Driveshaft length question, a little different

smithcaz

TJ Enthusiast
Original poster
Joined
Nov 26, 2018
Messages
120
Location
Central NY
My driveshaft bit the dust and I am ordering a replacement now, I have a measurement from yoke to yoke of 15.5 inches. I am being told that the driveshaft for this lift is normally 16.25 to 16.5 inches long. Anyone out there with a similar build that can do a quick measurement of their driveshaft while Jeep is on the level? I am wondering if my control arms are not extended enough. Based on the looks of my Jeep with the wheel sitting in the wheel well, I do not believe they are too short.

2006, 4.0L, NSG370, 231 with SYE (standard, not short or hack and tap), Dana 30, Dana 44.
Metalcloak 4.5 inch springs up front and 3.5 inch springs in the rear.
16 inch spring up front.
11 inch spring in rear.
 
Driveshaft length depends on far more than just suspension lift height. It also depends on what the rear axle is (a Dana 44 rear axle uses a slightly shorter driveshaft length when compared to a Dana 35), as well as what transmission and sometimes what engine is installed.

Your measurement is what it is providing you are measuring it properly. Which would be from the center-point of the yoke where the center of the u-joint bearing cap would be, to its corresponding point at the other end. Like the #2 example below. This drawing courtesy of Tom Wood's site at www.4xshaft.com

Driveshaft measurements.JPG
 
I have measured the distance as example 2 shows. I now wonder if the previous owner set the adjustable control arms to stock length.
Does anyone know the stock length for oem control arms?
My current length for the rear upper control arm is 13.5 inches.
My current length for the rear lower control arm is 16 inches.
 
From what I see on this forum, stock length for rear control arms are 13.25 inches upper and 15.75 inches lower. So my axle is roughly a quarter inch further back then stock and that could be the problem. I can adjust my lowers to push the axle further back to get my yoke to yoke number closer to the 16.25 inch distance then adjust the uppers for pinion angle.
 
From what I see on this forum, stock length for rear control arms are 13.25 inches upper and 15.75 inches lower. So my axle is roughly a quarter inch further back then stock and that could be the problem. I can adjust my lowers to push the axle further back to get my yoke to yoke number closer to the 16.25 inch distance then adjust the uppers for pinion angle.
Stop...What are you chasing? If it worked before, don't mess around with it now. What did the old driveshaft measure? Just replace it. Don't worry about what "normal" is. If you're that concerned, take a picture of your measurement and send it to Tom. I'm sure he'll be happy to verify or correct your measurement technique.