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MG MGB Technical - New rear suspension problem

I put new rear shocks and springs from Moss in my 73B roadster yesterday. As soon as I was done I road tested the car and found that the rear end is swaying back and forth when I step and and release the gas pedal. Stepping up acceleration makes it surge to the right, while releasing the pedal causes it to drop back to the left.

After reading the instructions in the factory service manual again I realized I had not had any weight on the rear axle when I tightened up all the spring bolts. I had just tightened up everything as I went along on each side.

So I loosened up everything and retightened. This made it a little better, but it still isn't right. When I did this I also loosened the U-bolt (axle to spring) nuts....which I now realize was probably the wrong thing to do.

I'm thinking the primary factor is this whole equation is the position of the U-bolts holding the spring to the axle. If the U-bolt is leaning too much in one direction or the other then the axle will be out of position either too far forward or too far backward on that side of the car. Is that correct?

So, assuming I do not have the U-bolts positioned properly here is what I'm going to do:

1. Put the car up on jack stands front and rear so it will be level. It will be supported from the undercarriage with the rear axle left to hang. Leave the rear wheels in place so they can give extra weight to the axle to help it "self center".

2. Loosen all bolts once again.....spring front eye bolts, rear shackle bolt nuts, shock link arm lower connecting nut and 4 U-bolt nuts on both sides. Also remove the rebound strap.

3. With the wheels still on for extra weight, retighten the 4 U-bolt nuts on both sides. The front and rear spring mounting nuts/bolts will still be loose.

4. Replace the rear jack stands with ramps so the car weight will be on the springs.

5. Now retighten the spring front eye bolt, the rear shackle nuts and the shock link arm lower nut. Reconnect the rebound strap.


I'm thinking that by first letting the axle hang down under it's own weight with the wheels, the U-bolts should self center. Is this correct?

If this doesn't do it I'll have to find someone close to eastern CT who can straighten this out for me.


Thanks,
BH
BH Davis

Problem solved. Someone pointed me to a discussion on how much torque for the axle/spring U-bolts. I didn't have them tight enough.

I was getting what I think is referred to as "torque steering".

Thanks,
BH
BH Davis

Along time ago I replaced the rear springs and U bolts on my 74B. I cannot remember how difficult it was to do but not real easy. When I tightend the U bolts it was not enough on the right side. The axel moved abit back and forth during acceleration or slowing. After tightening the right side down again everything stayed put and the car has driven well ever since. Bob
Bob Ekstrand

BH

Down here we use eight nuts under each side U-bolt. Two on each thread, the second to provide a locking system.

Of course, everything hangs upside down here, but it still seems a good prectice given the forces operating on that rear suspension system. Think about it.

Regards
Roger
Roger T

Roger,
Hanging upside down helps ensure that the nuts won't fall off, even if they come loose? But what I wonder is when you check the oil in your engine, doesn't it try to run out the dipstick hole? :>)

Ralph
from "Right side up Canada"
Ralph

It does Ralph, unless we seal against the drawn dipstick with a rag. Bu**ers an oil level reading but we make up for that by changing oil more frequently. Inverted filter changes are a breeze, so its an easy job!

We don't have to reset our tappets either, as they never wear running in the sump.

Mind you, soft tops don't last long.

Regards
Roger
Roger T

This thread was discussed between 26/07/2009 and 28/07/2009

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