Uneven Rear Beam

[j-16 1]

I'm totally confused!

 

I've recently removed, stripped, checked and rebuilt my rear beam. I've now replaced with group A mounts and refitted. Shock centers are 300m (maybe a couple of mm diffence) each side with shocks fitted but with the wheels refitted the car looks lowered two splines on the nearside and one spline on the offside.

 

Has anyone got any idea?

 

Any clues would be greatly appreciated - I'm going nuts!

[pug_ham 244 3 Cars]

A couple of mm each side can make a difference but it shouldn't really be that noticable imo.

 

This distance should be measured with the shocks removed though btw, this could explain why you have such a noticable difference. Is this sat on level ground with the handbrake off etc?

 

Graham.

[j-16 1]

Yeah level ish ground with no rear brakes, antiroll bar unatached.

 

I'll measure again today with the shocks off, I guess they could hold the trailing arms up to an artificial height.

 

Thanks for your help

 

James

Edited May 17, 2006 by j-16

[jonah 1]

Bear in mind that if the back is lower at one side than the other, then so is the front (unless the shell is twisted!)... so could it be that the front wheels are on uneven ground? Or uneven height front springs??

 

You could rule this out by jacking the front of the car off the ground with a trolley jack under the subframe, dead centre. Then only the rear suspension can affect whether the car sits level, although it would still be affected by unequal weight distribution. You haven't left a couple of bags of cement or something in the boot have you?

 

If the rears are still at different heights, then it must be either different initial height settings (bear in mind there's a 3:1 ratio between ride height and damper length so you have to set them quite accurately), or a seized damper, or unmatched torsion bars, or something badly bent...

[Guest puglet]

Bear in mind that if the back is lower at one side than the other, then so is the front (unless the shell is twisted!)... so could it be that the front wheels are on uneven ground? Or uneven height front springs??

 

You could rule this out by jacking the front of the car off the ground with a trolley jack under the subframe, dead centre. Then only the rear suspension can affect whether the car sits level, although it would still be affected by unequal weight distribution. You haven't left a couple of bags of cement or something in the boot have you?

 

If the rears are still at different heights, then it must be either different initial height settings (bear in mind there's a 3:1 ratio between ride height and damper length so you have to set them quite accurately), or a seized damper, or unmatched torsion bars, or something badly bent...

 

as jonah says if theres 2mm differenace on the shok then that translates to 6mm in axle / ride hight, best bet is starting there, if you are out on the shok, then it will be in the wrong splines on one side.

[j-16 1]

Thanks everyone - problem sorted. removed the shocks and I was a spline out as suggested, looks quite equal now.

 

Do other people have to jack their trailing ams sligthly to fit their shocks? I was just thinking, will my suspension work as it should like this or will the dampers be doing all the work rather than the torsion bars?

[pug_ham 244 3 Cars]

Do other people have to jack their trailing ams sligthly to fit their shocks? I was just thinking, will my suspension work as it should like this or will the dampers be doing all the work rather than the torsion bars?

You shouldn't have to, could you not extend the shock enough to get it all in line?

 

When the car has weight on wheels the shocks etc will be compressed so both the torsion bars & shocks work together.

 

Graham.

[j-16 1]

No, they don't quite reach. I have Spax ( I know!) adjustable rears. Maybe I bought shortened ones as I was lowering the front as well. Do you think i should swap back to standard if they are shorter? Anyone know how long a fully extended standard shock is? Thinking about it I'm sure they were the same length as shocks I removed

[Wurzel 16]

I have had a few 'standard' beams that needed slightly compressing to disengage the top shock bolt (beam off the car). Some need compressing more than others. A lot of cars 'bottom out' on the shock when the rear is jacked up hence needing slight jacking up of the wheel to compress the shock slightly.

 

I think it is this characteristic that prompted a few people to think the beams used to be 'pre-tensioned' at the factory and that taking it apart and lowering it buggers this up. There is slightly more to the argument than that but I'll not go into it here.

 

As long as the damper compresses slightly with the weight of the car on it, there should be no problems. Over compress it though (suspension too low) and again you can run into problems.