Another Driveshaft question.

[mopar_1974]

So i am getting my 904/7.25 driveshaft cut and having a new one made for my 727/8.25 duster. i know i saw the answer on here before but i cant seem to find it again the shop is going to cut off the yoke and ujoint and weld a new tube on. can anyone give me a measurement? also, i would imagine the old driveshaft had a small ujoint. (right?) how hard is it to upgrade to larger ujoint and where would i find the part numbers for that? anything else i might run into? thanks guys, i'll be sure to reward you with some burnout videos when it gets rolling again.

 

[mopar_1974]

Ttt

 

[crackedback]

about 45.60" would be my guess.

A 727/8.75 is 44.99 and the yoke on a 8.25 is about .66" further from the tailshaft.

 

[mopar_1974]

is this the length of the tube or overall?

 

['74 Sport]

A question pertinent to this thread...

I also need to have a shaft made for Aaron's Duster 360/727/8.75 setup. If I push the front yoke all the way into the tailshaft until it bottoms out, how far should I pull it out to take a measurement for the shaft length? I know there needs to be a little play to account for the suspension movement and prevent the shaft from jamming into the transmission when the rear axle compresses.

Rob, is that 45.99" a measurement you have on an actual drive shaft, or is that information available online somewhere?

I've been told that drive shaft measurements should be taken between the centers of the U-joints for an overall length.

 

[mopar_1974]

sorry but i'm bumping again. sending the driveshaft out this evening and just want to make sure. thanks

 

[crackedback]

That would be center to center of the U joints.

Bottom the slip yoke, pull back about 1" and measure would be the best way.

The 45" length is an actual driveshaft fom my 70 340/727/8.75 car. Aaron's DS should be the same basic length.

 

['74 Sport]

A 727/8.75 is 44.99...

Oops! Sorry, I mis-typed it as 45.99". I was thinking that would be a bit too long. Your 45" sounds closer to what I had calculated.

 

[Tony Fields]

The drive shaft shop that we use (Patterson Driveshaft) in Indy
wants a dimension from the seal face back to the center of the
yoke on the diff. They do the calculation for the length of tube
so that there is enough room for front yoke slip into the tranny.

 

['74 Sport]

They do the calculation for the length of tube
so that there is enough room for front yoke slip into the tranny.

That makes it too easy.
I was told there are two lengths of 727 slip yokes, so I guess you would have to take yours to them so they would make the correct calculation. I noticed that mine is not splined inside completely to the end. I would hate to run out of splines and twist them off on a hard launch.