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I didn't know any better and I let degreaser drip into the freewheel body of my Shimano FH-RM65. Now it makes a terrible retching noise when it rotates.

How do I clean the inside of this thing?

Shimano FH-RM65 Y-3CT 98040 Complete Freewheel body with Right Hand Dust Cap

Shimano FH-RM65 Y-3CT 98040 Complete Freewheel body with Right Hand Dust Cap

I'm afraid to put load on it until it sounds quiet and happy again.

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up vote 9 down vote accepted

That particular Shimano freehub can be disassembled, but it is quite a job to get it back together afterward. There are around 80 2mm bearings in two different locations in the freehub, and a skilled and practiced mechanic has roughly a 60% chance of opening without losing parts, and successfully getting it back together.

The good news is, there is a tool to lubricate the inside of a freehub, without disassembling it. It's called a Freehub Buddy.

Freehub Buddy

The photo shows the Freehub buddy, next to a freehub with a cutaway so you can see the rows of bearings I mentioned earlier, a tube of soup lube, and 2 new reusable seals.

It's made by Morningstar tools, and works very well. You will also need the proper lubricant, and new exterior seals for the freehub. Both can be purchased from Morningstar tools as well.

The other option is to simply replace the freehub, which should be readily available at your LBS, for about $20.

I hope that helps.

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1  
I think your definition of "skilled and practiced" mechanic is different from mine. I know winter bicycle mechanics who have disassembled, cleaned and winter greased hundreds of freehub bodies with no greater failure rate than any other service. It may help to think of it like your suspension, if your mechanic isn't familiar with it, you should probably send it off to a specialist. Sadly, like Shimano's Freehub tool, this one may no longer be available. – Suspended User Jun 23 at 8:07
    
@SuspendedUser My experience is different. A loose ball freehub has 2 layers of exceptionally small bearings in large numbers. I didn't say it was impossible, but I know many good mechanics who won't attempt it. Also, I know many "winter" mechanics who are skilled and practiced. I have no issue doing the job myself. But the OP doesn't (apparently) have the ability to recognize what needs to be done, and therefore is unlikely to have the skill and practice to accomplish this job reliably. – zenbike Jun 23 at 23:37
    
The loose ball freehubs hubs winterize much better because it's possible to get all of the factory grease out (reliably). I say winter with a colder climate in mind. Here (interior Alaska) if you do not disassemble and winterize your freehub it will either stop working, or worse, engage partially chipping mechanisms and destroying the freehub. All I meant was that a mechanic who does these regularly can do it with no issues. Agreed that if that isn't you, get (supervision) help or don't do it. – Suspended User Jun 24 at 0:20

I too have made this blunder.

The freehub buddy does work, but isn't in my toolbox.

The simplest thing I do is to first have the body mounted on the wheel. Be sure that one of the two slits in the body is at the six o'clock position. I then add just enough automatic transmission fluid (atf) to the body so that it covers up to the axle hole. I spin the outer body to help move the atf around and let it sit so it can soak through the whole. Repeat until things smooth out. There is no easy way to remove the old lube. the new atf acts to lubricate and neutralize any degreaser left. It may leak a bit at the rear of the hub, so have some paper towels stuffed under it to catch the errant drop.

I have hubs that are a decade old and I keep them alive doing this. Also, buy the cheapest ATF you can find. Don't waste your money on synthetics. Old fashion ATF is fine.

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