Driveline vibes and all stock?

[k1n3k]

I've had all 8 control arms replaced, and afterwards I now have some vibes at around 60-70 mph. The kicker is the whole suspension is currently stock height. The front doesn't have the cam bolts in it, just the centered washers and a regular bolt. I am waiting on a new digital angle finder to show up to measure it as the batteries leaked in my old one, but its looking like the front is pretty far out. The rear on the other hand ALSO looks like the pinion is too high based off of my eye-crometer measurements. More angle at the t-case than the rear axle. No, I'm not looking at the bottom face of the diff either, but looks like the bore face of the pinion seal is at a different angle from the t-case flange (np241or).

The front is an easy fix, but what about the rear? No cam bolts to adjust and stock upper and lower links.

I did notice the lowers on the front seemed a bit different from the lowers on the rear. There is a welded plate in the bottom of the front lowers while the rear are just the U bent sheet metal. Checking the PN's it looks like the lowers front and rear are interchangeable, any concern here?

 

[Chris]

Have you considered that in the process of this work a weight may have fallen off one of the wheels thus causing the vibration?

 

[StoneCold]

Discribe the vibes you are having? Is the steering wheel "shaking"? Or is it a vibration from your transmission / driveline?

The thing about older jeeps is once you fix something it can expose something else that needs done. I would definitely check you drive shafts u joints......and ball joints....and tire balance like @Chris said....

Also make sure your steering linkage etc are adjusted / assembled correctly....and front wheel alignment is correct....

Just some quick thoughts...

 

[GoldenGorilla]

What type of vibration and what speed range? I've had a vibration in my Rubicon from new at ~80mph actual with the stock gearing. I describe it as a thrumming on a roughly 3 second cycle.

I did notice the lowers on the front seemed a bit different from the lowers on the rear. There is a welded plate in the bottom of the front lowers while the rear are just the U bent sheet metal. Checking the PN's it looks like the lowers front and rear are interchangeable, any concern here?

The front and rear lower control arms are identical on all 03-06 TJs. Perhaps someone had swapped in some ZJ or WJ arms for some weird reason?

 

[JMT]

I've had all 8 control arms replaced, and afterwards I now have some vibes at around 60-70 mph. The kicker is the whole suspension is currently stock height. The front doesn't have the cam bolts in it, just the centered washers and a regular bolt. I am waiting on a new digital angle finder to show up to measure it as the batteries leaked in my old one, but its looking like the front is pretty far out. The rear on the other hand ALSO looks like the pinion is too high based off of my eye-crometer measurements. More angle at the t-case than the rear axle. No, I'm not looking at the bottom face of the diff either, but looks like the bore face of the pinion seal is at a different angle from the t-case flange (np241or).

The front is an easy fix, but what about the rear? No cam bolts to adjust and stock upper and lower links.

I did notice the lowers on the front seemed a bit different from the lowers on the rear. There is a welded plate in the bottom of the front lowers while the rear are just the U bent sheet metal. Checking the PN's it looks like the lowers front and rear are interchangeable, any concern here?

Make sure all the arms are in the proper location. Pics of the rear pinion will help people here analyze.

You could have a bad u joint or centering ball joint in one of your driveshafts. You can diagnose this by removing one and driving, then reinstalling and removing the other and driving.

 

[k1n3k]

My bad guys, I typed this post up in a hurry before I left for work this afternoon. Seems I need to be a bit more clear on the situation and the question. The Jeep is stock as in factory ride height and factory suspension and drivetrain. Literally exactly as it rolled off the lot in 2004.

Tires are all in balance and all the U-joints are in good shape. I routinely took it up to 80 MPH before having all 8 links replaced and it was smooth as silk. First drive after, I get a high frequency vibe at about 60-70. Smooth below that. the vibe is a driveline oscillation vibration due to mismatched angles, no question as I've dealt with that before on other vehicles. The only thing thats changed is the control arms and after that change is when the vibes started. It went from perfectly smooth, to vibes literally overnight and no miles.

I had someone do this work for me as part of the sale on my other Jeep, long story. Essentially I traded some of his labor for cash. He couldn't quite afford what I wanted for it, and I wasn't willing to go lower on the price. In the end I came out $500 ahead in labor costs and he was able to purchase the jeep with his budget. We're both happy with the deal. However he is not a Jeep expert. But with my bad elbows and lack of work facility to do the job myself, having him install the parts is really all I need. I can handle the details.

Eyeballing the driveshaft angles, it seems I need to rotate the front pinion down. Easy change as I just need to swap in some cam adjuster bolts instead of the centered washers and normal bolts that were put in the front.

the rear pinion ALSO seems high, I'll measure tomorrow with an angle gauge and find out. If it is indeed high, is there any way to correct for this? Thar be the main question I'm asking.

 

[CharlesHS]

When the control arms were replaced and the bolts tightened; was the Jeep up in the air with the differentials hanging OR was the Jeep on the ground ?
IF the differentials were hanging and you tightened the bolts; the control arm bushings would be preloaded when the Jeep was returned to sitting on the ground.
This could be causing the problem you are describing; also ensure the bolts are torqued to the proper values.

 

[TheBoogieman]

Harder rubber bushings causing vibes on the new Chinese arms. The driveline angles don't change by replacing control arms on a stock Jeep.

 

[Weasellee]

I’d wanna make sure the new arms are exactly the same as the old ones. $0.02

 

[k1n3k]

Alright!

So I went and measured the driveshaft angles.

We're calling the T-case flanges 0 degrees. everything is relative to them.

the rear pinion is up by 1.5 degrees. Not concerned with it anymore.

The front pinion is up by 10 degrees compared to the t-case. The u-joint at the front axle is damn near straight, 1 degree of bend there. That puts 11 degrees on the rear u-joint on the front drive shaft.

What I DID find that was concerning is one of the bolts was missing in one upper link in the rear. So i get to replace that, which is nice.


Anyway, here is what I've got. Thought on the front pinion angle? Just slap some cam bolts in it and drop it or what?

 

[topfuel83]

You actually want the double cardon joint on the t-case side taking up most of the angle. Steering castor is what causes a little angle on the 1st joint at the front pinion. So to me, your driveshaft angles look good. For the rear you want both sides of the shaft to have the same angle if you are running a stock shaft (see picture).

 

[GoldenGorilla]

Anyway, here is what I've got. Thought on the front pinion angle? Just slap some cam bolts in it and drop it or what?

View attachment 663602

My 04 did not come with cam bolts and I don't believe any of them did. Just a big centering washer. They were a thing on earlier years for sure. Is the upper front axle side bushing OK? That may not have been replaced. In addition the missing bolt on the rear upper could be resulting in the axle rotating the pinion down under load

As for the front diff - you're going to have to balance the effect it will have on caster and thus return to center and steering feel against any impact on vibration. The steering feel is best in the 6.5.-7.5 range if you can get there.

 

[Weasellee]

Is there a photo of the rear angle? Your drawing looks wrong if you have a 241 transfer case