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10/11/2016 1:42 pm  #1

seeking (rear) roll center ideas . . . .

What the title says.  I intend to make it adjustable, but what about a broad range?  

I think I understand roll centers adequately.   The front & rear RC's form a "roll axis" line upon which the body rolls.  The distance from the CG to the RC is the leverage that the body's weight has on the springs/shocks when it leans.  The roll axis line is better off sloping downwards towards the front of the car to some degree, so that it oversteers more in transient moves and less in steady-state cornering.  Solid axles don't have the kind of jacking problem that IRS's do when the RC is high. Jacking gets worse (on IRS's) as the angle gets steeper from the tire contact patch going up to the RC.  

The vehicle - 

It's a 100% street car.  Mid-size old musclecar chassis.  Street radial tires and the chassis isn't very stiff or low in the big picture.  Tires are perhaps 255/60/15.  

Front RC  - about 3" above ground.  
Rearend track width - 59" (center of tread).  
Tires - 27" tall.  
Wheelbase - 117" (kinda long for a sports car.  That would make the overall roll axis flatter for a given difference in F&R roll center heights. )

It was a solid axle & leafs car before the IRS conversion, with the factory rear RC probably 15" off the ground.  Of course that is too high for an IRS but I don't want to go too low with it now.  I seem to prefer it on the high side.  

How high is too high for this?  6"?  8"?  10"?   Any suggestions?   


Last edited by thedude (10/11/2016 1:49 pm)


10/25/2016 9:36 am  #2

Re: seeking (rear) roll center ideas . . . .

thedude -
"...just dropped in to see what condition my condition was in..."
That is a longish wheelbase - but the C4 corvette at 98 inches runs just at 3 inches front and double (+) that on the rear at 6 1/2 inches as I recall. 

Any hints as to the body style?  A Stutz Bearcat (120" was the shorter version)  - or something from the League of Incredible Gentlemen?

Hope you post a pic or two.

Cheers - Jim

UNDERCONSTRUCTION! Highly Modified C3 Corvette
         Dual Wishbone IRS w Subframe + Custom Uprights

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