Driveshaft Movement

[dagenham]

I am trying to track down a vibration in a 91 5.0 LX automatic that has a bone stock drivetrain. The u-joints are good, but I noticed there is movement of the yoke inside the tailshaft. How much movement is considered "ok" before the tailshaft bushing or the driveshaft yoke may be considered worn and in need of replacement????
I am trying to cover all the bases, and I want to take the driveshaft out to have it balanced too.
I am thinking that the trans crossmember bushings are getting bad also because the car has about 170K miles on it.

 

[MFE92]

Do you have non-stock gears in the rear?

 

[dagenham]

Do you have non-stock gears in the rear?

Nope, like I said ,bone stock

 

[vfast]

is the dog bone still there? i would replace the u-joints

 

[mikestang63]

Do you see any trans fluid leaking? Normally if the bushing was bad, it takes out the seal and you would see some fluid out of the tail shaft seal, unless that was replaced as a band aid. With that many miles on it I would suspect the bushing and/or yoke itself are scored. You can replace the bushing with the trans in the car, but it is easier to do on the bench as you need to pull it out and drive it in straight with a special tool. I'd recommend a timken bearing to replace the bushing.

Regarding balancing the driveshaft, it may be cheaper and better to simply by a new FMS alum driveshaft for $250 bucks. It will come with all new U joints, yoke, and is already balanced. Plus it will free up some hp and maybe give you a MPG or two more.

 

[dagenham]

Do you see any trans fluid leaking? Normally if the bushing was bad, it takes out the seal and you would see some fluid out of the tail shaft seal, unless that was replaced as a band aid. With that many miles on it I would suspect the bushing and/or yoke itself are scored. You can replace the bushing with the trans in the car, but it is easier to do on the bench as you need to pull it out and drive it in straight with a special tool. I'd recommend a timken bearing to replace the bushing.

Regarding balancing the driveshaft, it may be cheaper and better to simply by a new FMS alum driveshaft for $250 bucks. It will come with all new U joints, yoke, and is already balanced. Plus it will free up some hp and maybe give you a MPG or two more.

I can get the D/S balanced fairly cheap and replace the u-joint easily enough.
I have heard the aluminum D//S can have a "pingy" sound sometimes. Do any of you guys have that??
I think there is a leak somewhere on the trans but I am pretty sure it is not at the tailshaft seal.

 

[Gearbanger 101]

The aluminum driveshaft will transfer more road noise through the vehicle, yes.