uneven brake pad wear

[911tracker85]

I picked up an 86 944 turbo project car a few years ago.

in the process of rebuilding, I pulled and rebuilt all the original calipers and replace the flex lines with new braided steel.

due to a friend's suggestion who built/raced 944s I initially used hawk blues, but since went to pagid yellow. from that experience I really do not like the hawk blues, both eat rotors and create soo much dust that is hard to get off the rims. and had trouble modulating at threshold braking, just too grabby. I had used pagid yellow on my 85 911 when using it for DE and liked them.

during the only DE event with the pagid yellow I LOVED them.

the drives' side front caliper is my problem. one of the pads (outside) wear faster than the other. when I first noticed this with the hawk blue I pulled the caliper and moved the pistons in/out a few times, no real resistance or sign of binding / sticking.

I am going to have to check the last set of hawk blues I was using before the pagid yellow, but thought the uneven wear had stopped.

now preparing the car for the season and find one of the DR side front pads is wearing faster than the other. new padig yellow and new rotors before that event and this is from just one event.

Monday I'll pull the caliper ... again to check. no sign of issues on the rotor.

but curious if anyone has had a similar experience and if so what was the problem?

first pic is of the pads from that caliper showing amount of uneven wear.

second is the more worn pad, and the condition of the surface makes me wonder if may be defective?

third is the other pad from that caliper, looks pretty normal.

[djnolan]

What about the slide rails? Use a small triangular file to dress the slide rails and caliper grooves, they may be corroded.

Also what about differences in temps between the inboard and outboard sides? I have seen wear differences on every brake pad change on my 944 and 944S.

[v2rocket_aka944]

Luckily 944 brakes are stupid easy to take apart...
Grease the **** out of the slider pins (that held the spring clip for the pads down) and throw more grease on the areas where the piston assembly slides in the mounting bracket.

Uneven wear means the inner and outer sides of the caliper aren't moving the same amount.

[911tracker85]

this is a Turbo, with 4 piston calipers. but will check for any binding and grease it up a bit more.

thanks.

[honerboys]

yes check the calipers but i must say all those pads (inner and outer) look really bad - i've never seen pads where the friction surface is not almost perfectly smooth - your's look like chunks were ripped out of them - check your rotors

[RRRacing1970]

Hi Bob..
It looks obvious that the degraded (outside pad) that is worn down an is "chunking"... on the drivers side (outside rotor if the pad mount is binding on the pad and not releasing the pressure when u let off the brakes. I agree with the filing on the pad (mount or the metal mount on the back side of pad it's self) and binding fix as stated above... with using (Hi Temp. Graphite Grease. Just one quick question, are you running Big Blacks, Big Red's or the stock (951-S2) calipers. If you are running the stock (951-S2) calipers of which they look like that they (are?)... due to the size of the brake pads in the pic's.... do you have any wheel hoping on the drivers side or brake that locking up on hard braking going into a (Pos. +++) Camber Passenger's Side Turn? If so I may have an answer... "MAYBE?
Ron...

[911tracker85]

Ron,
stock 86 951 calipers. did not have any unusual braking, actually they worked great at the last DE in the fall with the pagid yellow, much better than the hawk blues. no locking up, great braking and easy to modulate at threshold.

Talked to the supplier yesterday. said he has seen worse... suspects that pad is being kept against the rotor and glazing and then flaking off. no damage seen on the rotor.


also pulled that caliper over the weekend, one piston on that side was hard to push in by hand, but did move. popped out the pistons and checked everything.

when I put it back together I could move the pistons in with just my fingers.

ordered a new set of pads. will find out in 3 weeks at the DE.

[RRRacing1970]

Bob...
That's great... in the past about (8) years ago when I rebuilt the same type of calipers I had a similar problem when racing... found out that one or both pucks were sticking causing a similar problem. Here is what I found... when I rebuilt the pucks I did not clean the cross over hard line with the old brake fluid in it. I went back into the pucks to pressure check and sure enough they had air in the lines (cross over) and they would not bleed down properly with the gravity method of bleeding the brakes due to the air and the old brake fluid and dirt in the cross over line at the caliper. Flushed all the lines down with kerosene and blew out all the lines... gravity bleed down the brakes again and the problem went away.
Glad to hear you fixed your problem... Good luck with your upcoming DE at Mid-OHIO... if u get down to a Fast Lap of 1:29:48... give me a call.... you are ready for SCCA Nat. Lic. & IMSA (FIA-Lic.) Racing!
Ron...