I need to get my XJS alignment checked out and I’m confused about the procedure. What I mean more specifically is:
Is a full tank of gas required?
Does 200 lbs./90.71 kg need to be placed in the drivers side front seat?
Are the two ride height hooks that are used for the pre facelift cars needed?
I have no idea about the very vague reference of the tubes that the ROM talks about for the front end. No idea what they look like or how they are supposed to be used.
Maybe it would be beneficial to mention what is your problem or concern in reference to geometry… Any issues? Recent repairs and change in handling? Ride height, pulling to rhe one side etc…
Perhaps my question wasn’t clear.
Is the 4 wheel alignment procedure on the six cylinder facelift cars the same as on the pre facelift XJS V12?
And what’s the deal with those tubes that are supposed to be made up by the user for the front end?
If you are really concerned I would go with a half tank of gas, (mid point)
If your driving is predominantly one up then maybe load the drivers seat up. With regards to the setting tubes I’m not sure that they do much? Every Jag I have had aligned the car was as it was driven into the shop, no idea what was in the tank no additional weights in the car, suspension sitting at its normal static position. The only thing I requested with the XJR was to give me max camber and zero toe as I do a bit of casual track work.
I imagine that most people that own these cars don’t own and are unaware of mid laden tools. I also suspect that wheel alignment shops just go about aligning the wheels the same way as they do any Ford or Chevy with no ill affects.
So, just so I’m clear. In order for the alignment to be done properly the ride height should be measured the bottom of the front cross member and the rear differential?
Caster is still aligned in the front by moving the shims from front to back and vice versa?
I haven’t taken any measurements yet but the front seems to be sagging because driveways and such needs to be encountered with care and I assume that a new set of shocks all around will do wonders in relieving that issue.
I am torn between Koni vs Bilstein any suggestions?
You won’t measure it to manufacturer’s standards, no way. They were assembling those on the special jigs, tthe other tools were just made to allow after sales checks which were always the same (shims) - at least to the specific tolerance level.
The ride height won’t change after replacement of the shocks. Correct springs with plastic spacer rings are the key to desired effect. Hard to make it right with replacement parts. So far I’m finding best results with new rear spings+spacer on each and no spacers on new springs in front. I wouldn’t touch anything else (if not fiddled already). I’ve also found that spacers are made by various suppliers and if measured with vernier - some are two times thicker than the others… If you willing to have flexibilty with ride height - just put spacers on the back with configuration 2springs with 2spacers-each, 2 springs with 1spacer-each. You can always compensate by placing toolbox, body bag, or spare cylinder heads (if you’re owning v12) in the boot…
Just reminded myself situation from UK KwikFit.
Went there to align front wheels. One of the technicians informed me that their programme forces alignment of front and rear so I have to pay for the set if both are wrong. Approx. £70…
I agreed straight away and paid in advance! Excellent deal. They’ve placed XJS on the ramp and informed me that it’s confirmed - both axles will need adjustment. After 1.5-ish hour and conversation with branch manager - they’ve aligned front free of charge and apologised…
I’ve owned and driven Jags for close on 40 years and never had problems with wheel alignment and I am fully aware of the mid laden setting bars that are recommended by Jag.
Those cars cover;
‘66 ‘S’ type
Daimler V8 250
XJ40 X 3
X300
X308 S/c
This is where you lost me. The rear has four shocks and springs.
Can you clarify the 2 springs with 2 spacers each - Are you talking about using one or two spacers on each side and if so, would that be on the front rear spring or rear, rear spring on both sides?
Whew, my head is spinning.
By the way, with whom have you had the most success with getting accurate spacers?
Yes by the look of my writing it’s messed up. To clarify - looking at the side one with two spacers, one with single. Corresponding configuration from the other side. So some twisting force within rear craddle but not that much… I’ve made front pair spacers doubled (so closest to the front bumper) and remaining ones single. Cannot say what the supplier was but those were cheap as sand. (either British Parts Stevenage) or JaguarClassicParts (now JaguarLandRover i think).
Buy specific front springs, even if they’re much more expensive. The last thing you want is to end up with V12 springs in 4.0. Rear springs - whatever. New spring will always lift your old cat…
+1 to Robin O Connors experience - drive it in and get it measured/adjusted as it stands - no issue with loadings, mid laden position etc.
First of course, check the ride height and replace springs/dampers as you wish. Measure form u/s front cross member to ground and u/s diff plate to ground. What measurements do you get?
Upon trying to get accurate ride height measurements it became apparent that the suspension is in need of refurbishment, so the measurements are meaningless.
I will replace all rubber items shocks and springs under the rear cage and front subframe before any attempt of alignment.
I’ve also decided to lower the center of gravity and convert the springs to the sports pack spec.
The question is the shock length compared to the shortened spring height. The original spring height measures 29.4 cm / 11.57480314 in. The sports pack spring measures 25.3 cm / 9.960629921 in. high.
I’ve not found any documentation where the shocks for the sports pack are any shorter.
Since the shocks will be at least an inch into the stroke at rest, will this end up working against me from a performance standpoint?
Kirbert
(Author of the Book, former owner of an '83 XJ-S H.E.)
13
I don’t believe they are. The Sportspac models aren’t any lower, just stiffer.
In the case of the rear springs, they are bound by the top and bottom stops on the shocks, capping the ride height to the same value in both cases. But the weight of the car will compress the springs further in any case. The amount they compress will depend on the rate of the spring, that is a function of the type of steel, the radius of the wire section and the coil diameter. A stiffer spring will compress less, that’s why the standard sports springs are shorter to give the same ride height. If you want to lower the ride height then you need to get specialist springs that are designed to do that. I have DB7 race spec springs in my car, both stiffer and lower.
Kirbert
(Author of the Book, former owner of an '83 XJ-S H.E.)
15
Ok, so between what both of you guys (Kirbert and CosmoXL) are saying, the appearance of the springs length in their relaxed positions should be inconsequential based on their stoutness. This information gives me a sigh of relief, thanks guys.
I am anxious to measure the height difference between the original front springs and the new ones but I’ve been to chicken $h&t to attempt removing the front springs so far. I have the Jaguar JD115 tool that I used on XJ81 but there is no sensible way to use it on the XJS because they didn’t provide any notches in the perch to get the T-shaped rod through in order to sit in the indents of the perch. By the looks of things the only way to actually use the tool is to completely remove the subframe and back the rod down through the top “sigh”.
I seem to have diverted this wheel alignment thread into a suspension overhaul type of thing, but it seems obvious to me that if the ball joints, radius arm bushings, tie rod ends, control arm bushings, etc… aren’t up to snuff, your wheel alignment will never be spot on.
I really do wish that someone, anyone could explain how to make and use those tubes that are used in the front control arms to set the ride height of the front suspension for measurement. The ROM is vague at best and I’ve not read or seen any illustration of their use. The closest I’ve come to an explanation is that the tubes are negligible. Does anyone actually know how to make and use them?
There are formulas online to figure out the rate/strength of a spring. None of them care about the height of the coiled spring, you should be fine.
I’m with you on the front spring removal = scary thing. I’ve done it a couple of times with homebrew tools, and didn’t relish the job. Worthwhile getting some penetrating oil on the spring pan bolts ahead of time, and checking you can undo each one. Got myself into trouble before, with a half done job and then a snapped bolt.
For sure, there isn’t much point doing a wheel alignment if the bushings and bearings are shot. And I’ve never seen any point with the mid-ladden tools thing (if that’s what you meant about the “tubes”). Partly because they’re not applicable to my XJR-S, and also because I’ve never seen them, even after asking at the Jaguar dealership.
Kirbert
(Author of the Book, former owner of an '83 XJ-S H.E.)
18
Well, not exactly inconsequential. The important thing about such springs is that it must require a very specific amount of force to compress them to a very specific length. That means that a lighter spring must start out longer, so you have to compress it farther to get to that specific length.
I suggested cutting the springs. The springs shown in your photo cannot be cut, because the coils are formed into a flat end at both ends. However, I think you can buy rear shocks that have adjustable spring seats, allowing you to dial the ride height up and down a little. Meanwhile, I believe the front springs can be cut, as at least one end is not formed into a flat but rather sits in a spring pan that’s shaped to hold an unformed end of a spring.
Yeah, its the elusive mid-laden tubes for the front upper control arms that I keep going on about. It’s probably best that I compose myself and just forget about it.
However, I have a set of mid-laden tools for the rear, though. Although I am not entirely sure if Jaguar did away with using them on the facelift XJS?
Yeah, Kirby, my intent about lowering may not have been clear. I’m not pursuing the lowering of the car, if that happens along the way then so be it. I guess my thoughts were misguided into thinking that the shorter springs would naturally lower the car. My overall intention is to try and mimic the sport pack suspension with a little bit of kick to it. I have zero interest in the cutting of springs.
As I understand it, because the car is a convertible and not a coupe, there is only so far that one should go before the ride quality becomes unmanageable. For example, I replaced the radius arm bushings with the OEM metalastik ones as opposed to opting for the poly bushings. I also kept the holes in the bushing pointing front to back instead of turning them 90 degrees. I am continuing to hang the both subframes from new OEM rubber, but will be using poly bushings for the control arms, steering rack, and sway bar. The sport pack springs as you said should be stiffer and the new KONI shocks are (off the car) adjustable (I’ll likely opt for the middle setting).
In making these choices based on how the car is normally driven, and I am betting that this setup will be more suited for long distance highway miles as opposed to stop and go city driving. Over time, I guess we’ll get see how well this all works out.
