Scooterotica

Following some advice on a video I have I fitted the flywheel bearing race on the crank by giving the race a good heating on the stove and it dropped on to the crankshaft beautifully. Couple is hours later I read stickies where it says under no circumstances heat the collar with a flame as can change the properties of the metal and wear badly or spin on the crank. The collar does have. But is a blue tinge to it now as per photo. Seems right on the crank tho.
So have I stuffed it and need to get the bloody thing off and replace?

Thanks

Tippo





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It's probably not ideal but I managed to blue one myself and it was ok in service. For future reference, the crank goes in the freezer over night and you warm the race with a got air gun

Thanks Coaster. So not worth the hassle of replacing just to be safe? Was thinking if could just replace the collar on the crankshaft with one from identical bearing maybe not too much hassle , but maybe that's asking for trouble too?


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tippo88 wrote:Thanks Coaster. So not worth the hassle of replacing just to be safe? Was thinking if could just replace the collar on the crankshaft with one from identical bearing maybe not too much hassle , but maybe that's asking for trouble too?


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I pretty much agree with 'coaster' on this.
The best way to heat the bearing inner track (for that is what it is called) is by putting the track in some old engine oil and heating it.
You could replace the inner track with one from another bearing (i did it once) despite Sticky advising against. The bearings are made to exacting standards and it is possible.

coaster wrote:It's probably not ideal but I managed to blue one myself and it was ok in service. For future reference, the crank goes in the freezer over night and you warm the race with a got air gun

I ruined one by using a hot air gun. I was surprised I could do it, but the whole bearing was blue/brown, which means it's lost its surface hardening.

Heating in the oven to about 150c shouldn't affect the hardening.

I changed the collar on one i done few years ago, same as you it went blue,both bearings were brand new and still ok,after all they are mass produced by a computer controlled machine now days not a man with a micrometer.

I don't heat them (or freeze the crank) any more. Just use some assembly lube on the race and the right tools to support the crank. You'll be fine to tap it home with a bearing race drift.

Grumpy225 wrote:I don't heat them (or freeze the crank) any more. Just use some assembly lube on the race and the right tools to support the crank. You'll be fine to tap it home with a bearing race drift.

or an old sundance grip

You should also leave a small gap between the bearing race and the raised section for the inner seal.

Dave h wrote:
You should also leave a small gap between the bearing race and the raised section for the inner seal.

The seal rides on the high part of the race so a gap won't help anything.

At best it makes the race a little easier to remove with a bearing splitter.

Thanks all. Going to replace to be on the safe side . Need to find myself an old sundance grip- there must be a good market for them !


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