how many crank shim washers are too many?

Discuss light weight issues concerning road bikes & parts.
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by motorthings

installed an FSA 386 crank with large spacer on each side (required on pf30 frame) 1 wave washer on NDS, and it settled in perfectly without any shim washers.
installed stages powermeter arm on same crank, and need 3 shim washers on NDS to get a reasonable amount of compression on the wave washer

I like it when things just line up without shimming too much, and wonder if 3 washers is too much, or if I should just tell my brain to shut up and ride.

by Weenie

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by bm0p700f

Something's not right there. It may work fine but you only meant to use one washer.

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by motorthings

that's what i thought...i may have complicated things by needing to pull the spindle from the original FSA NDS arm to get the Stages arm on.

I had first installed the FSA crank stock, and it bolted up as expected, with large spacer on each side, and wave washer on NDS (no shim washers) - no side play.

To get the Stages arm on, FSA sent me a new extraction spindle bolt for the NDS arm, so I pulled the stock 1pc bolt on that side, installed the 2pc, and used it to extract the NDS arm from the spindle.
I then installed the Stages NDS arm on the spindle, and found the side play requiring 4 shim washers
I then tried reinstalling the FSA NDS arm and found play again (a bit less than with the Stages, but more than when I first installed the stock crank).
I have now tried installing both NDS arms with the threads of the NDS bolt greased, and more grease on the NDS spindle interface, and have reduced the number of shim washers needed to 3.

My best guess is that neither NDS arm is seated as far down on the spindle as the FSA arm was originally, maybe due to a bit of blue loctite remaining in the spindle?

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by 2lo8

Use whatever number of washers you need, that's what they're designed to do. It is strange that you need a different number of washers, but there's no problem in using 0, 1, 2 or 3 washers depending on actual BB shell width. That's what they're there for. I seriously doubt that using more will be an issue, those cranks are designed to run with big spacers on BB30 frames. I beleive that 3 come stock with FSA cranks that don't come preinstalled, or at least they used to, although obviously you only use enough to get the wave washer to contact and squish a bit.
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by motorthings

that sounds a lot like "just tell your brain to shut up and ride."
thanks, i needed that.

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