Here is some interesting reading, since a local tyre chain are offering a free check, I decided to try out a comparative check.

The Hunter machine is supposed to be idiot proof, they are not.

On the first check the operator chose the wrong car, the second, the wrong regional setting, on the third I stood by the operator and told him what to select.

Three different machines (but the same model) and three different results. I did not let them make any changes to the car between checks. The only consistent reading seemed to be the toe.

 

No matter who made the machine you can measure a car, take it for a spin around the block, re-measure and get different results. No car rides in one spot, it's suspension is constantly flexing and as it does the measurements change. Add in a little play here, some operator error there, the last time a machine was calibrated, the vehicle 'settled in' a tad different on each rack, loose turntables...

Many years ago one of my bosses showed me how many alignments per day I averaged - 21/day. Considering that I worked six days/week for twenty-six years (at that point) the numbers come out that I had completed (not counting the ones I rolled off because of loose parts, etc.) over 136,000 alignments. Sound high? O.K., cut it in half and call it over 68,000. Now figure in I've been doing this for forty three years and I've done a few more than that but not at the same daily rate. I'd say I have a little experience in this department. I've worked with a variety of manufacturers also - Hunter, John Bean, FMC, Snap-On, Bishman, Ammco, et al. And all types/styles of equipment - magnetic, light beams, strings, IR, laser and even tape measure and level. They all will display these anomalies.

 

So what's the definitive answer? Find an experienced alignment tech you can trust, stick with him, and hope for the best?

I had a nearby shop that I have always trusted with my Ram pickup check the alignment of my wife's 2006 XK8 last October just prior to putting two new front tires on it. They gave me the printout showing that the car's alignment was already within specs, so no need to realign at that time. Saved me considerable money as a result. I believe they're honest and value their customers. So was I just lucky based on their alignment check at that particular time with that particular tech?

 

Actually I was trying to convey that the measurements were reasonably consistent given the nature of so many tolerances, etc. Even if an alignment performed is exactly on-spec it's going to change constantly as the suspension flexes. Hell, it's probably going to change just backing off of the alignment rack.

The most critical measurement is the toe. The reason for it not being 0 degrees, inches or millimeters is because as a vehicle is driven forward the tires drag and cause them to toe-out. Toe is set 'in' to allow for that dynamic (front wheel drive, toe on driven rear wheels, etc. have different factors to consider.) So, being as some tires have less rolling resistance, higher caster angles, scrub radii, blah, blah, blah, toe requirements change - but does your tech have the knowledge and experience to know when to accommodate those factors? What will he do when you change to wider tires or possibly install wheels with different offsets? And don't get me started on jacked-up pickup trucks.

I suppose my best advice here is to find someone experienced to know what is involved and willing to do his best for you - just as you would when hiring a plumber, banker or politician. Very little in this world is exactly black and white.

 

It's as I stated in your other thread. The results are consistent and within the bounds of what could be expected in going from machine to machine, or even the same machine twice.

It doesn't really matter what vehicle the first tech selected, because that only affects the "in spec" flags. The angles being measured are the same.

 

Of course it matters, the tech was ready to start making changes to get it in spec for the wrong car.

 

A good indication of improper alignment is tire wear. Unfortunately, it's an expensive way to find out you are out of spec. A test driver very familiar with the characteristics of your car could probably tell you how it is set up by judging the handling of the car. Seems like your best bet is to have the initial setup done by machine by a seasoned, competent tech, who can then fine tune if needed after a road test. Periodic checking of tire wear with a gauge would show any abnormalities and the need for more tuning. Or be like most people and just ignore the whole thing until the tires are shot.

 

I use a simple treadwear gauge on all tires every weekend just after I've checked their pressures. Takes about ten seconds per tire and if you keep up with it regularly, you'll quickly notice any irregular treadwear problems. I'll bet my treadwear gauge is at least 35 years old....

 

Guys, I know this isn't a Jaguar, but this is
the only real place I found with a grown up discussion on wheel alignment...

Had mine done today, and I'm a little concerned that some of the numbers look worse than the 'Before' numbers.. would these numbers be acceptable to you

 

Hi I

Welcome to the Jaguar Forums! It's great to have you with us.

Do you have the factory alignment specifications for comparison? Otherwise, how can you tell if the current settings are worse than the before?

Cheers,

Don

 

Hi Don.

Thanks for replying. It was only after I posted, that I realized how old this thread was!

The 'before ' figures are shown on the top of the attached Pic... That was the numbers before they did anything........

I don't have any other data

 

My point is that without the Mercedes-Benz factory alignment specifications, you really can't tell if your current alignment is closer to, or farther from, specification. You may be able to find the factory specs online. If you can't find them on one of M-B's references, Hunter or one of the other alignment equipment manufacturers may have an online reference.

Cheers,

Don