I have a rubbing noise somewhere in my truck. It sounds similar to the sound you hear when a brake pad is word down and the soft metal under the pad rubs against the rotor, but not that loud. I can only hear it when it's rolling at very low speeds and the noise stops when the truck stops rolling, and I can't hear it above about 10 mph. Applying brakes doesn't stop it or make it any worse. My brake pads and shoes have plenty of pad left on them. I have lifted the truck and rotated each wheel and don't hear anything and All of the wheels turn freely. I've reacently replaced all 4 front wheel bearings, and seals and have doubled checked them for adjustment and they seem to feel right and make no noise when I rotate the wheels by hand. I've also replace a broken rear brake spring on the right-rear wheel. I've pulled both rear wheels to make sure there are no spring or other problems with the rear brakes. The only anomaly I see is that the left-rear drum center looks like it has about 1mm of a tiny gap between the center of the drum and the part of the axle end that goes through it. The right rear one doesn't have any gap, and neither wheel makes any noise when rotated by hand and since the drum rotates together with the end of the axle that protrudes through the center of it, there's really nothing that can rub there. I've inspected the inside of each wheel and there is nothing close enough to rub the inside of the wheel and no shiny rings on the inside of the rims. I can't really even tell for sure what part of the vehicle the sound is coming from, front or rear. I know my front rotors need to be turned or replaced so maybe it's possible that the brake pad is dragging on the uneven surface of rotor. I was also wondering if the speedometer cable can be making that kind of sound. I know on cold mornings, the speedometer often stays on zero until I get up to about 30mph or so.

It's a 1984 F150 SC / 351 HO / Automatic / 202k miles

 

The speedo cable can make noises, but you usually hear them right at the cluster.

Do you think it's a slow noise like the slower turning wheels would make, or is it faster and possibly a rear u-joint getting dry.

 

This may sound stupid, but I had a noise maybe something like you describe that made me (censored) for a month. Turned out to be that one of the three screws that holds the center cap on came out, and the center cap was making a flexing/wobbling noise at low RPM.

I found it because I got pissed and started kicking one of the back tires. Happened to be the one with the loose center....

 

Thanks Dave and Anafiel. It kind of sounds like a low speed rub, steady and continuous anytime the vehicle is in forward motion, and not too loud - I have to be listening to hear it, not a squeak or chirp. I've had a speedo cable go bad on a gm vehicle before and it made a chirping noise but I'm kind of looking for anything so I thought about that possibility. I checked the u joints a while back just see if there was any loose play in them and they felt fine. I didn't grease them and it's been a while since they've had a shot of grease, can they make a sound like that when they're dry ? In fact, now that you mention that, the sound could be from underneath. I'll have to check that out. Anafiel, is the center cap in your wheel cover ? My wheel covers are one piece, covers the entire rim so there's nothing to come loose there, but it's good to look everywhere, thanks. I probably need to take some pictures of bigred.

 

If you hang your head out the window you should be able to tell if its front or rear, if you cant tell, get someone else to drive and listen from the pass side.

 

check the u-joints, the rear one is starting to go bad

 

This is my wheel. You can see the three chrome screws that hold the center cap on. One of these came out and caused the cap to start making noise.

Funny thing, I found that screw about six months later while walking to the NAPA store for a water pump. There it was, on the side of the road about two blocks from my house. It's now in my spare screw bag, as I replaced the original when I found it was missing.

 

Oh, I see. Here's the wheel cover on mine....
[hmmm.... the 'insert image' button doesn't have an upload option, Ill do that later but you can see it in the picture in my profile]

Well, I greased the heck out of the u-joints and that yoke on the rear u-joint this morning and they were dry dry dry. The rear yoke took about 3/4 of a tube of grease before I saw any coming out the back side. The u-joints still feel good but being dry like that can't do them any good. Maybe I'm just being paranoid over a normal sound but I can still hear it. I put jack stands under both sides of the rear axle and put it in low gear while idling an let the wheels turn so I could go back to rear wheels and have a listen up close. It sounds like it's coming from both rear hubs equally on each side. Maybe just a little bit of noise is normal for it. I watched both wheels while they were turning and they looks as close to round as tires can be and there's no other abnormal sounds anywhere. Neither hub, or axle end, heats up much after driving around all day, just a little warm from driving but no excess heat anywhere. It could be that a noise from the rear u-joint is carrying through to the rear wheels but I'm beginning to think that I might just be a little over paranoid. It hasn't been driven regularly for many years and with me having to drive it almost daily now I'm probably going to have to adjust. I'll post any further developments in this investigation as I go along. Thanks a bunch for all the input.

 

shine a flash light at that shaft while it's turning like that, if out of balance, or bad u-joints, it will "wobble" while turning. careful to not put too much grease in the joints, it will spray grease all over the bottom of the truck. do you have a carrier bearing on your shaft?

 

Check drive shaft carrier bearing.

My $.02 worth.

 

Yep, there is a carrier bearing - I guess that's what is right ahead of the
yoke at the rear u-joint.? I looked but there is no grease fitting on the carrier bearing. There is a hole about the size of a grease fitting in the bottom of the housing that holds it though. How big a job is it to to change that out ? Does the drive shaft slide apart at the rear-yoke or will I have to pull one of the U-joints ? I am suspecting that now - 200k miles and 26 years w/o being greased. I'm going to climb under this evening and turn the wheels with my foot and see what that bearing feels like.

 

Carrier bearing did not have grease fitting, It's a sealed bearing.

If you decide you need to replace it, unbolt u-joint at rear end. put tape around unbolted u-joint to keep the needle bearing caps from falling off and making a mess. Or not. You may choose to just replace the u-joints at this time. slide rear section of drive shaft out of front section and set aside. unbolt bearing housing and pull front half of shaft out of transmission. If it's an aod like mine you will lose some fluid here so have a pan ready. Bring the front half to the workbench.

If memory is good, the bearing fits snug on the shaft and is held in place in the housing by a rubber boot. WD40 will help get the housing and boot off the bearing. Some coaxing may be in order to get the bearing off the shaft.

reverse process to install.

If you opt to replace u-joints pay attention to the orientation of the grease fittings. Be sure they point in a direction that will facilitate future lubricating.
I learned this trick the hard way. Might consider replacing trans seal here too.

My feelings won't be hurt if someone corrects my possibly faulty memory.

 

Thanks DiggerRigger. After a little more investigation today, I've decided to go ahead and replace the u-joints. The carrier bearing is quiet and feels smooth when turning but if I don't have to have it pressed off I probably should replace it too. I remember replacing the u-joints last in 1995, and the carrier bearing is original. Today, I put the rear axles on jack stands and removed both rear wheels. With the wheels out of the way, I can tell that the sound is coming from the back of the drive shaft, probably the very back u-joint as somebody here already said. I'm going to replace the u-joints anyway, but is there anything in the differential that could be rubbing or making the sound I'm hearing ? While I have the rear u-joint out, what kind of movement should I have on that yoke that comes out of the differential ? Just incase the u-joints don't do the trick and I have to look elsewhere. Also, with no load on it, it sounds more like a rub-rub-rub in sync with the spinning driveshaft than the steady continuous rub when it's rolling on the ground. It'll probably be a few days as we're expecting snow and other nasty weather and I'm having to do this outdoors.

 

I did this a while ago for Md chapter. maybe it will help you some
How to replace a u-joint

 

Thanks for the guide Charlie, I bet that comes in handy a lot. That looks like the way it's supposed to be done. I'll be doing it that way this coming weekend for sure.

I missed that back u-joint somehow the other day when I was greasing everything. I needed to use my truck today so I went out early to put a shot of grease in the back u-joint to get me by another few days, and to put the hubs and wheels back on, and my grease guns (both of them) are empty and I'm out of grease tubes - dang it.