B4turbo

at what point does a sway bar get to be too thick?

I'm thinking of getting a custom front sway bar made. Maybe rear too but I can always use off the shelf A4 stuff for the back.

Should I get it made at 29 mm or go for it with 1.25"(31.75 mm)

I know the need to strengthen mounting points the thicker you go. Given that the mounting points are reinforced what thickness would some of you experts use front and rear.

cuatrokoop

It really just depends on the car and the suspension geometry. I doubt any of us here have enough time to get all the measurements needed to run it through ADAMS (I have access to a '95 90q & ADAMS, but have never used ADAMS, nor do I have time to pull measurements).

Also, sway bars should really just be used to fine tune the suspension. The vast majority of your suspension tuning should come from the geometry and spring/damper rates. Run a thinner hollow sway bar with adjustable link points at the bar end. You won't nearly f. the independance of the suspension (side-side), and can really get the car setup how you want it. With the car you are building, you should run an adjustable coilover setup, and pick some decently heavy spring rates. What rear bar are you going to go with? One of the bigger factory bars, or what? I'd probably start with 300lb/in springs front and rear since you have F&R bars from the factory (since I don't, just have a front, I went with heavier rear springs to get more neutrality in the chassis).

B4turbo

I'm just going with H&R springs & Bilsteins. I really hate body roll and want to get rid of as much as possible without actually hurting the handling.

I was thinking an adjustable 22 mm bar at the rear but I thought I saw a 25 mm rear available. Although I'm unsure if it was adjustable.

cuatrokoop

Go with the adjustable rear, and get the RS2 front bar if you can't get an adjustable front.

kung_fu_4.2

25 in the rear is too much - not safe in the rain but cool for autocross.

B4turbo

I even found sway bars up to 35 mm for the front of the A4.

28 mm for the front RS2 bar just seems kind of wimpy. Only 2 mm over stock. I'm really considering a custom 1.25" front to match an adjustable 22 mm rear on the hard setting.

MasterB

get things tight that way, then see if you still need them.

swaybars = dead weight

the H&Rs are progessive, you sure you want that? sounds like you're leaning towards better handling...

you planning on autocrossing the thing?

cuatrokoop

2mm translates to a rather large increase in roll resistance. Increases with the diameter^4...Just as a data point, the factory 90q20v with a 25mm bar gains 17% roll resistance by going to the 26mm bar from the B4q.

For your suspension, I would not go bigger than the RS2 bar. A bar should compliment the spring/damper combo, not over-power it.

B5 front suspension = apple
B3/4 front suspension = orange

Cannot compare the two, so don't ;-)

B4turbo

I'm gonna look into the cost of having 29 mm bars made and then make my decision.