About ready to give up- Front DS vibes, 01 xj- Advice appreciated

First- The jeep
01 Xj- 4.0/AW4/ np231
4.56 gears/33's
3.5 inch RE lift with RC long arms
HPD30- rebuilt recently- Pinion bearings are brand new (3 weeks ago)
Tom Woods front DS-Rebalanced and reworked by them -a year ago
New PORC SYE/good working front shaft- used in the rear

The subject-


OK! So I've been fighting this ever since I regeared to 4.56. Vibes start at 59 mph+, droning, pulsating vibration... Soaks through the whole body, and is a low bass frequency. Gets worse as it gets faster. No vibes with the front shaft removed.

I have tried
-Pinion angle at zero degrees, above zero, and below zero. Now sits directly at zero.
-3 different front driveshafts. All with varying degrees of vibration.
-Now running a custom, tom woods double cardan shaft. Had to replace the pinion-position u joint because it had bad needle bearings, but it was rebalanced by TW over a year ago. (Not since I did the ujoint however)
-Checked the pinion multiple times... torque is good, bearings are new
-New motor/ tranny mounts- No change
-Tires are balanced. (Wouldn't make a difference, it's smooth without the front DS.)
-Triple, quadruple checked all front driveline/ suspension parts- All good.

I thought it was the transfer case
With 178k miles, I figured it was the front case bearings. I noticed a slight bit of play in the front output.
So I bought a low mileage, (60k miles) 231 case, swapped a PORC sye into it, and swapped the whole case under my jeep yesterday. No change

See- new and pretty (kind of)


So after swapping in a whole new tcase... it still vibes. I've spent close to $700 on trying to fix this issue... With no results. It's unbearable to drive over 60mph. Is the only answer a hub kit? I'm not even geared that low... 4.56 on 33's?

I need some serious help, I'm beyond frustrated.

This sucked btw- LOL




Thanks guys.

Columbus

I'm not saying this is an issue but i don't usually see long arms on lifts less than 4" anyways...I'd first question your gear mesh on your recent install seeing as to that's where the issue started, maybe the pinion bearing wasn't replaced or is the wrong size or lose etc causing it only to vibrate when the DL is installed... I'm assuming your driveline u joints are ok, worn u joints are usually the source to vibrations, because your an 01 and your axles are directly connected to the gears/driveline could your axle u joints be worn and cause this vibration?

I'm grabbing at straws here cause you seem like you've went thru the process of elimination but just because something is new like your gears doesn't mean something there didnt get messed up or installed wrong...

This issue actually started on a different front axle, a good working HP d30 with 4.56, however vacuum disco, (It was given to me geared and locked) I just replaced the whole housing with a newer unit. (The current hp is out of a 94.) And I just had the backlash/ bearings inspected.

All u joints are good.

Since I now have a HD sye, I might swap my front shaft to the back, and back shaft to the front. That might help.

Whats caster at?

Not sure of the actual angle, but the pinion angle is zero degrees. (Checking using a magnetic angle finder.)

Don't no if i miss it did u pull the frt. Drive shaft and take it for a drive and see if it actually the frt drive!!

He mentioned that he had done that, multiple times. No vibes.
I have the same problem but I'm still using my LP30 ... I just take my front shaft off when not wheeling.

I've had front axle u joints and hub bearings create vibrations, just something to check.

In the past I reached a similar height of frustration trying to eliminate a death-wobble like sensation. In the end, it turned out to be my tires. They were slightly cupped.

edit:
never mind, i just re-read your post and noticed "No vibes with the front shaft removed." ... so I guess it's not tires.

I was also going to touch up on what maxx said. I had a stabilizer go bad and unveil a bad wheel bearing. Maybe the driveline is amplifying the resonance of something else being out of spec? Just a thought, id get the whole front end off the ground and start with the basics before you throw any more money at it.

I actually tried all that too. New ball joints, hubs, u joints, upper control arm bushings, tie rod ends... No change.

I actually just went out and put my Tom Woods DS in the rear position. Bolted right up, and I put the rear shaft into the front position-

Basically no difference. I'd like to think it is smoother, but I just think it's in my head.

Its a loud vvvrrrmm.......vvvrrrmm......vvvrrrmm......vvvrrrmm..... at 60 mph

At 68+, its more like vvvrrrmm..vvvrrrmm..vvvrrrmm..vvvrrrmm, so obviously speed related. Doesn't matter if it's in 3rd,4th gear, or if I'm accelerating/coasting/slowing down.

What if you now take the front driveshaft out, leaving the TW shaft as the rear?

If the vibes stay it's the shaft, if they go away, it's something about the front suspension / transfer case / front diff configuration.

I've done that many times. It's totally smooth without the front shaft. I've actually been driving without the front for a few months now, and I'm sick of it. So much good wheeling to be had up here right now. I want 4 wheel drive.

Especially snow... and I don't want to have to take the shaft out to drive up there then drive back.

I think the vibration is normal. A combination of the front shaft being driven from the diff end when driving on the road. There must be no slop at all in the slipyoke. Also I improved mine quiet a bit by fitting a new t-case rubber mount as the old one had sagged and the exhaust bracket was touching the crossmember. I have a 4.5" RE and 4.56 gears. The vibration drove me up the wall for years. I had the front slip yoke rebuilt even though it was not worn that bad. If you want to drive over 60mph with no vibes at all maybe a hub kit is the way to go.

srmitchell said:

I've done that many times. It's totally smooth without the front shaft. I've actually been driving without the front for a few months now, and I'm sick of it. So much good wheeling to be had up here right now. I want 4 wheel drive.

Especially snow... and I don't want to have to take the shaft out to drive up there then drive back.

Click to expand...

yeah, but have you tried the TW shaft in the back and nothing in the front? That would tell whether or not it's the regular shaft, the TW shaft, or what.

srmitchell said:

Its a loud vvvrrrmm.......vvvrrrmm......vvvrrrmm......vvvrrrmm..... at 60 mph

At 68+, its more like vvvrrrmm..vvvrrrmm..vvvrrrmm..vvvrrrmm, .

Click to expand...

Sounds just like mine on the freeway.

Does the vrrrmmm stop when you let off the throttle? Like is it constant or is it throttle related? Mine has some sort of weird slop spot where between on the throttle and off the throttle it has a quick weird vibration.... So I try I avoid light throttle situations

As my tires have worn, my in cab noise has grown. 33"km2's with about 7k on em... my dad has some about to the wear line (12-15k) and his sound like a new thornbird running down the freeway.... I know this because my bronco had thornbirds and all the stereo in the world couldn't cover that BS

Also, now that I think of it... stereo off and blah blah, my jeep is pretty loud heading down the road... zero vibrations, just loud... is it noise or vibration bothering you?

I also have an 01 XJ, same specs as the OP (4:56's and 33's with RE 4.5 but short arm with drop brackets) I have the exact same problem with the vibes at the same speed. It sounds just like the OP described. I just blew up the front differential or broke an axle last weekend (I dont know yet, I haven't taken it apart) Im definintly going with manual hubs when I put it back together, hopefully this will stop the vibes, I will let you guys know if you havent figured it out by then.