Drive side main bearing inner race removal

[BigJim]

Hi Steverat. Re bearings and shims. Buy 2 bearings from the same supplier. Measure and check there similarity if able(i cannot and try not to fret about it) then ease out the inner part of one until it is an easy slide fit(loose). Use that one as your spacer for shim measurement, then when happy freeze the crank and warm the unmolested bearing and hope it slips on.

[berger]

I have been to the pub *countdown*measure twice cut once and everything will be BSAish---and I can't remember what the subject is? o well everythings fine and dandy over.

[muskrat]

The required correct drive side bearing IS a C3. Tight on the shaft and in the case.
Cheers

[Steverat]

RD,

For "off," I suggested heat with a puller. For "on," I suggested cold on the crank and heat on the bearing. Maybe this fits your description of gentle persuasion, but experience with this bearing on my bike tells me it can't be gently persuaded off the shaft if the fit is right and tight. When dismantling with a puller, you need a puller that avoids the shims. This is what I tried to accomplish with my crude home-made puller, which has worked successfully several times now, despite its shortcomings.

Now. it might be that the cush nut is supposed to hold it all tight, but there are plenty of cases of wasted shims here that are not all due to a loose cush nut, I think.

If the following pictures come through, I have a feeling I will get some admonishment from a real toolmaker.


Richard L.

Thanks for the illustration! It looks to me as if your puller acts on the rollers is that right? Actually in the bearing I was removing, the rollers stayed with the outer race, leaving the inner race only on the shaft. Also the lip was on the inboard side of the race, hard up against the crank. So I couldn’t have used your method.

[Swarfcut]

 Steve.. Very strange what you found. The normal set up is a roller main bearing with a lip on one side. The outer race is fitted to the crankcase with the lipped side to the outside. On assembly the crank with the correctly shimmed inner race in place is simply inserted into the outer race.

   Looks like it is the wrong bearing, or the correct bearing fitted the wrong way round.  The outer race should be a tight fit in the case.... to remove or assemble the race  the usual hot and cold method avoids damage.  Fitted correctly, the bearing separates  easily allowing the cases to come apart. The rollers stay on the inner race. So if the outer stayed  on the inner, it could be that your cases are worn where the outer race sits.  Most likely someone has fitted the bearing the wrong way round.

  The correct quality bearing with its C3 internal clearance is usually quite expensive so be careful how you treat it.

  Swarfy.

[duTch]

 

......Looks like it is the wrong bearing, or the correct bearing fitted the wrong way round.  .......

 I doubt the correct outer  could be fitted wrong and still separate, the inner having a lip both sides.... I'm sure I've used bearings where the rollers stay in the outer and the inner slides into it.... maybe the Gutzzly gearbox I think, and that *may* work  if done right  (*edit*- on a Beeza Crank)

 Jimbo- as Swarfo says,  these bearings aren't cheap- maybe you have a mun-mun tree 

[muskrat]

G'day fellas.
The outer has a lip innermost into the case. The inner has a lip both sides and the rollers stay with it. I try to get bearings with a plastic roller retainer. The rollers can be picked out (a little more difficult with a metal retainer) and then a bearing separator type puller will get the inner off the shaft. If it's the correct fit a dousing with boiling water will expand it enough to remove with gloves.
Yes the correct C3 bearing is about $75 = 40 puid. https://tinyurl.com/ydh62nka
Cheers

[BigJim]

No mun mun tree here. Used my original bearing which was hopefully close to replacement in size (same nr). I know!Also the bearing fitted (same as original) had one of those plastic roller spacers. This made it easy to pick them out and get puller onto lip of inner race to remove. Tuck in with the abuse everyone. SOMEONE HAS TO BE A PREVIOUS OWNER!. Will hopefully be at Weston beach race so won't be able to hear you.
 

[Steverat]

Steve.. Very strange what you found. The normal set up is a roller main bearing with a lip on one side. The outer race is fitted to the crankcase with the lipped side to the outside. On assembly the crank with the correctly shimmed inner race in place is simply inserted into the outer race.

   Looks like it is the wrong bearing, or the correct bearing fitted the wrong way round.  The outer race should be a tight fit in the case.... to remove or assemble the race  the usual hot and cold method avoids damage.  Fitted correctly, the bearing separates  easily allowing the cases to come apart. The rollers stay on the inner race. So if the outer stayed  on the inner, it could be that your cases are worn where the outer race sits.  Most likely someone has fitted the bearing the wrong way round.

  The correct quality bearing with its C3 internal clearance is usually quite expensive so be careful how you treat it.

  Swarfy.

It is not possible to fit the wrong way round since that would trap the rollers between lip and crank. So it must be the wrong bearing. Luckily my friend Rodney managed to cut the old inner race off without nicking the shaft so now I am at square one with a lipped FAG bearing.and some shims coming from EBay- hopefully with lip on the outer race so that I can pull the thing off again by the rollers if my first guess on shimming doesn’t go right. Considering the disassembly problem, one wonders why anyone ever bothered with a lip on the inner race. Peaceful disassembly in a blind location like the beesa is pretty much impossible. Thank you all for your helpful comments.
Steve

[trevinoz]

If the NF206 bearing is not available, and it can be hard to source these days, an NJ206 can be used quite successfully.
This bearing has only the inner journal on the crank and the rest is in the case.
This type is used on Norton twins.

[Steverat]

The Hoffmann R130L bearing arrived and I attempted to fit this morning. Dismayed to find that the bearing width at 16mm is too wide for the bearing housing in the drive side case (14mm).

Reading up, the other equivalents to BSA p/n 67-0670 are also 16mm wide(e.g. NF206 from SKF).

This cannot be right, surely.
The case is datestamped 26 5 52
Case engine number is BA10 54xx

Here is a photo of the bearing outer journal projecting 2mm proud of its housing. Useless.
What bearing shall I fit?

Steve

[Swarfcut]

 Steve......,    According to my handy reference, the drive side bearing is a metric size.

      ID  30mm,    OD  62mm,  Width is 16mm.

   I have just clambered over my massive pile of plunger crankcases, selected one of the BA10 Series at random and found that just like yours the outer race is very definitely proud of the crankcase inner face. This is how it should be, otherwise the crank web will end up grinding away the inner face of the case.

  Looks like for once you have achieved success.

  Swarfy.

[berger]

i have not been to the pub, all my cases are same as swarfy says , that is normal

[Steverat]

What a relief. But how strange too. Thanks for the confirmation. Flywheels are in!