I have a 2004 jaguar xtype 2.5l v6 4 door sedan vin SAJEB52D64XE03351 and i need to know if a transfer case from a 2003 xtype vin number SAJEA51D93XD54231 will work for my car. Thanks for your help.

 

All transfer cases should be interchangeable. However, they changed them starting model year 2004 (or mid-2004?) by leaving out the viscous coupling. The change was supposedly to make the transfer case more durable, but at the cost of AWD performance inferior to the older ones.

 

No, that one shouldn't be used in your car. When the viscous coupling was deleted for 2004, the Engine Management and Brake systems were changed to make "electronic" AWD. You [meaning 2004 and later cars] are basically a front drive car until the front slips, then brakes and stability control take over to stop the spinning and transfer drive to the other wheels.

Cheers,

 

Is there a difference in ECU in post-2004 cars? Wouldn't this cause issues for engine swaps?

It's my understanding that post-2004 models without DSC (yeah, some exist, no VC/DSC!) tend to get stuck with their rear wheels spinning while the front wheels do nothing, as the power sort of "leaks out" the path of least resistance, just like electricity or water or anything really. The DSC applies ABS to the spinning wheels (which are assumed to be slipping), thus forcing power to flow to the other wheels.

 

Yes, there are all kinds of differences in 2004 and later X-Type ECU's; because of the integration of the systems with ABS, DSC or Interactive Vehicle Dynamics. Any option change meant a different ECU. Add that to the change to the PAN/PAG Engine Management in 2006, and the ECU's get pretty specific.

I can't really speak to the wheel spin you describe, all the cars here in the States got DSC in the later years; but I s'pose it's possible.

Cheers,

 

You mention that but I have an 2003 and my front tires are significantly balder than my backs...but I did notice in park all 4 wheels are locked when I was doing the rotors and brakes. So I am mildly confused

 

You have a 2003 car, so you still have the viscous coupling. So if you try to turn your wheels, even if all are off the ground, you will have some additional running gear to turn along with it. That will greatly increase the effort to turn that one wheel.

Since you have the coupling, you really should keep the tire tread depth as near equal as possible. Differences in rolling circumference between tires stresses the running gear, especially the coupling. In fact, that rotational "difference" that happens when a wheel slips is what makes the viscous coupling work.

Cheers,

 

I guess what I was trying to determine is my x type 03 is a full time AWD right?

 

Yes, 2002-2003 cars were, I guess we'll call it traditional full time AWD. Meaning both frt and rear were always being driven.

With 2004 and later cars, the transfer case is open, like an open differential, because there is no viscous coupling. Here the rear wheels just follow along until the front wheels slip. When that happens, the DSC applies brake to the slipping fronts and that forces the drive to the rear.

For all intents and purposes, one method is no better than the other really, but experienced drivers will notice the difference in the "feel" of the later electronic system. Those familiar with the sure footed feel of a true all wheel drive vehicle will know what I mean.

Hope that helps!

 

No, that's not the case. In the 2004 and later cars, whether or not fitted with DSC, the gearing in the transfer box is the same as in the earlier boxes with a VC. Under normal driving conditions, that is with no wheelslip, there is no difference in the performance of either box; 39% torque to the front, 61% to the rear. Without DSC, a front wheel spinning is fatal to progress! However, if it's a rear one, then careful application of the handbrake can get things going! If there DSC is fitted , then any wheelspin should, theoretically, be eliminated, but experience suggests it's not as good as the VC system.

 

Yes, that's my understanding of the system too!

 

I think you missed my point. In theory, you are correct. However in practice, the reality is a bit different. Let's take the example of a standard differential rear drive car. In theory, with both rear tires gripping the wheels should drive equally. We all know that's not wholly true, because the right rear tire always wears faster because it drives more; that's the reality. With an X-Type that does not have the viscous coupling this same thing happens, front to rear. For instance, raise that first car in the air and drive the wheels, the right wheel spins and the left wheel either sits there or spins way more slowly. With the later X-Types, when raised and put in drive, the same thing happens, front to rear; the front wheels drive constantly and the rears sort of free-wheel. Those cars with the viscous coupling will spin all four wheels because if it being there. It sort of equates to the limited slip discs of a Limited-Slip differential, as opposed to an open differential.

I'm not trying to be argumentative, that's just how things work.

 

That's an interesting hypothesis! Raising any car completely off the ground is the equivalent of putting it on the ultimately slippery surface - no grip on any of the four wheels. The natural variation in frictional forces to each of the four wheels combined with the three open differentials in later cars will ensure that all drive passes to the one which has the least friction as you suggest and equally, earlier cars will, because of the VC, lock the centre diff and turn one front and one rear.

But if the car is on the ground, without wheel slip, the drive will be distributed according to the mechanical ratios involved, that for all X Types, is 39/61 front to rear and 50/50 of that to each side. The VC plays no part unless there's a significant speed difference in the outputs to the front and rear. While there may be minor variations such as you mention for a righthand wheel in a rear wheel drive arrangment, that will not be anywhere near sufficient to reduce the rear wheel torque to a trailing value. I only wish my rear tyre wear was of the trailing wheel variety!!

Attached is a comprehensive Jaguar Training document that I think explains all this in greater detail along with excellent technical drawings of the box internals and a Power Flow diagram that shows how the drive torque is distributed.

It persuaded me anyway! Each to his own!

 

No significant tire wear here. But, I was told that due to the design of the AWD system, I would have more tire wear in the rear. I have my tires rotated faithfully and see no uneven wear. Great site and sharing of knowlwedge! Thanks.