The road to insanity. Brake grind continues.....

[hywy61]

Thanks to all who have responded to my other posts about this issue.

I'm lost.

Symptoms - Bad grinding passenger front when applying the brakes. I have attached two pics to show the results on the pad (pic is from outside pad) and rotor. You can see a big chunk that has come out of my brand new rotor. The top of the pad seems to have excessive wear already.

Here is what i have done so far.

1. New pads and rotors. The pics attached are from the brand new rotor and pad. This is only after about 10 miles at the most over the course of two weeks.

2. New Caliper. I replaced the upper caliper pin also but had problems with the lower one. I couldn't get the caliper screw to tighten all the way in to the pin. Pin just kept spinning.

3. New hub and new ABS sensor (already attached to the hub) - thought for sure this was it....damn.


At this point i don't know what the hell else this could be. Any suggestions would be appreciated.

 

[AfiRover]

couple things come to mind
abs system no releasing and keeping the system engaged
driving habits

 

[discostew]

What do the tires look like? Are they all cupped up like disco2's like to do? I've heard them make some pretty bad noises.

 

[hywy61]

Tires are great. New set of Michelins. Definitely not a tire issue.

 

[discostew]

So if that wear your showing us is the new stuff u gotta have something going on with that bracket or slide pins to make it wear on that outside edge like that.

 

[hywy61]

At this point that one pin andd bracket are the only things that haven't been replaced.

How the hell could the bracket go bad? I haven't been off road and hardly drive it anymore.

Test drove today after doing the wheel hub. No three amigos or any other lights.

 

[discostew]

At this point that one pin andd bracket are the only things that haven't been replaced.

How the hell could the bracket go bad? I haven't been off road and hardly drive it anymore.

Test drove today after doing the wheel hub. No three amigos or any other lights.

Sometime in the past somebody might have had to drive one or both of those caliper slide pins out of the bracket with an air hammer (my tool of choice for that issue) then the head of the pin that gets the caliper bolted to it is no longer straight and could cause the caliper to not apply perfectly aligned to the rotor.

Take both caliper brackets off and lay them on a bench to compare them for correct alignment.

 

[hywy61]

Not a bad idea. But I have always owned the truck. Never had to do what you described.

 

[Hubacek]

Sometime in the past somebody might have had to drive one or both of those caliper slide pins out of the bracket with an air hammer (my tool of choice for that issue) then the head of the pin that gets the caliper bolted to it is no longer straight and could cause the caliper to not apply perfectly aligned to the rotor.

Take both caliper brackets off and lay them on a bench to compare them for correct alignment.

Or rebuild/ replace the caliper and mounting bracket that is giving you trouble. Replace the whole unit with another one from a scrap yard donor. Clean it up good, lube the guide pins, install fresh pads and rotor. BLEED THE BRAKES. PROPERLY like the manual describes. Bleed at the caliper AND the ..watchacallit? modulator. The chunks taken from the top lead me to believe that the pistons are not exerting equal pressure on the rotor. the bottom half of the caliper is not functioning properly, if at all. Something to do with the piston or that guide pin that you said is faulty.

 

[hywy61]

I doubt its the caliper. The same issue occurs with the old and new calipers. So when reinstalling the pins it seems like they shouldn't rotate at all when tightening the caliper bolt. Both my old and new pins are rotating. I had to place a flathead screw driver underneath them to stop the rotation just to get the bolt tightened. It doesn't look like anything has been rubbing at those points though.

I can't visualize though how that could cause such a loud grinding noise. The pins seem to slide in and out ok.

I have attached a pic of the old pin which you can see has some damage. I replaced that one.

So I guess another question is should those guide pins not rotate when you are tightening the caliper bolts?
Seems like if the flat side was lined up on the caliper bracket they wouldn't rotate.

 

[ubuntu]

The flat part of the flange kicks against the mating surface when installed, so that the pin does not spin when you fasten the caliper bolt.

 

[hywy61]

Yes. I understand that. But

1. Why is that not the case with mine anymore? I see no obvious signs of wear on the caliper holding bracket.

2. If they spin at installation.... Would that cause a braking problem?

 

[Injuhneer]

couple things come to mind
abs system no releasing and keeping the system engaged
driving habits

The first thing I noticed is the bedding/wear pattern on the pad. If there is good alignment and contact it should be smooth across the whole surface of the pad.

That pad looks like the rotor OD is too small. Maybe the pad is tool tall. Wrong rotor OD or incorrect pad size while unlikely are not impossible.

 

[Injuhneer]

Or rebuild/ replace the caliper and mounting bracket that is giving you trouble. Replace the whole unit with another one from a scrap yard donor. Clean it up good, lube the guide pins, install fresh pads and rotor. BLEED THE BRAKES. PROPERLY like the manual describes. Bleed at the caliper AND the ..watchacallit? modulator. The chunks taken from the top lead me to believe that the pistons are not exerting equal pressure on the rotor. the bottom half of the caliper is not functioning properly, if at all. Something to do with the piston or that guide pin that you said is faulty.

That spalling on the rotor (missing chunk) indicates the load of the pad is overhung on the edge. Cast iron has very high compression strength but the shear is comparatively low; on a machined edge it would be weaker.

The pad wear pattern indicates that either the caliper is too high in relation to the the axle centerline (now sure how this is possible unless it is the wrong brake assembly) or the rotor OD is smaller than it should be. Or the pad may be too tall.

Compression on the edge of a vented rotor like this one will certainly result in spalling.

Can you post of photo of how it all looks when assembled and installed?

 

[razorkill12]

looks like the problem is in the first picture. that ding on the rotor.

 

[hywy61]

Thanks. The grinding was happening before and after I replaced the rotor. I have used the same brand of pads and rotors for years. It's not happening on the inside pad. Only outside.

I had the grinding before and after replacing the pads, rotors, caliper and wheel hub.

I will post a picture of the pad in the caliper bracket when I get back in town. But they look ok.

It's something about the pressure not being evenly applied.

 

[Injuhneer]

Ah, got it. I misread something earlier. So the photo of the pad and the spalling on the rotor speak to something else.

Post the photo when you can.

 

[razorkill12]

Thanks. The grinding was happening before and after I replaced the rotor. I have used the same brand of pads and rotors for years. It's not happening on the inside pad. Only outside.

I had the grinding before and after replacing the pads, rotors, caliper and wheel hub.

I will post a picture of the pad in the caliper bracket when I get back in town. But they look ok.

It's something about the pressure not being evenly applied.

OK, well I would lift it up and run the vehicle. See if you can duplicate the noise and try to isolate it more.

 

[hywy61]

So this morning i went ahead and replaced the brake line hose just to eliminate that possibility. I also replaced the old caliper pin.

And the grind continues......

I have attached a pic of the new pads in the carrier. They fit just fine. They are Ferodo from Atlantic British. I have used them before without issues. I also have a pic without the pads. Look like plenty of clearance between the rotor and caliper carrier.

I put the old pads back in until i figure this out. Don't want to ruin the new ones any more.

The grind is not as loud or harsh with the old pads but it is still there.

So at this point the only piece i haven't replaced is the caliper bracket/carrier. I have new pads,rotors, caliper, caliper guide pins, wheel hub and brake line hose.

I have attached a pic of the pads in the caliper carrier. They look fine to me.

 

[hywy61]

Here is another pic of the pads. Also the old pad. Notice the flex pin (whatever you call the silver thing on top) is a little bent. That was from the inside pad....where there is no damage on the rotor.