1fastline

I am re-visiting suspension settings with the addition of the new Hoosiers. The car is set to the generally agreed upon R. Kuss. settings which has my rear toe at 34' total, 17' per side. Is this still agreed upon? Can someone explain why so much toe in is needed in the rear?

Thanks.

va122

stability under braking, and to get the damn *** to turn in tight corners.

Leigh2

I always ask for the measurement in millimeters so that I can visualize what the toe in is. I run 3mm total toe in the rear and 1mm total toe out in the front. -2.3 camber rear and -2.8 camber front. Tire wear (Nitto) is nice and even. I had some problems getting an accurate rear toe settings earlier his year and the effect was unstable braking. The toe MUST be even side to side.

AllanJ

Don't know if this is true or not, but I read on RL somewhere about rear toe being so high to help compensate for squishy rubber in the rear suspension. If toe is going to move around then set it pointing in enough so you don't get dangerous toe out.

I'm mostly metal back there now because of this.

Thoughts?

AllanJ

Oh yeah....I'm at 12 mins per side (24 mins total) toe in. Very stable under braking (toe links, locking plates, dog bones, upper shock monoballs).

Cheers,

1fastline

Ok, I think it is clear then that we want to avoid major toe out, tbis causes instability and surprise oversteer. Sounds similar to bump steer? Heavy braking and thusly weight transfer cauese the toe to go out so we compensate by increasing toe in. Suspension compliance also plays a role I understand. Not sure what the conversion of deg./min. to length is, I cannot find it. Still 17'/17' sounds like a lot of tire fighting each other going straight ahead. From Tire Rack: "Consider that if the toe setting is just 1/16-inch off of its appropriate setting, each tire on that axle will scrub almost seven feet sideways every mile!"

va122

not quite bump steer, but similar feeling. the conversion is 360 deg = 60 min. think of a circle. mm to deg is about 1.8x

va122

Allan you have similar suspension as me so you do not experience what he's talking about. yuor dogs give you more toe in under load and keep camber changes to a minimum

Bob Rouleau

Minor correction 1 degree = 60 minutes.

The reason Roland Kussmaul suggested so much rear toe is that the rear suspension is fairly compliant with all the rubber bushings. If you (as some who posted) change to solid (as opposed to rubber) bushings then you can get away with less toe. With a stock 996 GT3 suspension, I tried 10 mins toe in per side and the car did a snake dance under braking. Not good!

AllanJ

Yup, that was the plan.

Thanks for the confirmation about what's going on, Bob. Right now the only time my car does the snake dance is when my rear tires puff up to 42+psi. I do have a bottle of argon here for my welder so maybe I'll see about removing some of that moisture from my tires....

Cheers,

1fastline

Thanks Bob and all for th egreat input. I have the Tarrett toe links and will get more metal soon. Last time out I ran with the 8 deg wing shim and liked the results especially under hard braking from high speed, and thru fast corners. I definately was out driving the tires though so on with the Hoosiers!