I'm reading through my 5 binder 93 factory service manuals to discover alignment specs for a fresh front end rebuild. The overhaul section says reuse the factory caster shims as is and don't ask any questions like "what does the factory set the caster to?" The specs section says caster range is 2 - 7 degrees. Well, ain't that a huge range with markedly different handling characteristics at either end. So to any and all of you 93-94 guys, what actual readings have you gotten from your tire shop so we can average them out and see what "factory caster" actually is? And has anybody mic'ed out the shim stack thickness for a known caster reading? Even "3 thicks and 1 thin" will be helpful.

 

Ok, so I'll try to share the records of when I've had my 2 cars done- a 92 and a 94. Specified camber is stated as -1 to +.4 degrees per wheel.
Caster is indeed specified at 2 to 7 degrees each wheel. Toe is -1/32 to +1/16 inch. My 92 was set at .6 degrees camber total, -1.58 degrees caster and 1/16 inch toe. My 94 was set at -.3 degrees camber, 2.5 degrees caster, and total toe of .12 degrees. Unfortunately they were done at different shops so the results page is a bit hard to compare (intentionally on their part). The 92 drives excellent, but since the 94 is on its approximately 4th life and a rebuild title it is never quite right steering wise. They seem like fairly standard numbers and if your car hasn't been seriously bent at any point you should be fine with a normal shop. The rear end has alignment specs but I haven't found a shop that will try to change it. Probably best left alone unless there's a noticeable problem.

 

My shop would not do an alignment because they did not have the tools to put the car in the mid-laden position. It seems that the tools are JD 145 for the rear and JD133 for the front. I am trying to find the tools, or a loaner program, or drawing/instructions/dimensions to make them myself. I have the inside of the left front goes bald, but my plan is to rotate often until I get it aligned.
ProQuest

 

What. That's just silly. I've had the shops tell me they can't do the rear adjustment, but on these cars the rear is Just Not That Critical. As for the front it's a standard rack and pinion set up. There's toe on the tie rods and caster by the washers in the top ball joints. Not that huge a problem! I suggest that they just didn't want to. My humble opinion.

 

ProQuest, setting the "mid-laden" position is nothing more than putting two full size adults in the front seats, or sand bags, or barbell plates, or what have you to get the front and rear crossmember to ground ride heights to the spec, approx 5.3" front, around 6" rear. Then measure everything and adjust. Factory suspension bushings are effectively rubber bands, that should be tightened down initially at spec ride height and then stretch to compress or extend during body roll, bump, and jounce. Then the factory spring rates, shock valving, and sway bar choices work with the rubberband action. When rubber suspension bushings fail or rotate freely as a pivot point like eurethane bushings or johnny joint race bearings are designed to do, spring, valving, and sway bar rates must be changed to reestablish neutral handling. Not something the average Jag driver gets involved with.

 

Finally got two 93 front suspensions torn down this week, one the driver, the other a junkyard donor. The caster shim stacks on both are two .040s and two .070s for a total of .220" Unknown what the caster setting was as the alignment shop copped out on alleged bushing failure and refused to measure. Assuming Jerry's 92 and 94 numbers are typical of the series, I guesstimate the factory was shooting for the bottom end of the scale around 2 degrees. This lightens the steering effort but requires more input to return to center, probably a nod to the ZF rack decreased assist compared to the earlier racks. So my wasted shoulder cuffs and throbbing lower back (these suspensions are like wrenching on a one ton truck, I can't believe how many hours of labor I've got into 2 teardowns...) have decided to double down on the shim stacks to shoot for as much caster as achievable with available parts. I prefer 7 degrees to use the self centering force to snap out of drifts in constant radius turns. Worst case I get a mediocre 4 degrees and live with it, best case I overshoot 7 and drop some shims to hit the number.

In other news, my brain is still hitting the blue screen of death over "Error 404 No camber adjustment found". Which tells me the next suspension build (all eurethane, custom coils, bars, and adjustable valving) may need to land at stock ride height for dual purpose street/windy mountain road monster 2 ton drift machine duty. But that's for another day.

 

Just to add to this great discussion, I recall from the old days on the Jag-Lovers forum that Jaguar's procedure for doing the XJ40 alignment called for tying the front end of the car down with chains to a specified height that would simulate the "mid-laden" position, and of course, none of us do-it-yourselfers had any kind of hook point in our driveway or garage floor to which chains could be attached.

One of the knowledgeable members spent considerable time experimenting with the front-end toe and settled on what I think I recall was a toe-in setting that resulted in 4 inches of slip per mile. This was a reading on the turntable-style gauges he was borrowing to do the job.

Cheers,

Don

 

Search threads; 92 XJ40 wheel alignment tech info. Post #2 has a file attached that talks about the mid-laden tools. JD 145 and JD 133 for the XJ40. Someone also alluded to the Kirby Palm book having instructions to make your own. I am looking for the tools to do both a XJ40 and a XJ6 series 3.

 

Back to caster again. After tearing down 2 complete frontends and reassembling the daily driver's front end, I finally read the manual a lot harder to discover it specifies 4 degrees plus or minus a half degree either way, several times no less. That makes sense. (RTFM, right?) Also explains why 2 different cars both had .220 shim stacks in each of the 4 upper wishbones. 3 of the 4 upper wishbones had all shims pushing the upper balljoint towards negative, big clue there. The daily car, driver side exception had all shims pushing toward positive, totally wasted lower wishbone bushings, tie rod ends way uneven thread count, the steering wheel mounted almost 90 degrees off rack center, and would immediately dive left if hands removed from steering wheel. That speaks for itself. Both Kudos and Curses to the alignment shop that implemented that attempted correction. I'd guessimate the PO barfed on the labor bill for bushing replacement and said no, adjust it as far as possible instead.
Once I get 'er over the pit and torque mid laden on all the new parts and corrections, I'll discover my new modified caster setting, a real nail biter...