Brake Guru needed urgently....

TT600Des · Jun 10, 2015

Trophy 900. 1993. Twin front non floating discs.

Dear Madge,

I've just rebuilt all three callipers inc' pistons. new brake hoses, rebuilt the rear master, and rebuilt the front one also.

The front master has two very small holes in the base of the resevior (over the piston and cylinder). The one furthest (countersunk) hole away from the lever constantly blows air bubbles when the lever is operated. Thinking the original rebuilt Master was Dog Food - I bought a new one. The New one (from Sprint) does the same as the old one, and blows air bubbles from the same hole. If you pump the lever it's quite possible that it'll blow fluid 'clean' out of the resevior!

Would we all agree that I've bought a duff-un? OR Is there something I'm not understanding here?

Any / all advice very welcome indeed, I'm getting pis*ed off trying to bleed brakes!

Yours sincerely.

'Worried of Willen' aka 'Des'.

#1
TT600Des, 3 minutes ago

camman · Jun 11, 2015

Don't really know the set up on your model, but they all work on the same principle with two piston seals passing through the two holes you mention. The position of the stroke relative to those holes is critical so that fluid is drawn in and no air.
This is usually achieved by the amount that the cylinder is screwed into housing, and some form of locking device.
On my '80 T140E it is simply a flat on the cylinder that is locked with a grub screw, and it was quite easy to set up with the workshop manual.
Do you have manual? if not I'm sure Google will come up with answer
I hope this makes sense

Keith Inglis · Jun 26, 2015

That happens with mine when I change the fluid but it stops after a while when working the leaver and I always put a stainley blade in the resviour to stop it splashing up and remove it when I have finished bleeding
Keith