Disk Brakes newby questions

[SwissVan]

Question for the disk brake profi's

 

Proud owner of some Avid Elixr CR brakes, 1st disk system Ive ever had.

 

This weekend decided to replace the avid standard pads with avid Organic ones.

Simple 2 minute job yes? Well No!

 

After fitting the new pads and a short ride around the garage the pads were rubbing on the disks hard enough to limit wheel rotation without applying the brakes.

 

Because I was in a rush to go ride I re-installed the old pads which still had enough pad material.

 

Yes I did push the pistons all the way back into the caliper before fitting the new pads and before applying the brake lever for the first time the wheels spun freely.

 

So what gives, do I need to do anything else like maybe let out some fluid or what?(rear brake has been bled a few times but the front has never been bled since new).

 

Thanks for your suggestions, ideas etc...

[Meentb]

Im not to familiar with Avid disc's, but here goes.

 

On my magura marta's I recently fitted new pads. After installation they rubbed. I then consulted the magura manual. In there it said that after installation of new pads some rubbing will be normal. The brakes need to be used for a bit and the pad/piston will find the correct working position.

 

The following is a direct copy from my magura manual.

 

Do not worry when you hear friction between rotor and pads. A slight drag is

normal on disc brakes with automatic pad wear adjustment during the break-in period.

This drag will disappear after a while. The reason for this is that the brake pads

find their optimum working position towards the rotor, only after a slight wear during

the break-in period. Slight drag might also happen after a brake pad change or in

case of an incorrectly installed wheel.

 

Hope you get sorted

[Meentb]

Okay. Quickly did a bit of reading up on the SRAM website.

 

Wont it help resetting the pad contact? New pads are just that tad thicker. By adjusting the contact it might help.

[SwissVan]

Okay. Quickly did a bit of reading up on the SRAM website.

 

Wont it help resetting the pad contact? New pads are just that tad thicker. By adjusting the contact it might help.

 

Dieter thanks for the reply.

The first suggestion may well be correct, I’ll give it a try and see if it improves (really hope so!).

 

The second suggestion regarding the contact point wont help, the contact point adjustment affects only the brake lever and not the piston / pad.

Basically the contact point adjustment adjusts how much movement the lever has before the piston is actuated.

[Vinnydabutcher]

Had a simlar problem with Avid - so I chamged to XT, but that`s besides the point.

 

The problem with my brakes were that the opposing piston did not move equally, thus if you reset the pistons all the way back and you pull the lever one piston moves 3mm and the other only 2mm - its refered to as a lazy piston. What happens is that pads wear down as the piston starts getting "lazy" but when you fit new pads its a mess. I could not get the caliper moved far enough to the one side to centralize the rotor so this is what i did:

 

Figure out which piston is lazy - the remove the pads and move both pistons all the way back. Then jam the faster moving piston with a tyre lever or screwdriver while you slowly pull the brake lever, preventing the faster moving piston, from moving - esentially just get the lazy piston to move 2mm or so.

 

Now re-install the pads and wheel, make sure the caliper bolts are slightly loose. Pull and hold the brake lever while you tighten the caliper bolts.

 

You should be cool like Fonzy now!

 

If it still gives you a hard time - get XT/Hope

 

Grow a Mo!

[SwissVan]

Vinny: Your story about sums up my avid experience very frustrating.

 

Avid have already replaced my one caliper under warranty because of this issue and now it seems to starting again. The 2011 XT / XTR brakes are beginning to look like a good Xmas present opportunity.