Hi,

Not a joke question. We're doing a topless XJ8, axle weights are going up with the added stiffening (different tyres required) and insurance is fun enough as is.

I would like to limit the top speed to improve tyre choice and placate the insurers - anything between say 95 and 130 mph would be fine. (I'd like more than 70 mph as it'll be heading over to the continent/for safe overtakes should a little extra be required in an emergency)

For everyday purposes its useless (the wind will get you long before silly speeds) but for the IVA (approval of radically altered vehicle) and insurers it has to be technically impossible, not just something that you promise not to do.

Japanese cars and Singapore cars are limited - how? Can the ECU be interrogated and a top speed limiter set?

Thanks!

 

Sorry I don't have an answer to your question, but wow I want to see pictures of this project! I'm also curious about the rigidity of the car being topless. These cars seem to have somewhat low chassis rigidity from the factory with the roof in comparison to its german rivals.

 

From what I've heard, yes. It'll have to be reprogrammed with IDS/WDS software, main agent or good dependent Jag specialist. I was told its a box you fill in with required top speed, within the program. Someone with IDS knowledge will hopefully chip in.

Are you making a Corsica rep then?

http://www.davidmarksgarages.net/dai...20part%205.htm

 

Corsica was my first thought, but that was only a 6 pot wasn't it? This does sound very interesting though. S.

 

very similar chassis Stu.

 

Yeah I know, I've seen (and sat in) the Corsica in real life. It is a pretty thing, but I prefer the V8 over the 6, so a V8 Corsica would be on my Lotto win bucket list I think!

 

Or how about a V12, that'd be very cool.

I posted Dave Marks page on the resto because he uses a very neat trick stiffening the chassis with a mildly modified XK8 cross brace. Hope that helps.

 

Two modern cars Jaguar should have made are a XJ pillarless coupe/convertible with frameless windows and a coupe/convertible S-type R with the also pillarless and frameless windows. There are pictures of a red XJ40 XJ6 coupe floating around on the internet that looks pretty nice. The Corsica concept is very nice, but would look better in a 'normal' color and with the X308 XJR visual upgrades.


Maybe I dream about coupes but I also think a Chrysler 300 SRT-8 coupe would have been beautiful too.

 

How can you satisfy the insurance company? Anything you can do to reduce top speed can be undone (short of cutting the rear cylinder off each side of the block). This, in and of itself, makes meeting requirements impossible, IMO.

 

Cheers Sean, sounds straightforward if I can find a decent indy.


Corsica rep after a fashion. 4 doors and the LWB version, rather than a shortened SWB and 2 door. (think Lincoln Continental with the suicide rear doors) Briefly considered using one of the last of the Daimler double sixes, but decided that people might disklike us for butchering one of those rather than an early X308. That, and 25 mpg rather than 15!


Have spoken with David Marks and it was SVO who did most of the shell stiffening when it was first made. (sill structures and the crossmembers) Not convinced by the X-brace from the XK8 myself because as soon as you put a kink in a slender beam its stiffness drops to tissue paper levels. Might stop the nose shuddering as the rest of the car twists over bumps, but won't prevent the central section of the car from moving.

Their tunnel work was nice though. Having double-plated the tunnel and tunnel stiffeners I can attest to that being an absolute nightmare of a job!

These are the existing underbody structures:



Crossmember/subframes in green. Chassis legs/sills in red. Properly stiff bits of floorpan in blue. You need to link those two subframes in torsion to stop scutle shake.

This is roughly where the extra underbody material is headed:



New sills. (150x150x5 mm) Double thickness transmisison tunnel. New crossmember between the front jacking points. New crossmember in front of the propshaft centre support, and new "crossmember" under the driver's seat. Substantially larger "handbrake linkage crossmember" and strengthened crossmember at the front edge of the rear seat. And some extra material in the areas that transfer load between the sills and the front/rear chassis legs.

Pillars all get plated up to 3 mm thickness to prevent the windscreen wobbling and b-pillar for moving in the event of a shunt. C-pillar is mostly ok as is. Gets a little stiffening on the inside face and inner of the wheelarch.


IVA and the insurers are happy with electronic limiters - so long as you can't override it whilst driving that's fine.