Shocks should be at full soft, as this will have the least stiction. Even some very good shocks will show some hysteresis, especially when cold. That's why most people bounce the nose of the car before corner-weighting.

Saddle-type gas-tanks should be near-empty or full, to avoid the slosh-to-one-side issue, assuming that the tank is left/right symmetrical (as is ours).

 

If the gas tank were to create that 1% difference, how would one corner balance a car with it in "race" setting (i.e. 1/4 gas)....I mean this seems like a variable that is so obscure that you won't even think it's a problem.

 

Well, we're talking about a 1% shift, which is moving 15# from one axis to the other. Gas weighs 6# per gallon, so it's possible, even if highly unlikely.

As to whether this is obscure, I agree, which is why I said a while ago that I would not be worrying about a 1% error in cross-weights. Maybe you are a phenomenal driver with exquisite feel, but I can't imagine it making much if any difference. And how many tracks are perfectly equal in terms of lefts and rights? The only one that I can think of is the figure-8 track that we use locally to run demolition derbies with retired school-buses. And what are you going to do about the fact that the CG is higher on the driver's side? That probably has much more of an effect than a 1% difference in cross-weights. You are going to drive yourself (as it were) crazy if you don't let this stuff go.

 

Completely agree, but in theory, it doesn't make sense that the cross weight cannot be repeated. Kind of like you can get -3.3 camber on the left side, but only -3 on the right side.

Not a phenomenal driver by any stretch, but it will always be in the back of my mind.

 

I thought that the different values could be replicated, just that there are two different sets of values depending on from which side you rocked the car. If so, I really believe that this is the shocks or an unlocked steering wheel, even if I have floated a few other, whackier theories.

 

You are correct. Sorry, I was not very clear with my previous post. I hope it's just the unlock steering wheel and not the shocks. I don't want to send them back for another dyno.

 

SUb'd!

 

Dear lord... Don't bring up locking the steering wheel while doing anything alignment related...

You get weight transfer with steering angle though because of the caster. You can easily see this by turning the steering wheel and one side lifts slightly while the other drops. The more caster, the more significant the change.

 

Thanks. Will make sure I lock the steering wheel next time when I go back. For now, the plan is to replace a few things with brand new parts to eliminate the variables.

Wheel bearings
Front control arms

Unfortunately, the Evo has not seen a single autox event this year which is a bummer, but hope the car will be back in 100% for 2015.

 

Maybe I'm way off base here, but what's the resolution of the measurement system? Could you ever get it to display values between 49.1% and 50.2%? For example, by manually adding 5-10 lbs of additional weight to one corner?

The difference we're talking about is tiny. I'm wondering if you ended up on the edge between two steps on the scales' resolution and the minor sticking after each rocking motion was just exaggerated by the quantization.

For example, if the scales only read in 10 lb increments and your measurements were almost exactly between two increments, minor stiction could result in one side reading 10 lb higher and the other side reading 10 lb lower even though the real difference wasn't that large.

 

Also: Next time, don't let your shop bill you for 3-4 hours of work while they chase down a non-issue. 1% difference in cross weights will be immediately lost in the noise when you drive on an actual surface.

 

Well, the "shop" didn't actually charge me because they couldn't figure out the problem. But out of courtesy, since these guys took their Sunday to help me out, I gave them some money anyways.

Again, not an actual shop shop, just a couple of autox guys working in the backyard to help car guys while making some money off the side. We need more of these for sure and not the so-called performance shops.

 

The scales are the Intercomp scales that read to the 0.1% accuracy. So, on a 3,100 lbs car, the most we should see would be 3lbs or so, not 13lbs.

http://www.jegs.com/i/Intercomp/541/...ihAaAoQn8P8HAQ

 

Same ones I have but for cars not karts. Also get this:

http://www.summitracing.com/parts/otc-4546/overview/

 

Perfect thanks. Yeah, they used car scales, not kart....I just put the link for reference.