bogus wrote:
the pad wear is odd. It should be even across the rotor.

Make sure the pads are seated evenly, and the calipers are set in securely. If they are off a bit, that would explain a lot.

bam wrote:
This is funny, I have the exact same wear pattern on my 93 after I replaced the read pads and rotors. The inside of the rotor is fine but the outside is just like yours, contacting on the top 1/2 only. I can even look at the pad next to the rotor and see a gap at the bottom of the pad. I was thinking my calipers are shot. Maybe the bearings (mine were shot on both sides) allowed the rotor to tilt in at the top and so the inside of the caliper is worn more on the top outside? Now that everything is new except the caliper, it is showing the bad wear pattern in the caliper. My car has 100,000+ mi.

bam wrote:
The caliper when it is new is perfectly aligned so that both of the sides are parallel where the pads sit, maybe it's possible for that to wear strangely when the rotor is not perfectly perpendicular since the bearing is allowing the rotor to move in at the top relative to the mounting of the caliper to the suspension, make sense? Just a guess, I can't imagine what else it could be. I am going to borrow a mike from a friend and check the two surfaces to see if the are parallel.

Matatk wrote:
I'm wondering if the caliper piston is hanging up inside the bore. Can you somehow mic it with a mic stand and see how far it is compressing? Or visually inspect it?

Also, are you sure the rotor is 100% level/flat or that the pad is the same thickness throughout?

Matthew

flyboy wrote:
I didn't think new rotors needed to be cut.

Matatk wrote:
Quote:

flyboy wrote:
I didn't think new rotors needed to be cut.

I think he meant from the factory.

But just because it's a new part, doesn't mean it's always good or in spec....unfortunately.

Can you mic the pads, too, and see if they are the same thickness?

jaa1992 wrote:
Caliper spread maybe? Caused by the wobbly bearing?
Try a rebuilt caliper on that side?
Check the mount as well.

Churchkey wrote:
After machining a kazillion rotors I can tell you that it is impossible to machine a rotor on a rotor lathe so that the brake surface is at an angle to the hub surface. If the rotor was mounted improperly on the rotor lathe the rotor will wobble (laymans defination of run out) when installed on the hub. The result is a pulsating brake pedal. If you have access to a dial indicator use it to determine if the rotor is running true.

IMHO the caliper is/has spread or the pads are not seated/installed properly in the caliper housing or the caliper is not installed properly on the upright. Perhaps some trash/junk between the caliper & upright

CentralCoaster wrote:
What does the backside of the rotor look like?

If its the same then yeah, I guess it'd have to be a spread caliper. Although even with that I would expect the pad to still lay flat on the rotor though, and to be not flush against the piston.

The caliper could have been spread previously but the pads eventually wore to compensate. What do the old pads look like?

Calm wrote:
You would think the measurement specs for caliper spread (and measurement points) would be published somewhere on the net?

biggrizzly wrote:
I have been following this thread with interest and don't want to add anything to confuse the subject, as I'm not real knowledgeable about brakes. However, since my wheels are off I went down and looked at my contact area. Mine contact area only looks a pinch wider than yours but starts closer to the outside of the rotor and leaves about a half inch or so of no contact on the inside. I just thougth I post this rusted ugly photo for some comparison.

biggrizzly wrote:
I know this is a silly question, but are the dia. of your rotors to specification and the diameter of the hats?

RestoMod57 wrote:
This may be grasping at straws, but have you checked to make sure each caliper has correct inner and outer pads?

The inner pads should have the wear tab indicator on them. And the tab should be closest to the abutment bracket (holds the e-brake cable).

Also measure the pads when installed for parallel. Measure one side then the other. The difference should be no more than 0.15mm. Then measure top to bottom. This seems like where your problem may be.

The picture of your wear says it's probably something other than mis-installed inner and outer pads - but at least you'll eliminate this possibility. Just trying to help.

RestoMod57 wrote:
Also measure the pads when installed for parallel. Measure one side then the other. The difference should be no more than 0.15mm. Then measure top to bottom. This seems like where your problem may be.

Steve40th wrote:
I did verify the pads were on the right side. The wear indicators were on the inside.
Whats strange is its only that pad, as the other three on the rear are fine.
And when you ask to measure them, is this sliding a feeler gauge in from left to right to verify how far the pad is off the rotor?

RestoMod57 wrote:
Use a caliper to measure between the friction surfaces of the pads. This shows any taper to the pads. Your taper looks pretty radical from top to botton of the pad surface.

By top to bottom I mean from the caliper valley to the open side.

The explanation for this seems to be something other than the taper of the pads, but again, it's something you can eliminate.

BillH wrote:
Quote:

Steve40th wrote:
I did verify the pads were on the right side. The wear indicators were on the inside.
Whats strange is its only that pad, as the other three on the rear are fine.
And when you ask to measure them, is this sliding a feeler gauge in from left to right to verify how far the pad is off the rotor?

I'll assume here but, I think Resto's talking about using a mic with the pads out of the caliper.

And you need to pull the good pads $ measure for reference.

It's always possible that you have a bad pad.

How many miles on them, just break in?

Steve40th wrote:
They were broke in and immediately looked like that.
They now have 70 miles on them, half way around my third world world country of Oahu. When I took them out yesteday, the outside pad was already worn. So, it is not flat anymore. The inner pad was flat.

BillH wrote:
Quote:

Steve40th wrote:
They were broke in and immediately looked like that.
They now have 70 miles on them, half way around my third world world country of Oahu. When I took them out yesteday, the outside pad was already worn. So, it is not flat anymore. The inner pad was flat.

Good, that's not enough to screw up the measurements.

I'd do what Resto said and then pull the pads & mic then compare those measurements to the set of another wheel.

Good luck.

biggrizzly wrote:
I have been following this thread with interest and don't want to add anything to confuse the subject, as I'm not real knowledgeable about brakes. However, since my wheels are off I went down and looked at my contact area.

RestoMod57 wrote:
This may be grasping at straws, but have you checked to make sure each caliper has correct inner and outer pads?

The inner pads should have the wear tab indicator on them. And the tab should be closest to the abutment bracket (holds the e-brake cable).

Also measure the pads when installed for parallel. Measure one side then the other. The difference should be no more than 0.15mm. Then measure top to bottom. This seems like where your problem may be.

The picture of your wear says it's probably something other than mis-installed inner and outer pads - but at least you'll eliminate this possibility. Just trying to help.

RestoMod57 wrote:
BUT when I removed the old pads and rotors, a complete contact patch was evident.

My pads are Raybestos and model specific. Hawk should be the same though.

Hope this helps,

Steve M.

RestoMod57 wrote:
You might also check to see if your outer pad is completely seated in the bracket. The hairpin spring should protrude through the caliper opening. Pic attached.

If it's your outside pad that's wearing incorrectly, it may also be your slide pins. Did you say you disassembled the caliper and greased them?

RestoMod57 wrote:
On fire? Yes, that would heat up the aluminum caliper nicely and could cause the spread. If one side heated up from the e-brake, the other side did too, just not to the point of catching fire.

Sorry to bring the bad news. Maybe other Gurus have better advice. Mine is to replace calipers.

RestoMod57 wrote:

CC may be correct in that the pad surface may not be engineered to contact the entire rotor, BUT when I removed the old pads and rotors, a complete contact patch was evident.

Steve40th wrote:
Quote:

jaa1992 wrote:
Caliper spread maybe? Caused by the wobbly bearing?
Try a rebuilt caliper on that side?
Check the mount as well.

If the aluminum caliper is spread, I think it would be cracked or show signs of wear. I just cant see aluminum forged calipers bending. Not that its impossible,