navigator brake lever throw issues

[lotec]

ive had a rear navigator brake for a little while now and recently did 3 days solid runs at Thredbo with it which would have given it one hell of a work out :rolleyes:(background info here guys) a few days after I got back I was just riding along (LITERALLY! :eek:) and noticed it was engaging after about twice as much throw as usual, didn’t think much of it and kept riding, put the bike away when i got home forgetting all about it, go to get the bike out next ride touch the back brake and it goes straight to the bars "what the hell" I pump it like 10 times and its engaging again but only about 1" from the bars, working fine, after about 30 seconds of no use I can pull it straight to the bars but keep pumping and it engages about 1" from the bars, I’m completely stumped here guys, any help would really be appreciated :confused:

[ajay]

Yeah, i had a similar thing happen, but in reverse...

Maybe there is a bit of air trapped in the system (around the master cylinder?) that playing with the throw a bit...

I re-bled mine to adjust the lever throw in a bit, but then it came back out again...??

Sorry, this didnt really help, but im in a similar situation

[lotec]

thought you might be the first to reply, thought of air but the lever feel is just so damn solid! ill try a bleed anyway... mineral oil right? :D

[S.]

ive had a rear navigator brake for a little while now and recently did 3 days solid runs at Thredbo with it which would have given it one hell of a work out :rolleyes:(background info here guys) a few days after I got back I was just riding along (LITERALLY! :eek:) and noticed it was engaging after about twice as much throw as usual, didn’t think much of it and kept riding, put the bike away when i got home forgetting all about it, go to get the bike out next ride touch the back brake and it goes straight to the bars "what the hell" I pump it like 10 times and its engaging again but only about 1" from the bars, working fine, after about 30 seconds of no use I can pull it straight to the bars but keep pumping and it engages about 1" from the bars, I’m completely stumped here guys, any help would really be appreciated :confused:



The obvious answer is that the system is losing fluid somewhere (internally or externally). AFAIK most hydraulic (open system) disc brakes have a bladder/diaphragm thing in the reservoir, to allow for fluid volume variation (due to heat). If this has been damaged somehow, it may be that fluid is sitting in the reservoir, but is not held under the slight pressure necessary to ensure that it actually enters the actual braking system (or is free to bugger off to other parts of the lever body), so the fluid volume in the system is not kept "topped up" so to speak. Alternatively, your brakes are simply leaking somewhere, but I doubt this is the case.

This sort of thing can be caused by hitting a tree or something with your brake lever (ie sudden, extremely forceful hit) and blowing the diaphragm off its seals or rupturing it or whatever. May also be caused by extreme amounts of heat, and fluid expansion stretching the diaphragm beyond its limit (NFI if that's possible, just a theory - I've never heard specifically of it actually happening). I had exactly the same thing (ran them into a tree) happen to my brakes (although they're Hayes) a while ago. *Should* be reparable (fairly easily) by a competent mechanic at ya LBS.

[ajay]

um, i just used dot 4 fluid...

Hope thats right :o

[lotec]

just pulled out my manual in the warnings section "under no circumstances should the system be filled with D.O.T 3 or 4 brake fluid. doing so may result in damage to the seals and the brakes to fail"
sorry to be the bearer of bad news, better late than never at least you know now not when they fail and you hit a tree? :(

[Gonzo]

I had this some thing happen to the brakes in my car. The problem was a leak in the master cylinder. Cost me $200 to replace. so try seeing if thats your problem.

[ajay]

just pulled out my manual in the warnings section "under no circumstances should the system be filled with D.O.T 3 or 4 brake fluid. doing so may result in damage to the seals and the brakes to fail"
sorry to be the bearer of bad news, better late than never at least you know now not when they fail and you hit a tree? :(

FUUUUUUCCKKKK....

its all good.

ive got a complete set of seals etc, and i was going to re-bleed on the weekend anyway.

[Ryan]

Bahahaha! I have nothing to contribute to your thread lotec, I just wanted ajay to know that I laughed out loud when I read that.

[udi]

lotec-
get someone competent to bleed your brake properly. that is the issue here I think, rather than a ripped bladder or anything. Just get it rebled properly, should be set after that.

ajay-
Personally I don't think it would be that big a deal, you will have a harder time trying to get all the dot fluid OUT to switch to mineral oil, if you can get the brake bled well with dot fluid i'd just stick with that.

DOT is water soluble while mineral oil is, you guessed it, oil, and the two don't mix, so changing your seals and flushing with mineral oil won't get all the dot out at all and you'll have a strange concoction in there.

Doubt it would cause any trouble that way either, but i think itd be cleaner to just stick with the DOT, rather than having bubbles of both fluid floating around not mixing... haha.

Personally I think the seals being damaged by the wrong fluid is a pile of bull but like everyone else on here I haven't been game enough to try it... now that you've done the deed i'd stick with it.

useless near 1am post finished. goodnight. :)

[ajay]

Bahahaha! I have nothing to contribute to your thread lotec, I just wanted ajay to know that I laughed out loud when I read that.

yeah, yeah, laugh it up mo fo :o


does that qualify me for choad of the week ;)