Propeller/Drive shaft question

[themechanic]

1969 Dodge Coronet R/T 440 TF727

I removed the front and rear U joints, cleaned and painted the drive shaft and yoke. Now I don't know which end the yoke goes on. They both look the same.

So, does it matter which end of the drive shaft goes in front. My 1969 Dodge FSM says I'm supposed to have a 3" shaft with inertia ring at front joint of propeller shaft. Mine does not. I have no vibrations. As these things are not cheap and the car is used on the street, should I buy the shaft with the inertia ring on the front that the car is supposed to have?

Thanks FBBO

 

[62MAX]

The inertia ring depends on build date,usually the taper end is to the rear.

 

[themechanic]

There is no significant taper. Both ends are almost identical. I just discovered the shaft is 2.75" instead of 3.0". I will be replacing it soon with a proper diameter shaft. Any suggestions where to buy?

 

[70redbee]

I have never used them, but from what I have read Denny's Driveshaft is the place to go. I will at some point be replacing the driveshaft in my Bee and this is where I am going. Hope this helps.

 

[Meep-Meep]

A straight and balanced shaft won't care. You will have a margin of error just from removing and installing the u joints and yoke, even if you put them back exactly where they came from, but that should be within the tolerance window where you won't feel it. I have changed plenty of u joints on old original shafts with no issues. If you do feel something shaking that would indicate a displacement issue so pop the yoke off, flip it around, and try again. You might also flip the yoke 180 on the same side to see if that helps. A PITA but it's all you can do on your driveway before spending $250.00.

 

[Supershafts]

There is no significant taper. Both ends are almost identical. I just discovered the shaft is 2.75" instead of 3.0". I will be replacing it soon with a proper diameter shaft. Any suggestions where to buy?

One end of the shaft the taper will be slightly longer, that end goes to the back, and you should never just pull apart the shaft without marking what came from where and how it was all oriented, slip yokes need to be on the shafts exactly as they were when built at the original factory as that's how they were balanced, and any change will effect the balance.

As for the proper diameter shaft, that shaft may be what that car is supposed to have, diameter is chosen by a few parameters and it may be what it was originally designed with.

If you want to change it though then visit your local driveline shop and speak with them about it, or when you see your local shop upgrade to something better.
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