Author Topic: Gearbox rebuild advice  (Read 5102 times)

Offline Jules

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Gearbox rebuild advice
« on: 22.03. 2011 12:04 »
Hi guys, I have just joined the forum and am from Melbourne, Australia. I have reviewed a considerable no. of posts and realise what an extraordinary wealth of information you all carry *smile* . I purchased my 1956 A10 around 1978 when I was gung ho about doing a restoration project. The bike had been bush bashed and the engine blown up, but I wasn't daunted by that since I had all the time in the world to get it sorted. I didn't allow for children and house and garden projects though, which became the priority *sad2*. I did however, set about trying to piece together all the missing bits and did reasonably well over the passing years. I restored the engine, although sadly the people that rebored the cylinder barrels dropped them and broke a couple of fins *eek*. I then found that the frame and forks were bent and have fixed them, so onto the gearbox. I stripped it down many many years ago, then got distracted. I have now retired and got it laid out on the bench. I've followed up on the advice on removal of the 2 ball bearings and have to say thanks a lot for the advice on removal - the BBQ process worked like a charm at 400 deg F, although I haven't checked for any distortion, but the cases look fine. Getting the replacement bearings appears like it should be ok, although there seems to be some conjecture about the tolerances/specs.
- any advice on a specific bearing that "works" or ones to avoid would be great about now ????
Now we come to the bushes, I have measured the clearances between the shafts and the bushes and they look like this :
- Layshaft open bush in case 0.0063"
- Layshaft blind bush in case 0.0014"
- Layshaft 1st gear 0.004"
- Mainshaft sleeve pinion 0.006"
I dont really want to replace these because I think it will be hard to obtain/remove/replace/resize them easily and accurately, but would appreciate your experience with these types of clearances. I'm not too worried about noise, more about gear selection/jumping out  ????

I have a clutch lever that has a much larger dia. shaft than the bush in the case (dont know/remember how or why this is *conf*) so I need to grind down the shaft, does spindle with the spline on it unscrew from the perpendicular clutch cable lever or are they welded together, does anybody know this please  ????

The gears and dogs and shafts dont look too bad, so I think I'll leave those alone, unless anybody has any experience with anything specifically that can go wrong with them, even if they look ok  ????

The gear selector fork and the quadrant both look worn but I suspect would be difficult to replace, are these parts "sensitive" to selecting/jumping out of gear  ????

The kickstarter pinion and ratchet teeth are quite worn and sharp, but seem to still mesh ok, is this a sensitive area or can I get away with this do you think  ????

The 4 nuts that hold the end cover on are well recessed into the case, what type of spanner do you use for tightening them without damaging the nut or case  ???? are there any alternate nuts around that are more decorative  ????

The book suggests that you cant remove the gearbox without removing the engine first, so I assume that I must reassemble the gearbox into the frame before I can fit the engine - is that really the case, or can I fit the engine first to the frame (its much heavier/harder to manage than the gearbox)  ????

Thats about all for now, sorry about all the questions but I would really appreciate any of your thoughts on any of the above - to put it into perspective, I guess I should say that I dont plan on riding the bike far/much, its really only for local, good days out for a coffee, not for racing around on, cheers


Offline A10Boy

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Re: Gearbox rebuild advice
« Reply #1 on: 22.03. 2011 14:00 »
I will leave the gearbox tech questions to those with more gearbox experience than I. However I took the gearbox out of my swing arm A10 with the engine still in the frame and had it professionally refurbed. You will need to fit the box and the rear engine plates together, its a bit fiddly but its OK.

HTH
Regards

Andy

1960 A10 - Black Golden Flash
Plus
1974 Kawasaki Z1a
Yam XJR 1300

Online bsa-bill

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Re: Gearbox rebuild advice
« Reply #2 on: 22.03. 2011 14:35 »
Hi Jules
parts for the gearbox are not as hard to get as you seem to think, AFAIK all bushes can be had and both bearings, also the blind layshaft bush can be got undersized (Lyford Classics)
Mainshaft and Layshaft both available new, although as you might imagine not for pennies but probably no more expensive than new for any other bike even modern?

If the selector pawl is worn I would replace it, kick start bits are also available new but one of them (can't remember if it's the pinion or ratchet) is rarer

Gears don't seem to take much harm, would be considered over engineered these days I think, but that to our advantage

Possibly postage to Aus is going to make it a more expensive exercise, so I leave it to your down under mates to come up with suppliers
Good luck with it - Bill
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Offline Goldy

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Re: Gearbox rebuild advice
« Reply #3 on: 22.03. 2011 16:44 »
Hi Jules and welcome. You will find service sheet No 702 gives the tolerances that you are looking for
.http://classicrider.dk/dokuments/ServiceSheets/sectionX_BSAservicesheetno702.pdf    All the best Goldy
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Offline Jim

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Re: Gearbox rebuild advice
« Reply #4 on: 22.03. 2011 18:24 »
The 4 nuts that hold the end cover on are well recessed into the case, what type of spanner do you use for tightening them without damaging the nut or case  I've always used a box spanner, I don't think that anything else will fit

The book suggests that you cant remove the gearbox without removing the engine first, so I assume that I must reassemble the gearbox into the frame before I can fit the engine - is that really the case, or can I fit the engine first to the frame (its much heavier/harder to manage than the gearbox)  I also have removed and refitted a gearbox without taking out the engine (I assume that yours is a SA version not the earlier plunger which can't be done without removing the engine).
Wimbledon, England.
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Online chaterlea25

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Re: Gearbox rebuild advice
« Reply #5 on: 22.03. 2011 22:22 »
Hi Jules,
Hope this is ok and helps, refer to the service sheet recommended , But
If the layshaft bush has 006 at one end I would think it willal so be much the same at the other?? put in the layshaft and see how much it will wobble!!!
0.006 is too much on the sleeve gear bush and will leak oil
Replace any worn or damaged selector forks/ camplate index plunger/spring

I dont believe there was a bush in the clutch case originally?? bore this out to suit the lever!! is the lever the correct one?
not from a plunger model box??
The kickstart pinion wears and causes jamming (so f***ing annoying!!)

The proper nuts for the gearbox outer cover are 3/16W hex and are "deep" nuts, correct socket no worries!!

Look for wear /pitting on the load sides of the gear teeth, hold the gear up to the light ansd you will be able to see if the tooth profile is flattened,
Have a look on the forum on noisy gearbox issues

The box can re removed with thw engine in place but its necessary to remove the rear plates
when building its easier to fit the box and rear plates first then the engine and finally the front mounts
To make it easier to work on a lot of people fit the engine bottom end into the frame then build the top end in situ

HTH
John O R
1961 Super Rocket
1963 RGS (ongoing)

Offline A10Boy

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Re: Gearbox rebuild advice
« Reply #6 on: 23.03. 2011 08:52 »
I had my gearbox re-built by a friend who repairs BSA boxes as a kind of semi retirement hobby. He has all the kit necessary and does a great job, he must have enough good serviceable or NOS parts to re-build a hundred gearboxes. I contacted a well known northern gearbox repairer and was quoted four weeks and £50 just to strip mine. My friend turned mine around in 3 days, and it works a treat. He fitted new bushes, bearings, seals and replaced any worn gears / dogs with un worn or NOS parts He can even polish the front case to a professional standard and replate any galv items if required. I think its brilliant that these skills are still being practiced in home workshops, he's an enthusiast rather than doing it for the money, and he won't do anything but BSA boxes. All done, mine cost about half the price of a commercial rebuild.

I know this isn't much help to you Jules, but if anyone in the UK is in need of a repair just pm me.
Regards

Andy

1960 A10 - Black Golden Flash
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1974 Kawasaki Z1a
Yam XJR 1300

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Re: Gearbox rebuild advice
« Reply #7 on: 23.03. 2011 11:34 »
Firstly, get new kickstart & pinion.
Don't even think of using the old ones if they are as worn as you suggest.
They can & will lock requiring you to engauge 1st & rock the bike back & forth, not fun at traffic lights.
Or the kick start ca fail to grab & the lever plumit to the ground taking your leg with it ( also not fun )
There is a mob in SA , "Classic Fasteners"   think that do a full range of BSA bolts in stainless at reasonable prices.
I find it easier to fit the cases into the frame then add the barrels & head, much lighter & easier to handle.
As stated before the separate boxes can be pulled out with the engine in place, the bolt up ones can not.

A set of deep 3/8" drive ww sockets will get you out of trouble.
Even better is if you can find some good quality 1/4" sockets but they need to be good not $15 for a set of 30.
Bike Beesa
Trevor

Offline Jules

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Re: Gearbox rebuild advice
« Reply #8 on: 27.03. 2011 03:31 »
First of all thanks to all for a great response and feedback, now I know I can fit the engine back into the frame and get on with some of the frame stuff, while working out how best to manage the gearbox rebuild.
For the gearbox then :
BSA_54A10 - thanks for the prompt on the nuts and bolts and spanners, I'll look them up and check out, would you have a list of "good" suppliers that you have used in Australia by any chance for parts and work? eg who did your g/box refurb. what parts did he use/cost? etc, the guy in UK sounds like a useful contact but I'm not sure I'll be "allowed" to carry it over (by my wife *eek*) when we go later this year.
A10Boy - actually I may very well be interested in your friend rebuilding my box. I just weighed it at around 12kg, so may be able to bring it with me when my wife and I come over later this year, then bring it back with me. Would you be prepared to let me have your friends email/ph. no.? and some idea of his charge for a rebuild please?
chaterlea25 & Jim - thanks for your tips partic. the confirmation about engine fit prior to g/box. The engine will be difficult to fit anyway because its fully assembled and heavy/awkward, so will help without the g/box being there I think.
Goldy - I downloaded the spec. sheet for the bush sizes, thanks, are there other spec. sheets like this available on line for other parts, do you know?
bill - thanks fpr the prompt on parts, I've looked up Lyford Classics, wow they have an incredible range, I reckon you could build a new bike from their parts (if you could afford it *smiley4*).
[i]Which brings me to the last question - is there a listing in the forum somewhere of all the useful suppliers/contacts that the forum has used over the years including o/seas suppliers??[/i] if not, does anybody have a "recommended listing please? I shall be in UK later this year for a holiday with my wife and might try and pickup some parts while there, cheers

Offline Goldy

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Re: Gearbox rebuild advice
« Reply #9 on: 27.03. 2011 12:40 »
Yes Jules all the service sheets are available online. There is the classic rider site (http://www.classicrider.dk/english/technic/ServiceSheets.php ) or of course they are all on this forum under the section BSA related links.
56 A10 Golden Flash - Restore, ride, relive.                                          
56 C12 BSA project ongoing

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Re: Gearbox rebuild advice
« Reply #10 on: 28.03. 2011 13:03 »
I do all my own save maggys , dynamos & speedos.
nuts & bolts from classic fasteners
M20 bits from Bill Green
A 7,10 65 & B44 bits from Mike Riely
Bantam its from various UK suppliers
Cables from Conwire
Batteries from Batterys direct
Bike Beesa
Trevor

Offline brackenfel

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Re: Gearbox rebuild advice
« Reply #11 on: 29.03. 2011 14:15 »
Hi Jules,
Welcome !! I've been away and am probably largely repeating what has already been said but here goes just in case I'm adding anything of value :-

Swingarm models box will come out without removing engine. It's a fiddle but possible. Loosen everything and remove the adjuster. Top plates need to come out, the RHS one is fiddly but you can just about angle it out past the timing case. I already had removed footrests , oil pipes etc - anything that could get in the way! I found no need to loosen the engine itself.

Dismantling the box is straightforward. I had the help of an ex Rolls-Royce engineer friend whose experience was invaluable with the replacement of bushes & bearings.. In the event though  bushes came out once the casings had been heated, you just needed a range of suitably sized drifts. The new ones went back in the same way but as they compressed slightly a small amount of reaming was often needed to get the various shafts back in comfortably..

As others have said, plenty of reliable suppliers with a good range of parts - I use C&D Autos, good service, well priced & very helpful with telephone advice.
All parts available but as far as I know the fixed part of the kickstart pinion is not available new at present, in the UK anyway.  If the kickstart jams I find use of the clutch and kickstart together will free things up enough to find a point where everything will mesh again!

I'm just at the reasembly stage now, box back in bike, just got to sort out the primary case outer & put the exhausts & footrests back on & tighten everything up!
Hope this is of use...

Adrian
1961 A10 650 Golden Flash - Blue
1954 BSA B33
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Offline A10Boy

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Re: Gearbox rebuild advice
« Reply #12 on: 07.04. 2011 20:16 »
For those who PM'd me for contact info of my repairer, I have PMd it back to you.

Cheers
Regards

Andy

1960 A10 - Black Golden Flash
Plus
1974 Kawasaki Z1a
Yam XJR 1300

Offline wilko

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Re: Gearbox rebuild advice
« Reply #13 on: 07.04. 2011 22:54 »
Why remove the gearbox?For the sake of removing the layshaft and mainshaft  bearings, i wouldn't bother. Easy enough to remove bearings insitu with a heatgun or propane.

Offline Jules

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Re: Gearbox rebuild advice
« Reply #14 on: 09.04. 2011 08:21 »
Andy, thanks for updating this post for me, glad you did actually because I haven't seen a PM from you yet? would you mind resending to my email please?...... I think I may be able to get the box to the UK  ;)
Wilko, I have the whole bike in pieces for restoration, so the gearbox is already out on the bench, however, I'm intesrested in your opinion regarding the bush wear, if you have any experience in that area?
Adrian, thanks for your thoughts, the issue on the bushes is that they are quite thin, hence drift sizes become critical I think, also the main ones that seem to have worn are in the gears/pinions, hence heating will not help much??
thanks also to BSA_54A10 and Goldy for their feedback, I've looked up your suggestions too, cheers