SYE, yokes, u-joints, axle shims, difference in axles for a beginner???

OK, i did the search but really need a GOOD example or deffinition on what SYE slip yokes do versus the difference in the dana 30-35-44 and 60's!?? Sorry im new and not the brightest bulb. I do know that transfer drops and axle shims will eliminate vibes on lifted vehickles but whats the need for the other stuff?? And when u got all that in check, whats the best kind of u-joints to run on ur lifted XJ for best strength & all????????

SYE doesnt have anything(directly) related to the axles. What it does is convert the slip joint in your rear drivetrain from a piece that moves in and out of the transfer case to a fixed piece and you get a driveshaft that has a slip joint built into it. Transfer case drops are just cheap ways of correcting your driveline problems when you cant/wont afford a SYE and CV driveshaft.

As the vehicle's suspension works through it's range... the distances between the t-case outputs and the pinions change (relative to their length when the Jeep is sitting flat & level)

Out back, the XJ came with a 1-piece driveshaft with a "slip-yoke" at the transfer case... it slips freely along the splined output shaft. Up front, there is a "fixed yoke" and the length difference is facilitated by a 2-piece driveshaft (that happens to have a double-cardan joint at the t-case end)

The traditional SYE (slip-yoke eliminator or 'short shaft' kit) replaces the tail end of the transfer case with a much shorter output shaft and a 'fixed yoke' -or a flange. To this, a 2-pc shaft with DC joint is attached. In the end, a SYE'd T-case looks similar comparing the front & rear outputs/shafts.

The SYE kit allows use of a longer driveshaft that lessens the difference in angles. U-joints have a range in which they operate without binding... operation at angles exceeding this leads to premature wear and possible failure The SYE & new shaft should extend that range (by the DC joint's two UJs 'sharing' the angle) Just like your fingers have three knuckles... put a loop of tape over the middle knuckle and you can see where I am going with this.

Some "HD" SYE kits also have a 32 spline output shaft, which is a strength upgrade vs a shortened OEM shaft. The home-fix ones are commonly called "hack & taps" because you hack off the old shaft, & tap it for a bolt that holds the new flange to it. Either one will require a double-cardan style driveshaft.

All the shims do is adjust the attitude of the pinion yoke relative to the output. T-case drops do that as well, from the opposite direction (but the T-case 'drop' also raises the front DS angle to a corresponding amount of degrees) They MAY OR MAY NOT eliminate vibrations... done wrong, they may INDUCE them... :dunno: YMMV.

I run NAPA Extra Strength greasable UJs with Mobil-1 synthetic grease and I haven't had an issue with these in five years of messing with XJs. If I had a local source for genuine Spicer joints, I'd consider switching over, but I don't and no need to fix something I haven't started breaking yet.

What axles you decide to build has no bearing on any of the above... other than that the angles have to be set/adjusted relative to the type of driveshaft used. A Dana Spicer Model 44 or 60 axle, being physically larger, will require shorter driveshafts than the common / OEM 30 front or 35 rear. With Dana Spicer axles, generally speaking, the larger the model number, the beefier the axle... (beefier in terms of housing strength, axle shaft diameter & spline count, ring & pinion gear/bearing size) Older model 60s and model 44s had smaller axleshafts/spline counts compared to the mid-1970's & newer. The older units aren't a bargain even if given to ya...

Tom Wood's site has good info and better parts... www.4xshaft.com
Anything else?

OOOh, lots of info there and thanks alot!! I still gotta research which road to travel but i do know i will be raizing my XJ more and im making my own leaf packs and adding a set of shackles. Will extend the brake lines and then prob just put coil spacers in front to level her out until i got more $$. But i wont ride her that hard until i do more of the work as sugested so thanks a bunch! I will measure out the new height when done and let u guys know if i get any vibes at all. I should be up around 4"-5" when done so its close!

You will probably want new coils if you are going to 4 or 5 inches of lift in the front.

You probably do not want to stack 2" lift blocks for that lift in the front.

Michael

2xtreme said:

You will probably want new coils if you are going to 4 or 5 inches of lift in the front.

You probably do not want to stack 2" lift blocks for that lift in the front.

Michael

Click to expand...

No, im not gonna use lift blocks at all. The rear sags a bit and so the coil spacers will be to level it out in-case i go to high with the rear leaf pack im puttin together. "Eventually" i WILL get a kit for the front anyway but for now it will do.

What he is refering to is that if you lift the rear end 4-5 inches, you should lift the front to match (or at least come close).

If you are running the stock coils and plan on only using coil spacers, you would need 4-5 inches of spacers (stacked 2" spacers for example) which is usually not safe. It put's the top of your coil too close to the end of the bump stop tower.

If you already have taller springs in the front, then it's different. If you have 3 inch lift springs in the front, than adding a 1-2 inch spacer (or another coil isolator) just to help even it out is safer, since you won't be moving the top of the spring too close to the end of the bump stop.

There's more associated with this, (performance, ride, correct technical terms) and other things that need to be taken into account, but I think this explains what he was talking about. Some more information on your current setup could help people who read to understand what you are doing.

HTH!

My XJ has a lift on it as i bought it like that but not sure exactly what! I have pics but dont know how to load em up. Anyone can lead me to posting pics and i'll show ya what i mean.