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I think I have a brake issue...but I'm not sure

CoronetDarter

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The back story: while restoring the Coronet a few years ago I converted the from drums to disc using The Right Stuff's kit, upgraded to the "big" rotors, slotted and drilled. Changed out the m/c and booster, new prop valve, new brake lines throughout. Driven about 2,000 miles since.

The car stops on a dime and gives $.05 change. Nice pedal, doesn't pull to either side whether slowing down or panic stop. No issues, except....
When slowing down, coming to a stale red light for instance, there's a slight moaning coming from the drivers side wheel (I know, insert pun here ______). Hit the brake hard, and the sound goes away. It's not a grinding sound, more like effort is being applied and the brake/front wheel is complaining. (Hard to explain).
Took both front wheels off. Checked all the castle nuts on the suspension; they have cotter pins installed so they're not going anywhere. The rotor is steady when force is applied so I believe the wheel bearings are OK (should be-they're brand new like everything else). Caliper mounting brackets are tight.
But, the drivers side rotor spins noticeably easier than the passengers side. The drivers side has some resistance which is expected; the passengers side seems a little too tight. Pulled off the calipers and checked the pads-see the pic.
IMG_4310.JPG
The passenger side outside pad has an irregular wear mark. The other three pads show even wear.
- So, could the rotor, even though new, be out of round? I don't have a dial gauge to check.
- Maybe the pad needs more miles to bed in?
- If the passenger side is tighter, needs less effort to compress onto the rotor, could that be causing stress on the driver's side causing the sound? Again, no pulling at all during braking.
- Anything else I should check out?


Pic of the passenger rotor for context. The discoloration at the top of the rotor is just a shadow from the fender overhang.
IMG_4313.JPG
 
The passenger side outside pad has an irregular wear mark.
I would tend to just dress up the one pad, using sandpaper, and a flat surface, to get the glazed high area down. All those pads should be about the same thickness.
Hard to say on the disc. If it was warped, it would show a wear pattern on it. Though you could always take it to a parts house, that cuts drum/disc, to get it looked at.
On the one 'tight' side, I'd suggest, with a helping hand, have someone apply the brakes while you watch the caliper on that side. Look for free movement/release, to be sure it's not hanging up on you.

On a truck I had, with all disc, one brake started making a terrible grinding noise. Wound up only one pad was going against the rotor, and had been like that the whole time. One side like brand new...the other side destroyed!
 
The back story: while restoring the Coronet a few years ago I converted the from drums to disc using The Right Stuff's kit, upgraded to the "big" rotors, slotted and drilled. Changed out the m/c and booster, new prop valve, new brake lines throughout. Driven about 2,000 miles since.

The car stops on a dime and gives $.05 change. Nice pedal, doesn't pull to either side whether slowing down or panic stop. No issues, except....
When slowing down, coming to a stale red light for instance, there's a slight moaning coming from the drivers side wheel (I know, insert pun here ______). Hit the brake hard, and the sound goes away. It's not a grinding sound, more like effort is being applied and the brake/front wheel is complaining. (Hard to explain).
Took both front wheels off. Checked all the castle nuts on the suspension; they have cotter pins installed so they're not going anywhere. The rotor is steady when force is applied so I believe the wheel bearings are OK (should be-they're brand new like everything else). Caliper mounting brackets are tight.
But, the drivers side rotor spins noticeably easier than the passengers side. The drivers side has some resistance which is expected; the passengers side seems a little too tight. Pulled off the calipers and checked the pads-see the pic.
View attachment 582257
The passenger side outside pad has an irregular wear mark. The other three pads show even wear.
- So, could the rotor, even though new, be out of round? I don't have a dial gauge to check.
- Maybe the pad needs more miles to bed in?
- If the passenger side is tighter, needs less effort to compress onto the rotor, could that be causing stress on the driver's side causing the sound? Again, no pulling at all during braking.
- Anything else I should check out?


Pic of the passenger rotor for context. The discoloration at the top of the rotor is just a shadow from the fender overhang.
View attachment 582258
You have a very slight alignment/spacing issue between the caliper and the rotor as indicated by the wear on one end of the pad. If the rotors are the "fixed" type the gap is not the same on either side of the rotor, if the calipers are floating the pads are contacting the rotor unevenly. Could be the pad is slightly thicker on one end.
 
A moaning sound like you describe has come from a pad that's not set tight in the caliper causing vibration and that could come from a loose or defective clip or seating in the caliper. Other issues would be the piston not returning completely in the caliper...some sticking going on from contamination/dust possibly. Shouldn't be an issue with new parts; but something to check for.
 
Just an evil thought...
I refuse to use riveted shoes, or pads. If you let them go too far (too much wear), and those rivets get to the drums, or rotors...usually have to replace the drums, or rotors, since the damage will be too much.
 
It looks like the caliper is moving up on one end by the looks of the rotor contact pattern on the pad.
 
You have two issues, and after 2K miles I certainly would go back and inspect things to make sure everything has seated and make any necessary adjustments.

The noise on the drivers side.
I would recheck the bearings and the nut on the spindle, sounds like its not equivalent to the passenger side, so which one is out of adjustment, the driver(easier to spin rotor) or passenger (harder to spin rotor). I would go back through the adjustment process and do both sides for tightening the spindle nut and make sure they are both equivalent. If the drivers side is too loose, you could be getting the groaning noise because the rotor is not perpendicular to the road or parallel to the caliper so when brakes are applied slower than a hard stop its causing the rotor to slowly stand up straight and may cause a vibration versus a hard stop where it instantly stands up and no vibration is heard. If its not that, then could be rattle as Ron H suggested from bad or loose brake pad clip.

Passenger side pad wear.
I would check the pad clips, if your car uses them, also if you have floating calipers, check the caliper bolts and make sure they are straight, and the rubber inserts in the calipers are in place and not rounded out, even though they are new, if one is bent slightly or the rubber inserts are off, it can put the pad out of position causing uneven wear. Did you use brake grease on the contact pads in the caliper cradle for the pads, its possible the pad just sticks on one side causing the uneven wear.
 
Thanks everyone, those are all good points that were brought up. I checked the movement of the pads as my wife depressed the pedal and there doesn't seem to be anything hanging up. The caliper stays rock steady.
I didn't think about the spindle nut - I'm going to pull the dust cap and check the torque on each side.
And BTW, are floating calipers the same as sliders? I have the sliders, not the pins.
 
Also, running a straight edge across the pad shows that it's got a high spot in the middle.
 
Another thing I forgot to mention - the pad ears on the passenger side have about 1/8" gap fore & aft in the caliper channel. Quickly rotating the rotor clockwise then counter-clockwise shuffles the pad back and forth, creating a clinking sound, completely separate from the moaning heard on the drivers side. In fact, with the engine on it's so slight you can't hear it. Probably not connected in any way to the original post.
 
Another thing I forgot to mention - the pad ears on the passenger side have about 1/8" gap fore & aft in the caliper channel. Quickly rotating the rotor clockwise then counter-clockwise shuffles the pad back and forth, creating a clinking sound, completely separate from the moaning heard on the drivers side. In fact, with the engine on it's so slight you can't hear it. Probably not connected in any way to the original post.
That may explain the wear pattern then, if it can move that much, its possible for it to get angled against the rotor, I would replace that pad with one that has better tolerance.
 
The "ears" should be bent slightly to sit tighter. Procedure is to carefully hammer down the ears until a tight fit.
Dr Diff kits have the procedure and pictures.
 
What about spring fingers(?) that stop vibration/for-aft movement, are they there? Did you put any “brake silencer” on the back of pads? Kinda like silicone gskt adhesive that dampens vibration. You may have an out of parallel rotor surface also.
 
The "ears" should be bent slightly to sit tighter. Procedure is to carefully hammer down the ears until a tight fit.
Dr Diff kits have the procedure and pictures.
Coincidentally I bought the disc brake kit from Dr. Diff.
 
What about spring fingers(?) that stop vibration/for-aft movement, are they there? Did you put any “brake silencer” on the back of pads? Kinda like silicone gskt adhesive that dampens vibration. You may have an out of parallel rotor surface also.
The caliper hold down bracket uses a rubber band for anti-vibration. currently has no gel on the back of the pads but I'm going to get some before buttoning up. And I slathered disc brake grease in the caliper channels.
 
Hopefully unrelated but on an old Corvette I once had issues with pad fit and wear and I discovered it had a bent spindle from some previous incident. The prior owner apparently ground one pad down to fit since the rotor was now tilted over and the caliper was no longer centered with the rotor and I discovered the issue when I tried to install new, full thickness pads and one side could not go. Just another possibility for the dragging pad to check and eliminate.
 
The caliper hold down bracket uses a rubber band for anti-vibration. currently has no gel on the back of the pads but I'm going to get some before buttoning up. And I slathered disc brake grease in the caliper channels.
Slathering grease anywhere near the brakes is asking to be dead. That grease will make it's way to the rotors or pads. Then you won't stop. If you put a straight edge on the brake pads, and they aren't flat, as said before, put some sandpaper on a flat surface, and make them flat, if they aren't too far out. Also as has been said, the tangs on the pads need to be tapped down until you get a snug fit at the pad and caliper. Put a little of the brake pad no squeal stuff on the back of the pad. Re check bearings are tightened properly.
 
Furyus makes a good point about brake grease, its not intended to go everywhere, just very light amounts on the contact points, I have always used it, and very sparingly with no issues, otherwise as stated, it can migrate onto the pad if too much is used.
 
A warped rotor will cause vibration in the steering wheel, only during braking.
You did not mention it so a warped rotor is not a reason/issue.
Your brake pad appears to be glazed up, in some cases (depends on what material it's made from) they tend to get sticky when warm. (causing sound)
As mentioned, a flat surface and sand paper to get the pad straight again works very well.
Other thing is, from time to time you could do some brake burning.
From "normal" driving they glaze up and never get hot enough.
Doing a brake burning causes the pads to harden (resin based pads) and cause them to bite better, plus you burn off all the glaze and other contamination collected over time.

Drive on a quiet road, 50mph and hit the brake hard until a near stand still, and speed up again to 50 and give it 30 sec and repeat.
By hitting the brake hard I don't mean as hard as you can but at least a fair bit harder then normal.
If you do that 5 -10 times you keep cruising at a decent speed and allow the rotors to cool down.
Most of the time you will notice a difference straight away after a single session, or after a cool down period you repeat it another time.
 
Great points again everyone. The calipers are coming off this weekend. Working on the pads and then check the bearings.
 
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