XJ XJ12 ( X305 ) 1995 - 1997

Transmission/Rear Engine Mount

Old 01-31-2019, 01:16 AM
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Default Transmission/Rear Engine Mount

Gday Gents,

I was doing some work on my V12s transmission today and noticed that there is nearly half an inch of space below the rubber mount and the large securing washer underneath which make me suspect that the spring part of the rear mount must have sagged over the years.

Does anyone have any information as to the free length of this spring?

Old 01-31-2019, 09:00 PM
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Old 02-01-2019, 01:58 AM
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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.


Last edited by watto700; 02-01-2019 at 03:25 PM.
Old 02-02-2019, 12:43 AM
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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:

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.

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.

Last edited by SleekJag12; 02-02-2019 at 12:46 AM.
Old 02-02-2019, 09:49 PM
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Location: Twin Waters, Sunshine Coast, QLD. Australia.
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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.
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