grinding sound while driving, wheel bearings, U-Joints, something else?

[teamsmith]

It sounds like brakes rubbing, metal on metal, and seems to have a 'rotational cadence', if that makes sense. The sound does not appear right away but starts about 10 minutes into a drive and never goes away. I can really only hear it while driving past a concrete wall or something that will bounce the sound off of it. It does seem to change the sound while turning the wheel slightly from top dead center.

 

It's not brakes because I have a new brake system (WJ MC/Booster, new pads, calipers, rotors, lines, shoes/drum/wheel cylinders and they all spin pretty freely while on the stand plus the sound does not react in the slightest when I brake.

 

I cannot tell that the sound is speed sensitive, it seems to be the same pitch and frequency at 10mph and 45mph.

The sound remains when I pull it out of gear and coast, so it doesn't appear to be drivetrain related.

If I had to guess, I would think the noise was coming from the front or near the front and on the passenger side, but that may be due to me hearing it the loudest while driving near a wall (on the passenger side).

 

I put the truck on stands and did the 'wheel shake' technique to assess bearing play. the front wheels are solid, can't detect any movement bottom-to-top.

On the rear, the left rear wheel does have some play.

 

Before I go pick up a wheel bearing assembly and tools for the rear left, how do I diagnose the U-Joints? I've read they can make some racket but would they still be the culprit in neutral? Honestly, I don't even know what a U-Joint is.

 

Any thoughts?

 

[yxmj]

IMHO u-joint have a different sound when failing.....not a grinding but a thumping or rattling.

 

If the sound changes when you turn the wheel I would guess a front bearing, 

 

Do you have any noticeable lean to either front tire?

 

It is a bit of work but to check my routine is this:

 

-jack and secure truck on stands

-remove front wheel

-remove front brake caliper

-remove front rotor

-flip rotor around and install it backwards with at least 3 lug nuts

-now grab the rotor and wiggle and pull on it.....the revers position gives you more mechanical advantage/

 

amy movement?

[teamsmith]

Thanks for the direction re the u joints. I don't think I have any lean in the tires. The change in noise when I turn could also be the rear end unloading weight, couldn't it? I can do the exercise of removing the brakes but wouldn't I have more leverage with the wheel still installed?

[yxmj]

Could be the rear. my guess would be front

 

By doing it the way I described you take away the hold the caliper has on the rotor......that might be just enough to keep it from moving  :dunno:

[SamHdz1]

Was this problem ever solved? I'm having the same sound with the drum brake set up

[teamsmith]

It was my front wheel bearings and I believe it was drivers side but I replaced them at the same time. I didn't feel any play or movement  in them but sound went away after replacement. It was really hard to locate the sound, even with someone in the sticking their head over the side.

[omega_rugal]

somethign touching the drivshaft? happened to me after dropping the tranny to change the rear freeze plug, i accidently left a wire hanging and was grinding against the driveshaft..