Rear brake 'plug'

[rcs]

Hi,

I was wondering if anyone on here could tell me what the hole in the rear brake is for? Should this have a plug in it? Metal/plastic etc?.... and just another question... what is the thread?

This is on a '65 Silverstone



Many thanks

[riflegreen]

It is for the speedo drive when used , when not used the hole was filled with a plastic plug - similar to a blanking plug in a light switch socket .

Can't remember what the thread size is .

Chris

[John Wakefield]

Speedo drive/brake arm

Its for speedo drive on roadsters & trials. (see pic) I note the brake torque arm has been drilled, if this is alloy then I would have thought this would make it weak. Were they originally like this on Silverstone? as the roadsters had a steel one (undrilled) If it breaks it will lock the rear wheel & you will be off.

[rcs]

Blimey, Quick replies!

Thanks, that does seem quite obvious now when you think about it, but I didn’t realise the BHC brakes were used so universally across the range (with this being a road racer).

If someone does happen to know the thread it would really assist in making a plug up.

As you noticed John it has been drilled (by the previous owner!) Its not something that I would do myself but it is fairly thick, I think it will be ok, but another will be made up over the winter. It came with the original steel brake stays so I expect they were the same ones as the roasters?

[John Wakefield]

Thread

If someone does happen to know the thread it would really assist in making a plug up.
Just put a rubber blanking plug/grommet in it as suggested by Chris. Most car accessory shops have these. Or turn plug up out of plastic such as nylon slightly larger than the hole & tap it in.

[rcs]

Cheers John, I was going to do something out of alloy, but yeah it would be easier to just turn up some nylon and tap it in.

[mike edwards]

thread size

Hi RCS, Interesting warning about the strength of the brake torque arm. I have recently had the misfortune to have lost the fixing bolt for the arm, luckily I was only travelling at 30 MPH but the results were still quite severe. A flat spotted tyre, written off speedo gearbox, written off brake rod and plenty of paint missing. There's a lesson here for us all, check the tightness of the fixing bolt. Imagine the result of this occuring at a higher speed or worse still a failure at the front wheel. Anyway to answer your querie of thread size, having just finished making a complete speedo gearbox, the thread is a 0.718 (23/32) inch x 26 tpi cycle thread.
Regards, Mike Edwards.

[merlin]

Thanks for the reminder Mike just had the front wheel out of my G3LS must double check all for a while untill settles down.
Regards
Stuart

[Andy Briggs]

I find that a sherry cork is just the right size to screw in, nice and tight!