Alignment help
 

Replacing the upper shock mounts on my 03 XK8 and figured while I have the upper wishbone loose I "might" adjust the shims to get my Caster more in range. Here are the spec's from my last alignment:

Camber: (Spec: Left -1.2 to -0.2, Right -1.3 to -0.3) actual: Left -0.6, Right -0.9

Caster: (Spec: Left 5.9 to 7.3, Right 6.6 to 8.0) actual: Left 5.7, Right 6.2

So, is it worth worrying about adjusting the Caster and if so which shims need to be moved? Currently I have on both sides one thick in front and one thick and two thin shims on the rear of the wish bone bushings.

All Ball joints, tie rod ends, upper and lower bushing were replaced around 15K miles ago and are in good shape however the upper shock mounts after 15K have deteriorated so am replacing with poly mounts.

Any and all advise is welcome and appreciated!

Every one of these cars is different now due to age and wear characteristics of the various components involved. If you choose to move those shims around, you will be guessing. I think the best action to take is to replace your front upper shock mounts with the Welsh Enterprises kit, then get your toe adjusted by a trusted alignment shop. You will find that with new front upper shock mounts and a toe spec in the proper range, your handling and treadwear will become much more normalized. Good luck and let us know what you decide to do....

Jandreu, if you're interested, there is a great post by Rothwell on September 29th 2018 that shows factory spec position and shim size.

John

Agree with Jon on the Welsh Poly Mts.. I have a 2003 XK8 Cpe. with 143K+ miles. The mounts helped immediately after replacement, but after 2 years and 25K miles the ride heights dropped down some. Decided the Front Springs needed replacement. 16 years with weight had collapsed them and allowed the camber to be out of spec. OEM Cpe. front springs are NLA. Purchased Suplex brand thru Victoria Auto Parts (on E-Bay) in UK. S&H + Parts were $250. Arrived in 4-5 days ,I was Shocked!. Just measured after 30 days, both sides at 15 5/8" ride height. Some US suppliers stock Suplex with good & bad info available, but I am HAPPY. My front tires were wearing on inside tread (as in toe out) prior to replacement. Hope they do better now. No extra labor involved since you have to R&R the springs for upper mounts.

One of these is a good investment to keep an eye on your toe in/out, I bought one after I burned through a set of front tyres in 4 k miles a few years ago due to a failing bush I didn't spot.

https://www.ebay.co.uk/itm/Trackace-...frcectupt=true

Tks all, I'll just leave the shims as is for now. Get the Welsh poly top mounts on and a new alignment. Will report back in a couple weeks.

TrackAce
 

i second the recommendation for the TrackAce. It’s fiddly at first, but accurate. Just be patient.

Ltd

Ok, on the toe adjustment, I saw a reference to "setting the toe in the red" in another thread.

does this mean to request it to be set "out of spec" and if so how much. There was a reference to this compensating for road force.

this is car specific!!! Not model, year or brand. I check deflection like mercedes wants alignment done by pushing out on inside of front tires to simulate road forces when driving on the suspension. Your car will not be like other because it takes into consideration the amount of deflection tolerances in "your" car. As a rule of thumb over the years i have found that setting toe to the inner most toe in tolerance will put you in the middle while driving. If put in the middle on the alignment then youll end up with too much toe out while driving and inner tire wear.
By checking toe deflection 2 things are acomplished.
1, you get the best toe setting for "your car" while driving
2, lets you see too much deflection and or uneven deflection from side to side which many times is not evident when checking and looking at the suspension. I can then do 2 things if uneven. Find what pieces or pieces need to be replaced for stacked tolerances. Or if not too bad just dial in a little more toe in on the side to keep a straight steering wheel. Im looking for even toe settings in the middle when i push out on the inside of the front tires in this case. Not a even, in the middle at rest position.
Only if you have so much deflection that setting into the red is the only solution for middle tolerance toe setting to be achieved should you ever set into the red. Yes I have done it, not often

Tks Brutal. I'll have the alinement tech read this.

FYI, merc recommend a 100N spreader bar for my 450SL to simulate driving condition forces with 0 deg 15mins of toe in, but I'm yet to find an alignment shop that has a spreader bar.

i use my hands, doesnt take much force imo to take out tolerances. Better than nothing at all. I used to wonder why mercedes wanted that. And the when i did it i realized why and that it really should be part of any alignment on any car when setting front toe

Well as promised here an update.

replaced upper shock mounts both side with the Welsh poly units, ride height is dead on at 15 .5 both sides. Took the Jag to a local alinement shop and had a good discussion with the tech before and after alinement. He checked everything and all's good, no slop in any components. The toe was way off, car drives better now and time will tell if tires wear good.

i'm still very disappointed with the steering feel, the car still wants to wander a bit. Alinement tech feels the issue is with the steering column joints being worn out as the steering feels a little better when the tilt is either all the way down or up against the stops.

Honestly this wandering steering is bothering me enough to sell the Jag and get an early 30's hot rod instead. I hate to say this as I love the Jag and really like having a car very few other people have but I don't enjoy driving it with the steering "feel".

i have a buddy with an 06 Vette and an 07 Viper, I had him drive it and he says it feels about the same as his cars, that wide tires combined with the poor roads are the issue.

Depending on the feel it is either inherent of the car or you have some pieces that while may not have play and enough wear to feel vague. The cars even when new tended to have a bit too much bump steer and wander when new

Are your tires Hunter Road Force Balanced? If not, have it done at your nearest Discount Tire store. You may be surprised by the significant tracking improvement you will gain....

Jandreu,
When you got your alignment did you need the camber kit and shims or did they do it without?
I am a new Jag owner (01xk8) and we just had the front suspension work done and all new tires and Bell tire said I need the kit and shims but they don't do it there and I called an alignmentshop and they said you don't need them so I'm not sure what to do.

Thanks
Phil

Update on my alignment issue.

Turned out to be a bad tire. Replaced all 4 and had another alignment done and all is good. It drives like new again.

Flipper, I'm no expert but did not have to have a "shim kit". The only shims on the front suspension are on the upper control arm fulcrum bolt.Send a PM to Brutal he knows more about this than most.

Yes, bad front tires can ruin the handling. I had been chasing a shimmy and a wobble, replacing everything I could with new or poly and alignments. Things didn’t get any better. When I noticed it was worse in the rain, I took a look at my tires. Bald and starting to dry rot. New, proper tires made a huge difference.

FYI toe is easy to measure and adjust yourself.

Bushing wear has been a bigger factor re: alignment on my car.