LS6427

iTrader: (2)

I posted it here, because there's no "Repair or Maintenance" needed. Just something weird.

Baer Erad rotors.......stock calipers.

Today I heard a grinding sound when pulling into my neighborhood. I had my new pads at home so I just pulled in a changed them.

I changed my 4 front brake pads, everything went fine except I looked at the inboard passengers side pad and it was almost totally gone, down to the metal on the upper half. There was more meat left on the bottom half, but still the brake pad material was almost totally gone. The rotor was not damaged at all, perfectly smooth.
The grinding sound was from that worn pad, the other 3 had plenty of meat left.

2 questions:
What would cause the top half of a pad to wear more than the bottom half?

What would cause just ONE of the four pads to almost wear completely away, while the other 3 pads still had plenty of meat left, maybe 2-3mm away from the metal squeal tab?

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HAZ-Matt

iTrader: (8)

Frozen caliper pins might do that. If they are stuck the piston will push in but the caliper won't move inward so it is really only applying the inboard pad. If it was uneven, perhaps only one pin is frozen, which could cause it to rotate a bit.

Try and pull the pins and regrease them.

LS6427

iTrader: (2)

huh....

Ok, so I took those 4 short bolts out so the calipers would slide off. But you know the other part that you have to put an open ended wrench to hold still while you take the short bolts out........How do I get those out, will they just spin out? Is that the pin?

Also, should that spinning part be tight up against the bracket where the short bolt goes into? I just put the bolts right back in while holding that spinning part with the open ended wrench so it would spin.

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LS6427

iTrader: (2)

Also...how do I clean out the tube where the pin goes? I guess light sandpaper to clean the pins, then degrease them, right?

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01 ss vert

iTrader: (1)

1.) Top worn pad would make me believe you have a spread caliper.

2.) Thinking stuck caliper. As cheap as OEM calipers are, I would try replacing that one.

LS6427

iTrader: (2)

HAZ-Matt....01 ss vert

Another thing I didn't mention.....

Both outboard pads were eveny worn...........

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LS6427

iTrader: (2)

So even if the pins are greased and freely moving, a caliper piston can get stuck and not retract all the way each time I release the brake pedal????

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HAZ-Matt

iTrader: (8)

As far as the pins, yes those are the things that you put a wrench on when you take off the caliper bolts. You should be able to pull them out by hand. The dust boot and any grease makes a little vacuum. If the boot is damaged, or if they have corroded over time they can get seized and then you might have to put a torch to heat them up to get them to move out.

I just wipe the grease off the pins and put some new grease on. I wouldn't sand them. If they look corroded you can just go to the auto parts store and get new ones. A set shouldn't be too bad and will come with new bolts too. If you need to clean the channel I would just try a piece of rag around a bolt or round file and just wipe it out. Could spray some brake cleaner in. After it is all cleaned up, get some decent caliper grease. Permatex makes a good one called "Ceramic Extreme Brake Parts Lube" and also one that is alright called "Ultra Disc Brake Caliper Lube." The pins when lubed should slide in and out easily without much play. If there is a lot of play, you will need new pins. If the channels in the pad abutment bracket are screwed up you will need new brackets. That is really rare, and so most parts places don't stock our front brackets.

I don't think the piston in the caliper is stuck, although perhaps it could be. If it was stuck I would have imagined you would have noticed odd braking performance, did it vibrate or pull to one side under braking? Additionally, if the piston is stuck but the pins are free it should have excessive wear on both inboard and outboard pads, right? When you inspected the pads, did you try to compress the piston? I just use a C-Clamp on an old pad to make sure I compress it back in straight so I don't get it crooked or bound up.

When you said top half of the pad was worn, I imagined the 50% that was towards the top pin. I would have thought a spread caliper would wear the outer edge more than the top.

LS6427

iTrader: (2)

Yea, I used a caliper clamp and the pistons went right in pretty easily. A new front pin kit at Advance Auto is $12.00, new boot kits are also $12.00, I'll get some new pins and boots and put them in with that grease.

You're right, it would have pulled to the right if the pistons were sticking out and not retracting. It never pulled.

Cool, I'll tear into it tomorrow night. Thanks for the info.

Also, when I put the caliper bolts back in.....do I let the pin get real tight up against the caliper bracket? So basically, hold the pin with the opened end wrench, then tighten the bolt all the way into it with a ratchet......? Which would have the pin and bolt sandwiching the bracket.

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HAZ-Matt

iTrader: (8)

If both the pistons were out the same amount and pushed in easily it probably isn't the pistons... I think what I said in the post above isn't quite right in retrospect if you only had one piston freeze. If they moved easily it isn't them though.

As far as the pins and bolts: the pin and bolt sandwich the caliper. The pin just slides in and out of the bracket. They don't fall out because the outboard edge of the caliper keeps them from sliding all the way out because the rotor is in the way. The torque spec for those bolts into the pin is only something like 23ftlbs for the front calipers. It isn't a huge amount of torque, but it should feel pretty snug if you are using a small wrench. The new bolts will probably come with red nylon patch applied to the threads to help lock them.

deatschwerks

iTrader: (2)

On my track cars and street cars with pistons on one side of the caliper, my inner pads have always worn out before the outers.

I would suspect the guide pins if you are getting uneven wear. While you are doing the pad swap, you can bolt up the caliper with out the rotor and pads there and see how the caliper slides on the pins. Granted, you won't be able to put near the force the piston can, but you'd at least be able to put a side load on the caliper to see how much off axis play is there.

wssix99

iTrader: (5)

Both sides have the same problem? If so, I'm wondering if there is a geometry issue with your aftermarket brakes. (I assume they are relatively new. If so, you shouldn't have major pin issues everywhere.)

+1 on on NOT using sandpaper. That will make the problem worse. The parts come with a coating/polish on them. I also wouldn't push your newly lubed pins all the way in. This could cause suction, which could make them hard to move in/out.

sjsingle1

iTrader: (1)

these caliper pins freeze up at the drop of a hat.....water gets in there and mucks up the grease and the pin freezes.....think of pin greasing as a regular to do item

jam01

if the rotors are the only aftermarket replacement part, that shouldn't have caused this problem. i would think something was stuck like the caliper pistons or the pins. i dont think you can mount anything wrong, like the bracket or the caliper.

wssix99

iTrader: (5)

Ah - I misread. Thought they were Baer calipers. Rotors would be irrelevant and if they are the original calipers, the pins would definitely be out of round by now.

In addition to greasing them, a new set of pins may be in order. After I took mine out at 90K miles, they had flat spots on the sides and were out of round.

LS6427

iTrader: (2)

No....both outboard pads and the inner drivers side pad....all wore identical and evenly. Just the inboard passengers side pad was almost 100% gone of pad meat. And the upper half of that remaining small amount of pad meat...was literally gone down to the metal brake pad bracket.

I'll see how pics come out tomorrow. Its crazy. My braking has always been perfect, smooth, silent and always even with absolutely no pulling left or right while on or off the brake pedal.

So, I guess "HAZ-MAT" and others are right......the pins need to be replaced and everything cleaned off...with a new pins and boot kit.

Gonna do it all tomorrow, both front calipers and pins. I drove the car this morning 20 miles round trip with the new pads on....it felt 100% perfect. But that stuck pin(s) is probably still messed up.

I have the Techna-Fit steel braided brake line kit to install also, but can't so that without my friends help on his lift. Maybe do that on Sunday. Gonna flush all the old fluid out in the process.

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LS6427

iTrader: (2)

They aren't original calipers as in 1998....but I think I replaced them both around 2004....so 7 years is still pretty old I guess. Yea....pin and boot kit tomorrow.

Thanks for all the replies everyone....................

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jam01

were the pistons on the calipers hard to compress? because you said just one pad was worn differently than the others, that really sounds like a stuck piston to me. do the other stuff to it wont hurt, i think you could check it by having someone step on the pedal and see if its clamping all the way( movment ).

HAZ-Matt

iTrader: (8)

Just to clarify when you go buy some new ones they aren't 100% round, there are usually a few small flat spots in around the circumference. I imagine that is to give a place for extra grease to accumulate. But yes, overall they should be symmetrical.

I think optimally a check of the pistons would be a good idea. If you could bolt up the caliper with just a worn out (evenly) pad and press the brakes then verify that both pistons travel out the same that would be a good thing to look at so you won't have to take a look at the brakes twice. But then again if the boots looked good and they both compressed easily I don't know if one could have only been partially seized or not.

LS6427

iTrader: (2)

So, the first 4 pics show the difference between the two INBOARD pads. You can plainly see the passengers side pad is basically all the way through the all the pad meat, bracket rivets can be seen at both ends.
See how the top half took the most of the wear though......

The last pic are the two outboard pads, both pretty much identically worn. The marks you see on the one pad is just from when I use it to clamp the pistons back down.......

So.....
1) either the top piston on the passengers side was doing most of the work and wearing the top of the pad out more, as well as the entire passengers inboard pad. ((But both pistons were all the way out when I removed the caliper and they went back in very easily with the hand clamp so the bottom piston didn't seem stuck))
Or...
2) The pin on the bottom was sticking...allowing the bottom piston to NOT squeeze the bottom half of that pad so much...allowing the top piston to come out and do its squeezing normally, which wore the top half out faster, as well as that entire pad.

Leaving know to get the pins and boots..........

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