i’ve been having some bother with a set of xt disc brakes on my i-Drive. The pads seem to keep glazing over, leaving very little friction between the pads and rotor. So far i’ve tried fibrax, ebc and will now try superstar pads, all of the sintered variety. I’ve tried filing them, sanding them, baking them, and cleaning the rotors with iso alcohol. These all work for about one ride, before the glazing returns. Has anyone else had similar experiences? Would i be better off going for organic pads?

Posted 13 years ago

are these the old 4 pot xt’s??

Posted 13 years ago

Have you actualy bedded them in though? Ride a short sprint (50m) flat out and brake hard without locking the wheel, repeat several times.

Posted 13 years ago

Probably would, sintered pads create a lot more heat(which is the cause of glazing)than organics, great in the wet, not so clever in the dry. Another thing that may cause it is dragging of the brakes on descents rather than short hard applications which don’t allow the heat to build up so much.

Posted 13 years ago

i know it sounds crazy but a light sanding of the rotor surface may help.

Posted 13 years ago

they’re not the 4-pot ones. I used sintered pads on those without any problems. I do always bed them in with several sprints followed by sharp braking to a stop. I probably am guilty of dragging the brakes rather than using them harder and less frequently. I’ll look into organics then. What do others use?

Posted 13 years ago

i always had this problem with my 4 pots and sanding the rotor helped.

Posted 13 years ago

thanks 111 – I’ll give that a shot while I await the organic pads. Am I imagining things or did I read somewhere about semi-sintered pads, supposedly offering the best of both worlds?

Posted 13 years ago

How big a rotor are you using?

Posted 13 years ago

200 on the front, 160 on the back. Both front and back have exactly the same issue. On thinking about it, the problems would seem to coincide with me gaining a bit of weight (13st -> just under 15st), so that would backup the too-much-heat theory. Maybe?

Posted 13 years ago

I get this on both bikes with XT sintered pads. I’ve used Shimano, Goodridge and Carbon Lorraine pads, all the same result. HT tows the kids trailer on tarmac – glazed pads (weight of me+trailer+kids+bike=170kg), and the FS with 200mm rotors, with just me, glazed. I’ve sanded both pad and rotor, degreased, deoiled, brakecleaner, alcohol, one ride later I cant lock a wheel. Jump on the road bike and I’m impressed by the power of the brakes.
It’s got me beat.

Posted 13 years ago

Try a smaller rotor. I’d say “not enough” heat actually. A smaller rotor will get hotter and won’t result in glazed pads.

Posted 13 years ago

Bin the pads off and go for the resin compound, miles better performance than sintered in all conditions IMO. Yes you’ll be replacing them more frequently but you’ll also have brakes that work!!

Posted 13 years ago

yeah my sintereds on 160s havnt worked since i boiled them coming down ben nevis , but the levers still feel very positive negating any possible leaks (given ive searched high and low)

i may go back to resins … infact i have a set of supershit resins here im willing to sacrafice in the name of science …. ive not dared put them near the bike for any other reason !

Posted 13 years ago

Druidh is right – glazed pads happen when the brakes are used a lot at below optimum temperatures / gently Brake in harder bursts or get smaller rotors

Posted 13 years ago

thanks all. Some really good suggestions there. I’ll try a smaller rotor first then resort to resin pads. Trail_rat, let me know how you get on!

Posted 13 years ago

I get this sort of thing too – XT M765s, the 2-piston, silver ones. I’m using the original pads, 203mm/160mm rotors and have the same problems. Feel great at the levers but sod-all stopping power. They certainly got better towards the end of my ride on Saturday (after 20km) and also perk up if you dowse them in water, until the water dries off.

What type of pads come in them as standard?

Posted 13 years ago

I get this sort of thing too – XT M765s, the 2-piston, silver ones. I’m using the original pads, 203mm/160mm rotors and have the same problems. Feel great at the levers but sod-all stopping power. They certainly got better towards the end of my ride on Saturday (after 20km) and also perk up if you dowse them in water, until the water dries off.

What type of pads come in them as standard?

Posted 13 years ago

Where are you riding that you think you need 203mm rotors?

Posted 13 years ago

Where are you riding that you think you need 203mm rotors?

I couldn’t get a suitable adaptor for the fork to allow a 180mm rotor! It was 203 or nothing, and certainly helps slow my bulk down…

Are standard Shimano-supplied pads resin or sintered?

Posted 13 years ago

a11y – Member

> Where are you riding that you think you need 203mm rotors?

I couldn’t get a suitable adaptor for the fork to allow a 180mm rotor! It was 203 or nothing, and certainly helps slow my bulk down…

a11y – Member

I get this sort of thing too – XT M765s, the 2-piston, silver ones. I’m using the original pads, 203mm/160mm rotors and have the same problems. Feel great at the levers but sod-all stopping power.

This doesn’t strike you as a bit inconsistent?

Posted 13 years ago

Well they worked fine for the first few months, that’s what I meant to say.

Posted 13 years ago

if you are getting a sort of uuuurrrrrrcccchhhhh noise then its pad contamination, probably from rather liberal spraying of GT-85 or WD-40 in the same room as the rotors. Most of my customers who have this also have OCD clean bikes. Remember that GT-85 etc sprayed in a confined place will somehow, defying the laws of physics, find its way onto the rotors.

Posted 13 years ago

My riding is around Scotland – mainly the Stanes or local trails (Falkirk/Stirling), but trying to venture out into nature more. The 200mm rotor came stock on my bike – this was before Shimano came out with the 180’s.

Rapiddescent – I think I know that uuuuuurrrrrcccchhhhh noise you mean, and yes my bikes are normally kept quite clean and well lubed, although I do tend to avoid spraying it unless I’m outside. One thing I had thought of was that when venturing further afield, my bikes are carried on a tow-bar mounted rack, and I was wondering if the emmisions from the exhaust were maybe contaminating the rotors, and then the pads. Is this likely/possible (I’ve no idea if burnt diesel is as slippy as non-burnt diesel). Do other people cover their discs when carrying their bikes on such carriers?

Posted 13 years ago

actually, hadn’t thought of that because the rotors would definitely pick up oils from the road and the back of the car. I don’t really travel with the bike in/on a car anymore because of the sheer number of trails local to Stirling and so I’ve not had this on my own bikes. Also I don’t really clean them well enough!!

If you need to burn off the oils, meet up with the stirling bike club for a fast ride down Dumyat (our local hill) and that will have the rotors glowing in no time at all !!!

Posted 13 years ago