Polybush Change (when the bolts are seized)

Baby Tux

Saturday, 16th February, 2008

This job took 5 hours approx per corner, it could be speeded up by having presses and a gas burner to remove the old bushes.

Firstly jack up the front of the car, remove the wheels, and support with axle stands, make sure that the stands are inboard of the chassis brackets for the lower wishbones.

Spray all the bolts with a generous coating of WD-40, this would probably be a good time to put the kettle on and enjoy a cuppa and biscuit, to let the WD penetrate, if you are lucky then they will move later.

As well as changing the bushes on the top and bottom wishbones, the shock absorber had failed on the offside so a pair of new ones had been purchased. The shock had likely failed as the bump stop/gaiter had split and was letting all the road crud get on the shock shaft.

Turn the steering hard to the side you are working on and clean as best you can with a wire brush the bolts for the roll bar link, the bottom shock bolt and the castillated nuts on the stearing rod, and top and bottom ball joints for the hub, give them another soaking with WD-40. Remove the brake piston and support.

Unless your lucky and the split pins come out, break off the ends then using a six point socket tap the correct size onto the stearing rack, or top or bottom ball joint in turn. Using a breaker bar start working the bolt off using anti-clockwise then clockwise movements (to help clear any remaining crud from the threads). Once the nuts are off, screw them back on four or five turns (this protects the threads from wayward hammer strikes) then using a large hammer hit firmly the side of the ball joint just above the seal/gaitor until it releases. Remove the wheel hub complete with disc and brake carrier.

This is where the fun began; the bottom bolt on the shock is seized inside the bush on the shock, the nut is free to come off and initially we tried to back it off and use some persuasion with a parallel punch (using the nut to locate the punch on the end of the bolt) unfortunately it was not for moving. Out came the hacksaw with new blades, this was used to saw down just outside the bush. On the offside we found it easier to saw horizontally through the bottom of the shock first to give more room (a word of warning the shock normally has compressed gas inside and this could lead to a nasty accident, we sawed the offside shock as it was the one that had failed). The roll bar link bolts did come off and it was removed. The adjuster bolts on the lower wishbone were more willing and came out of the bushes. The wishbone was removed leaving the now sawed bolt and shock.

With 2 of us the job split into; removing the old bushes, removing the upper wishbone.

The upper wishbone is held in by one long (about 300mm) bolt, this one also moved through the bushes and the nut came off okay. Firstly, if you haven't already done so remove the plastic engine guard (10mm bolts) to get better access to the bolt. The bolt slides out towards the front of the car but to remove it, partly remove the bolts of the roll bar bush which is directly in front.

Before removing the shock from the car, slacken but do not remove the central bolt, this makes removing it later much easier. Remove the shock by taking off the 2 bolts either side of the central bolt from within the engine bay.

Using a round file the inner parts of the wishbones were tidied up to remove any corrosion or burrs. As we had no presses, some threaded bar, nuts and various plain washers were bought to persuade the new bushes into the wishbones. Both the bushes and wishbones were greased to help. The washers were bought to space out the bush so the inner metal part of the bush did not have the pulling forced applied to it. The force was directed against the rubber part.

After all 4 bushes were fitted the wishbones were ready to re-fit to the car. Using spring compressors the new shock complete with new bump stop/gaitors were fitted.

On the front offside the lower wishbone bolt at the rear was seized, the nut was removeable.

Using a cutting disc the front of the bolt was cut between the bush and the mounting.

Once the bolt was cut the wishbone can be swivelled out of the position.

Using the threaded bar technique in reverse to remove the old bush if they are not too badly damaged, be careful that the force applied does not warp/bend the wishbones.

Wishbones, shock complete with spring were re-fitted to the car.

As the suspension had been fully removed, once both sides were completed the alignment was adjusted by a professional to return the car to the road holding beast it was before.