Transmission Tailstock Bearing Play

[jpikaart]

I have a vibration in my 1972 Duster at 45 MPH. One of the items I have noticed in my analysis of the issue is that there is some movement of the yoke at the end of the transmission tail stock.

Does anyone know what amount of movement is normal?

 

[cudascott]

I had the same problem with my 69' bee and had play at the Tailshaft bushing
replaced it and problem gone. Not sure of the clearance tolerance though

 

[fishy68]

As in Cudascott's car you'll most likely find the issue is a worn extension housing bushing, not the output shaft bearing. Output shaft bearings can go bad but what stabilizes the yoke is the bushing at the end of the extension housing. I have been rebuilding torqueflite's for over 30 yrs. and have never seen a spec as to how much clearance there should be but IMO it shouldn't be much.

What all have you checked/done to try to eliminate the vibrations? Original driveshaft or aftermarket? Can you feel the vibration in the steering wheel, seat of the pants, or both?

 

[jpikaart]

I bought the car about three months ago and was aware that there was a vibration. So far I have had tires spin balanced (off the car). In doing this we found two rims and one tire that had runout. I replaced the rims and tire, but vibration is still there.

This week, I'll have the tail shaft bearing replaced as there is noticeable play.

The vibration kicks in at approx 45 MPH and stays there up to to 70, i haven't taken it faster. The vibration stays when I shift to neutral and let engine return to idle.

I'm not sure on the driveshaft whether its original or aftermarket. I've asked PO for more history, but so far not much has come. The car was used as a drag strip vehicle, but, I know that rear axle is 1973 or later as it has 5 * 4 1/2" BC axles and disc brakes up front.

When the car is in for the tailshaft bushing; I'll check for U joint phasing. There was no noticeable play in the U joints.

I have developed a sheet to go through more vibration analysis after the tail shaft bearing.

Have you had experience with the steel beads that are supposed to dynamically balance tires?

I have also read that some people suggest drilling the drive shaft and adding ATF and welding hole back up.

 

[fishy68]

I bought the car about three months ago and was aware that there was a vibration. So far I have had tires spin balanced (off the car). In doing this we found two rims and one tire that had runout. I replaced the rims and tire, but vibration is still there.

This week, I'll have the tail shaft bearing replaced as there is noticeable play.

The vibration kicks in at approx 45 MPH and stays there up to to 70, i haven't taken it faster. The vibration stays when I shift to neutral and let engine return to idle.

I'm not sure on the driveshaft whether its original or aftermarket. I've asked PO for more history, but so far not much has come. The car was used as a drag strip vehicle, but, I know that rear axle is 1973 or later as it has 5 * 4 1/2" BC axles and disc brakes up front.

When the car is in for the tailshaft bushing; I'll check for U joint phasing. There was no noticeable play in the U joints.

I have developed a sheet to go through more vibration analysis after the tail shaft bearing.

Have you had experience with the steel beads that are supposed to dynamically balance tires?

I have also read that some people suggest drilling the drive shaft and adding ATF and welding hole back up.

Never heard of steel beads for balancing. Nor have I heard of adding atf to a driveshaft. I'd have it properly balanced at a driveline shop rather than do that. If you do take it to a shop make sure their balancer spins it at a good rate of speed. Some shops only have balancers that spin the shaft up to 1800 rpm or so. Fine for a tractor but not sufficient for a car IMO.

You don't feel the vibration when the car is in neutral and your revving the engine do you?

When you have the tailshaft bushing replaced make sure and check the yoke out for wear where the bushing and seal ride. Also make sure the yoke is engaging in the trans. good, i.e. the driveshaft is the correct length. If the driveshaft is the correct length you should only be able to slide the front yoke in about 3/4" when you unbolt the driveshaft from the rearend.

 

[Woods74]

What's a tailsock? Extension housing?

 

[jpikaart]

Sorry for the typo; it was meant to be 'tailstock'.

The bushing was replaced, and the play is gone.

The shop also tightened up the nut on the pinion.

The vibration is a little improved, but still objectonable. It is like a 'hum'. There relly is not much of a feeling in either the seat or the steering wheel.

The drive shaft is an aftermarket one made by PTI.

The transmission shops says that the bearings in the differential may need replacing, would this be the cause of the vibration at 45 MPH and higher?

 

[fishy68]

The transmission shops says that the bearings in the differential may need replacing, would this be the cause of the vibration at 45 MPH and higher?

It very well could be. Since you say it's more like a hum now I'd really suspect differential bearings. Plus you should never have to tighten the pinion nut yoke. If it was loose that's another sign the bearings may be toast.