Drive side roller bearing cracked

[spottycat]

Hi again. Continuing my work on the A10 as and when I can find time. I just removed the drive side bearing, which is cracked. See pics. Anyone come across this before. It seems a strange fault to me. Also, can anyone confirm if this even the right (or best) bearing to buy to refit?  Cheers, Chris

[berger]

just my opinion .someone might have had that in the freezer then got the case hot to drop it  in , then it went in at an angle and got stuck so it was thrashed with a hammer or a brass drift to get it in. instead of getting it back out pretty sharpish.

[spottycat]

Thanks. That's not impossible. When we buy a bike of this age we really have no idea what people have done or ignored in the past but maybe you're right.

[limeyrob]

I too have never seen one fail like that.  My gut feeling is that it either failed when being installed or after a huge mileage but nothing in between.  Looks unworn but its not clear from photo.

[spottycat]

Thanks Limey, I also find it a bit bizarre especially because other aspects don't look too bad at all. I need to measure out the timing side but if it needs seeing to it certainly isn't terrible. Weird.

[berger]

i can see now it has been whacked very hard.

[Jules]

I agree with Berger on that failure, its not a normal wear break, more like a big hit!

[Swarfcut]

    Hoffmann was a well established outfit, with a pedigree going back to the late 1890's. They were an original suppler to BSA and many unmolested bikes will be found to use this brand. My reckoning is that the brand was still available to 1969, when amalgamated with Ransome and Marles along with Pollard Ball and Roller Bearing Company, to become the more familiar RHP Brand.

 So with evidence of a fair amount of abuse, the bike must have run like this for a fair while... but I can't see it being a factory fitted original. With ham fisted treatment anything is possible, I'd check the crankcases for being a matched pair and undamaged.

 BSA Service Sheet 703 identifies commercial  bearing types against BSA part numbers. Sadly most of these great stalwarts of British Industry are no more.

 Post that cracked race in "Great Mechanical Disasters" Well worthy of note.

 Swarfy.

[limeyrob]

Pull the inner off the crank and save it with the rollers on, gets some emery and open it up a bit so its a slip fit on the crank, measure it and measure the new one.  They are very accurate to spec so even though it will be another manufacturer it could be with in 1/10 of a thou. Use this to get your end float then press the new inner on.  Obviously if its all a sliding fit, no need, but if its decent interference it could save some agro.

[berger]

i covered this bearing subject ages ago when i got bitten with two identical bearings , it all depends on the rollers and the lip in the outer race.  my bearing thicknesses were the same but i remember the crank locking up and it was all to do with the roller lengths and lip in the outer race, if i was as clever as MWAS i could explain why it didn't work out but all i know is the bearing overall widths were the same BUT the new bearing locked up the crank and that bearing wasn't exactly the same as the one i ground down to measure the end float but was the same width .

[limeyrob]

A useful "health warning"!

[Slymo]

Risking a censure from the Admin for straying from the Marque but working on a RE Constellation at moment and have just scored an NOS Ransome and Marles roller bearing for the timing side (surprisingly) the drive side being a deep groove ball race. The R&M bearing is a thing of obvious quality with a beautiful machine brass cage for the rollers compared to the riveted steel stamping of the Nachi bearing I was planning to fit. How someone managed to crack that outer shell is truly one for the Ham-fist's Wall of Honour!