front to back ride height (rake)

dougn1 · 03-06-2007, 04:36 PM

whats the desireable rake for a 964? and where the measurement point?

Lukesportsman · 03-06-2007, 05:57 PM

Do you want to do it the driveway special (using wheel well openings) or the factory route using frame points and centerline of the spindle? The reason the factory route is best is that it removes the wheel diameter from the equation and is only relevant to the suspension. The reason the "driveway special" is often used is that it is relative to looks and fender clearance. Becareful, though, if the chassis is twinked the fender method may severely throw corner balancing far off. And though CG may have been lowered, your handling may not improve.

Saying all that, most agree that a 911 looks best with about a 1/2 negative rake in regards to wheel well.

Did you want Euro, USA, or our opinion?

Cheers!

dougn1 · 03-09-2007, 03:43 PM

i have been fooling around with my alignment for some time.....changing things, driving for a while and noting obsevations.

one thing that puzzled me lately was:

after i aligned my rear end which involved reducing the camber from about -2.5 degrees to about -1 degree my car steered quite a bit differently. i also noticed that the rear ride height was increased as a result of changing the camber. this is just due to the way the adjustment is implimented. anyway the feel of the steering was different .....really noticeable at low speeds. when you turn the wheels and let go of the steering wheel, the car has less a tendency to straighten up.

so the long and short of this is: i think the steering change is due to the rear ride height increase and the corresponding change on the front caster. it works out to be somewhere around .5 degrees of caster change.

Bill Verburg · Bill Verburg's Garage

dougn1 · 03-09-2007, 07:05 PM

thanks Bill

i have to think the main reason for a rake spec is insure the castor is right. what do you think?

given that it is indeed true that one can tell the difference in stability of .5 degrees caster, it's amazing how sensitive the steering stability is vs. caster

i'm going to lower my rear end about .75 inch to see what happens

Bill Verburg · Bill Verburg's Garage

rake is more an aero thing

caster is obtained from the position of the suspension components

yes, small changes in suspension can have a big impact on handling.