Taking the plunge(r) into the unknown
3.45 AM. My God... what have I done!
This became a long & detailed story. Read it if you consider having work done on your crankshaft.
04 July 2000: Action Needed
The exhaust note could no longer hide an increasing deep noise coming from somewhere in the middle of the engine, so it was high time to act before any serious damage took place. The GF was still running fine and starting first kick, tough. After much mental activity & reading I finally made up my mind to dismantle the engine myself, which proved manageable for even a person with limited experience such as I. First the top, cylinder, dynamo, magneto, clutch etc were removed to make the engine lighter. On this model the gearbox is fixed to the engine (later A10s have a gearbox that can be removed while leaving the engine in place). The crank\gearbox where then relatively easy to lift out of the frame and onto the operation table. Keeping track of parts and a suitable place to work is vital, and suitable extractors to remove the cam pinion etc is a must.
Splitting the crankcase proved very easy, and it looked in good overall shape. Noticed the 2 halves had the same 3 figure number stamped on them, meaning they where made for each other. Inspection of the crankshaft revealed the expected problems: big ends & main bearing bush had done their job and were unfit for duty. Opening the sludge traps for cleaning revealed a lot of old sediments from time immemorial. On the timing side the sludge was thick and oily, on the drive side it was quite petrified & dry which I suppose shows less oilflow to that side due to worn main bush & subsequent loss of oil pressure.
A renovation of the crankshaft & new bearings is the only viable remedy, and this must be entrusted to someone with experience and tools to match the job. At the same time bushes for camshaft & idler pinion will be checked. With balancing, bearings, shimming etc it seems like an area where one can spend much money, so I have to figure out exactly what's to be done, and find someone that can do it.
The SRM timing side conversion was an option. If this was a Road Rocket or Super Rocket I'd done it without a doubt. The original timing bush design is according to owners opinions fine for the A7 & the GF's lower rpm\hp (provided regular oilchange etc) but it can wear down quickly in a RR or SR, as these machines stretched the basic A10 design by adding rpm's & hp's without strengthening the crankshaft bearings to match.
01 August 2000: First Steps
Finally decided to let a local company handle the regrinding & crank rebuild, as they have some experience with classic British & other motorcycles. Left them the crank & all the tech info I could gather, together with addresses where they could get parts. The guy I delivered it to seemed confident they could do it, we went trough all details, got an estimate, and they would look at it over the weekend. So let's see...
31 August 2000: Ready??
Fit for fight, ready to put the engine together. Called the workshop:
- Hello, can I come by and pick up the BSA A10 crankshaft?
- Crankshaft? what crankshaft... (-silence-) Oh... (-presumably looking around in the shelves-), that one... Sorry, we haven't looked at it yet. (-silence-)
- That was not the deal. Did you order the parts & bearings, at least?
- (-silence-) What parts, do you need any parts?
- Yes, I went trough all that in detail when delivering the crankshaft, and provided documents related to A10 crank regrinding & addresses to where to get parts.
- Was there any documents? Let me look... (-goes away for a while-) Can't find any.
- Holy #!*#!! Why did you take on the job, if you didn't intend to do anything?
- We are sorry, have had much to do. I'll look at it and call you tomorrow.
So, this was my first experience with professional help. Having acquired some skills in the art of patience & forgiveness (after starting with old motorcycles), I'll let them continue, as the guy I talked to showed traces of humility and willingness to do something.
01 Sept 2000: Plan B
They actually called, and said they could get the parts & start very soon (they said that a month ago also), their price estimate for the parts seemed much too high. But I already had a new plan. Due to the change of bearings, bushes & shimming etc involved it might be wise to go to somebody who can do the complete job, including reassembling & control of the crankcase. Finally found someone here that maybe can do the job, according to the Norwegian BSA club. So off it goes.
10 Nov 2000: It's back!
It didn't disappear in transit. Entrusted the crank to a company called Wagner's Mechanical. Talking to him on the phone before and under the process gave the impression of someone who may know what he was doing. So, just waiting for some gaskets etc, & I'll take refuge in the garage for a while. Over 4 months without driving the A10... The Triumph has seen a lot of road, but I miss the GF.
23 Dec 2000: The end is near!
All parts arrived some time ago (first class service from BAS Motor in Sweden) & have at last some spare time, planning on getting the bike on the road before the end of the year. Got the gearbox back on, fitted a new mainshaft gasket & a 21 gear drive to get the rpm down. Fitted a new chaincase oil seal (behind the clutch). All well... BUT, during the handling of the crankcase I got suspicious about the seemingly very large crankshaft endplay, the crankshaft moving back & forth with a loud "klunk". Not reassuring. This much movement from left to right must be damaging to both the lh roller & the rh bush. Did a measurement which showed the endplay to be over 0.01", books say max. 0.003". Madre De Dios! Don't like this at all. End of the fun, tools back in the toolbox, and will have to contact the workshop and ask what they were aiming at. May have to split the crankcase again & do the shimming myself. Didn't I just pay a professional to do this properly??? The workshop sticked to their 0.01" idea, mentioning Nortons & Triumphs. I was not sure this would apply to the A10, & they did not know that the Haynes manual & Bacon Restoration specified 0.003", & the BSA Service Sheet nr 208 & 215 specifying less than 0.005" & 0.003 respectively.
28 Dec 2000: All together now, attempt 2, 3, 4 & 5
Shimmed it down myself to right under 0.003", following advice received after posting on the BSA pitstop, and sticking to the available literature. Took the crankcase apart by gently inserting a thin kitchen knife at the edges & gently tapping it in, doing the same around the crankcase joint. Got the bearing off easily after heating it, took out the shims (which where 33mm, too big & loose!), put in new 30mm shims, and put it together again. 2 quite thick shims seemed right. Too tight, locked the crank. And again, did some filing work on the inner shim to make it fit the slight curving at the base of the mainshaft. Had to redo this a couple of times. In the end, Bingo. Looks tight & stable. The bearing makes good contact with the whole surface of the outer shim, & the inner shim is tight against the flywheel. Play is now between 0.003 & 0.002 at room temperature. All went very smoothly, starting to make use of the experience gained.
Received many different opinions about shimming, going from 0.01" to less than 0.001". Opted for slightly under 0.003 due to the temperature differences in Norway. If I understood it right, the aluminium crankcase might make the endplay too small when starting the engine at cold temperatures. It may be that in warmer climates the basic endplay can be set to sub 0.001, but I did not want to try that here. Will check the endplay again after a period of use.
Forced oil into the oil retaining ball-valve behind the oilpump, until oil got out from the big ends. This will fill the oil channels in the crankcase & the sludge trap, & should make the initial startup quite safe. Then oiled all the bushes, cam, bearings etc. Got the gearbox back on. While having the engine on the table I put the the oil pump in, with a new fibre washer at the front stud, and slightly enlarging the holes of the paper gasket, then taking care to align it properly with the crank & pump holes before tightening. Fitted the clutch & cush temporarily to see if everything aligned well.
So, "only" have to mount the engine in the frame, & the clutch, cylinder, top, carburettor, cables, oil, petrol tank, ignition timing, cush drive, valve setting, etc etc. Jezuz, never imagined it could be possible to do som much work on just one motorcycle. Now I know. And next time it will be easier...
22.01.01: Alive & well.
Back on the road, engine running. Started easily, great to be riding the GF again! After the running-in period I'll know if it's all been successfull. Looks good so far (anything else would be seriously unfair!).
20.04.01 All is still well...
900 miles, no problems. The cranckshaft endplay seems fine, and the oil does not contain (too much) metal particles.
So maybe the bottom end is sorted out. Time to think about a rebore, new pistons & a top overhaul. Great to have an old bike, no problems wondering what to do sunday afternoon, & what to do with any money that may lay idle.