Author Topic: B32 - Heavyweight Gearbox Speedo Drive  (Read 248 times)

0 Members and 1 Guest are viewing this topic.

Happyhenry

  • Star
  • *
  • Posts: 6
    • View Profile
B32 - Heavyweight Gearbox Speedo Drive
« on: 30 April, 2020, 16:19:47 »
Hello all,

I have a 1949 rigid B32 which has an M-Type heavyweight gearbox on which the speedo drive is mounted top-rear.

Risking life and limb by running the bike in gear on the bench I can see that the inner spindle rotates, so drive assumed OK.
Attaching the cable to a battery screwdriver I can determine that the speedo works (in the same rotation as the gearbox drive).
Connect the cable to the gearbox and the speedo doesn't work.

There seems to be a fairly long tail on the cable, but peering in with a torch I am concerned that the gearbox spindle is worn internally and not gripping the cable.
What is the best solution? I'm currently thinking of building up the cable end with solder and filing back to fit.
Must be quite a common problem. Any suggestions welcomed.
HH

Jim S

  • Blue Star
  • **
  • Posts: 68
    • View Profile
Re: B32 - Heavyweight Gearbox Speedo Drive
« Reply #1 on: 30 April, 2020, 16:52:14 »
Hi HH
I had a similar problem on my 1949 B33. I my case the speedometer was very erratic due to the poor engagement of the cable into the drive at the gearbox.
I cut a sliver of about 0.005 in thick brass shimstock, folded it in half and jammed it between one flat of the square cable and the gearbox drive. I think I also put a bend at the top of the shim to help to hold it in place, sort of hung on the top ridge of the gearbox drive untill I could slide the cable in place. Anyway, not too eligant but it worked for me.
Jim

Happyhenry

  • Star
  • *
  • Posts: 6
    • View Profile
Re: B32 - Heavyweight Gearbox Speedo Drive
« Reply #2 on: 30 April, 2020, 16:55:42 »
Thanks Jim,

I've plenty of thin shim stock, so I'll give that a go before trying to decontaminate the cable end sufficient to solder it.

Henry