer (not desirable in terms of handling), they increased the front swaybar size from 20mm to 21mm. A good performance mod would be to find one of the pre-recalled bars and rock it.

Swaybars do nothing for smoothness, until weight is transfered laterally they're just along for the ride. Smoothness is really a factor of tire pressure/sidewall stiffness/bushing deflection rates/shock valving/spring rates and ultimately the natural fequencies (swaybars don't add or remove smoothness).

In my TT, that I race competitively in SCCA solo and ProSolo, I succesfully modified the front OEM swaybar to reduce its rate. The result is better corner entry (no more entry push) and way better exit traction because the swaybar jacking effect is less. I run a stock rear swaybar, only because going softer in the back would dictate the need for real heavy springs to achieve the desired wheel rate and natural frequency. The TT's rear motion ratio of 0.63 make my 1300lbs rear springs act like they were only 819 lbs (1300X 0.63 = 819) so in order to escape very high spring rates in the back I keep the OEM bar.

How does all that translate into a street only car? The laws physics still applies driving down the road, and having big bars that remove traction in the front and cause rear wheel lift is nothing but a bandaid.
The real problem is the lack of proper spring rates and roll stiffness , I could get into it but that's another topic in itself.

This is what big swaybars do to the TT at the limit


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This is what softer bars and good handling looks like at the limit (my car and all 4 wheels are always planted on the ground)


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Possible to fix the links to the photos?

Also: front softer or rear stiffer? There is a post out there (currently trying to find it again) that describes the additional whole in the rear to increase stock stiffness for less understeer and good match for the stock front sway bar.

If someone has the link, may post up here as well.

 

Rear swaybar modification (stiffer) for understeer reduction:

The Audi TT Forum :: View topic - Adjustable OEM Rear Swaybar