The BSA A7-A10 Forum

Technical => Clutch, Primary, Gearbox => Topic started by: Minto on 12.09. 2019 19:43

Title: Gearbox leak
Post by: Minto on 12.09. 2019 19:43
After going for a longish ride with the North Bham VMCC at the beginning of the month, I put the A10 away and didn’t look at it for a couple of days, when I did, there was a proper puddle of oil under it, and the bottom of the gearbox was soaked in oil. I assumed from where it seemed to be coming from that the outer cover gasket had gone, so dried it all off and left it for a day with a clean piece of card under it to try to pinpoint where it was actually dripping from. Anyway, turns out it’s the speedo cable, not where it enters the box, but further up the cable where it’s routed close to the exhaust bracket, it’s worn through the plastic outer and oil has made its way up there then out and back down and onto the bottom of the box, frame rails exhaust and all over the garage floor.
I’ve disconnected the cable and left it hanging loose, and it’s dropping regularly from the end, so definitely from there.
I assume that oils not meant to make a bid for escape via the speedo?
So will a new cable sort it or will the lack of wear hole mean that I’ll end up with a very well lubricated speedo?
Title: Re: Gearbox leak
Post by: RDfella on 12.09. 2019 20:44
Ditto. My project bije has a S/A BSA box and there's a puddle collecting under it - coming from the speedo drive. There's no cable on it yet, but my concern is that if there was, presumably there'd be less or no leak - but the cable would be full of oil at the bottom end. Which can't be good.
I was going to post a similar item - it it usual for them to leak from the speedo drive?
Title: Re: Gearbox leak
Post by: muskrat on 12.09. 2019 21:21
G'day Minto.
There will always be a little oil in the bottom run of the cable but highly unlikely to reach the speedo. They usually leak from where the fitting is swagged onto the cable outer. I put a length of shrink wrap over this point. You could do the same where your leak is and rout the cable away from the pipe bracket or use a spring over the cable at that point.
Title: Re: Gearbox leak
Post by: Minto on 12.09. 2019 22:36
cheers Musky
It does seem to be a common issue, probably cos the speedo drive is lower than the level plug.
The spring around the cable’s a good call. I’ll wrap some PTFE tape round it first, then some shrink tubing.
Title: Re: Gearbox leak
Post by: Swarfcut on 13.09. 2019 08:15
 Minto....Yes, somewhat annoying to find your new cable outer melted by the hot pipe or cut by the nice sharp edge of the bracket. I got a 50mm long piece of cast off copper 15mm water pipe, slit it lengthways , slipped it over the speedo cable and gently crimped it to the outer. Mine wasn't leaking, so a wrap of PTFE  tape first or shrink wrap should help stop the leak. The copper tube armours the cable enough to prevent further damage.  There is probably some element of the lay of the inner cable wire construction acting as an Archimedes' screw to return oil to the gearbox, more by accident than design. Its a pretty poor set up anyway, with no robust seal on the speedo drive.

 Nice to know the VMCC Section is alive and well. I was a member years ago, when Jim Boulton was Secretary, and meetings were help at the Woodman Pub in Clent......which was quite a way from North Birmingham!

Title: Re: Gearbox leak
Post by: Minto on 13.09. 2019 08:33
Hi Swarfy
I’m not actually a member but tagged along for the ride and was made to feel very welcome. Well, meeting in Clent or Birmingham? I know where my choice would be. When I was a kid my grandad used to take me walking over clent hills, very fond memories.
Title: Re: Gearbox leak
Post by: Swarfcut on 13.09. 2019 08:42
Minto, The section may have started in North Birmingham, but tended to move over time... I first joined when it met in Clent, then it moved to Tipton, by the Black Country Museum. I left when it upped sticks to the backside of Wolverhampton! Never met in North Birmingham during my time with them.