Transmission/Rear Engine Mount
 

G'day Lady P,

Yeah I use that site a lot for tracking down parts and because of the age of and the mileage on my car I went ahead and ordered a new spring anyhow. It'll be interesting to see how the unloaded length of the new and old springs compare.

Cheers,
Jeff.

Hi Jeff,

No doubt the spring is sagged out. I've been meaning to get a new spring too. I looked them up again and saw one listing that said the height was 9cm. Forum sponsor SNG Barrett has them, as does Terry's Jaguar and others too.

Here's a story of some interest, since there's not always much new to read about in the X305 section (although I still love having it here)... When I had my car in the shop to have the oil cooler hoses repaired, I asked them to check the transmission mount while they had the car up, and advise if it needed a new lower foam bushing. I was told it did, so I had that work done too. I was shown the old bushing and it was severely eroded. The shop replaced it with a poly bushing. I thought "how cool, glad that job is done too."

Afterwords, I wondered why the engine seemed to "roar" so much more (although it is a Jaguar V12 after all). I had a talk with shop owner "Greg" about this, and he told me that the engine mounts were probably bad. I explained that it didn't roar so much before the repair, the V12 is known to be a quiet engine. He had no real answer for me besides that. I did not pursue new engine mounts, nor was I solicited for such. A few of months later, I decided to look way up under the middle of the car at the transmission mount. This is what I found:


https://cimg0.ibsrv.net/gimg/www.jag...0dbf3c33f.jpeg

Still messy with oil, there was no bushing at all on the lower washer. But, I could see what looked like a bright yellow poly bushing through the gap, above the assembly. :confused:


https://cimg3.ibsrv.net/gimg/www.jag...e0e1ce0b1.jpeg

Go figure. They jammed the poly bushing between the support bracket and the bottom of the transmission, inside the spring! This served to support the transmission better, but it certainly is NOT a correct repair. The spring should have been replaced along with an original foam bushing for the bottom washer.

I discovered that the hard poly bushing was transmitting a lot of engine noise into the cabin. For lack of a better idea at the time, I isolated the support bracket from the car frame with rubber strips. That did the trick. I later added a proper new foam bushing on the bottom washer.

At the time I chose not to return to the repair shop. Perhaps I should have, but I chose not to fight that battle. Thanks to Jeff, it is now time for me to go ahead and correct it!

Just goes to show that an independent service center with a very good reputation, which services ONLY "British Automobiles" and is well known locally for such, will still sometimes fudge a job and not be totally up front with customer concerns after the fact. I could understand it as a solution if parts were no longer available, but that was not the case. Maybe he wasn't aware of what was done here, or... maybe its because I don't bring in an E-type or an Aston Martin!

The take away: Always be wary until you can establish a trustworthy individual relationship with a service center. Thanks for reading. I feel better now.

G'day Richard,

When I get the bits I need for my transmission mount, spring and bush, I will take it off the car and completely disassemble it and rebuild it. I'll post the rebuild and the results of the spring comparison when it's all done.
Cheers,
Jeff.

G'day Gents,

Well I rebuilt my rear transmission mount with a new spring and rubbers and the difference is only a couple of millimeters, less than I expected.

The new spring was almost exactly the same length as the old one so probably not required.

Cheers,
Jeff.

I guess its time for me to go "down under" and correct that hack job on my car. In the case of a gap at the bottom, I bet a circular shim of the right size would compensate for a sagging spring, if the gap isn't too large. I've already got the new rubber isolators, which are certainly worn paper thin on the car by now.

Any troubles with clearance to do this job Jeff? I'm hoping not to disturb the exhaust pipes...

G’day Richard,

The job is straight forward and the exhaust can stay in place. After I had rebuilt everything, with the new spring, there was still a gap between the bottom of the rubber bush and the big washer. I rebuilt the mount mainly because the rubber bush has started to crumble even though it was replaced not long after I bought the car.

I haven’t been able to find out any information about whether this gap is normal or not.

Cheers,
Jeff.

P.S. I was just having a look at some pix I had taken while I did this work and it looks like I did remove the exhaust centre section.


https://cimg9.ibsrv.net/gimg/www.jag...51d580643.jpeg
New spring on left, not much different to the original.


https://cimg0.ibsrv.net/gimg/www.jag...740a232e0.jpeg
Still a gap between the washer and the rubber bush.

Gap is normal. Your good to go.

Thanks 1,

I don’t see how it could be anything else after using a new spring and rubber bush but to me it still doesn’t look ‘right’ I believe the XJR6 has two springs in the transmission mount, I wonder why the difference?

Cheers,
Jeff.

I just finished this job today. I just removed the bottom big washer and screw (T45) and dug out the remnants of the remains of the old bush, lubed up the new bush, than pushed it up into place with a floor jack and a large socket as my pushing tool. Put the washer back on and done. Easy and quick, and yes mine sags down quite a bit too.