Drivetrain vibration

S

Steve Zipoff 1

Registered
My 94 Mark VIII currently has 156k miles, and has recently developed a vibration that can be felt from about 50mph on. The vibration starts getting real bad and vibrating the mirrors around 80mph. About 90 the car feels like it will self destruct at any time!!
I changed the tires and wheels to the winter set(stock,20 spoke chromes),this morning and the vibration is exactly the same with either set of wheels. I have been under the car and all the U-Joints feel tight, and not sloppy in any plane. The rear transmission mount seemed kind of odd, in that I could grab the front end of the driveshaft and push it up and down, and it would also move the rear of the transmission. There is not a lot of movement, but I am wondering if this could be the source of vibration and has any one else ever had a rear transmission mount go bad? Could the vibration be a combination of transmission mount going bad, and driveshaft vibration?
 
RE: Drivetrain vibration

When I had my 4:10 installed, it vibrated really bad over 60, undriveable by 75 or so.

I ordered a MMC driveshaft, but before it arrived a bearing in my rear end seized up.

We replaced the rear end again, including shaft, and it has never vibrated again. So I never knew for sure what was causing the vibration, if it was the typical vibe that happens after 4.10 gear upgrade, if the vibration was related to the seizing. Different experts told me different things.

This was probably not much help to you. I am just trying to jack up my post count. :)


94 Mark VIII, Black / Black
 
RE: Drivetrain vibration

Mark VIII is famous for driveshaft vibration...check archives. Replace shaft with aftermarket shaft. See vendors.
 
RE: Drivetrain vibration

If you had no vibration until now, I would rule out the driveshaft. More likely the rear end needs servicing ( ever had the rear axle lubricant replaced ? ) since you're well over 100k miles. Also, the transmission mount you mention could be causing the vibration. I would replace the fluid in the center section, and if that doesn't fix the vibes, look elsewhere.
 
RE: Drivetrain vibration

Good morning Steve I do not know if your transmission mount is bad, but mine has been replaced and my car has 182,000 miles on it, my car vibrated only when I was sitting at a stop light I would experience a slight vibration it could have been a combination of my tranny mount and my motor mounts both have been replaced since, but I have not driven it since the replacement of both of the mounts. Hopefully I will be driving mine sometime next week. When my mechanic saw that the mount was bad he said that was probably the source of the vibration. The car never vibrated when I was driving along. I hope this helps you out.
 
RE: Drivetrain vibration

Thanks for the information. I will be purchasing a new transmission mount and if nothing else, at least it will be new, and can rule that out as a problem.
 
RE: Drivetrain vibration

After talking to a couple mechanics, I had the both U-Joints replaced. I would have done it myself, but I didn't want to deal with the gas tank issues. The front u-joint had a siezed section. Rusted solid. Had to place the joint in a vise and twist it off with vise grips. The back one looked almost new. I just came back from a test drive, I was well over 90 MPH and no vibration. I had almost forgotten how much fun this car is!
 
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