Modified XJ12 Options

Hey, I’m brand new to the XJ12 club. Pretty much pulling the entire car apart and refurbishing. Was just wondering what kinds of modifications people have done? Wheel well liners are pretty much rusted through. I was going to make my own with sheet metal welded and paint with a heavy duty truck bed liner. Also looking at putting newer projector headlights in. I want to keep the car “mostly original” but upgrades would be nice as parts become less available. CAD XJ12 Vanden Plas.

Hello Justin. What year is your XJ12?


Welcome to the list. Attached is a picture of my 1990 V12 Vanden Plas, essentially a Daimler Double Six trimmed for the Canadian market. The exterior is Jaguar Racing Green and the interior is Magnolia.

The car is basically stock since I compete it in Jaguar Clubs of North America (JCNA) concours in Champion Division. The only modifications to the car that make it different from factory configuration are the CD changer in the trunk, the burl walnut shifter “T”, the black leather sunvisors that I had custom made, and the modification that I made to the trip computer so that it reads in U.S gallons instead of Imperial gallons. I remove the non-factory items and replace them with the correct ones during the concours season. The Canadian market cars came equipped with factory mud flaps and I leave them on all the time as I like the look and the way they protect the paint behind the tires/wheels.


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It is a 1987 XJ12. Paul, your car is gorgeous! I have a lot of work to get mine fixed up. Thank you for the input.

Welcome Justin,

nice project! Without any personal V12 experience I’m happy to pass on just one very general experience: all of these cars are extremely well-balanced compromises with respect to performance and drivability, comfort and dynamics.

You can do a lot, but inevitably will put this compromise at risk. If you’re happy with it, you can make your Jag a slalom racer, but you have to make up your mind - not the least about what you’re willing to invest into a trial-and-error process. Many have put a lot of money into new “sports shocks” just to switch back to the originals later on.

Since you mention rust in the wheel wells, a contemporary improvement was the use of Lokari fender liners made from aluminium. Not very expensive, but helpful.

Another simple one is the Gardner/Napoli modification to the A/C system allowing ventilation without running the A/C.

Talking about the ride: poly bushings are generally recommended for the suspension, but nowhere else. A huge improvement, but somehow challenging is the use of a post 1994 XJS ZF steering rack. Below this the sportspack steering rack bushings are reported to improve greatly the feel of the steering. A rear anti roll bar - likewise from XJS cars - is also helpful.

Engine wise the easiest thing would be to use a full 6.0 litre engine from a later car. 322 HP + a vastly improved ignition are a clear technical improvement. Getting the engine and making it work in the series Jag are certainly not so easy.

Frankly, I’d probably be happy to start with an unmolested car and keep it in exactly this state for a while. Changing more than one component at a time for unknown other components might spoil a lot of the fun about driving the Jag. Look at Aristides’ XJ12 and his wonderful work on the electrics, if you feel like doing substantial work. Prior to that - just take care of every single bullet connector and fuse holder as their conditions pretty much determines whether you’ll enjoy a reliable ride or fall victim to the Prince of Darkness.

Good luck


75 XJ6L 4.2 auto (UK spec)


progress so far. Just working at pulling the body panels right now. Dropped the oil pan and have a gasket on the way. Injector hoses after. I’ll order the projection lights sometime in the fall. Ill definitely post updates as I go and any advice is more than welcome. Thanks all for the ideas so far

Here are two pictures of the engine bay restoration that I did on my 1990 V12 Vanden Plas a couple of years ago. I understand what you are doing, and I am very glad that I did this work on my car. The first picture shows how everything looked about in the middle of disassembly and the second shows how it looked when I finished and everything, inlcuding the R12 serviced climate control system, was fully operational again.


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Beautiful engine bay Paul. One question though. Was the battery box with the integral fan discontinued for the series 3 cars? I had it on my series 2 and although it looked very nice it really did not work very well.

Thank you for the kind words. The battery fan was not used in the Series III XJ6 or XJ12 saloons. The battery was moved to the trunk in the later Series III XJ12s (sometime after my 1990 was built) to make room for the Anti-Lock Brake System (ABS). The battery in the boot did not have a fan.


So I’ve just about got the passenger fender/wing off, 2 bolts left. Some broken, some intact lol. Was just wondering if anyone can identify this. I’ve looked for 2 days now and decided to turn to you gents.

The bolts are behind and I’ll pretty much have to cut the steel holders off. Just wanted to know what this is so I can refit after.

Vacuum reserve tank for the power brakes


Greatly appreciated Doug! Fender is off and regained the feeling of progress👍 I found some universal reservoirs online as well. Have any of you swapped the vac reservoirs out or had problems with the originals?

Never had a problem with the original, probably the only thing under the fender that I haven’t fiddle with.

By the way, have you downloaded XJS Help from this site? You will find all the important modifications and issues you need to address, V12 included.

Good luck with your project and keep us posted.

No problems here.

Is yours leaking …or ?


Thank you Aristides, that is an awesome source!

No issues with the reservoir Doug. I just found some universal reservoirs online that are stainless steel and have really easy mounts.

Oh the Joy of finding what others paint over.

It could be worse :slight_smile:

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Hi Justin, Where are you located?

…good christ.