hubs

How do the hubs in my 2000 XJ work? I have heard that they are automatic and locking. I assume they use some sort of vacum to lock themselves when shifted into 4? If this is the case I have a problem with my hubs. They will not unlock. While driving in 2wd the front drivshaft still turns. How do I unlock the hubs? or am I way off how this thing works? TIA
mike

Your situation is normal.

Earlier versions of the XJ had a vacuum operated disconnect on the right front axle, which allowed the right outer axle to freewheel. The left axle still turned, but the ring and pinion of the differential and the front driveshaft did not.

Since sometime around 1991, XJ's have not had any disconnect mechanism or other system to freewheel the front end. I guess they found that the fuel economy and longevity of parts didn't suffer much if they just left it engaged.

It's funny actually, that the dealers think they all have a SELF Engaging 4x4 mechanism on the front wheels when they are actually just simply splined and never disengage except at the transfer case. I've heard the same misinformation at at least 4 dealers when talking to service managers. You'd think they'd teach them better.

XJ_MAC said:

It's funny actually, that the dealers think they all have a SELF Engaging 4x4 mechanism on the front wheels when they are actually just simply splined and never disengage except at the transfer case. I've heard the same misinformation at at least 4 dealers when talking to service managers. You'd think they'd teach them better.

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This is part of the price we pay for having Jeep absorbed by Chrysler, and then Daimler-Benz. A Jeep is no longer a Jeep -- it's now a commodity, like a refrigerator, to be sold to any willing buyer with a minimum of dealer involvement and/or understanding. Most service managers today know very little about what makes an automobile tick. Their job is to schedule the work, make sure the factory pays them for warranty repairs, and tell the customer whatever he/she wants to hear (other than the truth) when there's a screw-up. In short, they are now "suits" rather than mechanics.

I don't have the vac disco on my 92. My old 85 had one tho. With all the problems I had with that thing and those my buddies have had.... I'm glad to be rid of it. Let the front freewheel, it isn't noisy (at least over my radio anyway) and it is one less thing to bust on the trail!