Pace RC35s - Reduce Steerer Shim - Lathe???

After a lot of effort getting hold of a replacement crown race for my 1" threaded headset it now appears that it's still the wrong size for my steerer. The steerer is 1" but the shim at the base measures 27mm- all my crown races must be 26.4mm :roll:

I have invested too much effort and cash searching for replacement parts for my old XT headset to now switch and try to get hold of another one, so I'm considering my limited options.

The shim has been designed with a split in so it's not a full circle - I'm thinking this would cause a fair bit of difficulty if I was to find someone with a lathe...

Has anyone else encountered this problem? I welcome any suggestions...

Where did you get the crown shim from? Isn't JIS standard 27.0 and international standard 26.4 when it comes to crown races? Perhaps you have a JIS shim?

ishaw":1umxf472 said:

Where did you get the crown shim from? Isn't JIS standard 27.0 and international standard 26.4 when it comes to crown races? Perhaps you have a JIS shim?

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Forks were built from scratch by Tim Price

Yep you're right with regards the standards and sizes...He seems to think that maybe the steerer was slightly oversize and it's reduced the tolerance fit with the crown race and shim

Might have to send them back to him to replace the steerer if I can't find a cheaper alternative..

Looking at your pic I would say turning that down to 26.4 shouldn't be any problem.

integerspin":1jewsm7s said:

Looking at your pic I would say turning that down to 26.4 shouldn't be any problem.

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It would be easier to make a new shim, and split it afterwards. Or maybe try boring the crown race out, it may be too hard though.

gtRTSdh":3m9kviuk said:

integerspin":3m9kviuk said:

Looking at your pic I would say turning that down to 26.4 shouldn't be any problem.

Click to expand...

It would be easier to make a new shim, and split it afterwards. Or maybe try boring the crown race out, it may be too hard though.

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!!!!
As I said I can't see an difficulty turning it down.
You could send it to me, but two lot's of postage will probably be more than it
will cost in a local engineering place.

integerspin":37rbihd6 said:

gtRTSdh":37rbihd6 said:

integerspin":37rbihd6 said:

Looking at your pic I would say turning that down to 26.4 shouldn't be any problem.

Click to expand...

It would be easier to make a new shim, and split it afterwards. Or maybe try boring the crown race out, it may be too hard though.

Click to expand...

!!!!
As I said I can't see an difficulty turning it down.
You could send it to me, but two lot's of postage will probably be more than it
will cost in a local engineering place.

Click to expand...

Cheers for the offer - but you're right postage both ways is prob a bit unnecessary - I just need to make sure I find someone local who understands fully the application - I imagine that I could skim off the 0.6mm using emery cloth but it's getting a concentric finish I'd be worried about. Thought about removing the steerer and attaching it to my drill somehow (thick dowel and a screw was what I had in mind!!) but I'm sure there are much more conventional approaches available :facepalm:

integerspin":2p6qmtxm said:

Looking at your pic I would say turning that down to 26.4 shouldn't be any problem.

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Ok, how are you actually going to hold it in a perfectly concentric position, not misaligned like a spring washer, that would be easier than starting again?

secondly 0.6mm off a diameter with emery would take longer than starting again. Polishing 0.1mm is a lot of work on a bar, let alone a fiddly piece like that.

gtRTSdh":2nuqciz7 said:

integerspin":2nuqciz7 said:

Looking at your pic I would say turning that down to 26.4 shouldn't be any problem.

Click to expand...

Ok, how are you actually going to hold it in a perfectly concentric position, not misaligned like a spring washer, that would be easier than starting again?

secondly 0.6mm off a diameter with emery would take longer than starting again. Polishing 0.1mm is a lot of work on a bar, let alone a fiddly piece like that.

Click to expand...

Right - correct me if I'm wrong but I'm thinking you're getting confused with posters here. I'm not the guy (integerspin) who was kindly offering his turning services...I'm the dummy who got himself into this situation in the first place. RE: it being perfectly concentric - it was going to be trial and error - hence the palm in face - very heath robinson - but then I don't profess to be a pro. As for the emery cloth, again I'm no pro, but with the right setip would it be that hard to reduce 0.6mm off an alloy shim with a bit of elbow grease and the right grit sandpaper??

Anyhow, this was highly hypothetical and as I said further down "but I'm sure there are much more conventional approaches available" :facepalm:

Still listening to sensible suggestions folks

It gets you back to the postage problem again, but I've got the combined 26.4mm cutter and facing tool required to reduce the size. Usually for fork prep, but it'll do the job nicely.
Happy to lend.

All the best,