A65 rebuild

[MITCHELL]

Hi , had a dry run today having put new bearings and bushes in the crank cases all going well until I nipped up a couple of boots and then the crank is almost impossible to turn, tried it a few times making sure the busy and bearing are well home but same result. When I stripped it there were no spacers or chip washer on the crank so presume it was a good fit before, any comments would been appreciated. Dave.

[cdsdorset]

Did you drop the barrels on to make sure the cases are going together square?

[MITCHELL]

Hi, no didn't go that far but all the studs are in the left hand case and everything  lines up well, the crank turns until I nip up a couple of opposite bolts.

[Spaceman]

The problem even with a properly set up A65 engine is that there is usually only a few thou of end float and so it doesn't take much to make this disappear because of a bearing that has not seated correctly.

Ideally, you need to measure the end float before you put the cases together and then shim as necessary to leave the specified amount. Out of interest, did you compare the flange thickness of the new bush and the thrust washer with the old ones to check there was no obvious problem?

[Mike Farmer]

 

Was your engine running previously with all the current components. I ask this because There is a difference in the years/casings/crank. I had the same problem (or similar) And the only way around it was to have a couple of thou machined off the cransfaft web I think on the timing side. SRM did mine.

However if it was running with the current parts, then it sounds like an ill fitting bearing, or your present shimming could be wrong.

Let us know please.

Mike

[MITCHELL]

Hi spaceman / Mike, I bought the bike 40 years ago in bits and knew nothing about its history.when I stripped the engine down last year I found a few horrors,one come of was all cast ali the other was fast ali with a steel bottom half, there were gouges on the inside of the crank cases and a split in one case adjacent to the bearing. I had the crack welded up before removing the old bearing to retain the shape. When I stripped the engine the were no spacers, cup washer or thrust washer on the crank but it did turn although I don't recollect how easy or tight it was.having measured it this afternoon as accurately as I was able there doesn't seem to be any difference from the length of the crank and the distance between bush and bearing. The bearing housing is a bit rough particularly where the oil seal fits ,see photo's, I'm thinking could I get these honed and killed to gain the required tolerance. what do you recon. Cheers,  Dave.

[MITCHELL]

Should read milled, bl...e.g. Predictive text. :😁

[Mike Farmer]

 

Killed is fine. I kmow how you feel.

Mike

[MITCHELL]

Hi, been messing with this in my head and on the bench and have decided to get some professional machining done. Does anyone know the dimensions of the thrust washer and the cup washer that fit on the crank? Also if I get the crank machined to the correct length  for the required drift do I need to put the cup washer and shimes on or just the thrust washer. Cheers Dave.

[Bess]

Hi,
    There are 2 different shim cups available, for the roller bearing or the ball bearing. They are pressed and cut to shape from 15-20 thou thick sheet, you are better off buying them for about £5 (I have 2 for the roller bearing if finding difficulty getting them, try Draganfly first).

The thrust washer will also be quite difficult to make cheaply and again would be cheaper to buy new. The best are the Vandervell they have a steel backing, again I have 2 and a solid if you cant source any, (again try Draganfly).

I wouldn't machine the crank the correct length to fit the crankcase. I would recommend investigation into why it is binding. Where in the country are you? perhaps a BSAOC member could visit and help.

Best wishes...

[Spaceman]

I wonder if it is possible that the two crankcase halves are not matched? For example, if you have a roller bearing RH crankcase and crankshaft but a ball bearing LH crankcase, then the crankshaft will be too long. Presumably, the engine number on the LH crankcase shows it to be at least 1966?

That said, the LH crankcase seems to be in poor condition and something has clearly happened to the engine to cause the damage that is evident. Presumably the roller bearing is still a good interference fit in the LH crankcase?

BSA designed these engines to have adequate axial clearance for the crankshaft requiring it to be shimmed. The fact that there is no real clearance in this engine suggests something is not quite right and may well point to you having a mix of incompatible parts?

[Bess]

Hi Dave,
             Spaceman maybe correct, the crankcase image you've shown is for a ball bearing (see alternator stud tappings) therefore no need for a thrust washer. Can you post some images of the other crankcase and crankshaft?

Thanks...

[MITCHELL]

Evening gents, I get the feeling that the engine was assembled haphazardly and when whoever tried to turn it over the damage to the cases occured. I found it in a cellar of a large house in Leamington spa that I was working on and the owner was pleased to see it go if I remember rightly. Spoke to an engineering company today who did the regrind and honning and they thought the same as you have suggested, there's a wrong bit in there somewhere. I live in Hollywood, not the warm one, the wet one just South of birmingham but obviously would be willing to take it all to wherever to get some help.have posted some photo's as requested. Thanks for your help Dave. Ps, some more photos on next post.

[MITCHELL]

Photo's.

[MITCHELL]

Even more photos