SYE

[MerkL]

I have a '94 YJ and total of 5.5" of lift. I currently do not have a slip yoke eliminator, and I have had no problems. Do you think I should go for the install or just keep what I got. If I chose to go with it, would I notice a major difference, or would it be like what I'm used to already?

Thanks.

 

[Snitty]

how much of that is a body lift

 

[Bounty__Hunter]

Depends on how much of that lift is suspension lift, and if you have a TC drop or not. A SYE will allow you to raise the transfer case back up to stock location, and even allow a flat belly skid if you want to go that route.

Does your wheeling warrant increasing your breakover angle?

 

[MerkL]

It's a 2" body, and 3.5" suspension. Yes the T-case is dropped. I have wondered about installing a flat belly skid plate before. I don't really need that much more clearance on an everyday basis, but I'd like to have it when needed. Which brand/type SYE would you guys recommend, or which ones are y'all using?

 

[LGR]

i heard after ya go 4"s or more do the SYE. I'm using an advance adapters SYE kit and a tom wood's CV shaft. Good kit, instructions could have been a little more clear.

 

[Junkpile]

I have mixed feelings about the SYE kits. The slip yoke sucks, no doubt about it. When I was running a NP231, I didn't know what a SYE was. I think a company called MIT had come out with one about the time my problems with the case were over. I had a 4" susp lift(with a 3"body) and 36s.....I couldn't feel the vibration even if it was there. I busted 2 np231s before I figured out the wedges on my rear springs had tilted the pinion up so much that when launching, the springs would wrap so much that the driveshaft was pulling the slip yoke out to the very end and breaking the shaft. Removed the shims. Broke 2 more np231s before I sent the Jeep to Stevenson Jeep dealership in Jacksonville NC. They installed what they called a "Heavy-duty chain and shaft kit" and "Heavy duty forks". I don't know what "Forks" are and I didn't see any of the parts, when I got the Jeep back the only visual difference was a new slip-yoke. I busted the U-joint at the rear axle and dropped a shaft a couple of weeks later. On the way off, the shaft took out the housing around the output on the t-case. After getting a new one and welding an aluminum ring around the mounting flange......I never, ever, not even once heard that POS 231 make another sound. STILL had a slip yoke hanging off the back. The reason I tell people to run them isn't because it removes the slip yoke, but because it allows a longer rear driveshaft. If you aren't having vibration problems, I wouldn't mess with it.

 

[LGR]

good point junkpile. if its not broke, don't fix it.

 

[TwistedCU]

I figured out the wedges on my rear springs had tilted the pinion up so much that when launching, the springs would wrap so much that the driveshaft was pulling the slip yoke out to the very end and breaking the shaft.

Did you have the transfer case lowered as well? Just curious to see if this is something my setup will be prone to. I have about 4" of lift (3 1/2" springs & 1/2" from shackles) with the xfer case dropped and the rear axle is shimmed. I don't have any vibration and didn't see any need for the SYE/CV conversion, but I don't want to bust my driveshaft output or NP231 to find out I should've put them on.

 

[LGR]

ahh..shims? i don't think i've ever shimmed my axle..i'm runnin a 4" suspension with the SYE kit and a CV shaft...do i need axle shims? and if so..what are they?

 

[Junkpile]

TwistedCopper, I wouldn't worry about it. It only happened a couple of times and then it was when I was REALLY getting on it on pavement. It sucked. Until I got that transfer case sorted out, I had to hold back coming off the line.

I don't really think it was the wedges that caused the problem, it was excessive spring wrap. The wedges just added that last little bit of way too much pinion angle when dumping the clutch.

 

[TwistedCU]

LOL probably won't be an issue with my 2.5L rocket :roll:

 

[Bounty__Hunter]

ahh..shims? i don't think i've ever shimmed my axle..i'm runnin a 4" suspension with the SYE kit and a CV shaft...do i need axle shims? and if so..what are they?

It's a YJ thing, used to adjust pinion angle. You TJ jeepers do the same thing with adjustible control arms.

 

[LGR]

phew..got me really worried for a second.

 

[hi_c]

I have 5.25" of total lift (4" suspension, 1.25" shackle lift) and with a dropped t-case, I have no vibes... at least none that I can feel. My axle is shimmed, too. I know that I've maxed out my suspension and the yoke didn't slip out, so it's not a matter of do I "need" a SYE conversion.

But I WANT ONE. They're just so costly for such and invisible mod. The biggest benefit I can see is my increased skidplate clearance. HOWEVER, on my 2.5 (and probably most others) my exhaust pipe hangs down in front of the skid plate and would get ripped out before my skid hit anything. So I think it almost helps to have the lower skid and protect my exhaust. I need a skid for my exhaust.

C

 

[jps4jeep]

I believe the SYE was first made to accomidate the 6" coil spring lifts for YJ's that were made by procomp and black diamond (warn) a while back (1996?)

Since then, they have been recomended for 4" lifts so there is no need for a T-case drop. I have 4.75" of suspension lift with axle shims. In the year that I had this lift with the original driveshaft, I when through 4 U-joints, and 2 pinion yokes. I went with the Advanced adapter SYE and Tom Woods (very popular selection) I have had no problems, in fact, I have less deceleration vibration, almost no vibration during heavy acceleration, and a lot more confidence in my U-Joints. Plus the output shaft is a lot larger and beefier, and this allows for future mods such as a belly up skid plate, a SOA lift.

The reason why some people have issues with slip yokes, and lift kits and some people don't. (I heard this straight from Tom Woods' Mouth) When Jeep manufactured YJ's, and early TJ's, Particularly 93-98, there is some discretion in the measurements of the drivetrain. When I first went to install my Tom Woods drive shaft for 4" lift it was about 3 inches too long.

It was the correct part, but for some reason my entire drivetrain was set further back than some other applications. The drive shaft I ended up using is for a stock ride height (even though I have 4 3/4" of lift). This was also the cause for all my previous U-Joint issues. Due to my drivetrains position, the angle of the U-joint attached to the pinion yoke was very drastic, hence destroying U-joints.

The story Junkpile described sounds like he had the oposite problem, his drivetrain was set further foward. Hence the slip yoke was pulling too far out.

As for the Fork and Chain thing. The New process 231 (most jeeps after 87 are equipt with this) are chain driven as opposed to the gear driven units found in many CJ's. The fork is what physically pushes the gear onto the front output shaft in-order to activate the 4wd. and the chain connects the two gears, one on the rear output shaft and one on the front output shaft.

And yes the instruction could have been better!

 

[Bounty__Hunter]

hi_c, my YJ exhaust used to be routed like yours until it was smashed flat between the bellhousing and a boulder. I had it redone to go in front of the oilpan sump like the TJ 2.5L design. You can buy a TJ 2.5L front pipe if you want to get your exhaust up and out of the way. I think mine cost about $40 to have custom made, with the o2 sensor boss.

Let's not forget the RE hack&tap SYE for those jeepers on a budget. Only $80 for '96+ jeeps and about $180 for older 231's. I'm going to use the $80 kit on my '95 YJ with a tailshaft housing from a TJ. Now working on mating a shortened TJ/XJ front CV shaft to the H&T SYE. Just have to locate the correct yoke or flange for the output.

 

[ecor]

The hack and tap kits suck!!! I have installed these before and would not recommend. The Advanced adapters kit is one of the best on the market and is only $295.00, as for the drivshaft I would suggest one from a TJ they are a little beefier although I have seen people use the XJ shaft. If you are one of the unfortunate one with a YJ that has the odd U-joint on the pinion, you can order a new pinion from Randys ring or you can buy a cross over u-joint. TJ shafts ussually are about $40.00 in a junk yard and cost $50 to get shorted and balanced. Hope this helps

 

[Bounty__Hunter]

Can you elaborate other than to say they 'suck'?

They're inexpensive, relatively easy to install, and don't break.

Why the need for the heavy shaft in the 231 if the stock one doesn't break?

 

[Snitty]

if the hack and tap sucks... then why don't we hear about stock Tcases "sucking"? Just curious on how the same parts are no good when modified. And... all of you 4"+ lifted jeepers without the SYE... are you 2.5 or are you 4.0... the 2.5 trans/case is slightly shorter, this does make a difference in whether you can or cannot get away with it

 

[ecor]

I'm saying they suck to install, To me it is much easier to pull the tc apart and replace the parts then it is to wack the end off and drill and tap the part. I guess I've gotten soft in my elder years. Your right you don't need that heavier shaft, but if your replacing it, why not. I have also seen hack and tap kits that don't change the tailshaft cover on the t/c not making your drivshaft any longer. I would prefer if making a new shaft to make it as long as I could. Just a personal preference.