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Author Topic:   rear roll center
Mark Wakefeld
Dirt Roller

Total posts: 9
posted November 23, 2005 08:38 PM  
Im jigging my rearend its for a full body car. 4 link.

Ive read I want the rear roll center 10-14 inches.

I plan to put the lower trailing arms about 5 inches below the housing but not sure on the tops.

If I put them close to level the rear roll center would be in the ball park.

Is there any advantage to having my uppers angled down towards the front of the car that would offset the higher rear roll center and make it worth while?

Dirt Forum Champ
Total posts: 512
posted November 23, 2005 10:50 PM  
Is this a converging 4-link like a a/g-body or fox mustang?

Mark Wakefeld
Dirt Roller

Total posts: 9
posted November 24, 2005 09:38 AM  
77 olds cuttlas

same uppers as a metric the lowers are 4 inches longer.

Mark Wakefeld
Dirt Roller

Total posts: 9
posted November 24, 2005 09:40 AM  
If I angle the uppers down, that will raise my rear roll center and roll less onto the right rear is my understanding.

Everything I read says as much angle in the lowers as possible so they are pushing up on the car more.

Dirt Freak

Total posts: 404
posted November 24, 2005 04:50 PM  
Keep in mind that alot of angle in the lowers will also cause alot of roll oversteer(the rearend steers to the outside when the chassis rolls). Dependig on the car and track that may not be the best thing. Lowers shoot for about 5 degrees up the to frame. on the uppers mount the bushings as close to the housing as you can. The only way to get them flat is move them out on both sides about 4 inches and mount them like a mustang with the uppers beside the housing instead of on top of it. Or raise the front upper mounts on the frame.

Mark Wakefeld
Dirt Roller

Total posts: 9
posted November 24, 2005 06:23 PM  
I jacked the rearend around with stock mounts and it had zero rear roll oversteer.

the rs moved out to the right but it stayed within 1\8 of an inch for and aft.

I was compressing the rr 5 inches and letting the lr hang as much as 7 inches.. just with jacks but it seemed like it should work maybe it wasnt working??

I can get my uppers close to level pretty easy, they are actually out in front of the 3rd member almost. this car is a longer wheelbase and it was done only by the way they mounted the rear trailing arms.

so your thinking the tops level is good so my rear roll stays low or any other reason??

is 5 degrees the max I should go on the lowers then??

I was thinking ls 2 degrees more than rs on the lowers If I can do it reasonably..

cant I use soft rs bushing to offset the rear steer if I dont like it??

Thanks for the help.

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