SYE questions

[Whiplash2130]

I recently had the rear output seal replaced by a local transmission shop. Well she’s still leaking. I keep hearing about Slip Yoke Eliminators. Can someone explain why these are changed? Advantages? Disadvantages? What other parts need to be changed if swapping over to SYE?

 

[Flyer58]

I don't think your Yj has any suspension lift kit installed so the SYE is not necessary. The SYE help solve the many geometry problems associated with the higher angles of the U-joints on the driveshaft and vibration problems when those joints are near to or exceeding their maximum angles. The SYE design is more like a front wheel drive CV joint than the traditional U-joint and can eliminate those problems.

Cost wise you're looking at a new seal of less than $10 vs an SYE kit plus labor of totally disassembling the transfer case to add the kit plus parts might be close to $800.

I would go back to the shop that put in the new seal and ask why it's still leaking. Wipe everything clean, maybe spray it with brake cleaner so it's dry, and a quick drive and try to positively identify where the leak is. Sometimes oil can travel a long way to end up at the back.

 

[Whiplash2130]

I don't think your Yj has any suspension lift kit installed so the SYE is not necessary. The SYE help solve the many geometry problems associated with the higher angles of the U-joints on the driveshaft and vibration problems when those joints are near to or exceeding their maximum angles. The SYE design is more like a front wheel drive CV joint than the traditional U-joint and can eliminate those problems.

Cost wise you're looking at a new seal of less than $10 vs an SYE kit plus labor of totally disassembling the transfer case to add the kit plus parts might be close to $800.

I would go back to the shop that put in the new seal and ask why it's still leaking. Wipe everything clean, maybe spray it with brake cleaner so it's dry, and a quick drive and try to positively identify where the leak is. Sometimes oil can travel a long way to end up at the back.

That explains it better, thanks. I have already verified the leak. Not sure how much is leaking since I can’t find my 1 3/16” socket. It’s probably with the 10mm sockets I lost . I think I’d rather take care of it myself. I’ll replace the yoke and seal.

 

[Flyer58]

When I had my transfer case out I changes all three seals, one input and two output (F&R) seals. My driveshaft had a ton of junk built up on the yoke which I was able to polish off with cleaner and a rag. I coated the yoke and inner seal area with Vaseline before putting them together. Pry the old seal out and I used a short piece of PVC pipe the same diameter as the seal to help evenly tap the new one into place on the T-case. No more leaks.

Front seal and PVC