Hi All,
Has anybody out there got experience of fitting the Alpha roller bearing timing side conversion to a B40?
Not being able to find any instructions anywhere I assumed it would be pretty straight forward. Since the whole thing readily comes apart, it seemed logical to fit just the outer ring and drop the rest in later.
I can now fit the centre into the rollers or the rollers into the outer ring, but not both. It will go in almost exactly half way with finger pressure, but no further.
I'm guessing I could pull it in with something, but don't want to damage it. Is my best bet to heat it up again, or is there a trick to it?
Cheers
Fitted this conversion to a 1961 B40 some years ago. Outer sleeve contracted when fitted to crankcase so that the crank and rollers would not fit. Took to my local bike dealer who honed the out so it all fitted.
Thanks Julian, though I confess it's not the news I really wanted to read.
Sometimes an outer will contract just a bit too much if loctite has been applied too thickly to the bearing/case.
No loctite at all, everything sparkly clean. I always assume that if heat is needed to fit it, it shouldn't need loctite.
It is sometimes used on a bearing which has spun in the case.
Indeed it is, but this one is keyed anyway.
Here's the explanation from Alpha
"We estimate how much the crankcase might reduce the bore of the outer race and trust that after fitting the retained clearance is adequate. This is an industry standard practice and in roller bearings denoted by "C" values. (Since we are normally expecting our components to be fitted to machines over 50 years old the expectation is that the crankcase to housing interference will not be excessive and most customers do not need to hone the outer race. We suspect your crankcase bore is better than most other customers' hence the issue with your cases)."
As an engineer, what Alpha has said is perfectly reasonable. With the more modern engines I also work on, you normally need C3 grade bearings which have enough initial free play to accommodate the type of compression of the outer race that is inevitable when they are an inference fit in the engine casing. I would carefully measure the bearing mount internal diameter and bearing external diameter and establish what the level of interference is - normally this should be only about 1 thou per inch of diameter. If it's much greater than this then it might be necessary to hone out the mounting to provide the correct degree of fit. This would be alternative to grinding the out race down.