Some time ago I rebuild a wd m20 gear box from parts I had laying around.
The problem was the new main bearing didn't clamp enough in the housing.
So I used a bit of loc tite to secure the bearing.
Eversince then I have been wondering, is that strong enough tot keep the bearing in place..?
Anyone ever tried this ?
(Ian W ?)
There is a loctite product for just this job (sorry can't remember the Loctite nuber off hand) so if you used this it should hold.
Loctite make a special "bearing fit" product. An absolute bugger to remove a bearing once it's been applied. Ron
email (option): ronpier@talk21.com
I recently used Loctite 609 to secure a loose outer race in another bike, which seems to've worked.
I would never glue a bearing in place. If the housing in worn it will be off center. The best way is to liner the housing.
email (option): pes.sales@btconnect.com
Or replace it...I probably have a good outer case if you decide to revisit the job but not immediately as I'm pretty busy at the moment....Just contact me off forum if it comes to that...Ian
email (option): ian@wright52.plus.com
Thanks for all the reactions and your offer, Ian.
But its a spare box so I will keep it this way.
Whether it's a proper repair will depend on the degree of damage and the product used. If the housing simply showed signs of the bearing moving or it has become a push-fit when cold then with everything properly de-greased, I'd expect it to be spound. It's quite common to use Loctite on Norton twin gearbox bearings 'just in case'.
If however you have a rattling fit then alignment is going to remain a problem.
Loctite do indeed do a bearing lock, 641 I think. I used to use it in my Yamaha TZ350 to stop the bearing outers from spinning. Even thought they were pinned to stop this they would still try to spin. By the way I never had a problem except as stated, it is a bit of a bugger to remove.
email (option): tony-wilkinson@sky.com
As for the bearing housing being off center if worn, I hate to give you the bad news but they are off center when new. Both the gearbox housing and inner cover were bored on different worn out machine tools. This is not just a BSA problem as all the brit bikes of the era have the same issue. One day when you have nothing better to do, measure the locations of the bores on a known good gearbox or crankcase. You will be surprised how bad they can be. This is why you can't run small clearances on the gearbox sleeve gear bushing or it will seize. On some bikes like Velocette you will see bearing bores not only off center but not even bored parallel.
Years ago before I retired, we put a set of unit Triumph 650 crankcases on a Coordinate Measuring Machine at work. Pretty much nothing was accurately machined but the engine ran perfectly when assembled.
It's funny you say that Bruce, for the unit singles we have manufactured tooling/match plates for them. This allows us to machine new castings and makes repairs easy. What we have found is that the very early engines hold very tight positional tolerances. The seventies stuff is not so good, but other companies latter work is beyond horrible.
I will in time produce Tooling plates for the M20 and it's siblings.
As for gearbox bushes, I expect firstly they were not machined concentric in the first place. Eventually being made worse when finished to size.
Another thing I discovered is that castings move with age. Not a lot, but they do move. Even solid material moves when we machine it. Where possible I leave finish cuts towards the end of the process to correct the shift.
email (option): pes.sales@btconnect.com
The question is of course too general since each case is on its own. If the play is too big, then as said here before - the glue will not do the job. The glue method is only to compensate very small gaps. If you are experiencing a big play, the only correct form is to machine the area and implant a new housing that will get a new bearing. All this has to be done with very tight tolerances, so the new bearing housing will need to be heated in order for the bearing to drop in place. It is true that in our ancient ladies produced for the war, the reliability is high and they are able to absorb a lot, but still, there is a right method and there is an improvised method, where everyone of course will choose what is convenient and suitable for him and according to their abilities.
BTW - it is easy to brake loose Loctite glue (and other brands), just apply a bit heat.
BTW nr. 2 - I stopped using Loctite many years ago and I now only work with the stuff from -
https://www.distrelec.ch/en/manufacturer/ergo/man_erg#productsCount
I find them better and also the price is good.
email (option): michasteinmann@gmail.com
I agree with Michael..You can't really generalise about about the solutions to varying degrees of wear...
I also think that applies to build tolerances...The various companies had different amounts of resource, different manufacturing equipment and different attitudes within the organisation...A broad assumption about the quality of machine tools throughout the industry is a fairly erroneous assumption IMO...For example, BSA used the same machine tools they manufactured gun barrels on to make telescopic fork legs post war, the former being a precision component that required specialised machine tools in good condition for accurate manufacture...
They also owned BSA Churchill, a machine tool manufacturer...During the factory bombing in 1940 over 1600 machine tools were destroyed and they were replaced largely by new machines of BSA's own manufacture...
Standards varied over time and the late 60's/early 70's in particular were not a good time, as the companies got into deeper financial trouble and tooling and production standards were allowed to slip (I saw that first hand in the 70's)...
My experience of 40's/50's BSA components is that it is possible to interchange components manufactured over extended periods without any real tolerance issues...That indicates that the production tolerances were routinely and consistently maintained. That might be expected perhaps, from a company originally set up specifically to produce interchangeable gun components....
A study of the M20 standards books (there was more than one issue of these publications) shows that production tolerances were entirely within the expected ranges for the period and are certainly not overly 'loose'.
The fact there is a publication that contains such information for use at overhaul would imply an expectation that those tolerances would be found when examining an engine...
Whilst everything was manufactured in a 'pre CNC' era when it was necessary to apply an appropriate tolerance to any manufactured part, it should be remembered these things weren't generally built without production and quality checks (for confirmation note all the inspectors stamps present on the engines)...The general rule was the closer the tolerance the higher the level of inspection...When I worked at the more extreme end of that regime at British Aerospace it was 100% inspection for some critical component batches...Ian
email (option): ian@wright52.plus.com
Hello Ian,
I currently own about 30 motorcycles, most are British from a 1929 AJS up to a 1972 Commando. I have AJS, Ariel, Triumph, Norton, BSA, Sunbeam, Velocette and Matchless. Also have some Italian bikes.
I worked at a dealer who sold Triumph,Suzuki and Moto Guzzi in the 1970's so I saw a number of new bikes that came in for warranty repairs. Triumph Tridents were the worst and some looked like they had been assembled by workers with their eyes closed! On occasion I would have to go to the Triumph/BSA headquarters in California which was only a few miles away. I knew the national warranty manager and he did not have a good job with dealers complaining about the junk the factories were sending them. They had a Triumph 650 on display that the frame broke injuring the rider (who was now suing Triumph)as they had forgot to braze the frame at all. It was assembled, drilled and pinned and than painted without being brazed.
From my first British bike, a 1972 Triumph Boneville, which had the improperly heat treated five speed gearbox which broke second gear twice I also had a 1973 Triumph T25T which would wear out exhaust valve guides in a hundred miles. The rocker arm on the T25T was made too short and was almost not long enough to even touch the top of the valve. The Boneville although it ran fine and I put many miles on it, when it came time for an overhaul of the motor, the cams bushings were seized on to the camshafts and the bushings were turning in the cases. Why did this happen, because the cam bearing bore in the two case halves were not bored in line. They were off by .010". This was the start of my learning that the factories were capable of doing very poor work. Later I got a 1961 Triumph Boneville where I could not tension the primary chain properly as it would be loose or tight depending upon where you checked the chain. OK so it has a bad chain, no they bored the hole in the center of the clutch basket .125" of center.
I could go on and on about Velocette as they take the prize for post-war bad machining. They bored the main bearings on a lathe and the rest of the holes on the cases were done on a multi spindle vertical mill that it appears no one ever checked the tram of the mill so all the the holes in the timing chest are never parallel with the rest of the motor. By the late 1960's with the money running out, Velocette did some very bad work.
AJS, Matchless seem to have the least amount of problems from bad workmanship.
On my M21, when I got it the magdyno had never been off the bike and still had the security screw on the mag. Bike was parked in 1961 with 2200 miles on it so no one had a chance to bodge it yet. Under the magdyno was a .016" shim. Without the shim the gears would touch and lock before you could even tighten the magdyno strap. And no the platform and magdydno base were not worn at all. The magdyno mounting platform was machined too low. The shim looked professionally made and was definitely added when the bike was built. As for the rest of the machining on the bike, all looked OK.
I have a complete machine shop at home and can measure and see things most people would maybe not. Had I not the tools for measuring this I would be oblivious to how bad they made some parts.
And finally, the majority of British bikes I have worked on over the years were machined and made fine. I don't want to give the impression they are all badly made.
Anyway this is a BSA M20 forum so I will shut up.
Hello Bruce,
Thank you, it is very interesting what you are telling here from your personal experience.
And in conclusion - and this is only my personal opinion - apparently this is the reason for the decline of the British Motorcycle Empire from its greatness.
email (option): michasteinmann@gmail.com
Lots of late Triumphs in there...I had a similar QA issue with a brand new T140V...Later BSAs also suffered from similar problems...
As a Toolmaker I have a good grasp of what I'm looking at and the fact I like 40s/50s BSAs is no accident...My experiences with BSAs of this era have been good on the whole...I certainly wouldn't suggest everything was perfect, it wasn't and a job like the M21 mag shim would have been a typical 'rework' of an incorrectly machined component to avoid scrapping it...
When everything was produced manually with the attendant 'errors' that occurred these strategies were not uncommon and after rectification the machine would have functioned without problems...Not ideal for sure as the crankcases would then be non standard...However, that is an entirely different problem to basic machining inaccuracies or similar that passed through inspection undetected...
Much of the production challenge pre CNC was to keep scrap levels at an acceptable level...The actual reasons for the production errors varied and having worked in various manufacturing environments it is definitely the case there were wide variations in performance from company to company...My point really was that a generalised statement regarding the performance of a whole industry will nearly always be incorrect as it is more nuanced than that...Ian
email (option): ian@wright52.plus.com
Thank you, it is very interesting what you are telling here from your personal experience.
And in conclusion - and this is only my personal opinion - apparently this is the reason for the decline of the British Motorcycle Empire from its greatness.
Failure to develope new products = bad mamagement
Failure to do appropriate research = bad management
Failure to appreciate the politics on the shop floor = bad management
Failure to upgrade production lines = bad management
DIverting money to buy non profitable subsideries = bad management
Now the reasons for all of this bad management are quite varied from the British Class system
Through to lack of availible finance
Once the person whoes name is on the products relenquishes control to money men in any industry , most are doomed to failure eventually .
Founders have a clear vision & purpose
Latter date dividend / bonus farmers are only interested in the money
Look at Apple after Jobs left, flounderd for a long while till a person with vison was found to run the company
Look at the US auto industry gone almoost nowhere since the 60's till Musk came along
Briggs & Stratton went down hill once the founders left ( to form OMG ) to the point that they are bankrupt again and look like going under all together .
When you move you factory 1/2 way across the state for no reason other than the wages there are 5% cheaper than in Wisconsin , it says some thing about how the management views the employees.
HD under the management of AMF
In the case of BSA they were doomed from the day they decided to put the pre WWII C series back into production .
The rejection of the horizontally split crankcases originally planned for the A 65 by a boad who would not know a motorcycle from a mixmaster ensured that the A65 would be plagued by warranty problems and cost 30% more to make than the original engine design .