64 Dart Driveshaft Length

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Vcode

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The driveshaft is a trunnion type and is original to the car. What was done is the 7-1/4 Rear End was changed to a 8-3/4 complete.
What is the best way to measure the driveshaft to see if it is the correct length now. I am not familiar with the trunnion driveshafts.
It is different than just center to center on the u -joint type that I know about.
Thanks Bob
 
Pictures of a trunion "replacement" driveshaft. was on a 64 dart 4 speed with 8 3/4.

20221025_113217.jpg


20221025_113232.jpg


20221025_113253.jpg


20221025_113417.jpg
 
Vcode said:
Thanks for the responses. My friend that owns the car would really like to keep the original set up. I am just trying to figure out if we need to cut a little off to make it fit correctly. It is in the car and running but seems a little tight to install.
Click to expand...

Is the trunnion shaft sliding freely? Normally the rear universal is removed and the trunnion unbolted from the transmission the trunnion shaft should compress to remove. Replacement the same if all things are the same.

I'd have to look at the difference between the yoke position on the 7 1/4 versus the yoke on the 8 3/4 which would create the "tightness"
 
I wanted to keep the original setup, but when I changed rear ends it was no longer original anyways. The driveline shop couldn't make a new driveline with a trunion because the required parts weren't available

Spicer hasnt had them available for many years. The original driveline was slightly bent from 45+ years use. My trunion was without a boot for 15 years prior to the change and not rebuildable.
 
chewy said:
I wanted to keep the original setup, but when I changed rear ends it was no longer original anyways. The driveline shop couldn't make a new driveline with a trunion because the required parts weren't available

Spicer hasnt had them available for many years. The original driveline was slightly bent from 45+ years use. My trunion was without a boot for 15 years prior to the change and not rebuildable.
Click to expand...
Understood, they may not be able to cut this driveshaft with the trunnion seup.
 
Vcode said:
Understood, they may not be able to cut this driveshaft with the trunnion seup.
Click to expand...

I believe it is still possible to shorten the rear portion (u- joint end) and retain the ball & trunnion front end. Then balance the shaft.

20221025_172220.jpg
 
So, what you need is a driveshaft from a 64 or 65 Dart with an 8 3/4 rear, I am not sure if they used 8 3/4 rears in A bodies in 64 so it may be 65 only. Also note that a Valiant won't work because of the difference in wheelbase. I believe shortening your current driveshaft would be the cheapest route assuming that your front joint is in good shape.
 
I am guessing the shaft should be pushed in enough to have constant pressure on the spring inside the trunnion but with some movement forward and backward. I do like the slip yoke replacement also.
 
Vcode said:
The driveshaft is a trunnion type and is original to the car. What was done is the 7-1/4 Rear End was changed to a 8-3/4 complete.
What is the best way to measure the driveshaft to see if it is the correct length now. I am not familiar with the trunnion driveshafts.
It is different than just center to center on the u -joint type that I know about.
Thanks Bob
Click to expand...
The question you need to ask is what is the difference in axle centerline to yoke center line distance between 71/4 and 8 3/4 rear ends. That will be the exact amount to shorten the driveshaft.
Click to expand...
 
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