Shuddering and Vibration in 4 Wheel Drive

[dhaase]

I have an 02 Envoy XL with 210,000 miles - I was up in Michigan last December when it snowed and realized 4 wheel drive was not working. I took it into a shop when I got back to NC and they put it on a lift and tried to engage 4 HI - but there was just a high speed gear whine near the front passenger side. There was also a lot of play in the axle right at the disconnect. After researching I ended up ordering a new (reman?) Dorman disconnect and replacing a few weekends ago. The outboard axle bearing (needle) was destroyed, and the pin on the yoke was sheared off. The axle shaft was also roughed up from the bad bearing so I replaced it with a new Cardone as well. It went back together ok. Took it out, engaged 4 Hi and it felt like it engaged fine. But as soon as I took off there was a vibration or shuddering noise from what seemed like the drivers side front end. This was in a strait line - from the moment I took off, and didn't go away as I sped up. It also seemed to get worse as I was breaking. The front diff had been leaking a while back so I guess that I had problems in it. I took it all apart the next day (I had to drop the oil pan - no way around it) and took the front diff to a local gear shop. They found the two smaller taper bearings to be pretty bad - and one race really pitted. Hoped that would have been the cause - however after putting it all back together last weekend - I still have the same symptoms. A vibration or shudder - from the moment I take off in 4 HI, Auto 4, or 4 LOW - it's the same in all setting. Everything seems fine in 2 HI. There is no clicking when I turn hard to the left or right. And when taking off from a standing start at just idle speed (2-3 mph?) - there almost seems to be a rotational cyclical lurching, like something is out of round.

The intermediate axle seemed ok although I didn't have it checked, or even roll it on a flat surface. the driver side axle seemed ok - so I reused. I talked to the guy that rebuilt the front diff and he didn't mention any issues with the box other then the two bad bearings - he put in a complete rebuild kit. Tires are relatively new. The front wheel bearing really don't make any noise (they are original) when in 2 wheel. It feels like the rotational lurching or pulsing (like when a rotor is out of round) is on the front wheel axis vs. the front prop shaft or transfer case - the front prop shaft seemed fine when I disconnected to have the diff rebuilt.

I don't want to start changing parts without a plan - and other then the intermediate shaft or driver side axle I am not sure what to change. Not sure if I have to pull front diff and have it checked again? If so not sure for what. I have even wondered if a motor mount might be bad and causing shifting when in 4 wheel?

Any thoughts from the really smart people out there?

 

[AtlWrk]

Given 210,000 miles, the inspection/ill-condition/replacement of the other components and the vibration/shudder symptom I'm particularly inclined to suspect the transfer case and then the driver's side half-shaft.

Does it feel like a once-per-rev of the tire or faster?

What's the maintenance history on the transfer case? Current condition/level of the fluid?
At 210,000 miles the transfer case fluid should have been changed at least 4 times.

 

[BRomanJr]

I have an 02 Envoy XL with 210,000 miles - I was up in Michigan last December when it snowed and realized 4 wheel drive was not working. I took it into a shop when I got back to NC and they put it on a lift and tried to engage 4 HI - but there was just a high speed gear whine near the front passenger side. There was also a lot of play in the axle right at the disconnect. After researching I ended up ordering a new (reman?) Dorman disconnect and replacing a few weekends ago. The outboard axle bearing (needle) was destroyed, and the pin on the yoke was sheared off. The axle shaft was also roughed up from the bad bearing so I replaced it with a new Cardone as well. It went back together ok. Took it out, engaged 4 Hi and it felt like it engaged fine. But as soon as I took off there was a vibration or shuddering noise from what seemed like the drivers side front end. This was in a strait line - from the moment I took off, and didn't go away as I sped up. It also seemed to get worse as I was breaking. The front diff had been leaking a while back so I guess that I had problems in it. I took it all apart the next day (I had to drop the oil pan - no way around it) and took the front diff to a local gear shop. They found the two smaller taper bearings to be pretty bad - and one race really pitted. Hoped that would have been the cause - however after putting it all back together last weekend - I still have the same symptoms. A vibration or shudder - from the moment I take off in 4 HI, Auto 4, or 4 LOW - it's the same in all setting. Everything seems fine in 2 HI. There is no clicking when I turn hard to the left or right. And when taking off from a standing start at just idle speed (2-3 mph?) - there almost seems to be a rotational cyclical lurching, like something is out of round.

The intermediate axle seemed ok although I didn't have it checked, or even roll it on a flat surface. the driver side axle seemed ok - so I reused. I talked to the guy that rebuilt the front diff and he didn't mention any issues with the box other then the two bad bearings - he put in a complete rebuild kit. Tires are relatively new. The front wheel bearing really don't make any noise (they are original) when in 2 wheel. It feels like the rotational lurching or pulsing (like when a rotor is out of round) is on the front wheel axis vs. the front prop shaft or transfer case - the front prop shaft seemed fine when I disconnected to have the diff rebuilt.

I don't want to start changing parts without a plan - and other then the intermediate shaft or driver side axle I am not sure what to change. Not sure if I have to pull front diff and have it checked again? If so not sure for what. I have even wondered if a motor mount might be bad and causing shifting when in 4 wheel?

Any thoughts from the really smart people out there?

The Transfer Case is very suspect here. Has the TC fluid been changed every 50K as required? This is required even if you don't use 4WD.
Low or old/worn fluid in the TC can cause the clutch to misbehave. It usually takes a double fluid change with a week between them to get the TC back to normal unless something in there is damaged.

 

[The_Roadie]

I agree with my smart colleagues. It should be easy to distinguish a vibration that happens at driveshaft RPM from one that happens at tire RPM.

You could also pull the front driveshaft to separate the transfer case from the front diff.

The motor mounts can't be the issue if you're in A4WD mode since a good transfer case won't be sending more than 5% torque forward until it detects wheel slippage.

 

[dhaase]

Thanks for the responses -

I just took it around the building and the vibration seems faster then one tire rev. I also took more notice of where it might be coming from in relation to where the TC is mounted - and it could be from that area.

I hate to admit this but... I bought it with 60k miles - and I have never changed the fluid. In my research over the past couple of weeks I now realize it should have been changed. I am going to assume that it wasn't changed before I bought it, so 210k miles on the fluid. I did buy some from the dealer two weeks ago and had planned on changing it (and the rear diff). In fact I started to but the hex hole on the fill plug started to strip so I stopped and sprayed some penetrating oil on it a few times hoping to loosen it up.

I guess my first course of action is to change the fluid now, and maybe again in a week or so as suggested and see if that makes any difference??

 

[tblazerdude]

You might need to heat that bolt up before you try to loosen it again. Propane should be hot enough. Sounds like your lack of vehicle maintenance led to the downfall of your transfer case. 4WD/AWD vehicles are significantly more expensive to maintain. People tend to forget that.

 

[dhaase]

You might need to heat that bolt up before you try to loosen it again. Propane should be hot enough. Sounds like your lack of vehicle maintenance led to the downfall of your transfer case. 4WD/AWD vehicles are significantly more expensive to maintain. People tend to forget that.

Acknowledged - thanks for the input. I will let you all know.

 

[northcreek]

Sounds like your lack of vehicle maintenance led to the downfall of your transfer case. 4WD/AWD vehicles are significantly more expensive to maintain. People tend to forget that.

WARNING!....failure to do so can lead to a shuddering and vibration in your wallet

 

[navigator]

when you say you feel the vibration in 4hi, are you by any chance on pavement?
If so, try it on something other than a hard surface. Our 4wd isn't meant to be used on pavement.

 

[dhaase]

when you say you feel the vibration in 4hi, are you by any chance on pavement?
If so, try it on something other than a hard surface. Our 4wd isn't meant to be used on pavement.

Yes it is pavement - the sound/vibration is so abnormal that I am limiting my time in 4 anything. Not unfamiliar with off road - my wife has even been through the Rubicon.

 

[dhaase]

I tried again to get the fill plug out of the transfer case - ended up taking it to the dealer on Saturday. $54 to get the plug out, flush and fill with new fluid (I supplied the fluid which I had previously bought and a new plug).

DRAMATIC improvement. 95% better, enough that I am convinced that it was the transfer case causing the problem. Still a little chatter sometimes when I am breaking but even that seems to be improving. I think I will take the advice - and change the fluid again in a week or so.

Now if I can just get the power steering gear to quick leaking - the whole job will have been worth my effort.

Thanks for the input.