Good method for sanding valve shims?

11 replies to this topic
  • radish150

Posted May 25, 2005 - 11:57 PM


Anyone got a "smarter than your average bear" way to make short work of shim sanding (bonus points for anything involving electricity) ? I wish I had a couple I could ruin, I would experiment with like a sheet of glass, super glue and maybe an orbital sander? Wether I do it by hand or power tool, I'm concerned about keeping them flat and true. (I wonder what dissolves superglue residue?)

TIA for any suggestions,

  • newthumper05

Posted May 26, 2005 - 08:50 AM


fingernail polish will remove super glue

  • newthumper05

Posted May 26, 2005 - 08:51 AM


correction:Fingernail polish remover will remove superglue

  • BIGMatt

Posted May 26, 2005 - 10:04 AM


Id be VERY careful about sanding valve shims and buckets. Don't sand through the hardend case depth into the soft center, or your shims will end up looking like pennies on the train tracks! SQUISHED FLAT!

Use valve lapping compound, or super fine 600+ wet/dry paper with water or isopropal alcohol. I would NOT use anything electric to to the work for you, unless you have a precision grinding machine. Lapp the shims in a figure 8 motion on the sand paper, re check thickness ever 5 strokes or so. You can use a peice of glass as a 'flat' surface, but ideally you should use a granite surface plate, or thick peice of machined steel or aluminum. If you have Corean, marble or granite kitchen counters, you can use that as a flat surface.

Why not just buy a shim kit?

  • tweek

Posted May 26, 2005 - 07:28 PM


No local dealer in Peru? I was able to swap them out free at the local dealer....

  • simon@vic

Posted May 26, 2005 - 09:31 PM


just buy the ones you need!!!!!!!!!!!!!!!!!!!
order them online if you must.

never sand any shims EVER!!

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  • Scuba_Steve

Posted May 27, 2005 - 08:31 AM


I agree with not sanding the shims. My local dealer was willing to swap shims with me without a charge. I also bought a few new ones and they weren't very expensive. You also need to know the height of the shim.

  • tweek

Posted May 27, 2005 - 09:03 AM


I agree with not sanding the shims. My local dealer was willing to swap shims with me without a charge. I also bought a few new ones and they weren't very expensive. You also need to know the height of the shim.

Good point Steve! If you sand the shim you don't know the true thickness anymore :) , so when you decide to replace the shim, what size do you need :D ? Better have a micrometer and a feel her gage!

  • jha07

Posted May 27, 2005 - 09:33 AM


I thought about sanding my shims too when I had to re-shim. But decided against it. It seems like a lot of work and you'll never be able to sand it down perfectly.
A lot of dealers will just swap shims. Just ask the service department.

  • simon@vic

Posted May 27, 2005 - 04:49 PM


shims are cheap!!!!
mushing important valve-train parts on a high performance bike is not cheap!!!!!!

do it right the first time. or just sell it ad by a 1982 xr200 hehehe.

  • farkawi

Posted May 27, 2005 - 07:19 PM


I must've missed something here. Why do you have superglue on your shims in the first place? If you're gluing something on them to get them popped out of their indents; there is a better way. Hit the shim with a stream of aerosol brake cleaner. This dissolves the oil bonding the shim to its cup and you can then easily remove the shim with a magnet. Hotcams sells an entire shim kit and I think K&L supply does or will in the near future. Sanding, grinding, filing or any other abrasive treatment of existing shims should be avoided at all costs!

  • radish150

Posted May 28, 2005 - 02:44 AM


Well, the "don't side" is certainly in the majority here on the sanding issue. Thanks BigMatt for some very usefull specific details on the options, pro and con. So, bottom line is, if they are available in a size that puts me in a good place in my range, then I will buy new. But, acording to my measurements I only need to take nearly exactly .001 in off of each shim to make these work and put me right in the middle. It's pretty obvious that people dont do this often, but it is done occasionaly and I have not seen a post about a failure. So, thanks all for the surely sound advice to get new ones, barring unlikely circumstances I will do just that. But honestly, I feel pretty confident that in a pinch, I could follow BigMatt's tips and sand off a mere 1 thousandth off of these things and be as flat as I need to be. Maybe I could just file a bit off my cam lobes. :)

Thanks guy's,
Mark Sheldon


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