Too much caster?

00fxd

Well-known member
Joined
Mar 25, 2008
Messages
549
Location
Western Canada
I have made some changes mechanically to the steering/suspension on my car and for the most part been very happy. Adjustable control arms and stuff. I've decided that every Corvette should have the "Bump steer blocks". One change that I'm not so sure about is the castor setting that has been recomended. Everyone has been gushing about cranking tons of castor into it. So I bought into it and I have about 6deg in it now. I now see my mistake. I have lost the "Nimbleness" of 1 1/2-2deg. I can relate to my motorcycle career. The Wideglides and Softails had 31-32deg Rake and it was well known that they were a more hi-way bike. The Superglides and Deckers had 28-29deg and were described as more "Nimble". I'm pretty in tune with this car and something hasn't felt right this season, it kinda "wallows" around corners. I wondered why Guldstrand's specs were so 'conservative'. Am I on the right track here?
 
All I know is there are 2 schools of thought on this, but can't rmember the players....

one school is stiff springs and no roll bars, the other is stiff roll bars and no springs to speak of....and that also plays out with the Caster settings....

I going to listen in for a review myself here....:bonkers::crutches:
 
I'm running 4 degrees caster and I am fairly happy with that setting for HPDE's. It does however make the car seem a little less nimble for autocross courses, but I don't do that but a few times a year.

Caster helps increase camber in a corner, but it does take some of the nibbleness out of the car. I dont believe their is a perfect caster setting, it just depends on how you prefer the car to feel and what type of driving your doing.
 
Caster gives you straight line stability, however it also gives you more steering effort. it does give better on center feel. The problem is, what else do you have? Wide deep dish (pos offset) wheels? A bunch of scrub radius? 6-7 deg. of caster is about max of what you would realistically want and less if you don't like the feel and/or don't need the on center stability.

What kind of adjustable control arms do you have? The pole position/savitske arms?
 
Thanks fella's. I've got 4.5" backspacing and Savitsky's upper adjustables with solid bushings. The better center stability is a nice but I miss the nimbleness a lot. Can someone explain scrub radius to me?
 
SCRUB RADIUS

Definition: The distance between the extended centerline of the steering axis and the centerline of the tire where the tread contacts the road. If the steering centerline is inboard of the tire centerline, the scrub radius is positive. If the steering centerline is outboard of the tire centerline, the scrub radius is negative. Rear-wheel drive cars and trucks generally have a positive scrub radius while FWD cars usually have zero or a negative scrub radius because they have a higher SAI angle. Using wheels with different offset than stock can alter the scrub radius.
 
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