What is this noise? Wheel bearing? Rotors dragging?

david05111 · 04:55 PM

1980 SC. Been driving the car for a few hundred miles since getting it back on the road last year, after it sat for about 25. I had it at a shop for a few months, which did quite a bit of work on it (top end rebuild, new rear axles, clutch, etc.). They also put the brakes back on the car; I took them off some years earlier to have them rebuilt.

When I was driving it the other day, a buddy pointed out that it was making a ticking noise up front. Hadn’t noticed it at all before, but as I listened for it, I could hear it too. It sounded like a rock in a front tire; it sped up and slowed down with the speed of the car.

So I drove it again tonight and then brought it back to get it up on jackstands. This is what I found when I spun both front wheels, first the driver side, then the passenger.

There’s something definitely dragging. On the drivers side, it noticeably slows the wheel when it drags. The passenger side is more or less consistent, and there is sort of a tick-tick on that side. It’s subtle, but it’s there, and that would explain why I couldn’t hear it that clearly and my passenger could.

What am I looking at here? I haven’t pulled the wheels off yet; that’s my project for tomorrow. But I haven’t seen any unusual wear on the rotors, just on a cursory look. There also is nothing foreign in the tires.

https://youtu.be/WaU8zEmoY9A?si=isp-hP4TapQnAUgK

Magyar Kiwi · 01-20-2025, 06:00 PM

Hi, Sounds like either:
1/ dragging brake pads, or
2/ a small pebble or stone trapped between the disc and the backing plate.
Try turning the hub; first with wheel removed and then with pads removed,
Cheers

A930Rocket · 01-20-2025, 06:58 PM

Make sure the backing plates are not rubbing on the rotors. Check you have clearance between the caliper and the inside of the wheels.

Aztim · Aztim's Garage

Sounds like pads rubbing

How old are your brake hoses, they could be swollen and not allowing the calipers to return

If everything is nice and new check your pedal push rod. It may need adjustment, could be pressing on the master and causing drag

david05111 · 01-20-2025, 09:07 PM

Quote:

Originally Posted by Aztim

Sounds like pads rubbing

How old are your brake hoses, they could be swollen and not allowing the calipers to return

If everything is nice and new check your pedal push rod. It may need adjustment, could be pressing on the master and causing drag

The actual flex lines (the short ones to the calipers) were replaced with brand new SS ones. They should be good to go. I'm not intimately familiar with the rest of the system, but I assumed they were hard lines from the booster to the flex lines. Please let me know if that's incorrect.

I did find this thread on the subject, and funnily enough, it's an 80 Targa like mine. The lines were mentioned in that thread, as well as the other stuff.

I'm hoping it's just something simple and that the booster or the master cylinder don't need replacing. Going to take the wheels off tomorrow and do some further digging

Aztim · Aztim's Garage

Have someone go inside the car and pull the pedal towards the driver sear and see if that changes anything

walt · walt's Garage

Slight warpage of the rotor maybe.

Aztim · Aztim's Garage

Quote:

Originally Posted by walt

Slight warpage of the rotor maybe.

Definitely possible but op mentioned redoing the brakes. Which doesn't rule out an untrue rotor

Aztim · Aztim's Garage

Another trouble shooting measure you can do is crack the bleeders. Pay attention when doing so, if a pressurized "stream" comes out without any pressure being applied to the pedal could mean you're storing pressure in your system somehow. IE collapsed/swollen soft brake lines, pedal needing adjustment, caliper pistons needing a refresh

Also does your car have vacuum assisted brakes?

david05111 · 01-21-2025, 01:52 PM

Planning on looking into this further in a day or two guys. It's pretty cold outside, and my garage isn't much better. I'll update you when I have the wheels off and can get at this a bit further

Aztim · Aztim's Garage

If you have a dial indicator you can set it up to see if your rotors are true

Bill Douglas · 01-21-2025, 05:25 PM

When I get this I do a few reverse then slam on the brakes. This fractionally loosens up the pistons in the caliper.

If that doesn't work I put a G clamp on the brake pads and push it back into the caliper a few times. This usually works.

david05111 · 01-23-2025, 11:25 AM

Quote:

Originally Posted by Aztim

Have someone go inside the car and pull the pedal towards the driver sear and see if that changes anything

Just a slight update on this one. Had someone pull on the pedal while I spun the wheels. No change.

Still too cold in the garage to spend a few hours in there tinkering, but I’m hoping in the next few days I can get at it

Funracer · Funracer's Garage

Quote:

Originally Posted by david05111

Still too cold in the garage to spend a few hours in there tinkering,

Haha. Ponte Vedra! Not making fun. I live in the panhandle. Record snow here. 17F two nights ago. Crazy.

No garage time for this Florida boy either.

david05111 · 01-23-2025, 05:46 PM

Quote:

Originally Posted by Funracer

Haha. Ponte Vedra! Not making fun. I live in the panhandle. Record snow here. 17F two nights ago. Crazy.

No garage time for this Florida boy either.

Haha yeah I know, crazy times. Garage has been reading like 37-40 the past two days during the day. Not motivated enough to mess with that haha

76FJ55 · 01-25-2025, 04:48 AM

The wheels actually seem to spin fairly freely in my interpretation, so I don't think you have a issue with the master returning or any thing like that. I would remove the wheels and spin the hubs. this will give you much better visibility to the system and may let you narrow down the source of the rub. I The noise sounds a little sharp (my description, so open for interpretation) to me to be normal pad to rotor contact. It sounds metal to metal to me, so I agree look at the backing plate to rotor gap and also if one of the pads lost it's friction material I could see that making that sharp grating sound. I'm guessing not, since they are mounted to the back side of the hub, but if you had the rotors off the car and didn't get the mating surfaces between the rotor and hub completely clean this could account for some warpage of the rotor,
Also, these have floating calipers, so even if the master is fully releasing, the caliper slides need to be in good clean lubricated condition to allow them to freely float to generate the clearance on both sides of the rotor since only one side of the caliper has a piston.

david05111 · 01-26-2025, 02:02 PM

UPDATE

Took the passenger side wheel off. When I got a good look in there, the pads are clearly touching the rotor. It's a light enough touch to not inhibit the car to functionally drive, but it's definitely scraping. The inner pad is most obviously against the rotor, but I think the outer one is as well.

I know the rotors look godawful in terms, but they actually look to have loads of life left, so please go easy on me. Neither side of the rotor looks glassy, which I admit I find a bit strange given the fact it's wearing them at all times when in motion. I'd drive the car and ignore it, but I do have some concerns about heat buildup and what it might do to the system in general.

I'm not really sure where to go from here. The car has been sitting since the start of this thread, so the brakes haven't been pumped at all. I would have expected that if there was residual pressure in the lines (by being gummed up somewhere like the master cylinder) that it would have bled out by now and the pads would have released.

Bill Douglas · 01-26-2025, 03:00 PM

Quote:

Originally Posted by david05111

I'm not really sure where to go from here.

I offered some advice. Did you follow it?

david05111 · 01-26-2025, 03:24 PM

Quote:

Originally Posted by Bill Douglas

I offered some advice. Did you follow it?

Not yet. I haven't taken the car back down off the jack stands to be able to do the reverse test you suggested. I could use a G/C clamp and compress the pads back away from the rotors while it's in the air. I'm just not quite sure what that will accomplish.

I've done something similar over the years when I've changed my brakes, of course, so I'm aware of the procedure for the most part. But if I compress them and put the calipers back in place, take the car for a drive, and it returns...have i solved anything?

It seems to me I'd be back at square one, where I'd be looking at either a problem with the calipers, a problem with the master cylinder, or a problem with the brake booster.

Unless the pads weren't seated properly into the caliper when installed, I'm just not sure how it would be a long-term fix of the issue.

I'm willing to try both of course, just can't really wrap my head around it.

Bill Douglas · 01-26-2025, 03:42 PM

You get small amounts of corrosion in the calipers and/or pistons. Pushing them back in with a clamp frees them up. I push mine in, and back out using the brake pedal, half a dozen times. I put a blit of wood about the thickness of the rotor in there so they don't over extend. If you see one pad and piston extending more than the other it shows which one is hanging up more and may need more pushing in and out. Good luck.