Hi I have problems with my existing gearbox and have obtained a refurbished one. Could someone advise me on the best sequence of steps for the removal and replacement of the gearbox and useful things to know, ie which side does the gearbox come out, primary side or timing side, do you need to remove the inner primary chaincase, can you get it out without removing the magneto. any tips would be most welcome. cheers, Cliff
Hi Cliff
I took mine out last weekend and stripped it, it's pretty straightforward. The BSA service sheets on the members area have all you need.
The primary chaincase and clutch has to come out.
From what I learnt and with hindsight it would have probably been better to strip the gearbox in situ as there isn't much to them. Unless of course you need to replace the shafts.
I'm not an expert by any means so I am sure there will be some knowledgeable people along soon.
Having removed the clutch and primary case you will need to remove the engine plates on the kickstart side. There is not enough room to remove it without doing this. Support the engine whilst doing this.
Robinson,
Depending on which A10 you have will determine whether it is easy or difficult to change, if it is a plunger model you will have to remove the engine, to get the gear box out as it's bolted to the engine, swinging arm models are much easier.
Just thought I would mention that as you did not say which model you have.
Regards TTJohn
Well done in obtaining a refurbished gearbox. Changing it out will not be a problem for a swinging arm model.
I have just stripped down my gearbox to find some horribly worn bushes on the layshaft. I will sort it out this week. Also I will put some pictures on the site in a new post.
I am interested in where you sourced a refurbished gearbox and how much it was. Depending on your model I may be interested in you old gearbox.
John
Thanks to everyone who replied, I should have stated that my bike is a 1960 swinging arm model, so the gearbox is not bolted to the engine. I'll let you know how I het on with the exchange. Cheers, Cliff
Hi All, I thought I would provide an update to this post having now fitted my refurbished gearbox; as with most jobs it was not that difficult once I made a start.
Sequence of stripdown:
1. removed exhaust system, foot rests and rear brake lever and disconnected speedo and clutch cables
2. removed primary chaincase cover, dismantled clutch and removed primary chain.
note: the clutch centre hub was a real pig to remove, but it succumbed to a combination of clutch centre puller, heat gun and hammer.
3. removed inner chain case
4. undid gearbox sprocket nut and then removed rear chain
5. removed air filter and "ski ramp" cover between engine plates
6. undid all the engine plate bolts and gearbox pivot and adjuster bolts
note: had to slacken and reposition oil tank pipes to clear top rear bolt. (no need to remove oil tank, carb or magneto)
7. removed r.h.side engine plates and lifted gearbox out from r.h.side
Following clean /inspection/refurbishment of parts, replacement of new gearbox was effectively a reverse of the stripdown, after loosely fitting bottom engine plates and lifting gear box into position. Getting all the bolts in was a bit of a faff but they all went in eventually. The clutch is best built up on the bench and the assembly carefully fitted to main shaft once the inner chaincase has been refitted.
Thanks to all for your advice, cheers, Cliff