Grinding noise when braking

[Mertz]

I have a grinding noise when braking or decelerating. I checked the rear brakes and one had a lot of dirt in it but the pads are fine. I reinstalled the bearings and per loaded them but the manual had me tightening the lock nut 175 ftlbs and that locked up the drum. I backed everything off and torqued the nut to 60ftlbs per the manual and that seem loose so I tightened them till I got some drag and backed them an 1/8 turn. Then I took it for a drive and still got the noise but not as bad. So I pulled the front wheel and checked the pads and rotors and they are fine. Just a slight rubbing noise when I turn the hub.

Could this be a driveline issue? It sounds like metal to metal grinding. The carrier bearing looks ok. I would think if it was driveline it would always make noise but it doesn’t when accelerating.

1972 C20 8 lug wheels

[awryexperiment]

If the sound only occurs on application of the brakes, then they are your most likely source. Maybe a rock in the dust shield? Did you spin each wheel when you had them off the ground? Another method I've used is to have find an open parking lot and have a helper drive the vehicle while you stand outside (as close as you can get) and listen for the grinding. The helper can apply the brakes under different conditions: driving straight, reversing, sharp left turn, sharp right turn.

[Mertz]

Just did another test drive with all brakes examined and spin tested. I thought I’d try backing up to adjust the brakes. When I did I heard the grinding noise with no brakes applied. It sounds like it’s coming from the center of the truck. Next step is to pull the drive line or is there a way to check the joints and bearing on the truck?

[awryexperiment]

Can you put the rear up on jack stands or a lift so that you can engage the transmission (forward and reverse) to get a better idea of whether the drivetrain is involved?

[connorm]

It's odd that you get the sound only while braking when driving forward, but all the time in reverse. Is that correct?

I was sold on it being a driveline noise after reading the first post, but then when you said it got better after adjusting the brakes I changed my tone. When you say center of the truck what makes you say this? Is it center front (transmission) or center rear (carrier bearing)? There are also u-joints in both of these areas that could be the culprit.

[slikside]

It still could be your carrier bearing. It happened to me. I thought I was dragging a brake, but it was actually the clamshell carrier bearing going out.

I confirmed it by setting the rears on jackstands, and spinning a tire with my foot while my head was near the bearing and drive line. Only then was it obvious where the sound was coming from.

[Mertz]

When it made the noise when I was in reverse with no brakes activated and having checked by spinning all the wheel forward and reverse I now think it’s more than likely the drive shaft. I will jack up the rear end tomorrow and run the engine in forward and reverse and see if I can isolate the sound. Sometimes running a brake drum in reverse regardless if the pedal is pushed can make a noise. It happened on my studebaker. I’ll post as soon as I can. Also found the outside tie rods need to be replaced.

[Mertz]

I jacked up the rear and ran the car in forward and reverse and got no noise when braking or just idling. I got up to about 15mph and hit the brakes and nothing. This of course did not check the front brakes but they seemed fine when I spin them. Does it need more load on the driveline?

[slikside]

The "grinding" you describe, does it sound like metal on metal, material on metal, or rubber on metal? In thinking back on mine, it was more like material (like brake pads) on metal(and had me chasing my tail for a while!), but was actually metal on rubber...more squeaky than grinding, if that makes sense. And was confirmed to be the driveline carrier bearing.

In my description above, I said I spun the wheel with my foot, but really it was just oscillating the wheel just a few inches in both directions...

I would recommend a more silent approach than running the whole drivetrain. With it all unloaded like that, it may be more difficult to hear a subtle sound, which could otherwise be louder when loaded up.

Keep plugging away, you'll get it figured out.

[Mertz]

It’s definitely metal to metal sound. I’ll do the foot test and see if I can hear something.

[Mertz]

I did some more checking with my wife listening for the noise. It appears the noise is coming from the carrier bearing area. I went under and saw the carrier bearing support was bent a bit to the rear and under the correct conditions with the drive line position, the rear driveshaft flange is rubbing against the carrier bearing support. I pried on it to get some gap and the noise lessened and seems gone in reverse. I’m going to pull the driveshaft and replace all the bearings.

[slikside]

Cool!

I know it feels good when you finally discover the root of the issue.

Kinda curious how the bearing got bent? Do you do a lot of heavy hauling and/or towing?

If you don't know how it was bent, it may be worth it to have a driveline shop spin and balance the driveline before you reinstall.

[Mertz]

I used to pull my 4500lb travel trailer with it until I bought a 95 F250 turbo diesel. I did haul a very heavy load of gravel a number of years ago but the problem did not surface until 2 years ago and then it went away after a few miles and hard braking. I’m taking it to a driveline shop and marked the drivelines to maintain the alignment and hopefully balance. I know I can probably change the 3 u joints and carrier bearing but I do want it done right. I have no idea how it got bent.

[slikside]

Originally Posted by Mertz

I used to pull my 4500lb travel trailer with it until I bought a 95 F250 turbo diesel. I did haul a very heavy load of gravel a number of years ago but the problem did not surface until 2 years ago and then it went away after a few miles and hard braking. I’m taking it to a driveline shop and marked the drivelines to maintain the alignment and hopefully balance. I know I can probably change the 3 u joints and carrier bearing but I do want it done right. I have no idea how it got bent.

Good choice. I did the same.