Correct SYE Driveshaft Measurements

Fred97TJ

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Mar 29, 2025
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Canada Quebec
Hi,
I've searched through and through on the forums how to measure, and how to interpret the measurements you get for a Rear Driveshaft with a SYE.
To be exact on my setup, I've got a 98TJ, but it's quite the frankenstein. It is a 98' with a 2006 Frame and a 2004 body. I've got a 4" lift I just installed a Teraflex SYE Extreme short shaft kit and my rear axle is a Ford 8.8. I do have a double cardan rear driveshaft for it, but I find it being a little short. Fully closed from center of the U-joint to the mounting flange, for the ford 8.8, it measures 17".

When I bolt the driveshaft in place, I've got about 4.5" of the splines showing and that means I've only got 1.25" of spline still inside the slip yoke. I'm scared that I'll pull the driveshaft apart when wheeling around with that. I've tried to measure between the flange of the diff to the yoke on the SYE, but how do I know what length my driveshaft should be fully collapsed. I'd like to know how much longer I should make my driveshaft, so I can bring it to a shop and get it lengthened.

This is just me thinking, but I Think at least 1.5" longer should be minimum. So that at Ride height, I'd at least have about 3" of the spline still in the slip yoke to drive and it should have enough length to not pop out when wheeling.


I'll read all of your answers and hoping some people with some expertise could have an answer to my question. Thanks!
 
Last edited:
Measuring Your Jeep Wrangler TJ Driveshafts
https://4xshaft.com/blogs/jeep-drive-shaft-tech-articles/measuring-your-jeep-wrangler-tj-driveshafts

How much of my spline should be showing?
https://4xshaft.com/blogs/faq/how-much-of-my-spline-should-be-showing

Call Shawn at Tom Wood's and talk to him, he's a wealth of information. And their service is fast, and quality is excellent.
He can lengthen your driveshaft for a reasonable amount, if it's in good shape.

Thanks! That is exactly what I was looking for. According to the measurements of how much spline should be showing, I'm far from at around 5" of spline showing from dust cap to weld.
Rotate the yokes until both ears are in the same rotation and measure from the same spot on one ear to the other.

-Mac

With the Ford 8.8 rear axle, it's a mounting flange and not a yoke that the U-joint fits into. I've seen on the Tom Wood's website to measure from yoke center to the flange face for proper measurements.
 
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