Topic: SYE?

[Liljeepz]

Can some one tell me how SYE works?
and with a lift do I need a CV joint too?
I know I need one, but i was trying to explane it to my dad... and relised i dont know how it all works.
I thought when I get a lift kit all I need is http://www.rubiconexpress.com/dynamic/mainpage.asp?folderid=208 ---RE1807 SYE Kit CV TJ/XJ 96+---  for $87.95 + S&H
&
http://www.rubiconexpress.com/dynamic/mainpage.asp?folderid=234 ---RE1860 Driveshaft CVO RE1811--- for $294.95 + S&H

Am I mistaken on the parts I need for the RE 3.5 super flex?

Sorry for the dumb questions, Im starting to rethink my wants/needs for my jeep....  :?

[Jeffy]

Standard Driveshaft

CV Driveshaft


You can see in the second picture that there are 3 U-joints rather then just two.  How does that help?  Think of it this way.  The 2 U-joint split the difference between the two of them and share the load.  So each U-joint takes half of the angle.  This reduces the angle for any one U-joint.  Does that make sense?

The only down side to a CV driveshaft is that it is weaker then a single U-joint.  The other thing to consider is that when you go with a SYE eliminator kit, you will gain anywhere from 4.5-8.5" depending on the kit.  This by itself reduces the angle of the U-joint.

[Liljeepz]

That makes a lot of sence!
But how dose the SYE work? and would I have to buy both CV and SYE for a 3.5 lift?

[Jeffy]

It replaced the slip yoke on the end of the transfer case.  Most driveshafts have a splined area that allows the driveshaft to lengthen and shorten as the suspension moves.  This is usually in the body of the driveshadt between teh two U-joints.  On a slip yoke driveshaft the slip joint is plated at the yoke end instead of the body.  This is done to speed up assembly when on the line since no tools are required to install that end of the driveshaft.

Here's a picture for ya.



The top one is the stock shaft.

Although if you have enough room, you can sue a SYE and a standard single U-joint setup.  Many jsut go with a CV because it gives you come leeway with your angles.  With the super short SYE's though, you could probably run a single U-joint.

[jackhammer]

i was under the impression that w the sye if u break ur drive shaft u could limp w the front drive working without dumping transfer case fluid along the way..correct me if I am mrong

[Jeffy]

Yes and no.  It really depends on what broke and how fast you're going.  If you're going slow and the U-joint breaks you might be ok.  If you're going fast enough though the driveshaft will flail and could take out the tranfer case.

With a slip yoke, you can also drive off in FWD but you'll need to stuff the yoke opening with stuff to prevent it from leaking before you try driving.  Still the flailing driveshaft can leave you high and dry, too.

[Liljeepz]

That makes a lot of sence! Thanks for the Pic's!