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I have tech 3 levers on M4 brakes (i think). I had a problem with in the back brake stopped excepting any power to the disc. It went totally wooden with no pressure ...
Easy, I thought ... needed bleeding. That didn't help.
I also thought the top diaphragm was knackered so that has been replaced ....
Today I have front bled the brakes, back bled the brake about 3 time each.
On the basis if true insanity is if you keep on doing the same thing and expecting a different result, I am there.
The calliper seals seem fine ... no obvious leaks, They move in as they should when the lever is used ...but exert little pressure.
The lever is totally wooden... it pulls back to 1,5 cm from the bars ... but no feel, and when you bleed the brake, you cannot feel any pressure. ( it normally builds up a the pads meet the disc)
When you front bleed , the lever pushes fluid through - but for the first two pulls nothing much happens.
There seems to be no leaks from the diaphragm or the master cylinder piston.
I can only come to the conclusion that seals in the master cylinder piston have given up the ghost...
Any other ideas?
When weird unexplained things happen with Hope's with no signs of leaks it's usually the piston in the lever, I regularly squirt silicone spray around the seals to keep them fresh. It's a bit fiddly but looks like replacing the master cylinder piston is your next job.
If this was a car I’d be suggesting the servo but yep, MC sounds like it’s shot.
They are v4 brakes...
Looked at the tutorial on how to do the master cylinder piston, and whilst it looks like it is do-able, there are a lot of small pieces to loose.
I might just send it to Hope to be done.
But because I want to reside I bought at new lever and e4 ... from CRC for not much more than the service will cost.
Thanks BTW
Are you bleeding it with the BPC wound out? The lever/cam/piston can bottom out if there's still air in the system
Yes , it is wound out ... should it be wound in?
No...out
Cool ... thanks
Watch the Hope video on how to do it.
Are the pistons moving in and out properly?
Sounds almost like they are sticking or one side is which would give a wooden feeling brake.
Had the seals in my rear caliper replaced twice because of this happening.
Max
Pistons are moving .... but with no pressure at all ...
Using fresh DOT 5.1 fluid?
Indeed ....