BSA Owners' Club Forum

The BSA Workshop => Twins => Topic started by: malzstx on 29 May, 2017, 14:04:28

Title: Speedo oil seal
Post by: malzstx on 29 May, 2017, 14:04:28
Hello members.....is there anyone out there can help me source the oil seal which is fitted to the alloy speedo pin located in the lower front of my Super Rocket gearbox to which the speedo cable couples onto. Many Thanks, Malcolm.
Title: Re: Speedo oil seal
Post by: JulianS on 29 May, 2017, 16:32:25
The original zinc alloy speedo drive bushes were fitted with a square section rubber ring, in the machined groove marked with arrow at top of photo.

I use a suitable size o ring here, you should be able to find one in the boxes of assorted o rings on sale.

This is to seal between the bush and gearbox outer cover and will not stop oil dripping out of the speedo cable, if that is the problem (quite common).

Some of the later speedo drive shafts are machined to take a very flimsy o ring, part 40 3039 (which nobody seems to sell), indicated by the bottom arrow in the photo. This is supposed to stop oil getting into the speedo cable, from where oil drips at the point the alloy ferrule is crimped to the speedo cable outer.

I have found that cables with a circular crimp keep the oil in more successfully than those with the hexagonal crimp.
Title: Re: Speedo oil seal
Post by: malzstx on 30 May, 2017, 11:33:06
Thanks so much yet once again Julian....great help and now for checking a selection of O rings!