Hi all couple years ago I had an issue which I posted about the rear brake locked on and melted the cables. Was fixed, and put a few miles on it since was fixed. However Went out on it yesterday and same thing happened again. So this would be the third time it’s happened. Has anyone had this happen at all? also, am I right in assuming that I shouldn’t be charged for this as well? thanks guys
Sounds like there isn’t sufficient free play between the brake pedal and master cylinder rod. This would mean the brake is slightly applied. I know this as I melted a brake caliper after fitting some rear seats and stoopidly neglected to check the play on the pedal.
Very strange given it’s happened before. However I’d be amazed if you got something done FOC on a 7yo bike.
I think they changed an o ring or something to that affect which would allow the lever to fully release after pressure has been applied?
It’s seven years old. Way out of its warranty period. And they “could” claim its down to how you ride/wear and tear etc. However I agree with @Advikaz that you should ask if they’d help you with the costs etc.
Thanks guys. Don’t get me wrong they’ve been really good in the past and been quick to help out so nothing against them.
Just a quick update. Mechanic initially seems to think it’s my aftermarket caps on the rear break fluid reservoir. Can’t be the case as it happened first time on standard caps… Would the caps do it??
Seems a bit excessive to me that. If there’s an issue with the caliper you’d think you’d be able to service it..
So just fyi guys, the aftermarket cap for my rear brake reservoir was designed for dot 4 brake fluid. They also don’t seal right which allowed humidity/water to get in with the oil. As a friend was riding my bike the time it happened this time he is heavy on back brake and I think the water must have boiled and forced the callipers on permanently.
What DOT brake fluid have you got in your system? Sounds a bit dodgy to me…who said that is the reason?
This is not my experience of a rear brake that had old fluid on my ST4, and seems counter intuitive as to the root cause of the problem. If your fluid has absorbed moisture and it gets too hot, it produces steam, which is a compressible gas. This would have the opposite effect and you would lose effective braking capacity when you apply the brake. Once the fluid cools the brake returns to operating normally. Unless there is something else going on, it should not force the calipers on permanently.
I did let it cool down when it happened and the lever and caliper were back to normal. Would this explain it? Appreciate the advice btw guys
1, You say it melted the cables? What cables? Your rear brake is operated by brake fluid. That may be just confusion. 2. I’d be very surprised if it’s your aftermarket brake fluid caps. If they weren’t sealing then they’d be leaking surely. 3. Since DOT 4 and 5.1 are both glycol-based brake fluids they are compatible, which means they can be readily mixed without harming your brake system. It is important never to mistake DOT 5.1 (glycol-based) with DOT 5 which is silicone-based and should never be mixed with any other DOT fluid. I can’t imagine your mechanic would have used dot 5 at any point. Here’s what I would do. 1. Change your brake fluid cap back to the original, just temporarily to eliminate that. 2. Find out what brake fluid is in there for sure. Make sure no Dot 5 has gone through it. 3. If the fluid is new it won’t have absorbed moisture. Only if it’s a year or two old. If it’s two old it’s too old. Change the brake fluid for new fluid. Personally I’d be sticking with Dot 4 as is recommended ( see the caps) but others on here may advise and be happy with dot 5.1. 4.Here is where my bet is. It’s very simple. Your rear brake pedal is adjusted so it doesn’t have enough movement. It may well be dragging thus heating everything up and locking up your rear. It’s happened to me. Slacken it off slightly at the pedal. 5.You don’t need a new rear brake caliper, certainly not just yet. Only if the pistons have seized, then you could get the seals replaced but because it goes away when it’s cooled down it doesn’t suggest seizure to me. This is just my opinion, I accept no responsibility.
