driveshaft problems?

[gt273]

i have a 1966 dart with 273 four speed factory. i want to install a 489 8 3/4 rear. i thought i could just have the driveshaft shortened but its has inner shaft with the outer tube shaft. question is can this shaft be shortened to work? it has a factory 7 1/4 posi unit now. thanks in advance.

 

[doug 371]

Maybe but I wouldn't use it. Looks like you have the big yoke on your 8.75 as well

 

[Darter6]

Usually driveshaft shop will tell you it's best to replace the old tube with a new one.
Did several of the iso tube 7 1/4'' change overs when going to a 8 3/4''.
Different shops,same answer. Just a thought.

 

[Bogie]

I’d have a new shaft made.
Consider upgrading U Joints to 1350’s to be completely trouble free

 

[wawarnick]

When I switched rears the driveshaft shop said they couldn't shorten the same type of "double layer" (actually they said they could shorten it but could not guarentee it). They made a new drive shaft, fits like a glove.

 

[gt273]

When I switched rears the driveshaft shop said they couldn't shorten the same type of "double layer" (actually they said they could shorten it but could not guarentee it). They made a new drive shaft, fits like a glove.

thats what i thought. done dozens of these swaps but never ran into the 2 piece shaft before.

 

[67Dart273]

Those can slip, too, and get "out of clock." U joints MUST be clocked rotationally. You should be able to sight down the length like a rifle barrel and the the caps should be "in line" with each other

 

[Vaanth]

question is can this shaft be shortened to work?

The topic of this type of propeller shaft came up on For C-Bodies Only (FCBO). I provided an information post there that I will also post here in the following.

Regarding the question of shortening, It's not advisable for this type of shaft, especially with its age and possible isolation condition. If attempted, it likely should be done at the front end. The back end with the outer and inner tubes coupled with the internal rubber isolation rings complicate any shortening, although it might be bypassed by removing the inner shaft and isolation and using just the outer tube and different universal joint yoke.

Borrowing a picture from the FCBO query, shows part of the rubber isolating rings failing in a 1968 propeller shaft:

Following is the posting I made on FCBO, FYI....

Chrysler introduced the Internal Vibration Absorber (IVA) propeller shaft (aka drive shaft) for certain applications for the 1966 model year. Applications were determined through Noise/Vibration/Harshness (NVH) studies. Two approaches include the addition of the inertia ring at the front of the shaft, or a rubber isolation with inner and outer shells added at the rear of the shaft. These approaches were phased out in later years as other NVH control methods were used in body structure, suspension mounting, etc. 1966 was also when the constant velocity joints were dropped in favor of cross and roller universal joints on all models except Imperial.

From:

Additional industry-wide information for the IVA Propeller Shaft can be found in SAE technical paper, " Axle Noise Control - The IVA Propeller Shaft", Product Code 690259, Jan 31, 1969.

 

[perfacar]

the 273 doesn't need 1350 joints, the 7290 is more than adequate. you would have to buy after market trans yoke and yoke for rear end. just food for thought.

 

[Dana67Dart]

either buy a shaft that can be shortened or have new one made. I bought a 1 piece shaft that was 2 in too long and had the local shop shorten and balance it 1/4 oz of weight was all it needed when they were done.

 

[Bogie]

the 273 doesn't need 1350 joints, the 7290 is more than adequate. you would have to buy after market trans yoke and yoke for rear end. just food for thought.

I’ve broken 7290’s with that combo (273/4speed) I said consider the upgrade as I’ve never had an issue with the 1350’s on my Dart or my Ram on 37’s

 

[Jim Kueneman]

My driveshaft guy told me to throw the rubber insulator type away. He had a stack of shafts in the back and made a solid tube one for me out of what he had.

 

[Mojoe9955]

I have bought a couple used driveshafts using this chart. The last one was for my 70 Duster, it had an 8.25 and 318/727. I swapped in a 8.75 and existing DS was too long. I found one from a Mustang on FB marketplace local that was 49.25" for $75.
A bit long but, it seems to work fine and I saved myself $$$. I swapped the 8.25 for the 7.25/904 combo in a 72 Demon. Again the DS too long. I posted in the parts wanted section here and got one from OldmanMopar for $60. I had to drive about 90 minutes so that added to the cost but, it was a nice day for a drive met a cool dude and still saved $$$.

 

[Blainethemono]

Ill just throw this out there for the fun of it, but Im eventually going to have to upgrade my driveshaft for my Ball & trunnion setup, AFTER I fix my pinion seal leak. I checked pricing locally & online, & I think Im gonna go with Denny's Driveline out of New York just cus they offer a full aluminum drive shaft for only a couple hundred more then a steel one. For my puny lil 6 cylinder Im looking for every weight saving advantage I can get...

 

[gt273]

Ill just throw this how there for the fun of it, but Im eventually going to have to upgrade my driveshaft for my Ball & trunnion setup, AFTER I fix my pinion seal leak. I checked pricing locally & online, & I think Im gonna go with Denny's Driveline out of New York just cus they offer a full aluminum drive shaft for only a couple hundred more then a steel one. For my puny lil 6 cylinder Im looking for every weight saving advantage I can get...

Had brand new shaft made 54 1/2 inch center to center with my factory front 833 4 speed input 7260 front joint with 7290 rear
275 cash at pittsburgh driveline .butler st
Works and looks perfect

 

[slantsixdan]

1966 was also when the constant velocity joints were dropped in favor of cross and roller universal joints on all models except Imperial.

I think you mean to say the ball/trunnion front U-joints were dropped after '65 in favour of cross/roller ones. Constant-velocity U-joints, consisting of two yoked cross/roller joints at each end of the shaft, were a feature of the Imperial starting in '65 and ending I don't recall when.

As far as I know, the ball/trunnion U-joint is not a constant-velocity design.

 

[Vaanth]

I think you mean to say the ball/trunnion front U-joints were dropped after '65 in favour of cross/roller ones. Constant-velocity U-joints, consisting of two yoked cross/roller joints at each end of the shaft, were a feature of the Imperial starting in '65 and ending I don't recall when.

As far as I know, the ball/trunnion U-joint is not a constant-velocity design.

You are correct Dan, thank you.

I intended to say the ball & trunnion joint was dropped in favor of cross and roller universal joints but something went amiss between the thought and the typing. Imperial continued to use its constant velocity joints until the 1974 model year when they were replaced by regular cross and roller universal joints.

 

[slantsixdan]

Additional industry-wide information for the IVA Propeller Shaft can be found in SAE technical paper, " Axle Noise Control - The IVA Propeller Shaft", Product Code 690259, Jan 31, 1969.

That was a Chrysler Engineering paper, talking about Chrysler's R&D and deployment of IVA driveshafts—no mention of the wider industry. At least not in my copy, which y'all can read here. It didn't come from or through SAE; it's left over from the shelves and stacks of Chrysler in-house tech publications I used to have. But I'm pretty sure it's the same paper. Same author, same date, apparently the same content judging by the preview at SAE.

 

[slantsixdan]

something went amiss between the thought and the typing.

Happens to me all the time. I type at over 130 wpm when I really stick my foot in the secondaries about it, and I cannot ever type a word other than "slant" that starts with "s-l-a" on the first try. Same with "c-h", "v-a-l", "h-e-a-d-l", and some others.

Imperial continued to use its constant velocity joints until the 1974 model year when they were replaced by regular cross and roller universal joints.

The first time I saw one of those CV joints under a car at a wrecking yard, I remember thinking "Damn, that is a lot of mass to hope is balanced!".

 

[chignikred]

Long thread and I'm on a cell phone. I have a custom made driveshaft for your exact application. I will sell 200.00
Pm me and give your text number.
Red.