The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => A7 & A10 Engine => Topic started by: Steverat on 16.10. 2018 20:41
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Difficult! I have several pullers but nothing with long enough reach, and even if they did I couldn't get them between the race and the face of the crank. Any ideas what to do without investing in expensive equipment?
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Whenever I've had a ball / roller race that's a problem, I've done the following:
Remove outer race and balls / rollers - easily smashed with a sharp blow from a hammer if it doesn't come apart naturally. Wear protective glasses.
Heat the inner race in one spot quickly - ie with oxy acetylene. The idea is to get part of the inner race red hot without getting too much heat onto the shaft.
With a sharp cold chisel, give the red hot area a sharp smack. This will expand the inner race so it'll slide off even after it cools.
I forgot to add: the bearing should be a push, not a press fit on the shaft. It should be able to be fitted with only very light persuasion. Remember the new bearing has to be removed after fitting to shim the crank, so you don't want to have to wreck that as well. If the shaft / bearing fit is too tight, clean the shaft with emery. The cush drive nut is what holds it tight.
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Steve...worth investigating local tool hire for bearing pullers. Have a look at Machine Mart. Not the cheapest, but good range of options. Once the bearing is off and your crank is sorted ready to be reinstalled, you have the delights of setting the crankshaft end float, a theoretically simple operation which has brought many A10 owners to the edge of insanity, me included. There is more than enough information elsewhere on this Forum.
Swarfy
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the delights of setting the crankshaft end float...
This was me six years ago
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We finally got the old inner race off the shaft mostly by cutting it with a slitting rotary cutter.
The next message is obviously that I now have to find a way to pull the inner race on and off the shaft several times without destroying it, in order to adjust the endfloat! Do you have any tips for me?
Steve
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you might *smile*be lucky if you clean the crank shaft up find a new bearing will slide on and off providing you offer it up very square, the only time I got one stuck it was a japanese made race that must have been very slightly different even though the supplier said it was the same but made in japan. the SKF that I fitted snuggly slid on and off. the only tip I can give is don't eat yellow snow *bash*
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I was able to shift my main bearing by using an old wood chisel to get it moving, then a tyre lever. I have some levers from an old Volvo tool kit, they are really useful! Used the same method when setting endfloat.
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Steve, I wouldn't have risked a disc cutter. Awkward place to get and a high chance of nicking the shaft, which would then cause a fracture point. Re getting the bearing on and off, like I said in an earlier post, the bearing needs to be a push, not press fit. If it is tight, clean up the shaft with emery until it is a light push fit. Then you will have no problem.
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We finally got the old inner race off the shaft mostly by cutting it with a slitting rotary cutter.
The next message is obviously that I now have to find a way to pull the inner race on and off the shaft several times without destroying it, in order to adjust the endfloat! Do you have any tips for me?
Steve
If you had the old inner race you could have ground out the ID a touch to use it as the test race. I din't think you should try to reduce the shaft diameter with emory, or any other way. When installing the new bearing for good, freeze the crank and bake the race. You could get over to the topic "Home Made Tools" and see a couple of different pullers, including mine. While puller force us applied you hit the race with a propane torch and it should come off. I'll share the link with the pullers when I am not thumb typing. If you end up with a loose fit of the inner race, you can use Loctite bearing retainer, clamping the race and shim stack against the web with the cush nut and spacers while the Loctite cures.
Richard L.
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aha Richard I tried that method of old inner race to get end float correct and it came back and smacked me in the face *problem* because I had the new outer in the crankcase there was a difference,[ not very much but enough] between the outer races and where the inner races sat in the outer races even though they were the same number. so to use this method you will have to carefully do bearing measurements with our friend mic and get the maths head on *pull hair out* hence I cleaned the crank until as RD fella says it was a nice push fit , after all this race is or should be clamped tight up to the crank web------ ok enough of this I am racing off to the barley pop shop cheers *beer* thanks for listening byeee *wink2*
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I cleaned the crank until as RD fella says it was a nice push fit..."
I'm open to being corrected (and, somehow, expect to be), but I think if you can push it on by hand it's too loose, Mr. Lautrec.
Richard L.
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A push fit does not mean it is loose or slides easily. It means a light force is required to fit the item. Maybe by hand, but usually requiring a gentle tapping for persuasion. A press fit requires a greater and varying degree of force depending on interference, certainly a hammer and drift or a press. The point with the bearing in question is that if it requires a lot of force to fit (ie a press fit) then something - certainly the shims - will be damaged when it has to be dismantled. Probably the bearing too, if it required driving on with a hammer and tube or in a press. And a press will distort the crankshaft unless it's carefully supported. But there's no need for that grief because the cush drive nut holds the bearing tight so, as long as it's not a rattling fit on the shaft, all will be fine. At least that's what a few years as a toolmaker and fifty odd years in mechanical engineering taught me.
I forgot to add:
When a bearing is a press fit, it closes up or expands by roughly half the interference. Therefore, when you have a ballrace or roller bearing that’s an interference fit on the outside (as ours are) and a press fit on the shaft, there is every likelihood the bearing will have lost its running clearance. In which case an extra clearance bearing should be used – such as C3.
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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.
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Neat job Richard. Dunno if several years in a toolroom making precision dies (punch and injection moulds) qualifies me as a 'real' toolmaker but I can't really fault your puller. Only difference I'd have made would have been cross-bolts rather than straps. That way, with a countersink on the plates, the puller could be forced in behind the race.
Only part I don't understand is it seems you have it where it should be - behind the inner race and not on the cage - but surely that involves damaging the shims to get it there? The whole point of my argument is that at some stage one is going to have to pull the new bearing off to place shims, so why give oneself a load of grief when it's not necessary?
As for the cush nut / shim argument, that's been covered in depth elsewhere on this forum. Suffice to say if the bearing is held tight to the crank web, no harm can come to the shims. It can only happen if the bearing inner race moves and I suspect tightening the nut with a spanner (as some do) when there's no safe way of locking the engine may well be the cause of failures. I recall when I first started with BSA's in the early 60's the main dealer warning me to do the cush nut up 'bloody tight' or else the crank would disintegrate (the singles are the same set-up but the mainshaft is riveted to the flywheel). In 50 + yrs of riding on the road and c. 20 yrs of racing, I've never had one come loose. And I don't bother with a split pin. What's the point? If the nut comes back that far, the crank is already damaged.
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I would say that my old and new bearings were a push fit. I didn't have any real trouble *bash* (this is Richard and others bashing me over the head for being a smug git!)
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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.
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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.
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The required correct drive side bearing IS a C3. Tight on the shaft and in the case.
Cheers
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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.
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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.
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......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 *eek*
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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
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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.
*beer* *wink2*
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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
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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.
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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
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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.
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i have not been to the pub, all my cases are same as swarfy says , that is normal
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What a relief. But how strange too. Thanks for the confirmation. Flywheels are in!