Rear Wheels Turning In Park

[Klaatu55]

I was doing back brakes on jack stands on my '99 4 wheel drive and discovered that both back wheels are freely turning and I"m in Park. Is this a natural situation? Would it have anything to do with the rumble strip noise and driveline vibration that recently developed in the rear (you can still feel and hear it with the engine off coasting) and the whir i hear in the back diff now sounds like more on the passenger back axle or in the differential housing. Any thoughts on this Thanks

[4x4Dalton]

Did you set the e brake?


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[Pookapotamus]

it is normal, well if you turn one wheel at a time it is normal, if you try to turn both the same direction at the same time they should not turn. unless you have a locker or limited slip.

what is happening is the tranny locks the drive shaft in park so that it cannot turn, when its off the ground the differential lets the tires turn independently, so basically park only works when both tires are on the ground.

make sense?

the noises you are hearing from the rear end while driving probably mean the rear end is wearing out, have it looked at, or at the very least check the fluid level in the diff.

Pook

[Klaatu55]

No brakes are emergency brake is off. Differential fluid is good. I'll put tires back on and drop it then. What does rear end wearing out mean more or less? Thanks

[4.3LXJ]

Before we panic here, let's narrow it down a little. Does the rumble strip noise come under acceleration or deceleration. The driveline vibes are likely a separate issue. Here is a link to address that

http://www.xjtalk.com/showthread.php?t=7299

[Klaatu55]

As I lurk around different forums.I keep hearing the Perm Pinion Bearing spoken off,and I gather it's not something for casual DIF job. If in fact this is what I'm hearing, what would the repair entail and what would be the cost of a fix or replacement in the NY NJ area.

[4.3LXJ]

No, not a casual job. You are looking at one to two hours of labor I think plus a bearing and seal. But narrow it down first

[Klaatu55]

I believe rumble is always there, now. Once I get up to any speed 20 30 it's pronounced,goes from noise to vibration through car (floor,pedal,steering wheel) I believe it's there at all speeds. Started about a week ago. I put rear up on jack stands and ran car. It seems to be in back. It rumbles also when I coast with the engine off.

[Pookapotamus]

Like Steve said, lets narrow it down, does the jeep have a lift? if so how much? are the ujoints good? have you pulled the drive shaft off and really inspected the ujoints?

Pook

[4.3LXJ]

Yes, I think U joints are the first place to start

[Klaatu55]

No lifts. I recently changed front driver side u joint. which was shot. I've shaken and tried to move other u joints they don't move at all (meaning no apparent play) . I'm in process of greasing I believe its the spline under the boot by the back differential. But all other u joints look and feel good.

[Pookapotamus]

No lifts. I recently changed front driver side u joint. which was shot. I've shaken and tried to move other u joints they don't move at all (meaning no apparent play) . I'm in process of greasing I believe its the spline under the boot by the back differential. But all other u joints look and feel good.


ok lets find out if those u-joints really are good, pop the drive shaft off, and try to move the joints, if there is any loss of range of movement in any of the joints, replace them, some times a u-joint will seize, it wont have any play but you cant really move it freely.

[Klaatu55]

Okay let me get busy before I lose the light and the temperature drops. Thanks I will report back.

[Pookapotamus]

Good luck!

[Klaatu55]

Snatched drive shaft out yesterday. Greased splines with anti seize. and changed u joint that was stiff. Preliminary first (short)test run. good, noise and vibration appears to be gone. Going to wait until late night to test it at higher speed on highway. The spring clips were rusted into and broke off into yoke grooves. It was PITA to remove. Caps weren't much better.