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My car has factory fitted uprated shocks, lower and stiffer than the usual ones, and I find that despite not abusing them I go through the back set every 30-35,000 miles. As new ones are quite expensive, I am interested to know whether there are simple things I can do at home that don't require a hoist.

They aren't adjustable, just the Subaru own 2006 STi shocks.

Any useful ideas gratefully received.

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what is wrong with them when you have to replace them? Do you have noticeable wave motions after a bump (bouncing up and down more than 2 times)? –  Patrick Mar 7 '11 at 22:49
    
@Patrick, the first time I had to replace them it was a strange clunking which was the issue, this time it was a clunk and a feeling that they weren't as stiff laterally - so my basic diagnosis is that something is being worn in the seals/washers that allows more sideways movement of the piston. –  Rory Alsop Mar 8 '11 at 14:28
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It sounds like the shocks are having some lateral pressure applied to them causing the seals to break or warp allow leakage of the fluid in the shocks. I would look at the control arms & linkages on the wheel arm to see if there is any 'give' there which would cause the arm to shift and when you hit a bump that would put pressure on the shock in a non-inline axis –  Patrick Mar 8 '11 at 15:08
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I'm not going to put this as an answer, because it's a vague remembrance and I could be mistaken - but back when I used to spend a lot of time on Subaru forums I could swear I remember this being a quite common issue, for STi shocks around that model year to go bad often.. something to do with being an inverted design iirc. Again, could be mis-remembering, but maybe a place to start research. You may have to go with an aftermarket strut to avoid the frequent replacements. –  qes Aug 15 '11 at 21:13
    
Also, "simple things I can do at home that don't require a hoist" - replacing your struts is one of those. Jack stand and less bolts than fingers on your hands. –  qes Aug 15 '11 at 21:14

2 Answers 2

up vote 3 down vote accepted

Realistically, there's not a whole lot you can do. What will help though is to clean them periodically, especially where the parts slide in and out of each other. The objective being to keep foreign matter away from the seals. Depending on shocker design a high pressure cleaner can be quite useful here.

A common cause of rapid shocker failure is faulty mounting points. This may not be at all obvious visually but if the mounting points cause either end of the shocker to be forced even slightly to one side it will cause all the wear in the shocker to take place in a concentrated area, rather than being spread over the diameter of the affected part. This most commonly results in rapid seal wear.

The same effect can be cause by over tightening the nut on the pin end of the shocker. It really doesn't need to be as tight as most people seem to think. Check your manual for the specifics.

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If properly installed, there's really nothing to be done. As mentioned above, you can clean them to prevent the seals from being damaged by grit. Most setups have covers over them anyways that keeps most of the dirt out. Those covers tend to fall apart after a few years though. Either way, I don't think I've ever seen a failure due to seal damage.

Have you considered going with a different brand? What are other people's results with that particular setup?

The clunk/lateral motion was most likely the top plate. Those, generally speaking, seem to be a weak point. I've had to replace the top plates on the struts on my MR2 multiple times (damper unit itself is still functioning perfectly).

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This service I got the garage to replace the top plate, so I'll see if that helps. It does feel much tighter round corners now, but not sure if that is the usual post-service feeling (new tyres, brakes, oils etc) –  Rory Alsop May 30 '13 at 14:12

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