ET: Engine (Twin) main bearings

erik

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is there a method to dismantle the inner parts of the cranks mainbearing avoiding the traditionel chisel method?
 

erik

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i have this Extractor set for my commando.i thought on the rapide is not so much space for this.
 

Cyborg

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I have a puller similar to the one shown in the link and have used it for removing crank bearings. It "just" fits. It would work better with smaller bolts and nuts (the nuts are right up against the flywheel). You can't grab the inner race with it, so it pulls on the cage which isn't ideal, but it does remove the bearing without risk to the crank. If the bearing isn't on too tight, you may be able to remove it without damaging the cage, but I assume that if you are removing the bearing you will replace it with a new one anyway.

Bearing puller.jpg
 

stu spalding

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With a pressed steel cage it is possible to get a small screwdriver behind each roller and pop it out of the cage. Once all the rollers and the cage have been removed it is a straightforward job to get a puller on the inner track and remove it. For reassembly, pop the rollers back into their slots and dress the tabs down a little. Cheers, Stu.
 

greg brillus

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use an electric heat gun and heat the bearing as best you can, they then just slip off the shaft no damage done using a pair of screw drivers. I also do this to install the bearings on the shafts, works extremely well.
 

Martyn Goodwin

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P1110669.JPG
P1110669.JPG I purchased this puller set on ebay for not very much $$ - made bearing removal a breeze.

When it comes to installing mains onto the main shafts the late Laurie Binns told me how. Put the bearing into a small saucepan of engine oil and gently heat it till the oil starts to smoke - then (using pliers or such like) lift the now hot bearing from the oil and drop it into place on the main shaft. Remember to use a tube spanner or similar and some weights to hold the bearing in place as it cools. Simple.
 
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Oldhaven

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I just intalled a set of mains and heat works very well for installing and for removing since the mass of the flywheel shaft and wheel will take longer to heat up with a heat gun than the race. It is winter here and one of the benefits is I get to use the oven in the Esse woodstove to heat up things. It has a good sized vented oven, big enough to take a comet crankcase half, and all the bad smells go up the flue, so no complaining is heard as oily parts heat up. I don't use a pan of heated oil but I don't have to get the bearings so hot that the oil in them dries out or gums up. Anyway, I have to say it is quite satisfying to drop the hot inner race over the cellar temperature mainshaft and hear it drop with a click all the way to the flywheel with no force required. I can't do a woodstove oven for removing them, but a heatgun works for that. If you have a good heatgun use the smallest nozzle that you can to concentrate the heat on the bearing.
 

Nigel Spaxman

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I bought a shaft collar, the split two bolt industrial type, almost big enough to fit over the rollers. Then I turned the ID so it would fit tightly over the rollers but I left a lip on one side. I put that on the beaing with the lip in between the bearing and the flywheel I was then able to put my gear puller on that to pull the bearing.
 

Albervin

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The timing side bearings just fell of my crankshaft but now I can see how to remove the primary side bearing. Thanks.
 
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