Help diagnosing hum

[john baldwin]

'89 G-50 3.2.

Recently tried to address a rear suspension hum when cornering by replacing worn out spring plate bushings with ER rubber bushings and new tires. I then lowered the car to euro height and had an alignment done.

I did this after checking the rear wheel bearings with a stethoscope with the car up on a lift, wheels under power then clutch in....no grinding heard. Also standard "wiggle" tests showed no play.

Rear sway bar mounts had been replaced/upgraded by PO's ~ 10 years ago....these seemed secure when on the lift. Car shifts fine.

After these changes, the car now develops a hum from the rear as I approach 40 mph....going straight ahead...no matter what the revs or gear...even when free-wheeling down hills to test.

When I corner to the right now, the hum goes away; cornering to the left, hum remains. Straight ahead, hum is very noticeable and blends into the overall din as I go faster.

Had all 4 CV joints repacked and new boots when I bought the car ~ 5 years ago. With winter coming, I'm ready to tackle this...but looking for direction here...

Motor mounts? G50 trouble? swap bearings anyway? Trailing arm bushings? Not enough grease on the torsion bars?

I'm thinking of pulling it all out...all suggestions appreciated (other than just "drive faster" ;}

[pete3799]

I would suspect wheel bearings myself.

[Bob Kontak]

Hum mentioned by PZ in final para. Just saying

[Targalid]

Your description of noise when turning one direction and not the other is kind of classic wheel bearing. Sorry. Often you can't detect it when moving the wheel by hand. Don't worry, it will be easier to diagnose as it gets worse.

[DRACO A5OG]

+1 bearings

[Alan Lindquist]

I had the same symptoms. It was one rear bearing. I had both replaced because the quiet one can't be far behind the other in wear.

Do what I did. Question it for months. Listen to it sing to you. Deny the inevitable. Then finally give in and have them changed or change them yourself.

Rear bearings humming and singing is a gentle message to you. You're hearing, but not listening. The slap across the face is probably a long ways off, so you have a little time.

[Bob Kontak]

Originally Posted by Bob Kontak

Hum mentioned by PZ in final para. Just saying

I am pretty sure someone posted and then removed in this thread where Peter Zimmerman had posted an article that stated that a hum will be present with rear wheel bearing failure onset.

Otherwise, I am losing my wee little mind. :-)

[pete3799]

Originally Posted by Bob Kontak

I am pretty sure someone posted and then removed in this thread where Peter Zimmerman had posted an article that stated that a hum will be present with rear wheel bearing failure onset.

Otherwise, I am losing my wee little mind. :-)

I saw it too. Don't know why it was deleted........zombies?

[john baldwin]

Thanks to all. New bearings have been sitting in my
garage for several years now...thought about tackling it while replacing the spring plate bushings but just wanted to get out and DRIVE! With winter coming time to do it all agin! Should I replace them with the trailing arms in the car or pull it all out and replace all the bushings while I'm in there?

[kodioneill]

No doubt it's the rear wheel bearings. When you put the car on a lift to check them you may or may not hear anything.

[Bob Kontak]

This may help for the bearing but I don't think it talks about the bushings.

Rear Wheel Bearing Removal

[DRACO A5OG]

For me I found on the car to work just fine, especially with the bearing puller/press. I used a long socket the same diameter to sledge the hub off per Bentley.

No Freezer or heating, the puller/press just pressed it straight and true