OLDS Driveshaft length measurement

[rfpowerdude]

When a driveshaft is measured for length, are there particular measurement points? Like center of yoke pivots? Or is it typically measured somewhere else? What and how is the driveshaft for an 8.5" rear Gbody driveshaft measured and what's the measurement it?
Thanks all,

 

[79 USA 1]

I've always used this sheet from Denny's web site.

Dennys Driveshaft How To Measure Correctly for driveshafts that fit right

Dennys Driveshaft How To Measure Correctly page makes it easy to order a driveshaft that fits perfect every time. Many diagrams to show you how.

www.dennysdriveshaft.com

 

[JAMCAR223]

Joe, it's easy. With car on the ground or a drive-on lift ( weight on the suspension ), insert the transmission yoke into the transmission. Pull it out 1 inch. Now measure from the center of the u-joint hole in the yoke to the center of the u-joint hole in the rear axle's yoke. That is the length of your driveshaft.

8.5" with 200-4r on my GN = 51.43 inches.

 

[rfpowerdude]

Ah cool guys, thanks. I may have a line on a driveshaft that "looks" like it may be for the 8.5" in a Gbody and I wanted to have the guy make measurements.

 

[57 Handyman]

Joe, if I recall correctly, I had 2" removed from my stock driveshaft in order to accommodate the 8.5" GN posi rear end I installed. My stock 87 El Camino had a 2004r and stock rear end assembly. I found that information on this site after searching "installing 8.5" rear ends". I believe a shortened driveshaft was needed to accommodate the larger 8.5" housing and provide sufficient play.

 

[JAMCAR223]

The difference in length between a 7.5 driveshaft and a 8.5 driveshaft is 1 inch. The larger case on a 8.5 rear axle will require a shorter shaft.

 

[64nailhead]

Very good info from everyone. Don'y get worried over this AT ALL.

I set the rear axle on jack stands, and the front wheels on blocks of wood. Push on the trunk to get the suspension to settle. Put the trans yoke all the way in, measure from center of UJ cap to center of UJ cap, the deduct an inch as James mentioned. My son's shaft is 51.25" with an 8.5 and 200-4R. But if you have adjustable uppers and lowers, then you can make up 1/4-3/8" in rear adjustment easily.

Don't go off from anyone elses measurement. Measure for your self. And being off by a 1/2" in either direction isn't any issue as long as your ride height doesn't change by 2 or 3".