|05-12-2013 08:22 PM|
OP and others interested, here is a great link to some more info, specifically on driveshaft geometry. Click the links to some of the other parts as well and read around. http://www.pirate4x4.com/tech/billav...ft/index2.html
|05-11-2013 09:41 AM|
|05-11-2013 12:53 AM|
|SCORE5150||Jerry, you always amaze me with your no nonsense straight forward answers, along with your cool diagrams!|
|05-10-2013 10:31 PM|
|Jeeping it real||P.S. I used to live in South Carolina, Shaw AFB to be exact. Used to roll to Myrtle Beach almost every weekend. That state is by far one of the better places I've been.|
|05-10-2013 10:26 PM|
|Jeeping it real||
To the OP, I wasn't trying to be rude in any way. This forum and community have answered many of my first time jeep questions over and again. Perhaps I'm among few who do extensive research, draw my own conclusions, and ask questions afterwards... I don't know. My point is the search bar is there, and it works wonderfully. Ask a guy like me, I use it repeatedly. All I'm am saying is that the info you have acquired with this post, is the same as you would find by tapping on the keyboard under the search board. Best of luck to you, and happy Jeeping. Stay thirsty my friends.
|05-10-2013 07:46 PM|
The short answer is a SYE shortens the transfer case's output shaft so a longer rear driveshaft can be installed. Why? To reduce the angles the driveshafts have to work into to eliminate drivetrain vibrations. And stay with me until near the bottom where things get italicized again... that part should put much of this together.
Why in the world is a longer rear driveshaft desirable? Because the TJ's wheelbase is so short, the rear driveshaft has to be short. That the rear driveshaft is so short means its angle is affected greatly by suspension lifts. The taller the suspension lift, the significantly steeper a short driveshaft becomes. Being able to install a longer rear driveshaft means its angle is less affected by suspension lift height.
Because a longer aftermarket rear driveshaft's angle is less steep with any given suspension lift height, that means the u-joints at both ends of the driveshaft can work into reduced angles and are thus less likely to vibrate which is the root cause of drivetrain vibrations.
So the bottom line is that tall suspension lifts causes drivetrain vibrations because they steepen the driveshaft angle excessively which creates excessive angles for the u-joints to have to work in which, again, is the root cause of drivetrain vibrations. A SYE kit reduces that driveshaft angle down enough that an aftermarket driveshaft can work without vibrating.
The first drawing below shows the stock drivetrain & factory driveshaft which has two u-joints. You can see that increasing the height difference between the t-case & rear axle would steepen the u-joint angles.
The next drawing below shows after a SYE is installed. Its driveshaft has three u-joints.
The second above drawing doesn't reflect the shorter t-case output shaft but it shows the type of aftermarket driveshaft that gets installed which is called a CV (constant velocity) driveshaft, aka known as a double-cardin driveshaft.
The 3 u-joints in the CV driveshaft do some neat magic. When a CV driveshaft is installed with a SYE kit, the rear pinion angle gets raised to match the driveshaft angle. You can see that in the second drawing above. Next, look at that rear-most u-joint. It is working into zero (0) degrees. Same angle going into it as is going out.
Then look at the two front u-joints inside the CV joint. The remaining angle between the driveshaft and transfer case output shaft is neatly divided by those two u-joints. That means those two u-joints are working into only half the angle that a single u-joint would have to. So the rear u-joint has zero angle to contend with, and each of the front two u-joints only have a very mild angle they have to contend with. Voila, a very cool way to reduce the angles the driveshafts have to work into which means no drivetrain vibrations.
I hope that brief explanation of why a SYE kit and CV driveshaft is so cool to install for taller suspension lifts made sense.
Above drawings courtesy of Tom Wood's very cool SYE & driveshaft site at http://www.4xshaft.com/
|05-10-2013 07:42 PM|
|05-10-2013 07:38 PM|
|05-10-2013 07:22 PM|
Better tech info here:
What is a CV shaft and why do I want one? - JeepForum.com
|05-10-2013 07:12 PM|
|05-10-2013 07:10 PM|
|O_M_Jeep||This is one of those topics that gets to clogging up a forum, when people ask instead of reading whats out there already, I got 1.28 million hits on Jeep SYE, none of them from this site so you can add about 75 threads to that, I got over 4k image results and over 1000 youtube video results. I didnt find the answer as useless as the new thread to ask a question thats been answered 1.28 million times already.|
|05-10-2013 07:02 PM|
|Water Dog||Khall7, moving the slip part of the shaft to the center of the shaft rather than on the end of the t case effectively lengthens your drive shaft meaning that there is less of an angle on the driveshaft. On a stock height jeep having the shorter shaft really isn't an issue, but as you raise the Jeep with a lift, the driveshaft angle becomes too much putting stress and clearance issues on the u-joints and related hardware.|
|05-10-2013 06:58 PM|
It was worse than low quality, it was worthless. I'm pretty sure he didn't need you to tell him how to use the search function or google. I mean he found this site before you after all.
khall7, the SYE benefits you by allowing you to run a different type of driveshaft geometry which is more suited for extreme driveshaft angles, that you would see on larger lifts like 3"+. You however need to be able to set the rear pinion angle to use it, meaning you need one or both sets of aftermarket adjustable control arms.
|05-10-2013 06:57 PM|
|pineda22||beat me to it gbendezu!!|
|05-10-2013 06:57 PM|
|05-10-2013 06:43 PM|
|khall7||thank you for the legit answer goldensahara. How does that benefit my jeep?|
|05-10-2013 06:41 PM|
|Jeeping it real||I don't think suggesting google or the forum search bar would be considered a "low quality" answer. An answer "lacking detail", possibly. Kudos to you though, haha.|
|05-10-2013 06:32 PM|
Real high quality answer up there. I think you spent more time typing that worthless response than it actually takes to answer.
A SYE replaces the slip yoke on the t case, which allows the drive shaft to slide back and forth, with a fixed yoke that a U joint would bolt into. The SYE is coupled with a new style shaft, often called a CV shaft, which is technically a DC or double cardan shaft, which has a slip point built into the shaft itself.
You can tell if you are equipped with a SYE by looking at your t case. If there is a long splined piece that the driveshaft can slip over, you're tcase is stock. If the driveshaft is bolted into a fixed yoke, it has an SYE or is a rubicon transfercase, the np241, or some other tcase.
|05-10-2013 06:25 PM|
|Jeeping it real||I'd suggest either google searching "SYE JEEP" or using the search bar on this forum. There is more than enough info on it with in depth details on this forum regarding it. After reading what you come across and you still have questions, come back here and ask. It's pretty simple, good luck!|
|05-10-2013 06:02 PM|
I was wondering if y'all could explain to me what a sye is exactly? How can I tell if one has already been put in my rig, and what are the benefits of having one? I'm always looking for ways to upgrade my rig