I have a set of M615 Deore discs, they feel great apart from the rear one has about twice as much lever travel before it bites than the front one does.
After a few pulls, it then sits at the right point but after a time the bite point moves back to where it was before. It's like the pistons aren't staying out. Yet, the bite feels really solid so I don't think it can be air in there.
How do I fix this? Pleeeeease don't tell me to bleed them...
You can try pre-loading the piston - take the wheel out, give the lever a pull or two, being careful not to let the pads get too close to each other and put the wheel back in.
You really need to bleed it. 🙂
P-Jay - MemberYou can try pre-loading the piston - take the wheel out, give the lever a pull or two, being careful not to let the pads get too close to each other and put the wheel back in.
Cheers, forgot about that. I'll give it a go.
Yak - MemberYou really need to bleed it.
bastad! 😆
There's a few threads on here about Shimanos and how the bite point likes to **** with you. Quite often there's pretty much naff-all you can do about it unfortunately. This is one of them but there's a much larger one somewhere too: http://singletrackworld.com/forum/topic/zee-brake-persistent-bleed-problem
Poorly aligned caliper/pistons will cause excessive throw
Caliper needs to be dead center over disc, pistons should be evenly balanced left and right and both contact the disk at the same time, I'm betting your rear isn't.
[quote=legend ]There's a few threads on here about Shimanos and how the bite point likes to **** with you. Quite often there's pretty much naff-all you can do about it unfortunately. This is one of them but there's a much larger one somewhere too: http://singletrackworld.com/forum/topic/zee-brake-persistent-bleed-problem
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Ah, baws. I'll put some kitchen paper behind the pads and go for a ride to see if any oil leaks out of the piston seals.
[quote=dirtydog ]Poorly aligned caliper/pistons will cause excessive throw
Caliper needs to be dead center over disc, pistons should be evenly balanced left and right and both contact disk at the same time, I'm betting your rear isn't.
Nah, they're centred, and the pistons come out evenly. Cheers though.
I had the same problem with both of my rear 615's on the XC and commuter bikes. Tried the preolading option, which worked for a while, but in the end I spent an evening bleeding the crap out of them both which sorted it. I had to put both bikes vertical in the stand to encourage the air to migrate out of the hoses, tapping the calipers produced a load more air to remove too! Finally did a lever top-up bleed and they've both been perfect ever since. I'm guessing the hoses hold onto loads of tiny air bubbles where they both run horizontal along the chainstays, add in the length of the hoses on the rear and it's a pain getting all the air out!
Forgot to update the thread.
I got the Epic Bleed Kit from ebay and a quick bleed with that sorted it out.
Only thing I don't understand is that I didn't see a single bubble come out, despite bleeding it in both directions, whacking the calliper and lines etc.