Should I use a SYE?

[HotChiliRam]

I've just bought a 1990 XJ Limited and I want to lift it with a RE 4.5" Super Flex Lift and I want to install 33's (With some fender trimming). I know that most of you suggest to use a SYE in any lift over 3.5" , but I have a friend that lifted a 2000 XJ with the same lift that I want and didn't use a SYE and has no vibs.
Should I use a SYE with this lift or can I skip that step?
Other question, how much lift should I expect with the RE 4.5"??, my XJ is pretty low.
Thanks in Advance

 

[fryed_1]

Depends... some people get vibs, some don't. I didn't with almost 6" on my 94 (though I have one, just haven't set it up yet along with a ton of other things) and it runs fine except for a shimmy around 50mph.

 

[dmillion]

Every Jeep is an individual when it comes to driveline vibrations. Someone else, who has exactly the same year and model of Jeep, could put on exactly the same lift kit as yours and he might get vibes while you don't, or you might get vibes while he doesn't. The only way to know for sure is to put on the lift and see what happens.

Having said that, there are some generalizations that can be made. Earlier models, like yours, are generally less prone to vibrations than later models. So there's a good chance you'll get lucky and not have a vibration problem.

Honestly, though, there are good reasons to put in an SYE even if you don't have vibes. With 4.5" of lift I would budget for an SYE regardless of vibes.

 

[XJ_ranger]

if you have to ask - yes

 

[HotChiliRam]

Every Jeep is an individual when it comes to driveline vibrations. Someone else, who has exactly the same year and model of Jeep, could put on exactly the same lift kit as yours and he might get vibes while you don't, or you might get vibes while he doesn't. The only way to know for sure is to put on the lift and see what happens.

Having said that, there are some generalizations that can be made. Earlier models, like yours, are generally less prone to vibrations than later models. So there's a good chance you'll get lucky and not have a vibration problem.

Honestly, though, there are good reasons to put in an SYE even if you don't have vibes. With 4.5" of lift I would budget for an SYE regardless of vibes.

Can you please tell me the reasons why I should put one?
One of the problems that I have in installing a SYE is that I have a NP242, and as I've read there are no good SYE's for that xfer.

 

[XJ_ranger]

Can you please tell me the reasons why I should put one?
One of the problems that I have in installing a SYE is that I have a NP242, and as I've read there are no good SYE's for that xfer.

www.4xshaft.com

there is an SYE for that t-case

think about the angles and the forces on the main shaft with the standard slip yoke - the force to compress is a side load on the main shaft (coming from the bottom) as well as an inward load.

with a SYE and driveshaft with a slip joint - the force to compress and expand is in the direction of the shaft

think about what you are doing - off road, if you kill a shaft with a standard slip yoke - you leak t-case fluid and burn it up with a SYE, you pull the shaft and drive out on front wheel drive and call it good...

the 242 has limited options for SYE's and personaly, unless you actualy use the AWD i would look into a new t-case - my choice being the 241J "Rocktrack" from a TJ Rubicon...

the 241 is a much stronger/larger case and the Rocktrack has a 4:1 installed on it.

Just My Humble Opinion (JMHO)

do whatever you want - its your jeep...
and telling your mechanic at the shop "some guys on a website told me it would work" is very expensive...

 

[HotChiliRam]

I'm not familiar with XJ's yet, but I had a lifted Ram before and wheeled the hell out of it and I never installed a SYE. The only thing that I did was clocked the axle till the pinion angle get straight, and I also lenghten (sp?) the DS 1" and I never had huge vibs and never broke the xfer.
I'm going to see what happens after I lift the XJ, if I feel vibs I would get a SYE, if I don't, I won't.

Thanks .

 

[XJ_ranger]

I'm not familiar with XJ's yet, but I had a lifted Ram before and wheeled the hell out of it and I never installed a SYE. The only thing that I did was clocked the axle till the pinion angle get straight, and I also lenghten (sp?) the DS 1" and I never had huge vibs and never broke the xfer.
I'm going to see what happens after I lift the XJ, if I feel vibs I would get a SYE, if I don't, I won't.

Thanks .

how long is the DS on a ram? 50" 60"?

on an XJ with a 6" lift i run a 35" rear driveshaft and most run about a 33" unit...

the shorter the shaft, the more the angles are...

 

[HotChiliRam]

how long is the DS on a ram? 50" 60"?

on an XJ with a 6" lift i run a 35" rear driveshaft and most run about a 33" unit...

the shorter the shaft, the more the angles are...

I know. I was just trying to explain what I did with my truck, that's it.

Anyways I will keep ya'll updated if I get vibs after the lift.

Thanks