Leaky Hydrolic disc brakes.....
litwardle
Posts: 259
Hi,
I have been finding that during a heavy ride the pressure in my rear brake droped to the point that the leaver hit the bars! It's a Quad QD1. After bleeding etc they were pukka until halfway through the next ride where they slowly did the same.
After some investigation it seems that the system is leaking from the reservoir. I got some new caps and that didn't stop it. I used some liquid gasket (I'm a coffee machine engineer so have loads of stuff for sealing) but the dot 4 oil just killed it. The rubber cap is in place BTW.
Apart from making a card gasket anyone have any thoughts?
Many Thanks
Lee
I have been finding that during a heavy ride the pressure in my rear brake droped to the point that the leaver hit the bars! It's a Quad QD1. After bleeding etc they were pukka until halfway through the next ride where they slowly did the same.
After some investigation it seems that the system is leaking from the reservoir. I got some new caps and that didn't stop it. I used some liquid gasket (I'm a coffee machine engineer so have loads of stuff for sealing) but the dot 4 oil just killed it. The rubber cap is in place BTW.
Apart from making a card gasket anyone have any thoughts?
Many Thanks
Lee
0
Comments
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if the rubber seal is there and there is no hole in it you need to look else where for the problem."Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
Parktools :?:SheldonBrown0 -
It's definatly leakig from the res caps though. The bike sat for a few weaks and you could see the drip building up over the course of a day. I'd dry it and it would appear again at the seal.
Lee0 -
replace the seal diaphragm then. as it breathes."Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
Parktools :?:SheldonBrown0 -
Yeah,that may be a goer. I can't work out how that actually seals it though? There was a really thin plastic gasket - Like cling film but I threw it away thinkin it was part of the manufacturing process?...Just remembered that. Maybe that was helping to seal the lid etc?
Lee0 -
if you look there will be a hole in the top cap to allow the air to move allowing the diaphragm to move allowing the fluid to move but to keep the fluid in the brake."Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
Parktools :?:SheldonBrown0 -
Yeah, thats right. Does the rubber diaphram do all the sealing then? I wonder if the cap is screwed down to hard? I had to replace the caps as I managed to crack one whist screwing in the bolts. :shock: I may have pierced the diaphram, but i did inspect it before re-fitting and I didn't notice anything. Maybe I should be bleed, chck the diaphramand if it's ok just don't frape it up too tight?
Lee0 -
it does not need to be that tight as the diaphragm does the sealing."Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
Parktools :?:SheldonBrown0 -
Right ok, thanks for that. I'll re-bleed it and put the cap on looser!
Lee0 -
not quite the right way. but ity does not need to be that tight that it splits the seal."Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
Parktools :?:SheldonBrown0
