What is a SYE???

[Steve F]

I notice we talk about technical stuff a lot but dont actually explain what it is, when you're new to Jeeps it can be difficult finding out the details so I thought we'd try and explain some of the terminology.

Thought I'd start with this one as I've already posted this on another forum.

The Slip Yoke Eliminator or SYE :)

This is a slip yoke, the splined section goes over the output shaft on the transfercase and is able to slip backwards and forwards over it, it allows the extension and compression of the driveshaft as the suspension goes up or goes down. The slip yoke sucks especially with bigger lifts as you get less output shaft inserted in the yoke splines due to the suspension being extended and therefore more leverage on the output shaft and a good chance of bending or snapping it. A slip yoke eliminator not only gets rid of this weak point but also lets you use a dual cardan driveshaft to help eliminate vibrations when you lift the jeep. The setup of this might be the next topic :)

http://www.4wdlinks.com.au/albums/album419/Slip_yoke.jpg

This is the output shaft of the transfercase ready for the slip yoke to slide on or in this case the SYE (the output shaft has been shortened and has had a thread tapped in the end)

http://www.4wdlinks.com.au/albums/album419/aab.jpg

This is a slip yoke eliminator for a NP242 (mine actually), commonly know as a hack and tap as you cut the output shaft and tap a hole in the end for a bolt. It replaces the slip yoke with a flange for the drive shaft to bolt to. The flange slides on to the output shaft (after it is shortened in this case) and is then bolted on through the end of it. Some replace the whole output shaft with a thicker shorter one etc but essentially they all do the same thing. The are other types of slip yoke eliminators like the heavy duty version available for TJ's and some XJ's and a super short one that replaces the rear part of the transfer case housing.

http://www.4wdlinks.com.au/albums/album419/aaa.jpg

This is a driveshaft with a slip yoke

http://www.4wdlinks.com.au/albums/album419/Slip_yoke_driveshaft.jpg

This is a new driveshaft with a slip JOINT not a slip yoke. The slip joint is in the body of the shaft and allows it to extend and compress as the suspension cycles :)

http://www.4wdlinks.com.au/albums/album419/aaf.jpg

The JK is the only common jeep that already has a driveshaft with a slip joint so does not need a SYE. Front driveshafts do not have a slip yoke and are already setup with a slip joint driveshaft.

Hope that helps :)

Cheers
Steve

[Wooders]

The JK is the only common jeep that already has a driveshaft with a slip joint so does not need a SYE. Front driveshafts do not have a slip yoke and are already setup with a slip joint driveshaft.


Great idea for a series of threads Steve.
If I might I will jump in here with a bit more information:

Stock XJ/TJ/ZJ's have Slip Yokes at the rear of the transfer case which look like:
http://www.4wdlinks.com.au/albums/album419/Slip_yoke.jpg

A SYE comes in either of 2 styles:
A. Flange (used in Light duty SYE Kits) which looks like http://www.northridge4x4.com/prodimages/RE1807.jpg
or B. Yoke (used in Heavy Duty & SuperShort SYE kits) which look like http://jbconversions.com/store/media/products/std_sye.jpg

Stock TJ/XJ/ZJ have fixed yokes on the front output shaft (hence why SYE's are not required there). And as Steve said these have the slip joint in the tailshaft.

JK's have CV joints Front & Rear, so a SYE is not applicable. Although CV's are weaker than Uni and double cardan joints and with larger lifts may need to be replaced to convert to a Double Cardan Tailshaft. But this is NOT a SYE.....More of a CVE ;)

For old Jeeps - the easy way to tell is by the transfer case. If it's fitted with a New process Style of transfer case then chances are it will have a slip yoke. If it's fitted with a Dana transfer case it will have a fixed yoke.

[ValiumMm]

How much are they approximately?

Cheers Alex

[azasjeep]

gees i wish this thread was around when i got my first jeep, i am into cars and have modified a few but the sye thing threw me i just couldnt follow what people were describing.

Then wooders showed me how it worked and i was convinced i needed it straight away and it couldnt wait till later.

Great work guys

[Steve F]

How much are they approximately?

Cheers Alex


Depends, the flange style is cheap, the yoke style is more expensive due to more parts etc. The driveshaft costs are around the same (you'll need a new driveshaft for both types)

Best bet is to give Wooders a call.

Cheers
Steve