Uneven pad wear after brake job - both sides!

[Dennis W]

I thought I would post an interesting problem I've had with the brakes on my 72 911t w/ M calipers.

After changing out a sticking rear caliper and installing new pads and rotors all around the braking performance just wasn't right. Not strong. I had the system rebled and inspected for leaks.

After about 50 miles of regular driving followed by a day with half a dozen hard, emergency type stops i heard the grinding noise that means no pad material - just backer on rotor.

After limping home an inspection in the garage showed the front passenger inside pad was totally shot - ground down to metal. The front passenger outside pad was still nearly new. It was close to the same situation on the drivers side as well. The front driver inside pad was heavily worn and the front driver outside pad was nearly new.

What are the chances both calipers have sticking pistons at the same time? Pretty weird.

I'm having the calipers rebuilt, new hoses installed and the master cylinder changed out as well. Probably best to do it all with an old car with an old braking system. Anyone ever have a similar situation?

Dennis W.

[Quicksilver]

The only way you can get that quantity of wear that fast (outside of over aggressive track days) is if the pad is going way over temp. It seems like the pad retraction must be messed up. The things I can think of are:
- Bad piston seals so the pistons don't retract. (I wouldn't expect a 2 day failure with this though...)
- Bad rubber hoses that are internally swollen so they retain pressure. (More likely)
- Brake pedal adjusted so it isn't releasing completely so the master cylinder is completely retracted. (Easier to check. As the brakes heat the fluid expands and the pads go bye-bye.)

[Dennis W]

I agree that to completely go thru a pad in 50 miles a caliper pistons must not be retracting properly, The funny thing is the pistons/pads retract when the car is up on the lift, but must be sticking when hot (?). It's also weird that it is doing it on both front calipers. Timing seems odd that both decided to freeze up at the same time. Maybe old/bad hoses can do this too. To be safe I am having the hoses and M/C replaced along with having the calipers rebuilt.

[tonythetarga]

edit: Thought you had the calipers rebuilt the first time. Sounds like they could use it and maybe replace the hoses as well. Make sure you use the 20 degree angle tool for piston location within the caliper.

[dshepp806]

Fresh parts time !!!!!!!!!!!!!!

New, again (all).

Done.

Best,

Doyle

[Dennis W]

Here's the followup to this. Had the front calipers rebuilt and new hoses, replaced the master cylinder. Now the car brakes like a Porsche should. Sometimes with this older stuff you have to replace as much as you can.

[Gogar]

Congrats for getting it right! +1 for hoses.