The BSA A7-A10 Forum

Technical => A7 & A10 Engine => Topic started by: a10gf on 18.03. 2010 11:48

Title: Spring is coming ... Crank renovation
Post by: a10gf on 18.03. 2010 11:48
Trying to get stuff sorted out before any fine weather may make it's seldom appearance (this is definitely not Australia). Noises (and play here and there) suggest the need for a proper job on the crank, big ends and crankbearings. Had it 'overhauled' some years ago by a local, this time I'd rather pay for some lasting result, using someone with real experience thus probably sending it to England, and at the same time get new bronze bushings all over.

Have been pushing this job away for too long, a relief to get started. Cylinders, cam followers, valves and pistons looks very nice (SRM job from many years ago). Will post my findings after inspecting the crank parts, and update as it (hopefully) progresses.

The question, is the timingside oil feed conversion + balancing worth it ?

Thanks
e
Title: Re: Spring is coming ... Crank-time
Post by: Desburnett on 18.03. 2010 16:48
Depends how old you are and if you want the bike to outlast you.

I had a similar decision to make last year and as I am 59 decided to go with standard set up (no oil feed conversion) as I am unlikley to see the benefits.
However if in 12 years time I am looking a a beat up big end then I made the wrong decision!

Des
Title: Re: Spring is coming ... Crank-time
Post by: Mosin on 18.03. 2010 16:52
My Engine is currently in having the full job done. But I am only 36 so I am hoping that I will be riding long enough to make it worthwhile. My other consideration was that just because one day I have to stop riding, that doesn't mean that the bike should bite the dust as well. It makes me quite happy to think that someone will still be enjoying my BSA in another 50 or 60 years. 
Title: Re: Spring is coming ... Crank-time
Post by: alanp on 18.03. 2010 16:54
My attitude to this is ...if you can afford it, get it done. Watch out for a long lead time to get it done before you send your engine over. Mine took 3 months, but this was not a concern because it was over the winter months. SRM do a good job though.
Alan
Title: Re: Spring is coming ... Crank-time
Post by: RichardL on 18.03. 2010 17:05
E,

I know what you mean about getting the winter work done before the weather turns good. For the last week, the weather in Chicago has been unusually beautiful for early spring (really, late winter). People don't exactly understand why I'm not that thrilled by that, but I haven't finished the valve job yet, with the valves are still on their way by Her Majesty's Royal Post. (Really, quite efficient and reasonably priced.)

Maybe Groily will chime in about sleeve versus needles on the timing side. I think he has done 1,253,400 miles on his sleeve bearing.

Richard L.
Title: Re: Spring is coming ... Crank-time
Post by: groily on 18.03. 2010 17:31
Not quite Richard! But I've done a good 20,000+ miles on what was an unknown bottom end when I got it, and it's still fine. No idea what it looks like in there, as haven't had to go down there. Only 2 bikes in my shed don't have to be looked at much - the other being the inimitable B31, which will outlive me for sure. It's 54 (well, the frame is) and I'm 55, and it's in better shape. If there was a fire, it's the B I'd try to save. Heresy I know.
My really high mileage bike's a really tatty AMC twin - we all know what they're meant to be like . . . and they are! But some of us are mentally deficient enough to like them all the same.
My lowest annual mileage bike is also - a (less tatty) AMC twin. Just put back the top end this very day after a fruitless effort yesterday to cure a sudden attack of chronic top-end over-oiling on a bitsa motor . . .some things are meant to try us. This afternoon's smoke haze over western France indicated it's probably worse now than it was the day before yesterday. But there's always tomorrow . . .
They've all ploughed on regardless through a medium hard winter - wear on tear on rider is probably more severe than on machinery. But with spring in the air, it can only all get better.
Title: Re: Spring is coming ... Crank-time
Post by: rocket man on 18.03. 2010 18:38
i agree with alanp srm are very good at what they do thieve been doing the needle roller oil end feed
mod for years and i had good service off them they did my engine and gearbox but it can get expensive
as i found out you could stick with plain timing bush but oil changes must be done regular my bottom end should be good
for 100,000 miles which i will never do i had it done for peace of mind its a very good mod also it increases the flow of oil to the big ends
which is a good thing 


dave
Title: Re: Spring is coming ... Crank-time
Post by: A10Boy on 18.03. 2010 20:55
SRM aren't the only company who do end feeds.

http://www.a7a10.net/forum/index.php/topic,2039.0.html (http://www.a7a10.net/forum/index.php/topic,2039.0.html)

Title: Re: Spring is coming ... Crank-time
Post by: olev on 23.03. 2010 11:30
Erling,
If you go down this path, please let us know how you arrange the balancing of your motor.
The two professional balancers I've contacted want a balance factor before they start.
I know the subject has been beaten to death but I can't find anything definitive on balance factors.
There have been a lot of figures thrown around but no one seems able to say <I had my A10 balanced to 58% and its sweet spot is between 4500 and 5500> as an example.
There must be a formula that gives an approximate figure.
It depends on the rev band in which you want it to be effective.
(Muskrat would probably select 10000 preferring to shake in horror)
There is no doubt a lot of accurate information is available but its near impossible to sift it from the myths and old wives tales.
As I said, if you go down this path please share the journey.
cheers
Title: Re: Spring is coming ... Crank-time
Post by: alanp on 23.03. 2010 12:05
SRM can do the crank upgrade and dynamic rebalance for you, at 58%, but don't forget to send them the con rods, pistons and gudgeon pins/circlips. They've been doing this for so long now that you get the feeling it's in good hands. They'll also examine the bits for potential problems.
Title: Re: Spring is coming ... Crank-time
Post by: trevinoz on 24.03. 2010 21:46
Olev,
              The A10 factor is 54% or 65% for racing, according to Eddie Dow.
The frame has a lot to do with the appropriate figure.
I had my Atlas balanced to 70% and it is great. none of the legendary Norton horror shakes.
My Flash is 54% and is not bad. Not as smooth as the Norton.
When my RGS was on the road, I had two different shops have a go at it but I am sure neither of them had a clue as it was always shaky.
The bloke that I use now seems to know what he is doing.
Trev.
Title: Re: Spring is coming ... Crank-time
Post by: Mosin on 24.03. 2010 22:46
I just collected my engine this very afternoon from Rob Wardle in Newcastle who has done a roller bearing and end feed conversion on it for me. I've also had the crank reground back to standard and he has welded up the nasty hole in the crankcase through which the con rod bolt had exited (pictures to follow).

Rob does all the end feed conversions for JB Restorations and seems to have done a cracking job.

Tonight I have fitted the engine back into the frame, fitted the primary inner and cush drive and fitted a new four spring clutch from Paul at JB Restorations. I am hoping to have the whole thing back together and running off its new Pazon ignition within the next couple of weeks and will feed back on how it's going. 
Title: Re: Spring is coming ... Crank-time
Post by: Jim on 25.03. 2010 11:14
Hello Mosin,

I'm looking at doing an end feed conversion on my bike. Could you please let me have Rob Wardle's details, I've tried to find him with Google but to no avail.
Title: Re: Spring is coming ... Crank-time
Post by: Mosin on 25.03. 2010 11:27
Rob Wardle - 0191 4696428

He is in Felling in South Tyneside
Title: Re: Spring is coming ... Crank-time
Post by: muskrat on 25.03. 2010 12:07
Olev, i can't quite get to 10,000 but at 7500 it's sweet with a 76% balance I did myself, but I also took about 2 lb off the flywheel first. *eek*
Cheers
Title: Re: Spring is coming ... Crank-time
Post by: Jim on 25.03. 2010 12:41
Thanks Mosin *smiley4* I'll give him a ring.
Title: Re: Spring is coming ... Crank renovation
Post by: a10gf on 04.04. 2010 19:24
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
Title: Re: Spring is coming ... Crank renovation
Post by: beezalex on 05.04. 2010 18:12
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?
Title: Re: Spring is coming ... Crank renovation
Post by: a10gf on 06.04. 2010 22:12
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
Title: Re: Spring is coming ... Crank renovation
Post by: muskrat on 06.04. 2010 22:35
Way too much. 2 thou max. That's what the noise is.
Cheers
Title: Re: Spring is coming ... Crank renovation
Post by: Brian on 06.04. 2010 23:23
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.
Title: Re: Spring is coming ... Crank renovation
Post by: MG on 07.04. 2010 16:42
You asked for some recommendations? Well, there you are:  *smile*

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  *smile*) 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
Title: Re: Spring is coming ... Crank renovation
Post by: a10gf on 08.04. 2010 09:58
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.
Title: Re: Spring is coming ... Crank renovation
Post by: MG on 08.04. 2010 10:15
Quote
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.
Title: Re: Spring is coming ... Crank renovation
Post by: muskrat on 08.04. 2010 14:01
That's a really good idea Marcus. I'll use that one at my next rebuild
Title: Re: Spring is coming ... Crank renovation
Post by: A10Boy on 09.04. 2010 15:27
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
 
Title: Re: Spring is coming ... Crank renovation
Post by: a10gf on 17.04. 2010 20:00
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
Title: Re: Spring is coming ... Crank renovation
Post by: chaterlea25 on 18.04. 2010 19:43
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
Title: Re: Spring is coming ... Crank renovation
Post by: A10Boy on 27.04. 2010 13:27
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.
Title: Re: Spring is coming ... Crank renovation
Post by: a10gf on 01.05. 2010 08:51
Just a thanks for lots of valuable info.
Title: Re: Spring is coming ... Crank renovation
Post by: MikeN on 01.05. 2010 17:56
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
Couldnt agree more
MN
Title: Re: Spring is coming ... Crank renovation
Post by: a10gf on 02.05. 2010 08:49
Quote
I would not try and knurl the shaft
agree

Quote
It was only 1 thou worn, any more and I would consider spraying
Difficult to measure, but inner bearing completely loose, slides off by itself from crankshaft in vertical position.

Quote
the crank spacer and the cush drive assembly should lock the bearing in place
I'd think my cush system, tightening and spring is fine, but still the inner bearing managed to rotate.

Here's a picture of the timing side wear. Top looks fine, bottom not (no marks on crankshaft surface). Comments as to the cause welcome (maybe metal particles from worn driveside shims in oil? Had quite some residues on the magnetic sump plug)

Thanks
e
Title: Re: Spring is coming ... Crank renovation
Post by: MG on 02.05. 2010 09:45
Looks like serious fretting/seizing to me. There are no signs of wear in the region around the oil holes, so I would think it had been caused by lack of oil pressure (and/or the crankpin is out of round), resulting in mixed/solid friction in the lower part of the bearing when exposed to combustion forces. If the premature wear had been caused by abrasive particles, I would expect signs of it around the whole bearing surface, so also around the oil holes and on the top side, but as far as I could see on the pic, everything looks pretty smooth there.

I can only suggest a theory here, however I dare to say that this is not what a timing side bush looks like when exposed to normal wear after considerable mileage, this damage looks very much like lack of lubrication to me.

I think it would definitely be advisable to check the whole lubrication system, incl. the pump(s), all valves (return, pressure relief) and passage ways.

You didn't have one of those anti-wet-sumping things fitted?

Open for discussion, looking forward to hear other's opinions. I think the evaluation of damage is one of the most interesting fields in engineering, although this probably won't be any consolation for the owner.... *roll*

HTH, Markus
Title: Re: Spring is coming ... Crank renovation
Post by: a10gf on 02.05. 2010 14:30
No anti-wet-sumping 'thing', all oilways fine, good return etc.

Crankshaft itself, bigend and timingside surfaces seems fine to me. Smoooooth to the finger, no feelable damage whatsoever (photos exaggerates scratches quite a lot). No feelable up-down play in conrods.

Oil must have been ok, or else I'd see damage on the bigend bearings?
Title: Re: Spring is coming ... Crank renovation
Post by: MG on 02.05. 2010 14:50
Quote
Oil must have been ok, or else I'd see damage on the bigend bearings?

Good point, that's true. If the oil pressure was so low as to wear the timing side bush, the big end bearings would have suffered as well, but they look pretty good.

Maybe the timing side bush hadn't been bored properly so that it didn't align with the drive side bearing?
Could also be the crank pin not being ground properly (not true to axis of rotation or geometrical deviations due to grinding wheel not running true). I have seen such results on some cranks before (unfortunately not every craftsman is as trustworthy and scrupulous like the local one I use).

Somehow I still can't believe this damage had been caused by abrasive particles, I would expect these to bed into the brass and rather damage the crank pin than the bearing itself with visible traces on the crank.


Do you have a micrometer to measure the crank pin? Would be interesting to see how far the wear had gone on the crankshaft. You could also check whether it is running true in the lathe.

Cheers, Markus
Title: Re: Spring is coming ... Crank renovation
Post by: alanp on 02.05. 2010 20:07
Just a small point - behind the drive side shock absorber the spacer which clamps up the bearing needs to be the correct way around. Mine was assembled with the spacer's bore chamfer facing outwards and the sharp edge facing the bearing. The chamfer is there to fit over the radius on the crank journal and hence reach the bearing inner race. My drive side bearing inner race chewed it's way into the crank journal (and any shims behind it if fitted) which was very expensive to repair. I'm not sure if all spacers only have one chamfered end but be warned.
Alan
Title: Re: Spring is coming ... Crank renovation
Post by: a10gf on 02.05. 2010 21:08
Markus, lots of good points to look into. Will come back with info.

Alan, thanks for the tip (no spacer on this engine, but will get one to align the primary chain, and maybe help to clamp the inner race -but, as mentioned, it's completely loose, I'd think metal spraying is the way to go). The picture should show the need for the spacer chamfer, one more detail learned.
Title: Re: Spring is coming ... Crank renovation
Post by: chaterlea25 on 03.05. 2010 23:12
hi a10gf
Interesting thread going on here!!!!
How well do you tighten the cush drive nut? I know SRM recommend 65ft pounds, I have made a tool which fits the slots in the nut with a hex for a socket on the torque spanner
From your photos it looks to me as if there were foreign bits floating around in the oil???
All the other comments are relavent too!!

Before you go off and have the crank built up have you tried a new bearing race on it?
As Markus advised a micrometer check is the only real test!!!

Regards
John O R
Title: Re: Spring is coming ... Crank renovation
Post by: IanH on 04.05. 2010 21:56
Hi all,
Only started posting today, this thread is just so interesting.

Regarding those horrible thin shims.
Finding a handful of broken razor sharp shim in my sump made me swear i would never use them again.

When I rebuilt my engine I ground out an old drive side inner race, having first checked it against the new one so the bearing would easily slide on and off the crank, that way I could fuss around with the shims and get virtually neglible movement with free rotation.

Instead of fitting all those skinny shims I measured the total thickness and used my lathe to turn and part off a solid thick shim/spacer. Gues my set was worn enough for the spacer to be thick enough for this to be practical. It certainly looked like a solid job after I finished and Ive had no problems since.

Title: Re: Spring is coming ... Crank renovation
Post by: olev on 26.05. 2010 10:51
Erling,
Have a look at Goffy's A10 rebuild on his web site.
Thats the one with character (and teeth).
He has only just finished rebuilding it and had all sorts of fun.
a good read.
cheers
Title: Re: Spring is coming ... Crank renovation
Post by: A10Boy on 27.05. 2010 16:53
The spacer is there to clamp the bearing to the shims and crank, not to align the chain. There are other shims to fit between the spacer and the cush assy to align the chain. Without the spacer in place, the whole bearing-shim-crank can float around, causing the bearing to spin.

The bearing and shims can't turn if the cush nut is tight, but often the nut loosens as far as the split pin and the owner doesn?t know its loose until it all starts rattling around and the shims are in the sump.