Strange rumble/hum

[bcliff]

My 71 B has started to make and odd noise. It sounds like one of my front tires (or something in that area) is now a snow tire with really bumpy tread. I have pulled both front wheels, checked and repacked the bearings. I replaced one inner bearing that came out in pieces. I have put the front tires on the back. None of this made it change. It starts about 35-40 mph. It makes the noise when coasting with the engine not running. The front and rear wheels spin freely when the car is raised. I spun the rear wheels up to 70mph with the rear jacked up and no noise there. Any ideas?? I'm thinking of checking u-joints next.
Bruce

 

[19_again]

Calipers on good and tight?

 

[bcliff]

Calipers are tight. Had to take them off to do wheel bearings. Wire wheels are tight and greased.
Bruce

 

[Bruce74B]

Check the clearance of your exhaust from the body underneath the firewall bottom...sounds like a slight shift in the engine position makes it rub...don't ask how I know or how to fix it, although I'd be happy to find out!

Bruce

 

[MGZT260]

Wheels might be tight, but if the splines are worn enough...
and one bad bearing up front could indicate other parts suspect.

 

[bcliff]

I pulled the driveshaft. U-joints are tight and now greased, and flange bolts are tight. No change. Checked clearance on exhaust system. I'm good there too. The noise/vibration will occur if the car is coasting and the engine is not running. Hubs and wheel splines are the best I have had on any of my many MGBs. Previous owner maintained them well.
I am going to try a different set of wheels/tires. If that doesn't work, I'm going back to the wheel bearings.
I dont think the front wheel bearing was necessarily bad, I destroyed it when I removed it and the grease seal from the hub.
Bruce

 

[bgbassplyr]

Check the toe.

 

[bcliff]

I guess I need to add more detail. Onset of this noise was rather rapid. alignment is good. Tires are almost new. The noise diminishes when turning right. Gets louder when turning left. I'm going to check the front wheel bearings again. I think I can feel the vibration in the steering wheel.
Bruce

 

[Kensai]

Swapped our wheels and tried it out a few minutes ago. Seems worse with my wheels on. You can also feel it in the pedals now when coming to a stop. Left them on for now so you can see for yourself.

 

[jhorton3]

If the front wheels are in the air and you spin with your hands really fast is there any noise? Might even want to have someone spin them while you turn the steering wheel left/right and listen for the noise.

Could a caliper stuck closed because the inner lining of the brake hose collapsed cause that kind of noise on a wheel?

 

[Kensai]

It's not a caliper stuck closed sort of noise. Wouldn't that cause a pull in the steering if it were only happening on one side?

 

[DrEntropy]

Right front wheel bearings and/or tie-rod... if the condition becomes more apparent in a left turn (the load being transferred to the right side) those would be my first things to check and double check. Steering rack "slop" would be a distant second choice and kingpin bushes last due to your comment: "Onset of this noise was rather rapid."

Another thought: if it got more pronounced with another set of wheels, that kinda rules out broken spokes, bad splines, etc.

 

[bob67bgt]

I also vote for the wheelbearings. Did you just replace the bearing or the race as well. The big clue is the noise changes when you turn and load up the bearings. Tires can hum and rumble if the toe was off for a long time but with it coming on rapidly thats out. Bob

 

[bcliff]

Re: Strange rumble/hum, Final Chapter

Well, I pulled both front hubs off and pulled out all the beariings and races, except the left inner which I replaced last week. I went to the local parts store and they had everything in stock. 2 outer bearings and 1 inner bearing, $13, not bad. Went home, installed everything and the hum is gone. The left outer bearing is a little rough, so I'm pretty sure that was it. It ran smooth at low speed, but started to rumble about 30 mph. Tossed that bearing in the trash right away. Glad it is all fixed, and I am good to go to Breckenridge.
Bruce