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Rear Slip Joint Play

B

BADaXJ

NAXJA Forum User
Location
Maine
I've got a completely stock 2000 with the 8.25 and AW4. There is a vibe around 55-65 that seems like a common issue after searching. I'm going to replace all the drive line u-joints today and see if that helps. I'll deal with the vibration later if it persists after the new joints.
What I'm really worried about is the stock slip joint at the t-case. There is a considerable amount of play, and probably 1/4-1/2 inch of splines that aren't engaged. Should the yoke be pretty snug on the splines? I assume it should be, I just wanted to see how much is normal?
Thanks
 
Play means loose, do you mean looseness in the yoke fit, or do you mean yoke engagement upon the Transfer Case splines ? The slip yoke at the Transfer Case needs room to both compress and to extend. The yoke should be be tight on the splines with no looseness.
 
Last edited:
Thats what I figured. It's definitely loose... If I grab the yoke and push up and down, it moves a considerable amount. I can move it in all directions. Guess it's time to pull the yoke and check it out.

What is the normal length of splines that should be exposed? (the length of splines between the end of the yoke and the t-case/ bearing.
Thanks
 
I heave never bothered to look. If its all stock, whatever amount is exposed should be good.
 
light vibe at 55 is usually tire balance
Click to expand...
I considered that, but I've ruled it out. The frequency is way too high for tire rotation and the tires are very well balanced. A couple of the u-joints had some slop so hopefully changing the joints will help, but I still think the slip joint is out of spec...
 
BADaXJ said:
What is the normal length of splines that should be exposed? (the length of splines between the end of the yoke and the t-case/ bearing.
Thanks
Click to expand...

I have about an inch and a half of shiny metal, but no splines exposed. Neither Jeep has exposed splines.
 
This is what mine looks like at ride height:

slipq.jpg



After removing the driveshaft and seeing how long the tailshaft actually is, I guess I'm not as worried about it anymore, and it doesn't seem too excessive. It's about 5/8" of exposed splines. As for the vibration, I'm going to replace both u-joints and pack the splines with some grease and see if it gets better. If not, I may start investigating pinion angle since my leaves are pretty worn out and a bit misshapen. IIRC, letting of the gas doesn't make it go away so it's probably not pinion angle though.

Anyway, what do you guys think of the spline engagement? There is plenty of engagement on the remainder of the tailshaft and I'm not worried about failure but if it's really not supposed to have any splines exposed I'm curious... Center to center of the joints is 27 7/8" which I'm pretty sure is correct for AW4/231.
 
Drive Shaft Length

29 spline 8.25 .... 27 7/8"
1996 + D35 ....... 28 7/8"
1987 D44 .......... 29 5/8"


Drive shaft length measured from the center of each u-joint on the tube of the drive shaft for 4.0L with AW4 and NP231.
 
Well, for starters I don't have a rubber boot...so maybe I'm comparing apples to oranges. That may account for the splines actually being visible (if you have a boot).

Seems you could just look at a stock 2000 and peel back the boot and see if it's set up like yours.
 
my friends jeep that i built the motor in is doing the same thing. but when he hits a large bump it sets the driveshaft into a vibration, and you have to slow down to get it to stop. i can also move the yoke up and down on the output shaft. tried new ujoints and packing the yoke with grease and it helped, but did not fix it, as it came back shortly after. thinking he needs a new yoke. its a 1999 btw.
 
Well I got the joints changed and I took it for a drive. The vibration seems to be much better now. I haven't had a chance to hit highway speeds yet so we'll see what happens. One thing I would mention: I put quite a bit of grease into the yoke and I couldn't push it onto the tailshaft because the grease trapped air inside the yoke. So, after digging most of the grease out it finally slid on all the way. The other thing I noticed is that the joint on the axle end wasn't preloaded by the pinion yoke so I pushed the caps together and then tightened the straps. Given that movement, it's pretty unlikely that it's perfectly centered. Lastly, under moderate to hard acceleration there is definite driveline vibration. I suspect the worn out and weak leaf springs are allowing the pinion to roll up, and this may also be a factor at higher speeds.
 
The u-joint caps at the axle pinon end are held in place with little "ears" on the pinon yoke. If your pinon yoke doesn't have the little ears (tabs) that keep the caps on and the u-joint centered, you need to replace the yoke.
 
it has the ears, but it's not a very tight fit... I just finished a 1000 trip, and nothing came apart. It still has a little vibration, but it's much better now than it was.
 
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