What is wrong with XT brakes? i have a set on the DH bike and they keep going spongy, they have been bled (twice) the feel good for a short time and then bam, gone again, they are driving me mental.
Any help would be great.
I'm having the same problem with my new XT brakes, they were fine first spin out but since then they've gone spongy. The lever nearly pulls to the bar but it you pump them they're fine but 5 seconds later when you need them they're spongy again. My Xtr's are bandy too!! Feckin brakes, that's Avid and Shimano i've had problems with. The only ones I've never had a problem with are Formula.
2 possible problems, both can effect any brand.
Firstly, a slight buckle in the disc can push the pads/pistons back in. this then needs to be pumped to get decent power again. this can even be caused by worn wheelbearings. it doesn't have to be much, just a tiny amount of play.
Secondly, make sure there is no air in the system. It will always rise to the top, but when we bleed them, we expect it to come out the bottom. In my MX days, I was told to reverse bleed, filling with a syringe from the bleed nipple. I still do this on my mtb. a bit messy, but it works. even try tapping/flicking the lever with the cap off. you sometimes see bubbles come out.
Have xts on my morewood never touched them in two years and great pad life.Try using cable tie to hold lever in hard to the bars and level out lever and take cap off leave overnite
Ask Ralfie... both of them are technically gifted geniuses & can fix anything.. one of them even invented disc brakes and mountain biking in general so he should know all the answers.. I'm sure he'll be along soon to explain everything in a clear and concise manner... they'll have you ready to roll in no time at all..
You should probably PM them as they might not have seen this post yet... or you should put the word 'AVID' in the thread title.. then they'll have plenty to say for sure..!!
Here's the two of them setting up their bike before last weeks spin...
What is wrong with XT brakes? i have a set on the DH bike and they keep going spongy, they have been bled (twice) the feel good for a short time and then bam, gone again, they are driving me mental.
Any help would be great.
Sounds like you have a hole in something or a leaking seal, if they are working well immediately after a bleed but then get spongy you are probably drawing air into the system.
Try replacing the bleed screws and any seals + re-bleed
Ok..
Thanks for the input guys, this is how i stand...
The discs are fine and the bearings are good so thats not the trouble.
The way they have been bled is the way you described it Stu, from the bottom up and i can't find any leaks anywhere. I'm gonna give Karls idea a shot and see how i get on.
I have the same problem with my formula oro rear brake Gaz, I've tried many things.. new seals, new hose, new master cylinder... still the same. I recon it's probably something in the caliper but I can't be bothered taking that thing apart.
This bit sounds like whats happening but the lever tends to come all the way back to the bar
"Not everyone likes the spongier (better modulated?) lever feel and, after two full days of riding, we found the levers needed pumping initially to get full power. This was partly down to pad wear but a re-bleed solved the problem."
