My 1997 XJR is in the shop, and while up on the lift the mechanic called my attention to the transmission mount and wondered if it may be broken or too loose.

As we all know, the X300 has a somewhat unique and complex transmission mount. Instead of a simple rubber block with mounting studs like most cars and engine mounts utilize, the X300 has a set of bushings and a spring, much like a wheel suspension, that isolates the movement of the engine and transmission from the chassis.

Also just like the wheel suspension components, the yellow bushing material that is used on the transmission mount tends to disintegrate in about a decade or so leaving the spring loaded mount to bounce up and down un-damped.

That being said, my transmission mount was replaced/rebuilt 5-6 years and 50k miles ago, so it may be fine, or maybe it's worn out. The problem is that I don't know how to tell.

I can tell that it appears that the bushings are still in place, and it moves without any "clunks" or other undesirable noises, but it does bounce up and down quite a bit.

So, for those in the know, I'll attach a short video clip of us bouncing the transmission up/down from under the car and let me know if you think all is normal, or not.

 

Appears excessive to my eyes; mine eventually became that loosey-goosely. I replaced the spring with anew part from Jaguar....which was a beefed-up design....to reduce the movement

Cheers
DD

 

Al,
As you already know, the amount of movement on this mount when in "perfect" condition would seem alarming to the untrained eye, and it is hard to tell from your video how hard a shove it is being given to produce the amount of movement shown. That said, at face value I would be inclined to agree with Doug, although on the basis that you havent detected an issue whilst driving the car, the mounting might be worth the benefit of the doubt for the time being? On the other hand, the foam part of the mounting isnt expensive, and is easily fitted while the car is on the lift, so a precautionary change might make sense?

 

Hi Al,

I agree with Doug and countyjag that your mount seems loose, but I think lateral or side-to-side movement is of more concern than vertical movement. Can you detect any excessive sideward play? As countyjag mentioned, the yellow foam rubber bushing is affordable and easily replaced, and they only last 5 years or so anyway, just like the yellow shock bushings. I like Doug's suggestion of installing the revised stiffer spring.

Cheers,

Don

 

Gratuitous commentary:

I've oft wondered why Jaguar is so in love with these convoluted transmission mounts. The X300 style isn't even as crazy as some of the others. A Series III XJ6 mount is an assembly of about 20 parts. Springs, cushions, movement limiters......

Surely it's all a quest for reduced NVH, which has always been a huge concern for Jaguar, and that's fine and well.

However, American luxury cars achieved smooth-as-velvet results with a very basic big-chunk-of-rubber transmission mount.

I doubt anyone here loves Jags more than I do but, honestly, Jaguar does love to complicate things at times.

"Never use six parts when twelve parts will do the job perfectly well"

Cheers
DD