Castor Setting

[Guest john]

Me too, Bob.

 

Never had any jumping/skipping with the sierra rear end, but since having the AVO's , ( on position 2 aswell ) its been very noticeable. I started off blaming the wife but go nowhere !

Then I thought it might be more noticeable because previously the front ( SP )used to jump all over place moreso.

 

I've improved things with rear wedges, and tinkering with the ride height a little to get the rear camber to change, but not had 100% success.

 

Please pass on the answer when you find one !

[Guest chris brown]

the back

seems to skip all over the place.

Bob

What tyre pressures have you got Bob? Mine skips all over the place at anything over 22 - 24lb or thereabouts 18 – 20 and its fine

[Guest paul091085]

I am running 20 on rears the same as i was before, so it must be somthing to do with the new setup. Ive got the Gaz shocks now instead of the Zeemerides and mine are 3 clicks off the softest setting. The car is sitting lower at the rear than it was before and there is a larger amount of camber, so perhaps i need to raise it more or add some wedges??

 

As John says, if anyone has the answer please post it on here

[Guest timswait]

What happens if you bounce the rear up an down and then release it? Does it carry on bouncing, or does it slowly return to neutral position without any overshoot? If it keeps bouncing the dampers are too soft for the springs, if it's very sluggish in creeping back to it's neutral position the dampers are too stiff for the springs, it should go back to neutral as quickly as possible but without overshooting.

I too went from Sierra springs and shocks to Gaz coilovers and 300lb springs. It's a bit stiffer than the Sierra set up but overall I find the handling better. On an extremely bumpy road it skips a bit, but then on the Sierra set up it would have been grounding out, on any sensible road I prefer the extra stiffness. I have my dampers set about 6 clicks from fully soft for the road and go right up to 18 clicks for the track. I've also stiffened the subframe mounting points and I think this helps make the back end feel more settled.

[Bob Tucker]

Bouncing at the rear stops almost immediately, definitely no rebound.

Im happy that the springs & dampers are well matched, Mr AVO supplied just the coilovers, & recommended the

300 pound springs anyway.

My thoughts at the moment are that the ride height could be a bit low, giving -ve camber which would cause the twitchiness, same as it does at the front.

 

Ive just measured it in front of the rear wing & its 6 & 1/2 inches, where it was 7 inches with the Sierra springs.

I'll wind it up a bit tomorrow & see what happens.

I'll also tweak up the rear subframe mounting bolts....I havent checked them in 5 years!!

 

Bob

Edited March 5, 2008 by Bob Tucker

[Guest SEgan]

My thoughts at the moment are that the ride height could be a bit low, giving -ve camber which would cause the twitchiness, same as it does at the front.

 

Bob

 

Just as a matter of interest what is your rear toe?

The sierra trailing arms toe-in as the ride height drops (as well as giving negative camber) I have found the rear 'twitchiness' is due to the excessive rear toe, mine was 1.1 degrees, I fitted wedges that reduce the toe to -0.1 degrees. It is the best modification I have ever made it totally transformed the way the rear rides over bumps.

 

Sean

 

RELATED DISCUSSION

[Bob Tucker]

I dont have a rear toe....they all point forwards

 

Seriously, NFI....its a standard unbent Sierra subframe.

 

Im guessing that if its riding lower than befor I have additional -ve camber & extra toe-in?

 

If thats so, I may well fix it when I raise the ride height back to what it was with the Sierra springs.

 

Just got a call that my lesson this afternoon is cancelled so guess where I'll be instead....

I'll post the result later

Bob

[Grim]

I still think I'm the weak link

 

Very much so for me too!