XJ6 being much quiter inside than the Mk10

I think it’s fair to say that the XJ6 is more quiet inside than the prefecessors. I think I read somewhere that the XJ6 has dual fire walls, and that this is what makes it so quiet.
Is this true?
I have Dynamat all over the inside, and have considered putting something similar, but black!, on the engine side of the fire wall, like many other cars had and have. But there is hardly any space, and esp hard to do with the engine and other parts in place.
I also have mild steel exhaust systems which are quieter than the common S/S systems. One G is noticeably wuieter but has identical setup as the others.
And one G makes a lot of induction noise on accelleration.
I like these cars to be as quiet as possible, as you might gather😊

Yes it is a dual firewall (bulkhead). I believe the volume between them is used as a plenum for the heater/ac. I never considered whether it makes the car quieter than the previous saloons.

Try this product: https://lizardskin.com/

It is highly heat resistant and comes in two formulas, one for heat and one for sound deadening.

I have had it under my hood for years with no problems coated in a gloss black rustoleum paint. It reduces the tympanic resonance of the huge metal expanses.


In Skilleter, it mentions Jaguar had a lot of problems with Resonance on the MKX

They are not a very quiet car

To control resonance requires large scale application of sound absorbing material on the surfaces that drum

ie the Inside door has strips of carpet glued on, which causes rust on almost every MKX or 420G I have ever seen.

If you are really serious, I have observed that one would have to go to extreme lengths to mute and block every possible source of noise…they are like a big double bass

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Did they not get around the resonance issue the XK caused by machining the rear main oval - I can look up an article on that.
The XJ has a double bulkhead so noise and heat are reduced. I think Lyons himself insisted on that?
Maybe gluing tar mats (as in many more modern cars) on is easier than the foam based stuff when in tight areas and would help with drumming as well as more specialized products would.

I loaded up on the sound deadening. Everything was coated in original Dynamat to include the doors and boot. This is good for resonance caused by vibration or heavy base.

The next step is to use material that absorbs sound. Bynamat use to sell a product that was a couple mm of lead sandwiched between two sheets of foam. I used this in floors and doors. The foam does not hold water and the original Dynamat sealed the metal. The floors also got a thick layer of jute.

In the headliner, I used the original dynamat and another product of theirs. Not sure if it is around anymore. It was called TacMat and was used in airplanes. It is a thin dense foam.

The firewall got Dynamat, TacMat, and vinyl backed jute. The sills got Dynamat and TacMat. The trans tunnel and the boot got original Dynamat and jute.

The aim was to use as much of the modern products as I could and the original where necessary. I spent weeks sniffing contact cement and sticking to the floor.

I can say that she is remarkably quiet inside. But cost about $1,000 when I did it ten years ago. I’m sure Jaguar had an advantage of more modern materials to use in the XJ series as well as a better understanding. You can certainly upgrade the Mark X with time and money.

I did not replace the under hood material. I like to hear those three carbs open.


Most impressive!

I have done about 2/3 of that on my 4 cars. Never the headliner, and on the blue one, acquired in Jan 1988, I had a new headliner installed. It was glued onto the metal. I didn’t know about the importance of the roof back then.

The BMW coupes (1969-75) had a good self adhesive sound proofing done at the factory. About 1/2” and on the engine side of the fire wall. Jaguar never did this. And there really isn’t soace for it.

The floors and under the rear seat and back against the trunk are important and easy to do.

The trans tunnel too. I have done the inside of all my cars’ doors, but dont know how much it helps. A bit more solid sound when shutting.

Original mild steel exhaust system gives the best noise but also quieter than the harsh noise from the s/s systems. Walker did them for Jaguar.

You must begin to use your fabulous car. Far more interesting than the orange jeep😅

I have heard about the exhaust differences but the stainless looks better to the judges when the peak under.

The door are important since they are just an open shell. Mine sound like shutting a safe door.

Yes, I need to get her out more. Maybe when the weather gets better.

As to the Jeep, she is just too much fun. Plus, I never worry about where I park her and I don’t have to wash her either. My three other cars always make me nervous to drive.


Just checked and they still make tacmat: https://www.amazon.com/Dynamat-11405-Tac-Mat-Sheet/product-reviews/B0007WRPHM

I also have used Noico which is thicker than competitors:


Ooo, I made my kidneys bleed in a '48, then a '50, just like that!