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1997 xr4 rear shock shim stack

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I am planning to take my all original xr400 rear shock apart soon to replace the fluid and try adjust the shim stack because it seems too stiff. I've been trying to find info on the shim stack searching around on this forum and found some info saying that the 1996-1997 model years had quite a few more shims in them than the newer versions. I think it would be safe to assume that the reason was because the shock was too stiff.  

When I take my rear shock apart it seems like it might be a good idea to remove some of the shim stack to try and match what the newer ones had. I know that might not be the perfect shock set up but it should be better.

I've never taken a rear shock apart before so I am wondering how I can remove shims and have the shim stack work at all?  I read one guy saying if you remove a compression shim you have to add on on the rebound side.  It looks like I need to remove shims from both compression and rebound.  If I remove shims won't the shim stack be loose and they will just be rattling around in there?  Wouldn't the shock shaft have to be longer on the older shocks to make room for larger stack of shims? Did they shorten the shaft where the shims are on the new shocks or do they just add a small spacer washers?  Can I just add small washers to take up the space of the removed shims?  

Thanks for the help. 

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I would suggest you experiment with spring preload, before you change shims. There is a lot of information on valving shocks, you can read about it. I would not suggest its as simple as removing some shims, to make it softer. Even though what you are saying is probably true. The valving, shim stack, effects the shock speed movement, not the "softness" one feels. But, on the other hand, change it, try it, change it again, see how it works. Problem is, usually after doing all the work to remove the shock, change the shim, and reinstall the shock, this labor intensive process is never repeated. its just a lot of work. buying another shock, having one modified, one stock, to try back to back on a test day, works best. I would strongly suggest using up all the easy to try adjustments, spring preload, first.

 

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I don't think it has much to do with the spring and more to do with the shock. I want to take it apart partially because it's never been apart and had fluid changed and the bottoming bumper at the bottom of the shock is split in half so I want to replace it. It's also 20 years old so I doubt it has much nitrogen pressure in it either but I've obviously never checked it because that let's pressure out. I'm also wanting to make sure all the pivot bearings are in good condition and lubed up. 

I'm just wondering how you can remove shims or is it even possible. Most likely I'll get it apart and see how it is put together and then I'll figure out how to do it. 

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Toad, you have a lot of homework to do before you even remove the shock from your bike. First thing is to get an OEM Honda Service manual. Then start reading every thread you can find regarding shock revalving/maintenance. Lots of homework. And do you even know if you have the right spring currently? What are your sag numbers? Have you inspected, re/greased your linkage and swingarm, that might be more of the issue than the shock?

Edited by YHGEORGE

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No I have not greased the hinges. The spring is stock and I weigh 220 lbs. I would think if anything the spring would be too soft.  I don't know what the exact sag is set at but the bike sags under its own weight so I know it not set way too stiff. 

The bottoming bumper is split in half. I would like to replace it.  Replacing it means a complete tear down of the shock so I figured I'd look into making a small adjustment to the shim stack while I had it apart.  I guess if I can't figure it out I'll just put it back together same as it came apart. I'll be checking the pivot bearings when I have the shock off. Do you think it would have the nitrogren pressure in it after 20 years?  I'd like to get new fluid in it and nitrogen back up to specs. 

Im pretty sure I can get the shock apart without any problems. I've watched several YouTube videos on how to do it and looks pretty easy. Just not sure about adjusting the shim stack. 

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