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First generation driveshaft ruminations

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Having replaced the output yoke bushing on my dynaflow (not a horrible job)  and waiting for a new yoke and  trans mount, I am stalled in my efforts to get rid of driveline vibration.  


Making a the tools to do the bushing replacement was fun, but now that I have a couple weeks until Steele sends back the mount, I am contemplating options.   Or fantasies. Take your pick.


Best result is that I, and my driveshaft guy, can get the original shaft to behave and run smoothly.   That may depend on whether there is some issue aside from the driveshaft, but leave that aside for the moment.  


I dug into my stash of stuff, and pulled out the complete 64 driveshaft that is part of my possible ST400 upgrade.   Not planning on it right now, but wondering what the differences are as Buick obviously saw the need to change the design.  Comparing the two, the U Joint at the front is the same (confirmed by checking CARS website) and the front half is 2 1/8 shorter.  The back half appears to be the same length when the different connection to the rear axle is taken into account.  The center bearing mounts are different (shorter).  Wondering if there be any possibility of adapting the later shaft to the earlier car.  


If changing over to an ST400, clearly the later shaft and bearing support would be the answer.  Changing the rear axle connection would be needed, but that is straightforward.  Getting the height of the back of the transmission would be critical and figuring out how to use the 64 trans mount would be necessary.  


But...…….  What if the dynaflow was to be retained?  Making a new front half of the 64 shaft would require that the phasing be maintained between the yoke and the spline, which would require someone with understanding and skill.  But, what if a longer front section was available, say from a 63 Electra?  It had a longer wheelbase and would have required a longer driveshaft.  I think it used the same design.   The front yoke for the dynaflow would work, as the U joint is common.  


Now that you have read this far, here is the question:  Is the front half of a 63 Electra driveshaft longer than the Riviera?    If so, it strikes me as an easier modification to shorten it, maintain the 67 1/2 degree out of phase set up at the yoke end only, and balance the whole rig.  


Of course, all of this could be ignorance speaking.   I am convinced that my vibration is a solvable problem, its just finding  the right solution.  



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2 hours ago, Zimm63 said:

First option is to work with my driveshaft guy to balance what I have.  

OTOH, that option has been expensive, time consuming, and -- so far -- unsuccessful.


Has it been conclusively determined that the driveshaft is the problem?

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Same car same vibration.  


History, once again:


Bad center bearing- replaced that along with U Joints.  Found bad yoke.

Yoke replaced, back half balanced.

Noticed vibration at 50-55 MPH.

Replaced 8 year old tires.

Still vibration

Performed the low range test for vibration from the manual.  No vibration at same engine speed as 55 in low range.  

Removed shaft, had it  all rebalanced.  Still vibrates, even seemed more noticeable.  

Noticed 20 thou movement in transmission yoke when pushing it up.  

Replaced out put bushing in trans, sent mount out to be redone, as it was swollen and oil soaked.  May be partially collapsed.  

Currrently waiting for parts- probably 2 weeks out.   New yoke and mount. 


Did run the car on stands and listened at each rear wheel for bearing noise.  Heard some noise in the rear, which seemed to be more one wheel turning while the other was still.  I have the gaskets and seals and will pull the axles to make sure the bearings are good.  


I spent some time chasing down the phasing rabbit hole, and now think I have an understanding of that.   


So, I am contemplating options while I wait.  Drive shaft guy suggested a one piece shaft, which won't fit through the tunnel, especially when the car is lifted and the rear drops down.  


Next up is check the rear bearings.

Then, install new yoke and have shaft balanced again- double check yokes on back half are perfectly in plane.  

If that doesn't work, follow the propellor shaft alignment process in the manual.  Yes, I have located the tools to do so.

If that doesn't work, try balancing each half of the shaft independently 

If that doesn't work, try another driveshaft.  Either an original 63, or a modified version of the 64 to take advantage of the CV joints.

If that doesn't work, take three steps back and think some more.  


I'll get it.  Might take some effort and $$, but I will get it.  

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  • 2 weeks later...



New trans bushing is installed.  That plus the new yoke has the movement there down to 7 thou or so.  

New trans mount arrived today.  Its about 1/4" inch taller than the old one.  Wondering if that may be part of the issue, as the angle the u joint operates within would change.  

More later as information develops.

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