XJ6 & XJ12 Series I, II & III 1968-1992

New XJ coupe project - 2017

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Old Jul 1, 2017 | 10:01 PM
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Default New XJ coupe project - 2017

Here we go again.... Will try to complete in 1 year or less. This new project will have a AJ16, ABS and all the great 1995 modern XJS wiring and features. I've learned a lot about XJ Coupes and how to improve them by de-constructing the XJS. Many of the structural improvements Jaguar made to the XJS will be transferred to the XJC.

The goal... a quiet, solid, light weight coupe with great driving dynamics. There will be heavy focus on refinement and reduction of NVH. The core of this refinement will be the an AJ16 from an XJS. Many invitations from the 2015 coupe will be re-employed and a few new innovations are in the works.

The Project Vehicle is a 1976 XJ6C, found on CL with just 43k miles. A compression test showed 1 cylinder with 0 compression. Paper work evidence and date codes on the tires suggest the vehicle's engine failed and it was parked in a garage in the early 80's. This car is REMARKABLY solid for a coupe and deserves a high end recommission. Good thing this isn't my first go around.

I've been working on some engine and electrical issue for some local XJ sedan owners. After many frustrations I feel strongly a re-do with XJS wiring is the prudent thing to do, especially since the 2015 coup has XJS wiring and it's been great.

The XJS parts come from 2 low mileage XJS convertibles the suspension bits have just 38k miles and the wiring, engine and transmission just 90k.












Still in messy mode deconstruction mode.. Cant wait to turn the corner and get working on cleaning and finishes.
 
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Old Jul 1, 2017 | 10:25 PM
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I'll be watching this one too.
(';')
 
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Old Jul 2, 2017 | 02:27 AM
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Great! Another cool build to follow. Will you be selling the old Coupe when this one's done?
 
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Old Jul 2, 2017 | 02:50 AM
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Cool, another great build to follow.
 
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Old Jul 2, 2017 | 05:06 AM
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Looking forward to the jag engine going in.
 
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Old Jul 2, 2017 | 09:53 AM
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Yow, huge carnage !!! Way beyond that that existed in my garage when my car endured a conversion.


And, no doubt about it, I'll watch with interest.... Lots of it.


Carl
 
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Old Jul 2, 2017 | 01:55 PM
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Originally Posted by scatcat
Will you be selling the old Coupe when this one's done?
Selling...I dont think so. I really love that car. It really drives great and has lots of unique technology I appreciate but I dont think the market would compensate me for. Cases in point, the ignition system, the in car entertainment system and the dual mode exhaust.

The ignition system is a distributorless wasted spark system with 2 crank sensors. This turned a shaky SBC into a smooth idling yet high reving LS like precision machine. SBC never came with DIS so this whole system was developed by me at great expense and time. This alone cost me 1/2 the price of a complete LS engine with transmission. I did it for the sake of doing it.

The in car entertainment is full integrated with my cell phone. The subwoofer was installed behind the seat and uses the trunk as a box so there is no loss of cargo space and very little added weight. The doors were modified to accept 6 inch full range speakers and it all sound great. It was tweaked to sound right over a wide variety of musical programs. This all took lots of time changes to the body... becasue coups are naturally boomy.

The dual mode exhaust. Also developed at great time and expense. The ECM controlled valve snaps full open 3 inch at 3800 RPM, maintaining sedate cruising and low end torque below 3800 and allowing easy breathing with an exhilarating sound from 3801 up to 6200 RPM.

These and other features like the Auburn locker, hybrid braking system, XJS electrics and the shut lines took lots of time and I don't think the market appreciates this type of work. The market seems to appreciate one legged burn outs of narrow tires and suede headliners. The 2017 coupe will certainly be able to burn up a narrow 205 tire and certainly will have a suede headliner.
 

Last edited by icsamerica; Jul 2, 2017 at 04:22 PM.
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Old Jul 2, 2017 | 08:26 PM
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Woo! Hoo!
full disclosure : I plan on copying a ton of your ideas! Please accept it as the highest form of flattery! FYI I will be heading for NY sometime mid July.

P.S. Are Xj engine bays color matched to the body?

Rusty
 
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Old Jul 2, 2017 | 11:38 PM
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Wow. Can't wait to see the outcome! Good luck!!!
 
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Old Jul 3, 2017 | 09:54 AM
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Originally Posted by Rustyxjc
Woo! Hoo!
full disclosure : I plan on copying a ton of your ideas! Please accept it as the highest form of flattery! FYI I will be heading for NY sometime mid July.

P.S. Are XJ engine bays color matched to the body?

Rusty
“The bad artists imitate, the great artists steal.”
Picasso/Banksy

Steve Job stole WYSIWYG from the Zerox alto
https://en.wikipedia.org/wiki/Xerox_...it_Rechner.JPG

Run with it...take and bring to the next level.

I'm flattered...check in with me on specifics, I tinker and improve endlessly and don't always post follow ups. Case in point... My brake booster failed.
After installing a new brake booster I re-did the MC for a 3rd time. Specifically speaking my old booster was weak before it failed and I didn't realize it, after installing a new and properly working booster it threw the brake feel totally off. To get it right I went back to a 1 inch MC bore and transferred the internal piston springs from OE Jaguar MC to the Mitsubishi MC.

I've taken a lot of Fiboys' ideas over the years and given credit where it's due. There is also this cleaned up nice blue coupe in AU with a 350 I've been inspired by. Cant find a pict at the moment.
 
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Old Jul 19, 2017 | 12:28 AM
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Progress...

XJ8 brake pedal and accelerator pedal setup. Installed as a unit. The accelerator pedal operation is much smother with is modern compound movement. The brake assembly has a modern booster with a 1 inch alu master cylinder and should offer up modern brake feel and performance. The housing is composite and the over all assembly it's significantly lighter than what came out.

Took many hours of fitting and metal work to locate the pedals in the original location.

An additional benefit will be the brake pedal switch and brake warning lamp will be a direct plug in to the XJS harness.

Another improvement is the angle of the pedal assembly and requisite sheet metal work effectively triangulates the area. The knuckle knock test indicates the new brake area and wheel well is more solid. By comparison the other side rings like a bell when knocked. I may triangulate it other to match just for the solidity.



 
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Old Jul 19, 2017 | 12:41 AM
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Default Solid!

Started making changes to solidify the chassis. This coupe is going to be the most refined coupe there is. Making a vehicle feel refined requires solidity and chassis rigidity. This is just the first of many braces and structural augmentations to come. Seems will be fully welded too.








This seem was full of bodyfiller. It's been removed and the seem will be fully welded.





Bracing was carefully fitted to the body.
 
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Old Jul 19, 2017 | 09:29 AM
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interesting thoughts on the bracing, will definitely consider this next time the engine comes out
 
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Old Jul 19, 2017 | 10:16 AM
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As a Novice could you please explain what forces you are attempting to counter here? what is the symptom or is this as you say part of a larger plan to generally stiffen the car. or in other words will these by themselves solve a certain problem?

I like the pedal combo its nice!

Rusty
 
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Old Jul 19, 2017 | 06:34 PM
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Originally Posted by Rustyxjc
As a Novice could you please explain what forces you are attempting to counter here? what is the symptom or is this as you say part of a larger plan to generally stiffen the car. or in other words will these by themselves solve a certain problem?
Coups flex. They are based on a late 60's sedan design. Jag simply lopped out the B pillar and called it a coupe. There was no other meaningful structural improvements.

If you jack up any one of the 4 corners of a coupe the door will misalign significantly. The rust free coupe I'm working on now has a pinstripe and I can clearly see about 1/4 inch of misalignment when 1 corner is jacked. On other coupes I've reinforced, I've got this down to zero. This would be considered a static loading. Dynamic loading is another matter and is why I'm taking these reinforcements to the next level.

This flex body flex expresses itself as imprecise steering feel and a jiggly feel. Alignment setting are often in increments of 100's of an inch so chassis flex of as much as a 1/4 inch will provide dull driving dynamics to say the least.

With an un-reinforced coupe, a small road bump can upset the chassis so much the vehicle will experience a perceptible change in direction. Modern performance tires exacerbate this effect.

You can see then many improvements that Jaguar made on the XJS. The XJS chassis is mostly dimensionally the same as the XJ sedan save for a 2 inch shorter wheel base. They gusseted the chassis is many ways that I mimic. I did this on the 2015 red coupe but with take it to the next with this coupe.

Look here...https://www.jaguarforums.com/forum/x...-122634/page7/


Most coupes sag where the rear of the front fender meets the door. I think this is called the A pillar. This effectively put the nose higher that is was when new and causes major misalignment problems with the door and fender. This happened becasue the chassis is weak in this area. The metal fatigues is this area and rust weakens it even further. This is another area Jag double re-inforced on the XJS while the XJC has a single thin sheet of steel. You can see significant sag and fender raising on the $103k lapis blue coupe.




I will use this famous coupe as an example, its note worthy and has many un-corrected coupe issues. LH side is sagged signifigantly, the RH side is sagged to a lesser degree.
 

Last edited by icsamerica; Jul 19, 2017 at 09:47 PM.
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Old Jul 19, 2017 | 08:51 PM
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Will the car be media blasted inside out? This is a fantastic build. ...I did notice the LSx motor in the background. That would be nice and torquey

I'll have to revisit the 2015 coupe, is there a thread here?
 
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Old Jul 19, 2017 | 10:08 PM
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does that problem happen on the sedans as well or no?
 
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Old Jul 19, 2017 | 10:12 PM
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Thanks, for the reply awesome as usual!

I'm pretty happy with the lines on my car now that I know what t look for!

Thank you.

Rusty
 
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Old Jul 19, 2017 | 10:51 PM
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Default Vote for the LS......

[QUOTE=slofut;1724495]Will the car be media blasted inside out? This is a fantastic build. ...I did notice the LSx motor in the background. That would be nice and torquey

Yeah, the LS (and that's a truck LS- likely 5.3 or 6.0 I'll bet) will make a ton of torque (but still be pretty smooth) and with these 3.31 rear gears (or maybe even the 3.54 you're thinking about from a late XJS) would be quite the car. Keep it pointed where you want to go.

The AJ engine? Ok, but not nearly as much fun.....
 
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Old Jul 19, 2017 | 10:55 PM
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Originally Posted by sunchip
does that problem happen on the sedans as well or no?
Yes... but to a much lesser degree. The presence of a B pillar helps.
 
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