The BSA A7-A10 Forum

Technical => Clutch, Primary, Gearbox => Topic started by: ADP91 on 10.07. 2015 21:03

Title: Gearbox overhaul
Post by: ADP91 on 10.07. 2015 21:03
Hi everyone,

Just picked up my swingarm a10 gearbox and I'm in the process of making a list of parts to order for an overhaul. What parts should I be looking to replace? I'm assuming gaskets, seals, and bushings but are there any other wearable parts that I should be aware of?

Cheers
Title: Re: Gearbox overhaul
Post by: chaterlea25 on 10.07. 2015 23:35
`Hi,
If the gearbox came from an A10 then usually theres wear on the layshaft where it runs in the case bushes
The shaft can be machined or ground undersize and bushes made to suit.
Look for wear on the gear  engagement  dogs,
Quite often the final reduction gears at the inner end of the box will have wear on the gear teeth
Look for wear or pitting on all gear teeth
Check for wear on the selector forks and camplate,
Usually the kickstart quadrant and ratchet gear will be worn
Its good practice to replce the gearchange return spring/ kickstart spring, but not essential
The clutch arm pivot can often need bushing as the case wears

HTH
John
Title: Re: Gearbox overhaul
Post by: KiwiGF on 11.07. 2015 01:28
The sleeve gear bushes are often worn....you can check for this by seeing if the final drive sprocket has up and down play....they are not expensive but need honing to size after fitting.

Edit: not the sprocket but the shaft....see below....

You might want to replace the ball bearings on the main shaft and lay shaft whilst you are doing the job.

Best thing is dismantle and inspect and then make your list up?
Title: Re: Gearbox overhaul
Post by: duTch on 11.07. 2015 03:26

  *????*
Quote
The sleeve gear bushes are often worn....you can check for this by seeing if the final drive sprocket has up and down play...
*????*
 Am I missing something, or did you mean the clutch end of the mainshaft...?

Title: Re: Gearbox overhaul
Post by: KiwiGF on 11.07. 2015 07:30
Dutch you are right I meant the play will be felt in the main shaft not sprocket  *doh* *problem* *dunno2*

Oh, and the oil seal on drive side of the main shaft will probably need replacing....
Title: Re: Gearbox overhaul
Post by: Rocket Racer on 11.07. 2015 23:44
I'm just refreshing an SC box and the sleeve gear bushes were really bad. And has the usual layshaft wear issues.
The Kickstart gear on the end of the mainshaft are also often clearly visually worn but readily available. Bit hard to miss the wear on that.
If the dogs are pitted you will typically find gear noise when riding. These boxes are pretty robust and foolproof  *whistle*.
Replace the sleeve gear seal and the natural time to review the final drive sprocket