Uneven pad wear ?

[PeteInCT]

After multiple pad replacements on my LS this season i'm seeing a pattern with uneven pad wear:

1) Front pads: Inside pads wear faster than the outside ones. Drivers and Passenger side wear rates are even though. Also, lower inside pistons seems to push the most, so the inside pads can wear unevenly (bottom has more wear than the top). Outside pads wear evenly top to bottom.

2) Rear Pads. Wear top to bottom across all 4 pads is even, however amount of wear from pad to pad is not. The Outside drivers side wears the fastest, followed by the inside drivers side. The Passenger side pads have much less wear than the drivers side with those two pads wearing pretty much at the same rate.

For #2 above I'm thinking that a lot of trail braking while rotating the car may be causing this. For #1 above, I don't have an answer. All I can say is that the pistons don't seem to be hanging up and the piston boots all look AOK.


Has anyone else seen this kind of pad wear ?

 

[ArizonaBOSS]

Mine are all very even; you might want to bleed your brakes and consider rebuilding your calipers.

 

[CaliMR]

It is common on some cars, my E30 track car wears inside fronts faster than outside and the are just a little pyramid shaped. My Evo, which had similar Brembos to the Boss, would wear like that too on the track but not nearly as pronounced. I think it is pretty normal if driven hard, but have not actually pulled the pads in the Boss yet to check them. I will be soon.

 

[steveespo]

Pete I am seeing the exact pattern on my car. Left side sees more loading on clockwise tracks we run so more wear on left side brakes and tires.
Steve

 

[cloud9]

Pete I am seeing the exact pattern on my car. Left side sees more loading on clockwise tracks we run so more wear on left side brakes and tires.
Steve

Left side wears faster on mine too and I run all clockwise tracks.

 

[cloud9]

Mine are all very even; you might want to bleed your brakes and consider rebuilding your calipers.

How do you know when it's time and where do you get it done?

 

[ArizonaBOSS]

Mine are all very even; you might want to bleed your brakes and consider rebuilding your calipers.

How do you know when it's time and where do you get it done?

Great question; TBH I have no hard data on this. I haven't experienced uneven pad wear on my old GT with Brembos or the Boss w/ the same Brembos, either front or rear. To me, the uneven wear is a sign of a sticking piston. Quick and cheap idea is to bleed the brakes again and make sure there's not a bubble in there somewhere, although I think this would be evident from pedal feel if it were present.

You can order replacement parts from Brembo, we have 40 and 44mm pistons. There is a dust boot that we see normally, and a lower seal that contains the fluid inside the caliper during piston movement.

I have not rebuilt calipers yet, although I did just install a brand new set a couple months back.

 

[cloud9]

Mine are all very even; you might want to bleed your brakes and consider rebuilding your calipers.

How do you know when it's time and where do you get it done?

Great question; TBH I have no hard data on this. I haven't experienced uneven pad wear on my old GT with Brembos or the Boss w/ the same Brembos, either front or rear. To me, the uneven wear is a sign of a sticking piston. Quick and cheap idea is to bleed the brakes again and make sure there's not a bubble in there somewhere, although I think this would be evident from pedal feel if it were present.

You can order replacement parts from Brembo, we have 40 and 44mm pistons. There is a dust boot that we see normally, and a lower seal that contains the fluid inside the caliper during piston movement.

I have not rebuilt calipers yet, although I did just install a brand new set a couple months back.

Thanks. I had the outside pad on my left front wear unevenly last set, but now seems ok on this set. Hopefully I don't have a sticking piston.

 

[steveespo]

Gary
The best way to tell is the amount of force required to push back pistons when changing pads. I can still push piston on the front with my hands if I crack the bleeders open. When I inspect the boots and piston faces still look good so I think they are ok. I did have an issue with my right rear caliper, piston was very hard to turn back in after 10000 miles and 1 set of Hawk HPS. I changed calipers on both sides, axle bearings and seals. So far no problems at 20600 miles.
Steve

 

[Grant 302]

#1 - Probably/possibly air in the inboard side of the caliper. There are two high spots on these calipers. Use the inside bleed screw before using the outside bleed screw.

 

[cloud9]

Gary
The best way to tell is the amount of force required to push back pistons when changing pads. I can still push piston on the front with my hands if I crack the bleeders open. When I inspect the boots and piston faces still look good so I think they are ok. I did have an issue with my right rear caliper, piston was very hard to turn back in after 10000 miles and 1 set of Hawk HPS. I changed calipers on both sides, axle bearings and seals. So far no problems at 20600 miles.
Steve

They are still easy to compress. Won't cracking the bleeder when compressing draw air into the lines?

Grant- I thought you bled inside first but others have told me follow the same logic of bleeding the furthest from the master cylinder which means outside first ???

 

[PeteInCT]

For mine, pistons and boots are fine. I bleed insides first, then outsides. I may be wrong but I think you want to have the last flush taking place the farthest from the MC.

As far as disproportionate wear in rears (L vs. R). I do think its due to trail braking and all the right turns...

 

[roywilk1960]

Uneven wear is normal. Even real race cars do the same. The outside corner, the left front on a clockwise track, the right front on a counter-clockwise track, will wear more. Also the caliper flexes. that will also cause some uneven wear

 

[cloud9]

Uneven wear is normal. Even real race cars do the same. The outside corner, the left front on a clockwise track, the right front on a counter-clockwise track, will wear more. Also the caliper flexes. that will also cause some uneven wear

Cool, thanks for clarifying. I have noticed it intermittently over the years and hoped it was normal. Thanks for confirming.

 

[CaliMR]

For mine, pistons and boots are fine. I bleed insides first, then outsides. I may be wrong but I think you want to have the last flush taking place the farthest from the MC.

As far as disproportionate wear in rears (L vs. R). I do think its due to trail braking and all the right turns...

There are a few people on this forum who have said that, but I have never heard that anywhere else. Also the instructions that come with the tools, and various shop manuals I've looked through, all say furthest first. I haven't actually checked the Mustang manual yet though.

 

[cloud9]

I may be wrong but I think you want to have the last flush taking place the farthest from the MC.

You definitely start at the right rear, then left rear, then right front, then left front, I'm just not 100% sure on the inside versus outside bleeder on the 4 piston fronts.

http://www.zeckhausen.com/bleeding_brakes.htm

 

[Grant 302]

Grant- I thought you bled inside first but others have told me follow the same logic of bleeding the furthest from the master cylinder which means outside first ???

I probably should have clarified...I bleed the outside first. Brembo directions are for the inside if I remember correctly.

I might be thinking too hard about it, but I start with the outsides because I think it will make sure more of the fluid is swapped. Doing the inside first might make more sense if air is the concern and that you would push air from the inside to the outside if you do the outside first. For people who bleed or change fluid often it probably doesn't matter.