Violent shaking at low speed turn

[mike_wiz]

99 XJ 4.5" Rubicon lift up front Alcon lift in back. 4.3 Atlas II. I did not build this, it was my intention to not have to build another rig, just wanted to buy one and wheel it. When I picked it up it had a violent shake with the front end engaged. I had him knock some cash off the price as I assumed the Detroit was bad and I drove it home for 2 hours with no issues.

So I pull off the front diff cover and see the pinion gear is missing chunks of teeth. I replace the gearset and notice that the Detroit has a spun bearing and it wore down the surface. I roughed it up enough and tried it. Same result. I get a new Detroit figuring that must have been it. Same shaking happens.

So at higher speed turns (30-40) it vibrates a little but not bad, but when I slow down and take a turn in the neighborhood it is making an awful clanking sound and shaking like crazy in the front.

Here are some things I tried and the results.

Front atlas disengaged and both hubs locked - no shake

Front atlas engaged with both sides locked - shakes

Front atlas engaged with Pass side only locked - shakes

Front atlas engaged with Driver side only locked - shakes

Front atlas engaged with neither hub locked - no shake

I was told it has a "Durango" steering box? Could this be the problem? It rolls fine at 0-80mph without the front end engaged though.

Sorry for the long post I just wanted to get all the info I could out there. I am coming from the full size crawler world and this is my 1st Jeep (bought it as a family rig) but have plenty of experience building things. This just has me lost......Thanks in advance for any and all help!

Mike

Edit: I did all the tests on the new Detroit and it is locking/unlocking just as it should.

 

[98stocker]

I was going to say bad driveline ujoint until I read that there is no shake with the front axle engaged, and both hubs unlocked, so that said, the shake must be coming from either the left or right or both front axle shafts. Maybe bad ujoints, maybe something else like a spindle bushing if it has those. Kinda confused about what axle you are running, but sounds like a 44?

 

[mike_wiz]

Dana 30 High Pinion.

 

[muddypunk]

Try rotating your tires and see if maybe you have a bulge in the sidewall of one of your front tires.It might be you do or like me I lost a radial tread belt and felt great untill I hit a bump in the road and D W like a Mother it was that way in corners and any speed .

 

[GordoSmasho]

May just me but it sounds like your trying to drive with 4 wheel drive engaged on the street. That is a no no. Just checking. It's sounds like what your experiencing is driveline binding in the transfercase. If this is the case your lucky the transfer case hasn't blown. Rear wheel drive only on the street unless in serious snow.

 

[mike_wiz]

May just me but it sounds like your trying to drive with 4 wheel drive engaged on the street. That is a no no. Just checking. It's sounds like what your experiencing is driveline binding in the transfercase. If this is the case your lucky the transfer case hasn't blown. Rear wheel drive only on the street unless in serious snow.

It has detroits front and back. The detroit is designed to unlock when taking turns as it senses the torque difference. I drove my last rig for 10 years with a detroit up front and flanges. Ran great and never experiences this even a little bit.

 

[Ronbo]

So at higher speed turns (30-40) it vibrates a little but not bad, but when I slow down and take a turn in the neighborhood it is making an awful clanking sound and shaking like crazy in the front.

Front atlas engaged with both sides locked - shakes
Front atlas engaged with Pass side only locked - shakes
Front atlas engaged with Driver side only locked - shakes

Front atlas disengaged and both hubs locked - no shake
Front atlas engaged with neither hub locked - no shake

Unless I'm reading this wrong, you're driving on pavement with 4wd drive engaged - with either the left or right or both hubs engaged and that's when the 'shakes' occur?

 

[GordoSmasho]

Unless I'm reading this wrong, you're driving on pavement with 4wd drive engaged - with either the left or right or both hubs engaged and that's when the 'shakes' occur?

This is what I'm reading as well. You should never drive in 4wd on dry pavement unless you have a full time transfer case. The atlas is not full time just to be clear

 

[Darky]

It has detroits front and back. The detroit is designed to unlock when taking turns as it senses the torque difference. I drove my last rig for 10 years with a detroit up front and flanges. Ran great and never experiences this even a little bit.

A Detroit only unlocks/locks for left to right. It has no impact on whether the front and rear axles are moving at different speeds. If you're steering on pavement, with 4wd engaged, your front tires will each be spinning at different speeds from the rear tires. Your t-case will want both ends spinning the same speed. If they don't it binds and could either destroy the t-case or if you're lucky, just cause the tires to break traction or be difficult to steer.

Your last rig with a Detroit and flanges, did you drive it in 4wd on the street? A stock Cherokee doesn't have unlockable hubs and as such, most have the front axle shafts engaged at all times, just like locking the hubs for you. But, until you shift into 4wd, engaging the front axle, there's no problem as the front end isn't tied to the back yet.

 

[whitexj98]

What was your last rig and what t case? As stated your attempting to power the front axle on pavement with lockers.....all xjs will do the same under these conditions...

 

[IdahoEagle]

Have you bothered to check your knuckle U-joints? They could very easily cause that kind of vibration and even contribute to deathwobble...

 

[Royal_Highness]

Jack up your front axle turn your wheels and see if you can spin them freely. If you have a bad axle ujoint then it will bind and you wont be able to spin it very easy.

 

[yossarian19]

I'm going with transfer case on this one. I think the atlas needs to be inspected, or at least drain the oil out of it & see what color / consistency / chunks (if any, hope not) hits the pan.
From what you write, the only time you don't get shakes / binding is when the atlas is effectively cut off from the front wheels - either by disengaging the atlas, or disengaging both hubs.
The fact that it shakes regardless of which side is locked or unlocked, as long as one is locked, and the R&P + detroit are fresh, makes me say the axle is probably fine - unless the U-joints are toast & clanking. The speed variable could then be written off, as high speed turns are rarely if ever as sharp as neighborhood right-angles at stop signs.

In the case of a bad atlas, I don't see how the speed would effect things but hey, what do I know anyway? I'm in an armchair.

 

[mike_wiz]

Thanks for all the replies.

My former rig was a full size ramcharger on 60's. Welded rear detroit up front.4 speed Atlas. I have ran it on the street in 4wd and it was fine, seemed like the detroit unlocked just as it was supposed to.

I had my local guru come over today and we troubleshoot the hell out of it. We took it in the field out back and it did the shaking only a couple times in low speed turns on dry dirt field. back on pavement it is 50-50 shaking. We ran some more higher speed turns and there is a slight shimmy for sure as well. We jacked up the front and ran it though the gammet.

There is a vibration and sound with the front end engaged and riding the brakes to the tires move slow (creating tourqe) with the same conditions as above. We pulled the front driveshaft and it seems that this is a standard CV (not high angle) and it has been binding for sure as shown by the shiny dents etc. We spun the atlas yolk and it was clean turning, no binding or rough spots or play at all to speak of.

At this point I am going to clearance the front driveshaft a bit and see if that helps anything. If that does not work i will just take out the Atlas and pull it apart to be sure it is all good. yossarian19 you are saying what I think too but just do not want to say. I could have traded my 4 speed to a guy with a brand new 2 speed 4.3 Atlas but figured no need Atlas's are bulletproof......we will see if it comes to this.

I have a good question I think though. Some of the slickrock at Moab is just as (if not more) "grippy" than road surface. If this is just "the way it is" I am concerned about binding issues all day long in Moab? That would honestly suck real bad. Dropping the front axle in and out 50 times a trail would suck to.

Again thanks for the replies. I do appreciate it! It is kinda cool working with parts so small again!

Mike

 

[larsen]

May just me but it sounds like your trying to drive with 4 wheel drive engaged on the street. That is a no no. Just checking. It's sounds like what your experiencing is driveline binding in the transfercase. If this is the case your lucky the transfer case hasn't blown. Rear wheel drive only on the street unless in serious snow.

Unless I'm reading this wrong, you're driving on pavement with 4wd drive engaged - with either the left or right or both hubs engaged and that's when the 'shakes' occur?

This is what I'm reading as well. You should never drive in 4wd on dry pavement unless you have a full time transfer case. The atlas is not full time just to be clear

Many Dodge trucks had FULL TIME 4-wheel drive. Atlas is PART TIME. PART TIME BINDS if there is no tire slippage, like ON PAVEMENT. Lockers have nothing to do with it. Same thing would happen with open differentials. Tires MUST slip using part time or something in the drive train will bind or break.