Mechanics

DRIVETRAIN VIBRATION

1993 Ford Thunderbird

Drive Train Axles Bearings problem
1993 Ford Thunderbird 6 cyl Two Wheel Drive Automatic 120000 miles

My thunderbird has a low pitch, loud vibration that seems to come from everywhere under the car. It used to only do it at highway speeds, but it's getting worse and now I notice it starting around 35 mph. At highway speeds it sounds like you are going over a metal grate bridge. It's strong enough to make my rear view mirror dance and steering wheel vibrate. Taking my foot off the gas makes it slightly louder, stepping on the gas makes it slightly quieter. Taking it out of overdrive and into 3rd makes no change. Putting it in neutral and coasting makes no change. Turning/cornering makes no change. Braking makes no change. My tires were recently balanced and show no unusual wear. There is no play in my ujoints. The transmission shifts fine through all gears and does not seem to affect the vibration. It had an alignment recently, and everything in the front end is tight. I'm thinking something in the differential? Maybe rear wheel bearings?
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Jnver
May 17, 2009.




Ok are your ujoint greasable? If not you could still have a bad ujoint. It may be that if the u-joints are not greasable that one it dry. Do you get a squeek from under the car at lower speeds? Get back to me.

Racefan966
May 18, 2009.
The ujoints are not greasable, and I am guessing they are original. There is no squeaking at any speed, just the low pitch rumbling vibration. My first thought was ujoints, but I don't think it's them. It doesn't squeak and it doesn't clunk when going into gear. The joints are tight. I suppose they could be dry, but then it should have totally burned up by now. I am tyring to avoid doing them unless I know that's the problem, looks like it's going to be a real pain to get the driveshaft out.

Tiny
Jnver
May 18, 2009.
Well if the yoke on the rear end is tight and has no play. Then I would plan on balancing tires and if it is still there I would pull the driveline and check to see if the u-joints feel realy tight by moving then around and such.

Racefan966
May 19, 2009.
I had a minute last night so I unbolted the driveshaft from the differential. The rear ujoint is bad, it moves on one axis, but is locked up on the other. I have never encountered a ujoint going bad in this fashion, I always had the ones that got worn out and loose. I will be replacing both joints soon, hopefully that fixes it.

Tiny
Jnver
May 19, 2009.
It don't happen very often but it happens and I have ran across this a couple of times myself. I am sure that will fix it by your discription of the problem. Thanks again and let me know how it goes.

Racefan966
May 19, 2009.
Drives smooth as a baby's butt now. I'm glad you talked me into looking at the ujoints again, when I posted my question, my rear differential was just about to get it. What a pain in the ass though. Had to drop the gas tank. That was for the best, as I discovered my sending unit had been leaking. Thanks again

Tiny
Jnver
May 21, 2009.
Wow that is great and fixed some unknown problems while you were in there. I know it wasn't easy but great job now it drives as it should and you are safe now too. If you have anything more problems or questions just ask. Thanks again and have a great holiday weekend.
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Racefan966
May 22, 2009.
One more question for you. Last time I changed my oil, a small amount of coolant came out the drain hole, then the oil. Of course I thought bad head gasket. The problem is that the car does not exhibit any of the other signs of a bad head gasket. It runs fine, it does not ever get hot, doesn't smoke, doesn't bubble in the radiator etc. Is there any other way for coolant to get in the oil? I want to rule everything out before I tear those heads off.

Tiny
Jnver
May 23, 2009.
Well it could be an intake leak. What you could do is call around and find a shop that does a chemical test. What this is, is a devise you put on the radiator neck with the cap off and it has a chemical in it and it will detect if there is any combustion in the radiator. If there is no combustion detected then no head gasket problems.

Racefan966
May 25, 2009.

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