AAR Cuda Driveshaft Questions

[cwestra]

I have determined that the driveshaft on my AAR is the source of a vibration at around 70 mph.  I would like to just have mine re-tubed but wonder how easy that will be on this shaft.  Below are a few questions I have.  Any comments would be greatly appreciated.

My driveshaft is stepped or tapered at the rear.  For re-tubing, they must use a similar type shaft in order for the yokes to fit properly.  I am assuming, then, that these tubes are being reproduced and are available.  Is that a correct assumption?

How critical is the speed in balancing a shaft?  I have had guys say they balance up to 3,500 RPM while others say they only balance up to 500 and let the computer extrapolate the data out to higher RPM's.  Which, if any, are correct?

I can visibly see my shaft with some amount of run-out when I have in 1st gear on jack stands.  If I can see it, is it too much, typically?  And is this usually the result of a bent shaft or would it be something going on at the joint(s)?  Can a bent shaft with minor run-out be compensated for with a good balance?

My driveshaft has the larger 7290 in the rear and smaller 7260 in front.  Was that unique to AAR's and T/A's or were there other vehicles that used this configuration?

Any recommendations in the mid-west area for a reputable company who can help fix my driveshaft?

[Haddixj]

My advice is to find out who is building them for the drag cars and go there. They will have all the capabilitys to Do what you need and more

[Chryco Psycho]

Talk to Mancini , they build new shafts , probably similar cost to have yours re tubed for a complete new unit .
If you can see it , it is too much , it could be a bad U joint sitting offcenter as well , balancing a shaft can help if it is off but I have seen tires perfectly balanced shake the crap out of a car because the tire is not round but a tire is in contact with the road the sahft is only contacting air . tire balancer operate at relatively low speed it shoul dbe the same for the shaft balancer

[AARuFAST]

Do you drag race or do burn outs?  Are you sure it is the driveshaft....did you check the nut on the yoke?  Put car on jack stands or on lift, car in neutral grab driveshaft at universal joints shake for play. If original u joints they could be worn........
 I replaced the u joints and the nut was loose on yoke

[Chryco Psycho]

HE has been chasing this vib problem for a Looong time now but worth checking the pinion nut for sure

[cwestra]

Do you drag race or do burn outs?  Are you sure it is the driveshaft....did you check the nut on the yoke?  Put car on jack stands or on lift, car in neutral grab driveshaft at universal joints shake for play. If original u joints they could be worn........
 I replaced the u joints and the nut was loose on yoke

Last Friday I swapped my driveshaft for an identical one out of another AAR and took my car out for a test run.  I ran it up to 90 MPH several times and the car did not vibrate.  Before, a vibration would have come in at around 70 MPH.  So I'm pretty sure that is the source.  The thing I need to do now is try and figure out where, within the shaft, the problem is coming from (rear joint, front joint, tube, slip yoke, poor balance).  If I can isolate it and fix it I'll likely take that route.  If I can't isolate it or if the problem is not fixable then I'll be searching for a new shaft.  I'd much rather have it fixable because I have new Spicer joints and a new slip yoke and with a new shaft these parts are typically included.

To answer your question, though, I don't plan on racing, just want it to be comfortable at highway speeds.

[Changin Gears]

You can do the hose clamp balance procedure that's in the shop manual.  I've done it and it works.

[cwestra]

You can do the hose clamp balance procedure that's in the shop manual.  I've done it and it works.

I may consider that, thanks.

[cwestra]

As I mentioned in my initial post, my drive shaft has the larger 7290 joint in the rear and the smaller 7260 in the front.  This seems very odd to me.  Can anyone comment on whether they have this same combination on their car, or if you know that certain cars came with this configuration?  I am suspicious that my front joint may have been replaced with a smaller joint at one point.  My car is an AAR Cuda.

[ShelbyDogg]

My drive shaft has a large joint up front and a small rear.  The larger the tube, the higher the speed it can handle. The larger joint can handle so much more torque too. If you have a shop replace the tube, they will give you a straight tube, front to rear, and probably sell you a new smaller front yoke.

I get a used shaft from any other car, with a big joint in front, small joint rear, then take it to "Driveshafts Unlimited" in Arnold, MO.
E-bodies use some of the shortest shafts around so you can use almost any other body's shaft.

Carefully measure yoke center to yoke center because my small joint shaft uses a longer measurement than my shaft with a small rear, large front shaft.

[Cuda54]

If I remember right I had the big u joints front and rear in my AAR 4 speed 3.91 posi. I had a drive shaft from a full size car cut down for my 1972 440-6 Cuda with the big u joint both ends and bought a rear yoke. I had the small ones in it when I bought it. I dropped the drive shaft and broke the rear yoke. After I put in the new drive shaft I had to rebuild the 727 trans to I put in a 2800 stall converter too.

[GranCuda1970]

That is basically what I did also. Took a longer mopar shaft with the big 7290's had it cut to fit. I was a little surprised at how smooth th car rides at 40 + miles an hour on windey riverside roads even with the 391 suregrip.