Loose Bearings

G

Graham Smith

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Am busy rebuilding the engine on Joshua’s 1979 Yamaha RD125DX.

Unfortunately, one of the crank bearings is a bit loose in the case.

Am after suggestions for the best type of Loctite to use?
 

Bazlerker

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Graham..I found these..




I also found suggestions for using masking tape or tin foil..
 

John Reynolds

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Graham

If the bearing is really loose you could try Loctite 660; it is suitable for filling gaps of up to 0.5mm. See data sheet
 

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oexing

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No type of Loctite or any other equivalent will keep the bearing put when you try to glue it in a cold alu case. The heat growth at these dimensions is enough to undo the glue as you have to remember the bearing is steel and the case alu - with twice the growth. So really you have to drop the bearing in the heated case with Loctite applied to both items - quick !! I´d go for 100 degrees C of case for this.

Vic
 

Robert Watson

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Maybe you could loctite it and then stake it like we do with Vincent mains. Those are c/sunk screws and then the outer race ground with a dremel to match the c/sink so the screw holds the whole plot in place. Making a jig that slips in the bearing bore before the bearing goes in helps to put the screw in the exact right spot.
20180122_142403_HDR.jpg
 

Martyn Goodwin

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No type of Loctite or any other equivalent will keep the bearing put when you try to glue it in a cold alu case. The heat growth at these dimensions is enough to undo the glue as you have to remember the bearing is steel and the case alu - with twice the growth. So really you have to drop the bearing in the heated case with Loctite applied to both items - quick !! I´d go for 100 degrees C of case for this.

Vic
Correct Vic -

That Loctite will grip in a fraction of a second - and once it does, it's a bugger to get it to release.

Martyn
 

Pete Appleton

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You could always just fix it properly, with metal. Can we see a picture? How loose do you mean?
 

nkt267

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Back in 1970 I used a ring of shim steel to hold the loose bearings into my 1932 sunbeam crankcases..they're still in place.
 

timetraveller

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Graham, it's probably not what you want to hear but Oexing and Pete probably have the right ideas. If it is intended to keep the bike for a long time then it would pay to do the job right. There are probably enough competent engineers in the club who would be prepared to help you out in view of the remarkable amount of work you put in. Let one of these masters of machining have a look at the job. I expect it would only be a relatively small job to machine out the bearing housing, make an insert and then shrink in a new bearing.
 
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