drive line vibration '05 TJ

[prariepunk]

I recently had a rear u joint failure where my drive shaft slid off the yoke and got all banged up on the road. Afterwards it had some nasty drive line vibration (starting around 30 mph) so I installed the SYE kit that I bought thinking that would remedy the situation... well I'd kinda did. It now shakes around 55 mph bad enough to make my feet tingle line using a chainsaw & shakes down to around 35 mph. What could be causing this? It's definitely drive line but I replaced the rear bearings in the t case & got a new Tom Woods driveshaft. I'm thinking either bad t case mount bushing or bad pinion bearings (or both)

 

[JPNinPA]

I didn't know you dropped the shaft. Did you have it balanced? I'd check the pinion seal or shaft for damage bending?

 

[prariepunk]

The u joint failed last Sunday & I put the new Tom Woods CV shaft in along with a TeraFlex Super Short SYE. So I've got a new output bearing in the t case & brand new driveshaft from Tom Woods. It doesn't shake every time I dive, some times it's as if nothing is wrong... other times, it's a scary ride.

 

[prariepunk]

I'm thinking it's the rear pinion bearings (inner/outer)... I'd like to get 4.88 gears to throw in while I'm replacing bearings. How much play should I have in the rear output shaft while in neutral?

 

[prariepunk]

Maybe pinion angle? I don't have adjustable arms... yet. I found a pair of adjustable LCAs for an unbeatable price (many thanks, Terry Mason), could I get away with just adjustable lowers?

 

[JPNinPA]

Oh I figured you got the adjustable arms since your last thread. Yes check your pinion angle and the control arm bushings. If there is play even a little in the control arms it will show at speed cause the angle changes under stress due to the play in the bushings.

 

[prariepunk]

There is some play in the rear but I'm gonna need air tools (maybe heat) because the bolts are rusted tight. The bushings in my lowers are rebuildable and uppers are still stock. Play in lowers only. I have cam bolts for the lower rears & I'll hopefully be getting the adjustable lowers someone this week. Only time will tell if this does the trick, I guess.

 

[Bounty__Hunter]

The rear pinion should be directly inline with the rear driveshaft.

 

[prariepunk]

Yeah, mine's about 15° off :-(

 

[JPNinPA]

Yeah, mine's about 15° off :-(

http://www.stu-offroad.com/axle/pinion/pinion-1.htm

 

[prariepunk]

Yeah, I'm stuck in "wait" mode until adjustable lowers get here. Same principal except I'm shortening the lowers to bring the bottom of the axle forward to raise the pinion angle. It's what I can afford for right now but I'm looking into getting uppers & lowers asap

 

[Bounty__Hunter]

I understand doing what you can afford, but you want to keep wheelbase in mind. This generally means lengthening both uppers and lowers to keep the wheel centered in the wheelwell.

 

[prariepunk]

There won't be any wheeling until I get adjustable uppers & lowers. Wouldn't you shorten the lowers & lengthen the uppers to keep the axle centered?

 

[prariepunk]

There won't be any wheeling until I get adjustable uppers & lowers. Wouldn't you shorten the lowers & lengthen the uppers to keep the axle centered?

 

[Bounty__Hunter]

There won't be any wheeling until I get adjustable uppers & lowers. Wouldn't you shorten the lowers & lengthen the uppers to keep the axle centered?

No. When you lift the Jeep the axles move towards the center of the Jeep. You have to lengthen the lower control arms to get your wheelbase correct and then adjust the upper control arms for the proper pinion angle. Using a rear CV driveshaft means lengthening the rear uppers and raising the pinion.

 

[prariepunk]

As of right now, I only have adjustable LCAs. I found a pair of adjustable UCAs/LCAs but the gentleman is taking his time shipping them

 

[prariepunk]

Without adjustable uppers, lengthening the lowers would be making my pinion angle even worse, right?

 

[JPNinPA]

Yes

 

[Bounty__Hunter]

Without adjustable uppers, lengthening the lowers would be making my pinion angle even worse, right?

Correct. Keep in mind once you get the adj. UCA's and rotate the pinion angle upward, it's likely the track bar will be in a bind at the axle mount. This often requires a bracket specific to running a SYE, or modify the currect bracket. I've had good luck taking a notch out of the front of the bracket, bending it forward, and welding it.

You also have to watch the trackbar to fuel tank clearance, this might limit your wheelbase slightly.

Seldom can you modify one thing without a domino effect haha.

 

[prariepunk]

Geez, they don't mention any of this when you first get addicted to Jeeps.