Driveshaft measurement

[roadrunnerh]

Ok, please give me your thoughts fellas. So I pulled the 7.25 and installed the 8.75 in my Scamp.
The measurements for the axle centerline to the yoke center line for an 8.75 is 12.35"
The measurements for the axle centerline to the yoke center line for an 7.25 is 10.09"
To me, this means I need to have my driveshaft shortened by the difference 2.26".

I've been told to climb under the car with all four wheels on the ground and measure the distance.
Why would I do that when I know the difference in the two rears? Someone told me to shorten the driveshaft 1.75" and said shortening it by 2" would be too much.

What am I missing here? :huh:

 

[69hemibeep]

I was always told to measure with the car on the ground center of u-joint to center of the other. But you know the difference in length I don't see a problem. Does it use the same joint?

 

[roadrunnerh]

Yeah Bob, it makes sense to measure on the ground, but since I have the measurements...
Yes, both are the small one 7260.

 

[moparchris]

No 2 cars are alike. When you remove and replace a rearend it can move up to 1/2 inch and the holes in the perches can allow movement of the rearend on the centering pin on the leaf spring. Also the perch location can vary from the factory by up to 1/4 inch. So do yourself a solid and measure twice and cut once. It would suck to come up short and have to replace the driveshaft.

 

[69hemibeep]

No 2 cars are alike. When you remove and replace a rearend it can move up to 1/2 inch and the holes in the perches can allow movement of the rearend on the centering pin on the leaf spring. Also the perch location can vary from the factory by up to 1/4 inch. So do yourself a solid and measure twice and cut once. It would suck to come up short and have to replace the driveshaft.

Good point on the centering pins, Harry get on your back and crawl under that thing

 

[A31PKG]

I have an extra A-body drive shaft that you can have (free) if you need it.

It came out of a /6 Dart...not sure about the year. It was in a garage full of parts I picked up a few years back.

 

[george68hemirr]

heres where i go

http://www.markwilliams.com/driveshaftOrdering.aspx

 

[roadrunnerh]

Thanks for the feedback guys!
And thanks A31PKG for the offer, but I'm gonna have mine cut down.

Looks like I'm squeezing under the car to measure.

Chris, really? That much variance?

 

[moparchris]

Thanks for the feedback guys!
And thanks A31PKG for the offer, but I'm gonna have mine cut down.

Looks like I'm squeezing under the car to measure.

Chris, really? That much variance?

Yep, I have 2 A bodies both Darts. One fits a 28 inch tall tire with a half inch clearance at the front of the wheel opening. The other, the 28 inch tire touched the quarter.

 

[roadrunnerh]

So I spoke with Dr. Diff, aka Cass, who I need to give props to. He's a good dude and he knows his shit.
Anyhow, he advised (as you guys did) to measure with car on all fours. He told me to slide the tranny yoke in til it bottoms out, measure from center of yoke ears to center of 8.75 yoke ears, then subtract 1 inch.

Guess what I came up with? 2.25"

The 7.25 / 8.75 difference between the center of axle tube to center of yoke ear.....

 

[generaljmwlee]

Thanks for the feedback guys!
And thanks A31PKG for the offer, but I'm gonna have mine cut down.

Looks like I'm squeezing under the car to measure.

Chris, really? That much variance?

why squeeze under as long as the weight is on the axle and front suspention ,put it on jack stands !

 

[moparchris]

So I spoke with Dr. Diff, aka Cass, who I need to give props to. He's a good dude and he knows his shit.
Anyhow, he advised (as you guys did) to measure with car on all fours. He told me to slide the tranny yoke in til it bottoms out, measure from center of yoke ears to center of 8.75 yoke ears, then subtract 1 inch.

Guess what I came up with? 2.25"

The 7.25 / 8.75 difference between the center of axle tube to center of yoke ear.....

And now you know for sure.

 

[roadrunnerh]

Yeah Chris, I didn't want to rely just on those axle tube to center yoke measurements.

generaljmwlee, yes I had some tell me what you said - including the good Dr. Diff.
And although I could have just put jack stands under the axle housing to load the rear suspension,
I squeezed under to measure at actual ride height. Not sure it made a difference, but like Chris said, just to be safe.

 

[moparchris]

Yeah Chris, I didn't want to rely just on those axle tube to center yoke measurements.

generaljmwlee, yes I had some tell me what you said - including the good Dr. Diff.
And although I could have just put jack stands under the axle housing to load the rear suspension,
I squeezed under to measure at actual ride height. Not sure it made a difference, but like Chris said, just to be safe.

You actually squeezed under the car at ride height?! Either your super skinny or that thing has a lift kit!!