I'm at the "optimism" phase of a bare-metal resto on the Wolf ('94 V12 coupe).

After getting two quotes north of £20k I thought "**** it" and have determined I'll do it myself. If you want a job bodged properly, etc...

The wife and I like to haul stuff. The XJS is a step up in style but step down in luggage capacity from the normal estates we use. One thing that would really improve the XJS for us is a rear seat delete that opens the boot right up to the front seats - a "folding seat" mod, if you will, except we'll just leave them at home. In fact, the rear seats will sit in the garage for 11 months a year. (There was a comprehensive seat delete thread at https://www.jaguarforums.com/forum/x...ce-box-223882/, for reference, but those people aren't touching the bulkhead.)

I have to pass a UK MOT, so the seats must be _removable_, not permanently removed, IIUC.

I am well aware that the bulkhead and, particularly, the sun deck provide a lot of stiffness - the convertible needed significant strengthening due to changes there.

I will have to move the fuel tank. MOT guidelines don't seem to mind this! https://www.motester.co.uk/mot-test-of-fuel-system/ (although any mfr shields must be in place). I'll also have to move the battery.

I don't really want to lose much fuel tank capacity or spoil the line of the underneath of the rear.

So my thoughts:
- cut out most of the bulkhead behind the rear seat squabs
- reinforce what remains with basically a big steel O
- don't touch sundeck
- battery in the "cubby" behind the wheel
- custom alu fuel tank along boot floor, raising height of boot floor but gaining length
- spare (space-saver) on floor or upright against side

Alternatively, could look at the fuel tank going along one side, but less keen on that.

Alternatively again, could look at fuel tank underneath where rear seats go, with firewall to seal off from cabin.

I don't know what I don't know. What are the issues and concerns?
- heat from the diff / exhaust?
- bulkhead constitutes "fuel shield" in the eyes of the MOT?
- lose too much stiffness?
- tank on the floor will starve when the fuel sloshes?
- I am literally insane and should stick to wrenching kiddie toys?

 

Removing the rear bulk head and putting the fuel tank in the boot effectively puts the fuel tank inside the passenger compartment. That's not a great idea. Most modern estates, hatchbacks or SUVs have there fuel tanks under or outside the passenger compartment. You'd need to raise the rear floor and put the tank below it on the outside of the vehicle and add a rear collision sheild and bar.

 

Madness! You will have to get insurance clearance on all the mods from your UK insurer before you can drive the car. Your chances of getting this are vanishingly small with any mods at all to the tank and the structure of the shell rear cabin bulkhead. Wherever you place the fuel tank inside the vehicle cabin/boot space, as you are opening the space between the cabin and the boot, the passengers cannot be sealed off from the fuel tank, which immediately renders the car illegal and appallingly unsafe.
The tank would have to be beneath the boot floor, which could be raised to make room, but then you are slinging the tank weight out behind the rear axle instead of over it, which would ruin the handling of the car, and very likely still fail the required safety regs as it would be highly vulnerable to a rear end shunt. Whisper it softly, but the position of the fuel tanks on the series I, II and III XJS saloons (in the rear wings as it is) is no longer safe enough for modern car regulations.
Buy a Lynx Eventer if you want and XJS estate car! Or make one yourself?

 

Cheers Greg, that's probably the last word on the subject for us Europeans who live under the august sight of vehicle safety laws. Perhaps an American will try it ;-)

I was anyway more "musing aloud" than seriously planning a big mod like this.

In the realm of purest speculation, I wonder if there's enough space between the catalytic converters and the rear axle to raise the floor under the rear seats and put the tank there?

 

and i thought mine was a little to much body mods!!
building a roadster from an XJS coupe!

 

As long as you are OK with changing a classic why not try to use early xjs convertible side tanks.