Help on servicing XT hubs

[Lukep]

Okay I am confused now!

I have a 2010 Merida 96 3000d, I am running hayes stroker carbon brakes with Shimano SMRT77 160mm rotor, the reason for running this rotor is because I have XT hubs whihc take a centre lock rotor only so my LBS put these rotors on,

My problem is that the disc makes contact with the brake pads all the time.

Yesterday I went for a ride at teak, I check that the wheel spins freely before I strated the ride , about 15km in i could feel the wheel was not running freely and stopped to check I spun the wheel and it was not spinning freely at. This is not the first time I have had this issue on this set up.

In order to fix this I have to :

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Removed

the wheel and the calliper unit from the fork

 

Removed

the brake pads and pushed the pistons back into the bores

 

Reinstalled

the wheel onto the fork

 

Centred

the brake unit to the disc with a business cards around the disc

 

Loosely

reattached the brake calliper

 

Pulled

the brake lever fully compressed and realised the lever (repeated several

times)

 

Fully

compressed brake lever and secured to the handle bars

 

Tightened

the brake calliper

 

Released

the brake lever

 

Spun

the wheel to check for contact points

 

Fine

tuned the brake calliper so that there is zero contact with the disc

 

Tightened

the calliper

 

Spun

the wheel to check for contact points

 

There

was now zero contact with the brake pads and the disc

 

This is a copy and past from a mail I sent to Hayes , I also contact magura and both Hayes and Magura say that there is no compability issues between the fork and the brake.

They both say it could be the rotors or the hibs, my LBS says it is not the rotors as they have run this setup in the past and no issues.

I was told to check that my hubs cones are tight and to try another skewer.

How do I tighten the cones?

Are there any other suggestions on how to fix this?

 

[Mecnic]

Try to sand the edges off the pads themselves with fine grit sandpaper

[swoosh1973]

Good tip Mecnic. Also you can try the followng: From my experience ensure the basics are done first.

 

1) Loosen the caliper bolts, then pull the brake lever so that calipers "grab rotor" and keep them clamped whilst retightening caliper bolts. Release spin wheel and check alignment and spacing between the pads and rotor whilst wheel rotates. The pads and rotor needs to run parallel to each other.

 

2) If this is done make sure that your caliper bolts also have "loctite blue tape to prevent loosening whilst braking. The calipers are exposed to lots of vibration and this can cause your bolts to loosen and misalighn causing rubbing during the ride.

 

3) Make sure your rotor is not bent. Those fancy dainty looking rotors with the lizard designs might look cool but they bend and warp easily if exposed to exsesive braking. Forget the fancy pansy weight weeny crap and go for heavy duty rotors that wont warp and bend easily if exposed to a bit of heat.

 

3) If all the above is in order and they start off perfect and at the end of the ride end up rubbing it means you have air in your hydraulic line. Its not catastrophic as with a car but can be disconcerting. What happens as the pads heat up the oil heats up. Then the oil heats the air trapped in the line causing the air to expand which in turn pushes the calipers up against the rotor. However if this is the case you should have noticed that at some points you have to " pump" the brakes  occasionaly. To solve simply blead the brakes properly.

[Johan Bornman]

3) If all the above is in order and they start off perfect and at the end of the ride end up rubbing it means you have air in your hydraulic line. Its not catastrophic as with a car but can be disconcerting. What happens as the pads heat up the oil heats up. Then the oil heats the air trapped in the line causing the air to expand which in turn pushes the calipers up against the rotor. However if this is the case you should have noticed that at some points you have to " pump" the brakes  occasionaly. To solve simply blead the brakes properly.

 

 

Hmmmmmm

[swoosh1973]

HELLO MR BORNMAN!!!!!!!!!!!!!!!

Hmmmmmmm these tips that I learnt from your truly! How are the coarses.going? Fully booked no doubt. I have had a great time modifying my bike.

By the way I have succesfully repaired a cracked alu mtb frame with carbon. I cracked it on the SABIE EXPERIENCE on day 2. Took plenty pics and plan to post the thread here. Im not sure the specialized guys will like it very much but I still love my Specialized bike.

[Johan Bornman]

Your hub fix sounds interesting. Please show.

I think we should start a virtual monument for Sabie Experience parts victims. That race is lethal on parts, thanks to the extreme mud.

 

Just to clarify: Lots of people are worried about air in their brakes. The way to diagnose it, on your car or brake, is to let the bike stand for a while - say 10 minutes. Then pull* the brake and notice how far it travels. Now pump it and see if the travel reduces i.e. the brake pumps up. If it does, you have air in the system and you have to bleed it.

 

Further, if you are going down a looooong decent and you hold your brakes in all the time without releasing it, the system will eventually heat up and since the fluid has to expand, it will expand "downward" to the brake pads and increase braking even though you are not increasing the pull on the lever.  This will normalise the moment you release the lever and pull on it again.

 

*Dont pull on your car's brakes to do this experiment. Push.