How to properly measure driveshaft length

[rdf]

My 73 ;Cuda used to be a 360/904 setup but I've swapped the motor and transmission for a 440/727.  I still have the driveshaft from the 904 setup but obviously it doesn't fit, so my question is how can I get an accurate measurement of the length needed so I can get it cut?  The yoke on the driveshaft doesn't fit either so I'm assuming I will have to swap that out for the correct one then take measurements?  Where exactly can I measure to and from?  I've seen some posts that say from the center of each u-joint cap and others that say from the seal to somewhere on the rear-end yoke, so I'm not too sure which is more accurate.

[JS29]

Make sure the rear end is NOT hanging when you measure! best to have the weight of the car on the suspension.   

[1 Wild R/T]

What axle?

[Rich G.]

You usually measure from the end of the tail shaft on the case to the center of the rear yoke which is the end where the cap bolts to. A good drive shaft guy would figure out the length he needs to allow for the shaft to move in and out. Like they said car has to be on all 4 wheels

[anlauto]

If you still have the 8 3/4" rear axle, just go with 42.6" from the center to center of the U Joints.

[rdf]

it's an 8 & 3/4

[rdf]

If you still have the 8 3/4" rear axle, just go with 42.6" from the center to center of the U Joints.

42.6 or 43.6?  I've read 43.6 in numerous threads/articles.

[anlauto]

If you still have the 8 3/4" rear axle, just go with 42.6" from the center to center of the U Joints.

42.6 or 43.6?  I've read 43.6 in numerous threads/articles.

You're absolutely correct...my mind was thinking one thing, but typed another 42.6" is for a Dana 60....8 3/4" would be 43.85" sorry for the confusion.

[Burdar]

I've read other people say to push the slip yoke in as far as it will go.  Move it out 3/4" and measure the center to center length of the u-joints.  I make a habit of measuring how far the yoke sticks out of the trans before I remove the driveshaft.  Then I install the slip yoke to that measurement before measuring the center to center length.

[chargerdon]

I've read other people say to push the slip yoke in as far as it will go.  Move it out 3/4" and measure the center to center length of the u-joints.  I make a habit of measuring how far the yoke sticks out of the trans before I remove the driveshaft.  Then I install the slip yoke to that measurement before measuring the center to center length.

That's how i did mine when i installed the A518.   PS, i did NOT have the car sitting on the floor...    I had the front on jack stands on the front of the frame, and put jack stands under the axle on both sides, with the stands high enough so that the car was sitting level, o that the weight of the car was compressing the springs, just like when it sits on the floor.   

Gave the maching shop the distance between the center of the u joints.  worked.. 

[docmel]

I went thru this myself a couple of years ago  As you can see, lotsa dif opinions out there,   If you having a shaft made, or oredering one already made, call those folks on how THEY measure,

[PLUM72]

No one has factory measurements or a chart for this?

[Rich G.]

I always thought they were short from the factory. Measure it and it will be the correct length.

[rdf]

I went thru this myself a couple of years ago  As you can see, lotsa dif opinions out there,   If you having a shaft made, or oredering one already made, call those folks on how THEY measure,

This is exactly what I did...called them up and asked how they wanted me to measure it and went from there. They want the measurement from the transmission seal to the u-joint bolt hole, with the car on the ground or if it's on jack stands, have the stands under the rear axle. Mine measured 47 & 3/8", so they will shorten it based on that along with putting a new 727 yoke and u-joints on it and balancing it as well.  Should be done in a few days too 😁