driveshaft / yoke question

[68bowtie]

My driveshaft is currently 1 to 1.25" too short. I was going to have it lengthened, which I expect will cost me $200+ since I'll need a whole new tube.

Then I realized you can buy longer slip yokes. Seems like it will work, but I am wondering if anyone is aware of a problem I might encounter.

The yoke currently sits 2" out from fully inserted in the trans, meaning only about 1.75" of spline engagement by my measurements.

I think I can buy this yoke which is about 1.25" longer, which should result in the yoke sitting about 0.75" out from fully inserted in the trans, and around 3" of spline engagement:

https://www.summitracing.com/parts/axe-lt675

What's wrong with this? Will I have issues with it bottoming out in the trans? Will it cause any vibration or unusual loading on the tail shaft?

[Sheepdip]

1" out on the splines is the norm .75 won't bottom out with stock suspension articulation but may or may not give you enough extra slide inward to make the ujoint slide in at ride height. Nothing a floor jack can't overcome.

[68bowtie]

Yeah, I'm 2" out now, so I think the extra 1.25" on the yoke should put me in the right spot.

[my67c20]

Slide the yoke all the way until it stops, then pull it out 1" and get the driveshaft made to fit. If the longer yoke, which has the largest mass is not balanced, you may be going thru seals left and right. When was the last time you replaced the u-joints? Lots of driveline places in Turlock, so shop around and do it right the first time.

[HO455]

This web site addresses your question.

http://www.alldrivelines.com/faqs/

[68bowtie]

Thanks guys. This is helpful. It made sense in my head but I suspected there might be a downside. Glad I asked, it needs to be done right. I'll have to pony up the cash.

I sketched this up to scale to get my mind around it (I'm a visual guy) and I can see how this might add balance/vibration/seal issues.

I also added a snip from the link provided for anyone else thinking about this in the future.

[HO455]

I think if you added the output shaft to your drawings it would help it make sense. As it is I can see how when the drive shaft begins to jump rope how that action would affect an over extended yoke. It believe the the problem is how much unsupported splined area there is and how that might distort at RPM under load.

[Katrina/10]

I had the same issue (driveshaft too short) and I few years ago I came up with the idea of a longer slip yoke for more spline engagement. I bought one and found it was actually a little too long, so I cut a little off the end and smoothed it out. I installed it and never had any problems. I agree a new longer driveshaft would be better, but I didn't have any trouble with the longer yoke.