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

The Handling Thread

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  #21  
Old 09-08-2012 | 10:03 PM
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Originally Posted by Jose
the problem Doug, is that I am old skool, I don't like sensors, or nitrogen-filled tires, or run-flat tires, or anti-lock brakes, and more sensors which sense the sensors, and EGRs and Carbon Canisters, none of that.

give me an old carburetted car that spits fire through the exhaust pipe, and I'm happy.

everything is so "sensor-based" now-a-days that it makes me sick. And when something goes wrong, no way to fix anything. My three cars are old. I'm happy. They can be fixed without parting the car for a "bad computer". You know exactly what I'm talking about. (the '95 XJ). Nobody could fix it so they decided to sell it in parts. They're still selling it in parts.

No argument form me, Jose. My '95 is as "modern" as I'm likely to ever get....and I have worries about future repairability. My next Jag will probably be another Ser III.

But technology has done wonders for automobiles from a driving standpoint.

Cheers
DD
 
  #22  
Old 09-20-2012 | 07:12 AM
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It would be nice hear some thoughts from someone who races these cars to get the full spectrum of experiences/opinions etc.

It seems like the racers are using 17 or 18 inch wheels which would allow for a lot wider rubber in a greater variety of styles and compounds.
 
  #23  
Old 09-20-2012 | 10:23 AM
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Default XJ40 rim on S1 are wider and lighter

My 1971 XJ has XJ40 rims that are one inch wider. To use them on the front you must take off the front grease caps and use spacers to create room for the wheels center caps. Plus, you must use the XJ40 wheel nuts that fit these rims. Plus, I shimmed out the steering arms 1/8" for more clearance with the tire rubber and the lower ball joint ends. The car also has a large front sway bar added for better handling. No rear sway bar yet, but am considering installing one soon.

The wheels are lighter and wider but retain the "Jaguar" look and tire size can be wider, 215/70/15 fit well and there is no problem at all in the rear. Michelins are too hard a rubber for the car and I use Goodyear currently.

With directional modern tires, still 15", plus poly rack bushings, the car will handle much better.

The seats with the lack of side bolsters and the poor original seat belts then become a hindrance when cornering. You can corner better than the seats hold you in place.

Get rid of the large school bus steering wheel first thing!.
 
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Last edited by Roger Mabry; 09-20-2012 at 01:40 PM. Reason: Rear sway bar info
  #24  
Old 09-20-2012 | 11:01 AM
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Default I installed XJS rear sway bar and it works for me.

Stock XJS rear sway bar did it for me. I installed a 400 SBC with trick flow heads roller cam, fuel Injection and made a very powerful car that was unruly at speed. The suspension was totally out gunned but the motor. So I removed the soft Monroe shocks and Installed KYB all around. My impression was that the car is much more controlled but slightly harsher but when pushed it became loose. Then I installed 17" wheels with 235/55 series tires which are taller than spec so I retained a compliant sidewall. It was still a great ride but handling and steering feel are much improved. When pushed it hard it still got loose. The car was still scary sloppy in speedy maneuvers because the rear leaned so much. As the rear trailing arm moves it pulls the rears suspension out of alignment. This happens so suddenly it becomes dangerous. Then I installed a smallish factory XJS rear sway bar. It transformed the car. The rear doesn’t pitch so violently now and the small sway bar lets the rear move enough to maintain steering feel and a compliant ride. So for my money the stock XJS rear sway bar is all up side no down side. I think Jaguar should have included the small sway bar from the factory and is probably why Jaguar got trounced as other European car makes came up in the late 80’s. Once I installed a larger rear sway bar in another car I owned and the car was more controlled but twitchy and the steering feel diminished greatly on center so lesson learned. For the smooth Jag I tried the small sway bar / stiffer shocks combo and it works for me.
 

Last edited by icsamerica; 09-20-2012 at 11:12 AM.
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  #25  
Old 09-20-2012 | 03:32 PM
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Very interesting, good information there.
Was that the sway bar off a standard xjs or the sportspack one? I presume it was an easy fit or was there welding involved?

Do you think uprating/installing the front sway bar from an xjs (sports pack?) as well would be a good idea.
 
  #26  
Old 09-20-2012 | 07:12 PM
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Originally Posted by anjum
Very interesting, good information there.
Was that the sway bar off a standard xjs or the sportspack one? I presume it was an easy fit or was there welding involved?


Do you think uprating/installing the front sway bar from an xjs (sports pack?) as well would be a good idea.
Standard and I have to "fabricate" and weld in attachment points to the trailing arms. Very easy to do though.

Probably not for me....I removed lots of weight from the front of my XJ6C so the front bar I have seems right. I dropped the weight by removing the federal bumpers and installing the much lighter European ones. My Chevy SBC was built lite and right. Aluminium intake and heads, I used the a lite weight R4 A/C compressor, aluminium radiator and headers. I dropped so much weight I had to add thick spacers on the spring perches to get it to sit right.
 

Last edited by icsamerica; 09-20-2012 at 07:20 PM.
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  #27  
Old 09-21-2012 | 08:34 AM
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Thanks icsamerica, that's just the kind of feedback I was after.

I've got some alignment settings from Jaguar World Monthly that are supposed to improve the handling. They are:

Front Camber: 0.75 deg negative
Front Castor: Max achievable (S2 Front End with S1 Upper Wishbones help this)
Front Toe: 1/8" toe in
Rear Camber: 0.5 deg negative

For those who don't know, positive Castor adds the dynamic camber effect, that is, as you turn the steering to the right, the left hand front wheel increases it's negative camber. The feeling of better front end grip and 'turn in' are normally the result. (this is all very general of course)
 
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  #28  
Old 09-21-2012 | 09:41 AM
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Default Rear camber on the IRS

Just went through all of this due to rear bent wishbones from a prior accident. According to "Jaguar lore", the cars were assembled with (4) shims for the camber and then taken to the alignment area. Toe out now is "zero" on the rear where before it out 3/8" on BOTH sides due to the damaged parts.

After putting on the "setting links", JD 25, they can easily be made out of large turnbuckles - the front and rears were aligned. Most cars ended up with two shims left in the IRS... They usually left with the proper camber that was achievable with the new suspension parts. Cannot find out if the weight of the driver was ever considered as a change when the car was not "perfect" any longer or if it had full tanks.

When I finish up the current front end work - new front stub axles, bearings, races and seals, new shock mount rubbers and a lower ball joint gaiter - I will do a full alignment check - again - front and rear. Last month I was zero camber without the "setting links" but with a full gas tanks and it handled perfectly with the new Goodyear tires.

I still have two shims to work with and removing one, if required, will bring me to 0.5 degree negative. This time I will have the setting hooks with me for the shop to use.
 
  #29  
Old 09-21-2012 | 07:49 PM
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More great feedback Roger.

It would be great if you could let us know your final settings and how they translate to the handling and feel of the car on the road.
 
  #30  
Old 10-09-2012 | 08:03 AM
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What are the possible wheel sizes that can be fitted to S1-3 cars. This is not to say what effect they may have but just what will physically fit and still be functional.

The JEC Race Series says that the max allowable wheel size that can be fitted within the regulations is 9x18 but, I suspect that encompasses all models and might not be possible on an XJ?

My initial assumption was that an 8x18 would fit if fitted with 245/45/18 tyres?

For those that have fitted some of the larger possible sizes, can you please explain what difficulties you experienced during fitment.
 
  #31  
Old 10-09-2012 | 12:37 PM
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Originally Posted by Woznaldo
What are the possible wheel sizes that can be fitted to S1-3 cars. This is not to say what effect they may have but just what will physically fit and still be functional.

The JEC Race Series says that the max allowable wheel size that can be fitted within the regulations is 9x18 but, I suspect that encompasses all models and might not be possible on an XJ?

My initial assumption was that an 8x18 would fit if fitted with 245/45/18 tyres?

For those that have fitted some of the larger possible sizes, can you please explain what difficulties you experienced during fitment.

Woz, one concern is the speedometer calibration will be off; The bigger the wheel diameter, the smaller the tire walls will need to be to retain the speedo calibration to original size tire ratio, so the effect will be that the ride will be affected, it will feel like running on stone tires, like The Flinstones' car.

another concern is steering geometry could be affected,

another concern is your car will looked "pimped". You might be banished from Jaguar car shows forever.

however you can stick to 15" wheels and use real fat tires, it's been proven that the more rubber on the asphalt, the faster will be the response from any given car.

I have Dunlop 235/60/15 installed on XJ-40 wheels, the only problem I had was fitting the two XJ-40 wheels to the Series 3 front hubs, the hub sticks out too much preventing the center hubcap to sit flush, but I resolved it with a 7/16" spacer. I also needed longer lugnuts at the front. The two rears went on like butter, no clearance problems.
 
  #32  
Old 10-09-2012 | 02:09 PM
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Originally Posted by Woznaldo
This is not to say what effect they may have but just what will physically fit and still be functional.
I don't know if you read this yet, but it has a lot of good info. Unfortunately, most of the fitment information is for the XJS as opposed to the XJ6, but still a good read:
https://www.jaguarforums.com/forum/x...-wheels-65576/

This is worth taking a look at, too. It is a list of most Jaguar wheels used in the last 30 years. It states their height, width, name, and vehicle fitment. It will help you do research by letting you know what Jaguar OEM options are out there. Starting with the wheel name and size, you can use Google to find the offset, etc. There are a couple 18x8 front/18x9 rear combos from the XK8 and XKR that should fit SIII XJ6 cars with a tweak or two, if any. (You can ignore the whole chrome-plated thing - this is just for reference.)
www.wheelconcepts.com/JAGUAR.htm#JAGUAR XJ
One word of caution - check the bolt patterns. I think Jaguar went from the 5x4.75" to a metric pattern on both the XJ and XK cars somewhere in the late 90's or early 2000's. The later wheels will not have the same bolt pattern as our SIII cars.

I am really curious about this question, too. I'd like to see what kind of fitment experience people have had putting on larger wheels and tires. Right now I am leaning towards a set of 17x8 XK8 "Lamina" wheels - I like the size and the look, though they'll prob need a small spacer. The 17x8 XJR "Sports" wheels fit for sure - a lot of guys run them. (I have a couple I probably won't use.) One of the members here has 17x8 XK8 "Revolver" wheels on his SIII, but he told me he used a small spacer (1/4"?) to clear the dustcaps on the front wheels.

It's good that you're thinking about tire size, too. That can definitely be a limiting factor. Further, not all tires with the same shelf size are actually the same size. For instance, in the 245/45-17 size, the BFGoodrich g-Force Pro Comp 2 puts almost an inch more tread on the road when compared to the same 245/45-17 size tires offered by Michelin, Bridgestone, etc. (See the "specs" for each tire at tirerack.com) That means that 1) you're getting more tread on the road -yay!, and 2) you have to make sure that extra tread will fit in the wheel well.
 
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  #33  
Old 10-09-2012 | 02:54 PM
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You do need to be careful and not to overload the aluminium rear hub carriers, which is inevitable with installing fatter tyres and putting in sway bars. These are castings and can (and DO) crack if overloaded. This was found in the 70s when British Leyland undertook a programme to race the XJ12C.
 
  #34  
Old 10-09-2012 | 07:41 PM
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Originally Posted by Doug
But technology has done wonders for automobiles from a driving standpoint. Cheers DD
yes, like the new buttons-only plastic Corvettes; everything is push button, no keys, nada. I wonder what someone will do if the battery becomes dead. How do they open the doors? ("They" because I'm not messing with the car).

same with the Bentley 2-door Turbo. They brought one in for storage where I work, I got to drive it, park it, connect it to a battery maintainer. My my, it drives unlike my Jaguar, not smooth at all, I expected a super-plush marshmallow and I got a Flinstones Hot Rod. Hard like a rock, visibility to the outside once you're inside is terrible. Interior is dark, beautiful leather though; Everything is motor-operated, the trunk can't be opened by hand, it's opened by electric motor and there is a 8 second delay before it will open. Beats the Corvette because it is steel, but feels like it weighs 8,000 lbs.
 
  #35  
Old 10-09-2012 | 10:03 PM
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Look what came in today! Six new KYB shocks/struts. I was really thinking about the Koni's, but these were much more affordable and very well might achieve my goals. If I put these in and still want a firmer shock for more control, I'll move up to the Koni's. Plus the King springs are a little stiffer (15-20%) so that should take away some of the "float" that I am trying to eliminate.

I plan on dropping the IRS next week, and it should take me a week (here and there) to refurbish everything and get it back in. I'll report back about the handling and ride quality!
 
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  #36  
Old 10-10-2012 | 07:37 AM
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While you've got the rear IRS out, will you be fitting/welding the arb (brackets at least), if you haven't got an arb already.

Would love to hear another report on that along with the KYBs
 
  #37  
Old 10-10-2012 | 05:56 PM
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Thanks FastKat, that's great info and has certainly given me some direction for some more research.

Like anjum, I would love to hear how the KYBs turn out and if you haven't made Anti-Rool Bar provisions yet, some photos would be great.
 
  #38  
Old 10-12-2012 | 01:02 AM
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Default Rear Tire Spacing question

Do you have to remove the snubber in the rear arch to intall wider tires on a 77XJ12L?

Thanks
 
  #39  
Old 11-10-2016 | 05:39 AM
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I've been enjoying my old girl for a while now on the standard suspension, but the rear shocks are not at their best. To this end I've taken the punt and got a set of Gaz Adjustable Shocks. I'm not sure whether to get some new springs too if only to ensure they are at their standard best? I'll get some pics up when I fit them.
 
  #40  
Old 11-10-2016 | 12:45 PM
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Default '71 XJ with some good mods

With the V8 engine and using lots of aluminum in the accessory mounting - the weight is farther back than normal... that one change made the most handling difference. Suncoast mounts put the engine as far back as is practical. I plan to get it weighed soon but I imagine it is close to 50/50.

Plus the XJ40 seven inch wide wheels and modern directional tires. Spacers had to be used for hub clearance so the width is even wider than normal... plus the steering arms are shimmed out about 1/8 inch for tire clearance at the tie rod ends. A good front roll bar and good shocks completes the changes. No rear roll bar yet as it does not need one.

It is a SWB car and even though it is still higher in the front for my liking, it handles EXCEPTIONALLY well.. it will make other sports cars that try to follow get into trouble on tight sweeping turns... especially Porsche...

Old photo before the recent paint job and fuel injection conversion.. I am still putting the interior back into the car... SOON!
 
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