Mk2 4.0 IRS project

I wanted to give you an update on my Mk2 project, which has finally taken up some speed now. I am in the process of I building what could have been. In my case, it’s a Mk2 with an IRS from an S-type. I am also putting in an 4.0L AJ6 engine in together with the ZF 4HP24 gearbox.
Google Photos

Add power steering (Series III), 4pot calipers in the front (XJ12 SIII) and outboard brakes in the rear (XJ40) plus ABS brakes (XJ40).
Google Photos
Google Photos

I hesitate to call it a lump in this particular case, that’s why I am posting it in the saloons section.

I have to give credit to the late Jyri Järvenkylä; my Mk2 project has been heavily inspired by his Mk1 AJ6-project. And a big thank you to Andrew Waugh who has been helping out with measures and documentation on the S-type which has been the donor of the IRS.

I initially went for a XJ40 IRS which has been half way done.
Google Photos

But I did not like the modifications to the Mk2 body required to fit the XJ40 (modified) IRS subframe. While the mods necessary for the S-type-IRS are still quite extensive, they rather result in replacement of existing body structures with stronger parts.

New longitudinal members
Google Photos
Google Photos

Trial fit of S-type IRS

I will keep you posted



Greetings All,

Slowly becoming a fan of that engine. The weight savings alone intrigues me.

The IRS? At least it’s being put in a car that has spats. It was annoying on the S Type, clearance issues.

Good Luck, nice work so far, very nice!

All I can say is: “Wow”!

That’s a great project, cannot wait for more.

That is some kind of great work. Sir Lyons would be proud.

When it’s in the family like this one - maybe it’s a pimple, not a lump. Really nice work. Paul

Quick update here. As posted in another thread, I had some height issues. The Mk2 shop manuals show a ride height that is way too low. I don’t know at what height their drawings were made, but it can’t be anything like mid-laden. This forced me into repositiong the IRS cage together with the new rear frame rails. This also required some minor modifications to the rails.
Cage now 30mm lower compared to initial position. Both lower control arms fitted at “mid-laden position” as per shop manual. And aligned to centre (not my fingers, I do wear gloves):

After some tack welding, the support braces have been removed

Final result for today

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Progress is slow, but steady. So far, I am still busy with rerouting the longitudinal member. I have had some extra panels made an welded in.
Left side

Right side

It’s back on wheels, sort of

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I’ve the photos
Is she on the road yet?
I was contemplating doing the same, any information regarding creating the structure would be appreciated.
Regards SW

I think @600 will find this interesting!

Progress has been really sloooow. I have been somewhat sidetracked by fixing up my XJ81 (rust, paint).

And I had to take it for a test drive

That’s a matter of definition. It is on its 4 wheels now. Although the workshop floor isn’t quite a road, its surface quality has similarities with an ever increasing number of roads.

I am currently routing the exhaust.

I have spent quite a bit of time converting the differential to LSD using internals from a salvaged unit from an XJ81

Completing the front suspension except for brake calipers

And trial fitting the steering column plus steering wheel

Please PM me with anything you need to know in particular

did you use e,s 10 or some other starting point for geometry, i always envied s handling with little in back and about 15% greater power?

If its legal where you are take out the cats, it’ll give the car a bit more umph :slight_smile:

did you have that ugly heavy stuff and periodic testing? $$

No testing for emissions here in NZ but cars manufactured after 2000 are required to retain any Cats, pre 2000 we could take them out, did it to both my 4.0 ‘40 and brothers 3.2 X300, that made a difference to his that was quite obvious to the Butt Dyno. I had my 4.0 tested (just because I could) and it would have passed the (then) current standards.

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I have used an IRS from a 3.4S. The track width matches the Mk2. Then, I used the Mk2 wheelbase for positioning of the IRS unit. I have adjusted height of the IRS to the “mid-laden-position” (as described in the s-type workshop manual) and matched that to the vertical wheel center position of the Mk2. I have then tacked the new longitudinal members to the Mk2 body.

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sounds like it will be great car, lots of flexible compatabilitty , good tire ( tyres) , shocks etc.
yourself Robin & PJB are inspiring me. thanks muchly ! john