antijam
CCCUK Member
I decided it was about time I did something to tighten up my back end. At my age I don't think anything will do much good 
- but at least I should be able to improve things on the 'Vette . For some time I'd been seeing a visible change in rear end camber, suggesting that either the strut rod bushes were knackered or the adjuster was slipping. The cam adjuster on the strut rod bracket is not easy to access and adjustment can only be done with the wheels off the ground; it's also not easy to calibrate camber change against rotation of the adjuster and it's prone to slipping under shock or high loads. I intend to replace the struts with polybushed adjustables - the polyurethane will last longer than rubber but still provide some compliance - and since I've read horror stories about the difficulty of removing the shock absorber mount without damage, I invest in a new pair of these as well.
So, it's up on the Quick-Jack, off with the wheels, undo the spring bolts, disconnect the shock absorbers and dig out the 4 lbf club hammer. Initial thumps on the end of the shock mount produce no discernable movement and I'm fearing that the metal sleeve in the strut bush has possibly rust-welded itself to the mount. If this won't break after flooding with Plus-Gas, the only solution seems to be to slice open the end of the strut, expose the sleeve which is a rolled metal bush, and pry it open to release the mount. In anticipation of this possibility I disconnect the strut at the inner end and swing it down. I'm surprised to note that as the strut rotates about the shock mount it moves freely and with a metal on metal sound rather than a rubbery one, which suggests that the bush is in fact free on the mount and the latter is being held in the spindle bearing support by friction in the splines. I redouble my thumping with the club hammer, still wary that a serious thump could result in a broken lug on the bearing support, and eventually detect movement - a few more clouts and it's free! Identical result on the other side.
With the struts, adjusters and shock mounts off the car inspection reveals that all parts are not in bad condition; the strut rubber bushes still have life and the shock mounts are potentially re-usable. One thing I do note though is that the cam adjuster has been assembled with only one bushing cap per side (arrowed red).....
These reduce the bore in the bush to match the cam adjuster bolt which is smaller than the bush diameter; the missing one can't have helped adjustment stability.
The new struts are set to the same length as the originals as a starting point and the position of the lock nuts noted.....
I find fitting the new struts will be easier with one rod end mounted to the strut rod bracket before screwing on the strut itself.....
The square plates (arrowed yellow) .......
........need a little fettling with a file to achieve a snug fit with the bracket and excess material needs to be shaved off the polybush to fit the rod end with the reducing caps. The struts are obviously threaded right and left hand at opposite ends and to ensure that strut adjustment is made in the same direction each side I mount a left hand threaded rod end to the strut rod bracket on the left of the car and a right handed one to the bracket on the right of the car. With the struts now screwed onto the inner rod ends to the preset locknut positions, the trailing arms are jacked up to align the outer rod ends with lugs on the bearing support and since I have them, the new shock mounts inserted. I need my impact wrench on the castellated nut to pull the shock mount splines into the bearing mount, but with this tightened and the split pin fitted the only thing left to do is refit the shock absorbers and the spring bolts.
With the car back on the ground I check the camber - there's quite a lot of negative on both sides and I adjust the struts to achieve zero; one full turn of the strut produces approximately 1° change in camber. I'll recheck this after a few miles when it will probably have settled to a small negative camber. Rear camber is specced at -1.375° to -0.375° on my '71 but with my style of driving (old fogey) I can detect no change in handling with small changes in camber and the nearer to zero the longer my tires last. The car drives no differently but hopefully now without random camber changes.
- but at least I should be able to improve things on the 'Vette . For some time I'd been seeing a visible change in rear end camber, suggesting that either the strut rod bushes were knackered or the adjuster was slipping. The cam adjuster on the strut rod bracket is not easy to access and adjustment can only be done with the wheels off the ground; it's also not easy to calibrate camber change against rotation of the adjuster and it's prone to slipping under shock or high loads. I intend to replace the struts with polybushed adjustables - the polyurethane will last longer than rubber but still provide some compliance - and since I've read horror stories about the difficulty of removing the shock absorber mount without damage, I invest in a new pair of these as well.So, it's up on the Quick-Jack, off with the wheels, undo the spring bolts, disconnect the shock absorbers and dig out the 4 lbf club hammer. Initial thumps on the end of the shock mount produce no discernable movement and I'm fearing that the metal sleeve in the strut bush has possibly rust-welded itself to the mount. If this won't break after flooding with Plus-Gas, the only solution seems to be to slice open the end of the strut, expose the sleeve which is a rolled metal bush, and pry it open to release the mount. In anticipation of this possibility I disconnect the strut at the inner end and swing it down. I'm surprised to note that as the strut rotates about the shock mount it moves freely and with a metal on metal sound rather than a rubbery one, which suggests that the bush is in fact free on the mount and the latter is being held in the spindle bearing support by friction in the splines. I redouble my thumping with the club hammer, still wary that a serious thump could result in a broken lug on the bearing support, and eventually detect movement - a few more clouts and it's free! Identical result on the other side.
With the struts, adjusters and shock mounts off the car inspection reveals that all parts are not in bad condition; the strut rubber bushes still have life and the shock mounts are potentially re-usable. One thing I do note though is that the cam adjuster has been assembled with only one bushing cap per side (arrowed red).....
These reduce the bore in the bush to match the cam adjuster bolt which is smaller than the bush diameter; the missing one can't have helped adjustment stability.
The new struts are set to the same length as the originals as a starting point and the position of the lock nuts noted.....
I find fitting the new struts will be easier with one rod end mounted to the strut rod bracket before screwing on the strut itself.....
The square plates (arrowed yellow) .......
........need a little fettling with a file to achieve a snug fit with the bracket and excess material needs to be shaved off the polybush to fit the rod end with the reducing caps. The struts are obviously threaded right and left hand at opposite ends and to ensure that strut adjustment is made in the same direction each side I mount a left hand threaded rod end to the strut rod bracket on the left of the car and a right handed one to the bracket on the right of the car. With the struts now screwed onto the inner rod ends to the preset locknut positions, the trailing arms are jacked up to align the outer rod ends with lugs on the bearing support and since I have them, the new shock mounts inserted. I need my impact wrench on the castellated nut to pull the shock mount splines into the bearing mount, but with this tightened and the split pin fitted the only thing left to do is refit the shock absorbers and the spring bolts.
With the car back on the ground I check the camber - there's quite a lot of negative on both sides and I adjust the struts to achieve zero; one full turn of the strut produces approximately 1° change in camber. I'll recheck this after a few miles when it will probably have settled to a small negative camber. Rear camber is specced at -1.375° to -0.375° on my '71 but with my style of driving (old fogey) I can detect no change in handling with small changes in camber and the nearer to zero the longer my tires last. The car drives no differently but hopefully now without random camber changes.
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