Spring is coming ... Crank renovation

[Jim]

Thanks Mosin I'll give him a ring.

[a10 gf]

Thanks for all the input. Engine is out and will soon split case for inspection (time and health allowing). Then choosing a uk company and ask for a complete overhaul \ renewal, hopefully getting it ready before summer.

e

[beezalex]

With a properly working oil pump and return side oil filtration I see no need of the end feed conversion.  There is nothing principally wrong with this setup.  Just about every single automobile on the road today uses a similar setup.  Are they all just waiting to implode?

[a10 gf]

Before going further, just to be sure, see picture, this is way too much wear, ain't it? .006 feeler goes in, and I can move the cs up and down by hand. Symptoms were a nice quiet engine with cold oil, then deep metallic 'clank' noise (seemingly following crankshaft rotation) with hot engine (thin oil). Apart from this, big\small ends seems fine, needs re-shimming endplay (behind the drive side bearing this time, as the ones on the shaft itself disintegrated over time, probably due to inner bearing rotating on crankshaft).

Thanks for any extra expertise.
e

[muskrat]

Way too much. 2 thou max. That's what the noise is.
Cheers

[Brian]

Among the books and manuals I have there seems to be some variation as to just how much is too much. At the absolute worst .004" is maximum so at .006" you are way past the limit. I have just done one of mine and put it together with .001".
With the end feed modification I dont think it is necessary, put together well it will do many thousands of miles with the original set up.

[MG]

You asked for some recommendations? Well, there you are:  

The shims for adjusting the end play definitely go behind the drive side bearing race. I have no idea why the service sheet and Haynes manual (I think) say to put them on the timing side also, imho that's nonsense, you've seen the result yourself. If you don't ride it in cold weather, you can shim down to almost zero. I shimmed mine down 0.5 thou. The alloy crankcases will expand much more than the steel crank, so that's absolutely no problem.

2 thou on the timing side bush is fine, like muskrat said. From what you have described (play, noises) I would be surprised if the big ends were okay. Definitely check the journals for wear (measure with micrometer) and regrind if necessary. Very often the cold oil remaining on the bearings disguises the play caused by wear, so it's hard to tell whether they are really worn or not just by rocking the conrods up and down. A play of 2 thou is what you would want here, too.
Probably the timing side crank journal will need to be reground as well. Check this for wear or ovality prior to purchasing a timing side bush.
The bush itself has to be line bored with the crankcase halves assembled with ALL bolts. It's also good to fit the barrels in order to prevent any distortion later on when assembling. The alginment of timing and drive side is very important, so give it to somebody who knows what he's doing.

If the crank is out, you could consider having it nitrogen hardened after grinding. This improves the surface hardness significantly, the EN40B it is made of (learnt that here on the forum  ) is very well suited for nitrogen hardening. Also the fatigue and tribological behaviour of the material become better. I had all my cranks, camshafts and followers treated this way, as its not really expensive (3,5 Euros per kg of material here).

Cheers, Markus

[a10 gf]

Thanks again for all the info, and Markus, a very good list of tips. Am currently sitting here looking hard at the crankcase\shaft, and evaluating all the what, who, where and when to get it right.

About the crank endplay, I've not had shims on the timing side, but between drive side bearing and crank. Idea is to get larger diameter shims, and put them in the crankcase behind the bearing. I probably have a worn shaft on the drive side, and the inner bearing cup has been slipping on the shaft, and destroying the shims. Must anyway get the shaft 'redone' to the proper diameter.

Some writings about my crank work 10 years ago http://www.a7a10.net/BSA/crankcase.htm , this is the job that has lasted until now. Did a few tests with crankcase temperature and expansion, and as you mention, the case expands much more than the crankshaft, and very quickly, so unless one uses the engine in freezing cold, the endplay can be very small indeed.

[MG]

I probably have a worn shaft on the drive side, and the inner bearing cup has been slipping on the shaft, and destroying the shims

Yep, that must be the culprit. If this is cured, there's no need to fit larger ones behind the outer race.

Another idea ref endplay shiming: I use an old inner bearing race, with larger inner diameter (by grinding), so that it is a good sliding fit on the crank. This way you can easily determine the correct shims prior to pressing on the bearing race.

[muskrat]

That's a really good idea Marcus. I'll use that one at my next rebuild

[A10Boy]

One thing springs to mind. Make sure you use the correct lipped roller bearing on the drive side. If you use this and have the cush nut fully tight, the inner race cant spin and destroy the shims.

In the Uk, I always use these guys.

T & L Engineering
www.vintage-engine.net
1 Wilstead Road
Bedford MK42 9YG
01234 352 100
 

[a10 gf]

Sooo... got the beast split, good condition case I've got, matching halves, no ugly signs of previous owners activities, oil tight, easy to separate.

As expected, the shims (or rather the paperthin leftovers of shims -no doubt were all the stuff that grew on the magnetic sump plug came from) were ground down by drive side inner race rotating loose on shaft, so the shaft needs to 'get thicker' (metal spraying?), and new shims will get behind driveside case and outer bearing cup.

No surprises on the timing side, bronze plain bearing worn prematurely (on the downside), 99% sure the results of a bad reaming job, but it did provide some 1000's of miles. Shaft itself looks very nice. No play to be felt on big \ small ends (oil cleaned out). Will inspect BE shells and sludge trap.

Now, just the thinking to be done, 2 options, sourcing parts and take the chance of finding a decent local machinist, or sending to England (whenever -or if- any airplanes may fly again...)

Regards
e

[chaterlea25]

Hi All,
terryk, I would not try and knurl the shaft, that is a bodge of the highest order in my opinion!!!
it will come loose again, if there is only a thou or two play a loctite type product will help
When the engine is assembled "properly" the crank spacer and the cush drive assembly should lock the bearing in place preventing any relative rotation between the two!!
HTH
John O R

[A10Boy]

Yes, I had an engine with a slightly worn drive side bearing journal, it made the shimming very easy. I fitted it with some quality bearing lock and did the cush nut up to the right torque. Still got the right end float after 1000s of miles. It was only 1 thou worn, any more and I would consider spraying.

[a10 gf]

Just a thanks for lots of valuable info.