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rebuilding a Shimano freehub: super-thin washers

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rebuilding a Shimano freehub: super-thin washers

Old 01-20-21, 06:30 AM
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breadboard
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rebuilding a Shimano freehub: super-thin washers

I flushed out the freehub on a Shimano Tiagra FH-4500 and noticed a few fine metal shavings in the solvent. I opened up the freehub and found two paper-thin washers sitting on the pawl unit under the outer cone (ID 0.750", OD 0.900”, Th. 0.003"). One is slightly damaged, the other is cracked and pitted. Pawls and pawl springs are fine, and I can’t see any damage to the bearing races, so I would like to replace the bearing balls and the two washers. The freehub body itself is hard to find in the US.

Are there any sources for these washers aside from a similar freehub? I tried a couple of industrial suppliers but it doesn't appear to be a standard size . . .

Last edited by breadboard; 01-20-21 at 02:10 PM. Reason: corrected part number
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Old 01-20-21, 08:10 AM
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As I understand it, those washers are actually shims used to set the proper bearing clearance and are chosen individually (obviously by an automated machine) for each freehub body during assembly. They are not a standard part and probably unobtainable as replacements.

Finding an exact replacement freehub body may not be easy but most Shimano 8/9/10-speed freehub bodies are interchangeable and a Google search turned up several in the $20 price range.
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Old 01-20-21, 09:30 AM
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While you might not be able to buy ready made shims in that exact dimension, Iíve had good luck making my own from a cut up soda can. A bit fiddly but entirely doable.
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Old 01-20-21, 12:05 PM
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Originally Posted by HillRider View Post
As I understand it, those washers are actually shims used to set the proper bearing clearance and are chosen individually (obviously by an automated machine) for each freehub body during assembly. They are not a standard part and probably unobtainable as replacements.

Finding an exact replacement freehub body may not be easy but most Shimano 8/9/10-speed freehub bodies are interchangeable and a Google search turned up several in the $20 price range.
Ok, so that bearing is not intended to be adjustable and the thickness of the shim/shims is critical.

Yes, I saw a bunch of identical-looking freehub bodies and wondered if they were interchangeable! According to the spec sheet for the FH-4500, there is one officially interchangeable freehub = FH-M495A. I found one online for about $35. I have an exact match on backorder for about the same price, but who knows when that will come in.

Originally Posted by dabac View Post
While you might not be able to buy ready made shims in that exact dimension, Iíve had good luck making my own from a cut up soda can. A bit fiddly but entirely doable.
I think I'm going to try to reshape the cracked shim or just find a soda can and start trimming. Either way, I should get several more months at least from this freehub. It will also give me a chance to use some of those 1/8" BBs I ordered by mistake a few years ago . . .

Thank you both for your help and advice!
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Old 01-20-21, 12:22 PM
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If the soda can shim is the correct thickness it will be just good luck. Why not buy a small piece of 0.006" shim stock (the total of the two you removed) and try to cut a replacement from it.
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Old 01-20-21, 12:50 PM
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According to this (https://si.shimano.com/pdfs/ev/EV-FH-4500-2582A.pdf), the freehub body that you need is Y-3CR98070, found in stock here:
https://www.universalcycles.com/shop...3&category=574
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Old 01-20-21, 02:05 PM
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Originally Posted by breadboard View Post
I flushed out the freehub on a Shimano Tiagra HB-4500 and noticed a few fine metal shavings in the solvent. I opened up the freehub and found two paper-thin washers sitting on the pawl unit under the outer cone (ID 0.750", OD 0.900Ē, Th. 0.003"). One is slightly damaged, the other is cracked and pitted. Pawls and pawl springs are fine, and I canít see any damage to the bearing races, so I would like to replace the bearing balls and the two washers. The freehub body itself is hard to find in the US.

Are there any sources for these washers aside from a similar freehub? I tried a couple of industrial suppliers but it doesn't appear to be a standard size . . .
FH bodies are really hard to find anywhere for a FRONT hub.
You mean FH-4500.
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Old 01-20-21, 02:07 PM
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Originally Posted by aggiegrads View Post
According to this ***, the freehub body that you need is Y-3CR98070, found in stock here: ***
Wow, thank you for checking this today! I checked Universal two days ago and only saw the FH-M495A substitute here. I can't remember whether I saw an 'out of stock' listing for the FH-4500 at Universal two days ago. It's likely that I landed on a page that showed only MTB freehubs and not road freehubs, and I didn't realize I wasn't seeing the full selection . . .

I ordered a new one and will rebuild the other one for the fun of it. Then I'll decide which to install and which to keep for backup . . .
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Old 01-20-21, 02:20 PM
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Originally Posted by Bill Kapaun View Post
FH bodies are really hard to find anywhere for a FRONT hub.
You mean FH-4500.
Corrected! Thank you.
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Old 01-20-21, 08:53 PM
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Brass and SS shim stock is easily available from any number of industrial suppliers. Like here Shoulder Screws | McMaster-Carr

Now cutting a well fitting shim/washer at the handful of thou thickness is the next challenge. For really thin brass I use a knife with a fair amount of rocker to the blade and press/rock the blade into the brass sheet to cut it, for the tiny pieces that scissors can't do.

This is but one reason why many don't overhaul their second freewheel or FH body. Andy
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Old 01-27-21, 02:35 PM
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Originally Posted by Andrew R Stewart View Post
Brass and SS shim stock is easily available from any number of industrial suppliers.

Now cutting a well fitting shim/washer at the handful of thou thickness is the next challenge. For really thin brass I use a knife with a fair amount of rocker to the blade and press/rock the blade into the brass sheet to cut it, for the tiny pieces that scissors can't do.

This is but one reason why many don't overhaul their second freewheel or FH body. Andy
This sounds like fun and I will eventually get around to trying it. But in the meantime I was able to obtain a new freehub and I went ahead and installed it.

I would like to thank the person who wrote to me privately, offering to send me shims from a decommissioned freehub. Because I have only posted to the forum a few times, I am unable to reply to private messages yet, and I think my attempt to send an email failed too . . .
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