Uneven brake wear AGAIN😡

[The_Vermonster]

Originally Posted by ScrapIron

You have had this same issue multiple times so theres a common denominator here someplace and the odds of slide pins sticking on multiple calipers on both sides coincidently over and over is a bit unlikely IMO.

I just happened to watch a "customer states" video that had a similar problem. The customer complained that the brakes were dragging even after a shop replaced the calipers and hoses on both sides. It turned out that the issue was a kinked hard line where it came out of the master cylinder.



The fact that this is happening to both sides, and with different calipers would lead me to start looking for those common items.

[arctictraveller]

RE: The loaded caliper info, the information included in the quote is not limited exclusively to our Ford calipers, and mentions both single and double acting calipers. The Ford calipers are single acting, that is the pistons are only on one side, where as double acting calipers have pistons on both sides, which certainly would increase the braking force. A sticking double acting piston could certainly account for pad wear on only one side where as a stuck piston on a single acting caliper should still apply equal force on both pads, unless it would cause the sliders to bind up and not move equally. The fact that it is occurring pretty much the same on both sides makes me wonder what the chances are of two bad calipers at the same time? I've replaced all the flexible hoses with stainless ones thinking that if the rubber hoses collapsed internally it could cause brake drag. I suppose there could be an issue with the ABS module not releasing the pressure, but again, maintaining unintended pressure on the calipers should still provide equal wear on both pads. At this point, all I can come up with is that somehow the caliper brackets are getting twisted into a bind and not sliding as designed. If one piston were to become stuck and put unequal force on the pads, it could distort the slider pins or brackets and not apply force to both pads equally. Other than that, I have no further ideas. For now, I've replaced everything, pads, calipers, rotors, and parking brake shoes, I've liberally lubed the pins and pad contact areas with the silicone grease that comes with the Powerstop pads and torqued everything to Ford specifications. At this point, I don't know what else to do........................

[marret]

I see ScrapIron mentioned whether it could be the proportioning valve earlier, but didn't see a response.

I assume the uneven wear is occuring on the piston side?

[arctictraveller]

Originally Posted by marret

I see ScrapIron mentioned whether it could be the proportioning valve earlier, but didn't see a response.

I assume the uneven wear is occuring on the piston side?

Wear is on the non piston side. If the proportioning valve was sticking, why would wear only be on one side?

[marret]

Originally Posted by arctictraveller

Wear is on the non piston side. If the proportioning valve was sticking, why would wear only be on one side?

Don't disagree and not likely, but on the same vein as your ABS pump question. Since the cause hasn't been determined, just covering all bases. If on the piston side, just thinking somehow the proportioning valve might have a part.

At the risk of stating the obvious and as you have mentioned, seems like there is binding on the non-piston side as the pads are remaining in contact enough to get more wear. Cause undetermined.

Some undetermined issue with the caliper brackets?

[arctictraveller]

Originally Posted by marret

Some undetermined issue with the caliper brackets?

That's my best guess, but the last two sets of calipers came with new (reman?) brackets, so I think it's unlikely the bracket it self, but possibly the surfaces where they bolt to the axle are uneven, bent or on a different plain? Interestingly, I had the same problem with the stock semi float axle. Once the calipers are bolted up with the pads, it's nearly impossible to see that they are free to slide properly. I suppose I could force the pistons back for a little free play, but with new pads there is very little room to move them. I'm at a loss here.......................

[marret]

Maybe I am misunderstanding the photo of the pads, but it looks like the wear is on the piston side? Are those the two pistons barely visible on the bottom?

Maybe the axle mount/flange is not on plane?

Do you have a photo of the brakes all mounted up?

[posplayr]

Originally Posted by marret

Maybe I am misunderstanding the photo of the pads, but it looks like the wear is on the piston side? Are those the two pistons barely visible on the bottom?

The only way that it seems possible to wear the piston side and not the other is that the other is not pressing against the rotor. The only way that is possible is that the caliper is not free-floating which would allow pressure on both pads to be relatively equal.

The net result would be only half braking effectiveness (for that caliper)

With the pistons recessed into the caliper (and perhaps with pads removed), does the caliper slide in and out? If so what happens after putting the pads back in? Does it still slide? Are they the correct pads?

https://www.repairsmith.com/blog/uneven-brake-pad-wear/

[arctictraveller]

Originally Posted by marret

Maybe I am misunderstanding the photo of the pads, but it looks like the wear is on the piston side? Are those the two pistons barely visible on the bottom? Maybe the axle mount/flange is not on plane?
Do you have a photo of the brakes all mounted up?

Yes, your correct, the wear is all on the piston side. Interesting, this happened on the old axle too, and two different flanges being off would be unusual. I'll get a photo.

[arctictraveller]

Originally Posted by posplayr

The only way that it seems possible to wear the piston side and not the other is that the other is not pressing against the rotor. The only way that is possible is that the caliper is not free-floating which would allow pressure on both pads to be relatively equal. With the pistons recessed into the caliper (and perhaps with pads removed), does the caliper slide in and out? If so what happens after putting the pads back in? Does it still slide? Are they the correct pads? https://www.repairsmith.com/blog/uneven-brake-pad-wear/

I totally agree. When on the bench, the caliper moves on the carrier with one finger. With the pads installed, it's impossible to see any movement because the pistons are fully retracted and provide very little clearance to slide the pads over the rotor. I have not tried to see how it moves once bolted up without the pads since I needed to get back on the road, but that's a good question. The pads fit perfectly, so I assume they are correct. Interestingly, in the link provided, the number two reason for uneven wear is sticking caliper pistons, which I've suspected all along. If one piston were to be stuck, the remaining one might apply enough pressure to warp the carrier and cause it to bind up and not slide. With the lack in quality of "re-manufactured" parts these days, its not uncommon to see early failures. Thanks for the link and your ideas.