Custom drive shaft.

[Edelbrock]

So I'm wanting to shorten a driveshaft to fit a 77 K5.

The rig is lifted maybe 4 inches.

U-Joints on either end, with a slip in the center.

This will be for the rear.

How do I know the proper length? Do I just shorten the driveshaft so that when its installed, the slip yoke is in the center position? Obviously, I want to avoid the driveshaft from being compressed too far resulting in damage to something, and I also want to prevent the slip yoke from coming apart.

Any info available on this?


Slip in the center, similar to this:

 

[Strick]

The slip yoke should be half it's travel with the vehicle suspension supporting the sprung weight.

HS

 

[Matt69olds]

I just had a driveshaft built for my son’s 92 Yukon. Same thing, we just installed a 4 inch lift. Even though there was no mention of driveshaft modifications in the instructions, common sense made it obvious that about 25% of it’s normal engagement wasn’t going to cut it!!

The shop that built the driveshaft said that the weight needed to be on the suspension, in other words at normal ride height. Install the yoke fully into the transfer case, then pull it out about an 1.25 inches, then measure center to center on the yokes.

Once I installed the new driveshaft, the yoke position was about 1/8 further out than it was originally.

Having said all this, I’d find out exactly how your driveshaft shop wants you to measure. Do exactly what they say. The total bill for the driveshaft was a bit over 300 bucks, it would suck to have to spend the money twice!

 

[Zelph]

Courtesy of Tom Woods Driveline
https://cdn.shopify.com/s/files/1/0266/9871/1137/files/measuring_guide_without_logo_photos.pdf?1908

Courtesy of Denny’s

Dennys Driveshaft How to Measure Correctly Diagram B

Dennys Driveshaft has the best measuring diagrams in the business. It easy to get a driveshaft that fits perfectly. Printable sheets for a variety of auto and truck applications.

www.dennysdriveshaft.com