Thumb Brake

[phild]

Hi to all,

was thinking about fitting a thumb brake to my 97 storm, was wondering if anyone out there had done so and what where your thoughts on any pros and cons.
Would it need a splitter valve to keep foot brake or could I just replace banjo bolt with a double straight into the existing piston?
Any comments appreciated

Cheers Phil D

[Zakalwe]

Wouldn't a thumb brake completely replace the footbrake?
If you just put a double banjo on the rear caliper, then when you operated either brake, the fluid would just flow into the other reservoir (the reservoir is not sealed off when the master cylinder is not being applied.

[AMCQ46]

Zakalwe is correct, 2 master cyl's cant be fitted to a single caliper, unless you get one with 2 seperate circuits [like the Honda linked brake systems use].

simple solution most of the stunt boys use is to fit a 2nd caliper which is then operated by the new master cyl fitted to the bars.

[blacknek]

Hi to all,

was thinking about fitting a thumb brake to my 97 storm, was wondering if anyone out there had done so and what where your thoughts on any pros and cons.
Would it need a splitter valve to keep foot brake or could I just replace banjo bolt with a double straight into the existing piston?
Any comments appreciated

Cheers Phil D

hi there, iv got a thumb brake on my storm, im disabled so I can use the front brake with the thumb brake on my left hand....I just use the pipes from my front brake to the thumb brake, if use using the foot brake as well or just the thumb brake? you can but bleeding it is a pain....

ed

[warby221]

Zakalwe is correct, 2 master cyl's cant be fitted to a single caliper, unless you get one with 2 seperate circuits [like the Honda linked brake systems use].

Not strictly true

It’s down to how it’s plumbed in
You need to plumb it in the same way as you plumb a hydraulic handbrake in a rally car
The master cylinders need to be in series.
So the set-up would be

Reservoir to thumb brake master cylinder>thumb brake master cylinder outlet to foot brake reservoir inlet > foot brake master cylinder outlet to rear calliper.

When the foot brake master cylinder isn’t being used its in an open circuit position and allows brake fluid to be pushed through and when it is being used it just uses the open circuit of the thumb brake to draw fluid from the reservoir

[AMCQ46]

yup, from the hydraulic point of view, I can see how that could work and stand corrected.
From the practical side you would need to machine up the standard master cyl reservoir connection [on the rear cyl] to allow it to become a high pressure fitting rather than a low pressure fitting, but it could be done.

[warby221]

Never had to on my cars that I’ve had them on usually a standard Hillman imp chappy (going back a bit now) and you just screwed it in to the master cylinder fitting using an adaptor not had the bike one in bits so you may need to tap it and make an adaptor for it but it should work ok

[phild]

Many thanks to everyone for the ideas on running both pedal and thumb but to be honest I will probably disconnect the footpedal as I struggle with it due to an old ankle injury, but do use the rear brake quite alot, hence the thought of fitting the thumb. Anyone know what the MOT situation is re thumb brake?

cheers Phil

[goody]

As long as it works then it should be OK. There's nothing to say the rear brake has to be operated by your right foot. The bike in my avatar had a rekluse auto clutch and the rear brake was operated on the left handlebar by a master cylinder from a scooter.