3+" of lift=vibrations question

jjnord · **Posted:** Tue Jan 03, 2006 11:35 pm

do any of you think that the vibrations could be from not having a slip yoke eliminator or transfer case lowering kit? I know it's apples and oranges, but my YJ vibrated like cazy with a 4" Skyjacker lift unitl I did the transfer case lowering kit. Vibrations went totally away after the SYE kit.
Just a thought.

kevh · **Posted:** Wed Jan 04, 2006 12:56 am

not having a sye shouldnt be the direct cause but yes, not having a t-case lowering kit could be. either way, the problem is driveline angles (too steep/not evenly opposed)

lowering the t case or installing a sye (with a longer driveshaft and/or a high angle cv) fixes the driveline problems and therefore gets rid of the vibrations.

4" on your yj put the rear drive shaft at a pretty crazy angle. i had the same problems with 3.5" on a tj. in my case even dropping the t case didnt help much. at full droop i would be busting u joints. a longer driveshaft and getting rid of the slip yoke solved my probs. a good slip yoke shouldnt cause vibes even when extended (tom woods makes some really nice ones if i remember right) but the yokes under most jeeps get sloppy once you extend them too much. they are only meant to run at the shortest length when the vehicle is running at a decent speed. with a sye you get the added benefit of ditching the slip yoke which means you can pull the rear driveshaft if there is a problem and drive home on the front end without puking fluid out of the yoke

ManicMechanicJoe · **Posted:** Wed Jan 04, 2006 4:16 am

it isn't the vibrations that hinder our lifting, its the CV's. Untill a good replacement (JE Reel may already be on the market, have to check with Al) is on the market, then the lifts can get bigger. Let's also not forget the front Diff, plus the fact that there "isn't enough demand" for a kit.

Jeepjeepster · **Posted:** Wed Jan 04, 2006 12:23 pm

Anyone care to tell me what a sye is and how it cuts down on vibes? I know it does something to the transfer case.

chemguy · **Posted:** Wed Jan 04, 2006 12:39 pm

sye = slip yoke eliminator

uvalax236 · **Posted:** Wed Jan 04, 2006 1:02 pm

A sye kit will only help if you have a big lift on. Its not practicle for 2.5" lift.

jjnord · **Posted:** Thu Jan 05, 2006 2:02 am

interesting. I happen to have a sye on my KJ, but I didn't know if it actually was any benifit for it...I guess not. Damm those CV's! My Daystar 2.5" puck lift just isn't near enough!

ManicMechanicJoe · **Posted:** Thu Jan 05, 2006 2:38 am

the advantage to a slip yoke eliminator is that you can run without a rear driveshaft (if you break it 4x4ing). Without one your t-case will puke its fluid out leading to an early death. The reason it would cut down on vibrations is due to the fact that many SYE kits require a new driveshaft and therefore get CV driveshafts which can run at more extreme angles. An SYE will help without the big lift and makes the vehicle more versatile (something we all need).

04kjsport · **Posted:** Thu Jan 05, 2006 10:30 am

does tom woods make one for the kj, if so how much??

ManicMechanicJoe · **Posted:** Fri Jan 06, 2006 12:28 am

Yes Jeepinal sells em on the site, the 242 kits cost more then the 231 kits. It's $585 for the 231 kit and $685 for the 242 kit. Then after you are done you return the core for a $200 refund or $385 for the 231 and $485 for the 242 kit. It also includes a sweet CV driveshaft. The kit is made by Tom Woods (well known for quality among Jeepers)

04kjsport · **Posted:** Fri Jan 06, 2006 9:46 am

when you say 242 and 231 i assume ure talking about the t-case??

jjnord · **Posted:** Fri Jan 06, 2006 12:49 pm

04kjsport wrote:

when you say 242 and 231 i assume ure talking about the t-case??

yep

uvalax236 · **Posted:** Fri Jan 06, 2006 1:01 pm

242 is Command-Track and 231 is Selec-Track.

Jeepin Al · **Posted:** Fri Jan 06, 2006 3:52 pm

Tom has the SYE old style 242 transfer case. The 242's in our KJ's have been upgraded and have two plantary gears, which changed the output shaft (I think that is the way its working). The kit he has now, does not fit the KJ. He should have something to go by the end of Feb., beginning of March. HA-HA mine will be the first with the new kit!!! Test vehicle! But anyway, as soon as the kit is ready I will let everybody know!

Just to add to the explaination. The current slip yoke set up works fine, its a little weak, since it sticks far beyond the case, but it works. When you go to SYE you eliminate the long output shaft allowing you to use a longer driveshaft. The longer driveshaft effectively changes the driveshaft angle, thus "flattening" out the driveshaft. The drive shaft angle is increased when you lift your KJ. There should be no ill effects until you get to lift around 5 inches (experience told me). The universal joints and driveshaft will start to bind a little, and vibrate. This is transmitted to the cab through sound and feel. It will eventually damage the transfer case and the differential.

So as the lifts get higher and the driveline angles increase, you will need a SYE, or drop the entire drive train to keep the factory angles (this kinda defeats the lift).

Al

ManicMechanicJoe · **Posted:** Fri Jan 06, 2006 6:35 pm

uvalax236 wrote:

242 is Command-Track and 231 is Selec-Track.

Sorry uvalax, you got it the other way around, 242 is selec-track and 231 is command-track. Other then that, the cases are nearly indentical with the exception of the ability to leave the case unlocked (full-time) in selec-track

3+" of lift=vibrations question

Who is online