While replacing the rear diff, I removed the tops of the rear ProComp dampers to fit new rubber boots, with the plan of adding some oil to lubricate the pistons in the top seals to stop them creaking so loudly. Â The left damper was fine and the plan worked perfectly, but when I removed the top of the right damper, I found that it was completely shot – the gas pressure had leaked out and there was no resistance to compression on the piston, though it still had resistance to extension.
I had this afternoon free, so I fitted the 1-Ton original spec replacement dampers I bought yesterday. Â The inside of the steel piston shields were bare, so I sprayed in some waxoil and then sloshed around a generous amount of the used axle oil left from the diff swaps before fitting them. Â I then installed them with their new bushes and finished with a smooth coating of thinned Underbody Seal (Schutz) – it thins very well with a splash of white spirit to make brushing on really easy for a decent finish. Â I made sure to apply plenty of copper grease to all the fixings and bushes, just like the old dampers, to make sure they come out as easily as the last pair when they need replacement in the future. Â The creaking has gone and I should have a better ride once the gearbox is done.
I used original spec 1-Ton dampers because ProComp dampers have, in my experience, a very short service life and better quality gas dampers are awfully expensive. Â These 1-Ton units should be quite capable of dealing with the parabolic springs, given that the car is rarely laden, and being cheap, will be cost effective even if they fail as quickly as ProComps. Â I have yet to test the front dampers, but I am not optimistic about their condition.
I bought my procomps from Rocky Mountain and they are a slightly different design having the full metal shroud rather than rubber boot. However build quality was dreadful, the welds look like they had been done by me (I’m useless at welding) and the paint finish was so bad they would have rusted within days of being fitted.
I sanded mine down and painted them myself and gave them several coats of HD lacquer. I also squeezed a big dollup of grease inside the shroud before fitting. The result is that the ones fitted to Annie are now over three years old and have done 15K miles trouble free and still look like new. However it is difficult to judge if they are actually still providing any damping as she is fitted with 4 leaf HD paras. They seem OK while driving though.
In all honesty the 4 leaf Bearmach paras and procomp shocks have not provided any less jarring driving experience than her previously well used stock leafs and stock dampers so in hindsight I reckon they were a waste of money other than the lovely suspension lift they gave her which allows the 33″ tyres plenty of clearance. A lot to pay for nothing more than aesthetics though!
Don’t forget that parabolics don’t seize up as they rust, so unless you don’t mind regularly oiling or stripping and greasing the standard springs, they will provide a better ride in the long term even if they are comparable to new standard springs.