Rear driveshaft u-joint issue

RubiconBear

Well-Known Member
Joined
May 31, 2012
So my 99 TJ had a 3" lift on it when I bought it in May. It's driven fine since then until it recently developed a vibration (in the steering wheel; trans and t-case shifters didn't move) mostly in 2nd and 3rd gear with a rhythmic, but not very noticeable vibration in 4th and 5th. After researching it appeared to be a u-joint issue. There was no movement in the rear driveshaft, but I still took it out and took it for a short drive in front wheel drive. The vibration was gone.
So I changed out the rear u-joint in the driveshaft which did have some movement inn the two pinion that attached to the axle yoke (see pic). Put in a new Spicer 5-153x and the first couple drives were good. Now the vibration is back, exactly the same way with just a little less intensity. The new u-joint is move and right in the driveshaft, but the cross moves side to side in the caps that are strapped in the yoke. The caps themselves do not move and are mounted in the yoke properly. So why is the cross moving? That's the question.
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Shouldn't be much discernable movement side to side between the cross and the caps.. I wonder if it's not fully seated into the yoke? That or possibly the yoke is spread or missing retaining tabs that hold the caps from moving out (radially).
 
a_kelley said:
Shouldn't be much discernable movement side to side between the cross and the caps.. I wonder if it's not fully seated into the yoke? That or possibly the yoke is spread or missing retaining tabs that hold the caps from moving out (radially).
Click to expand...
It moves a little less than 1/16". The yoke still has the little "ears" that place the caps and the caps are all the way in with the straps bolted in where they should be. There's no up and down movement, just side to side. I did think about the yoke being spread open a little. Why, I'm not sure, possibly previous abuse since I haven't been able to really wheel if myself. I'll take the driveshaft back or and measure the inside of the yoke today once it warms up a little.
 
is it a double cardan or just a standard u-joint? Is there any geometry correction for your lift?
 
I don't have an angle finder, so I'd have to do some math to find the angle. If it looks like I need an sye, so be it. Just doesn't seem that steep. I know all Jeeps are a little different, but most seem to not need those for just 3". It does have a ~1" t-case drop that was also already there.
 
your pinion is the issue. Buy an angle finder at lowes.

This is what I used to fix mine after adding more lift. I was able to remove all my Tcase drop. no vibes at any speed.

Driveline 101
 
Yeah..... I figured I may end up at least having to get adjustable control arms and possibly mml and body lift. I don't mind getting an sye either, it would allow for future upgrades anyway. I just thought it was odd that the cross was moving in the caps, unless it started to west that quickly. I'm just curious as to why it waited 6 months, or longer since the u-joints looked original. The owner before me had it a year or a little less, bought from a guy in Greensboro I think that had put the lift on. The guy I bought it from had put new shocks on it.
 
a_kelley said:
Just put an sye in and your pinion angle will be almost right...
Click to expand...
Yeah, it's pretty much pointing right at the tailshaft, ready for a DC driveshaft that would be needed with the sye. Debating on JB Conversions SS sye, which would allow for future "tummy tuck", or a regular sye from there or another reputable company. About $100 difference, plus the added cost of a speedohealer with the SS. I had hoped the u-joint would have lasted at least a couple months, still gotta get a few Christmas presents, lol.
 
Ok, got the driveshaft off. It measured 3 5/16" inside the "ears" and when I put the driveshaft back in, I noticed that the play isn't in the cross, it is the caps. There's a 1/16" gap between the ear and cap when fully seated on the other side. So it would appear the yoke is a little stretched, or did I miscalculate the difference between 1330 and 1310?
 
As mentioned in the "What did you do to your rig today?" thread, I ordered a bunch of parts to remedy this, i.e. sye.
 
For future reference, if you have a smart phone...then you have an angle finder. There are a lot of awesome, free apps out there these days!
 
Got all the parts in. Started a little last night just PB Blasting bolts. Loosened the t-case skid bolts. A couple felt a little iffy, was able to spray some PB Blaster into the frame, though not site of it hit the bolts. Tightened and loosened them a few times and I think they'll come out just fine. Just need to brave the trans. and t-case while it's off. Then it's on to the gas tank. Hoping for no broken bolts/parts. [emoji1696][emoji33]
 
Welp, first bolts broken. Luckily they're just the two bolts for the tank straps. I'll order those and I'm thinking of getting a new gas tank skid. Mine's a little rough and has a rust hole in one corner.
Also going to take the hitch off. It's not 2" and I don't plan on using it. The bolts for it are in bad shape though.
The rear crossmember behind the bumper has to be cut off and welded back on, right? Asking because I'd like to clean inside the frame back there. I'm a little worried about the condition of it the more I look.
 
I had the same issue with my Dana 60. Was going through u-joints big time. Was changing it on a friends list, and noticed that the fit wasn't right. Got a new yoke, and didn't have any more issues.
 
Here's a pic of my yoke. So it didn't actually stretch, but beat the little tab (on the left) nearly to death.
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Also, got the gas tank and exhaust out (muffler back). Little crusty back there. That's an 11mm socket for ref on the dirt in the skid (10mm is missing, shocker). I probably need to get new filler hose stuff, though it doesn't leak.
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