Wheel Alignment

[greardon]

Hey all,

Was wondering if any of you have ran into this and have a proper explanation on it. I called my tire place today to get summer tires back on and get alignment done since it was a new car in October and the wear and tear of winter roads to get the most out my tires.

So its a tire place, that is all they do for Michelin and always treat me well, so he asked my car and tell him its now a speed 3 2010 and says for that car please come in with a full tank of gas for the alignment. I was like ok and never really triggered till after why a full tank a gas?

some friends and myself are all like WTF is that all about, I have looked on line but can't seem to find a proper definition as to why that would be required as we all think it is BS

Please reply to thread if you have some insight as to this or if you have run into it before specifically

cheers,

Glenn

[seelsy]

the reason they ask for a full tank is because factory specs are based on "unladen" measurements, meaning ur fluids are full, therefore to make sure the car is within spec, they need the same weight displacement putting force on the suspension and tires. If ur tank isn't full they need to place weights around the car to distribute the weight of the missing gas. It just makes it easier for the shop to do a proper alignment

[little_wheelz]

My guess would be that the proper procedure would be to perform the alignment with the car weighted down (i.e. full tank of gas). The weight of the gas would affect the rear camber settings, maybe other settings as well. I seem to recall you are actually suppose to do it with a full tank + 300lbs to simulate a driver/passenger. That is my guess ... I'm pretty sure they don't want to go for a 'joy ride' ... lol

[greardon]

cool thanks seelsy i'll also question them on friday just to see what they say and may ensure someone is sat in the drivers seat, maybe even me

[seelsy]

ya they are supposed to put weight on ur seat to adjust for a driver. so u sittin there would work haha

[greardon]

ya for sure, just never heard of it before, my buddy who is a diy mechanic and is very knowledgeable is still calling shenanigans on it, and yeah I understood the fact it wasn't for a "joy ride", seen some guys say to sit in it yourself if ur real anal, either way i'll post up the results on Friday after its done just so you all have the info

[seelsy]

cool, keep us posted

[greardon]

so they claim that in the small hatches you need the weight of a full tank since all the specs are based on full fluids , also said that empty the tires point out a little, full tank are straight , with 2 people in the back they lean in a little.

either way i left them to it, not a area i'm knowledgeable about, it seems fine , if i find something i don't like I'll go back

[notthesnail]

FYI: My car, at maximum negative camber, both sides are pretty close to equal with me in the drivers seat. When I'm out, the settings aren't very equal at all.

If the car was aligned to equalize maximum negative camber without a passenger, they would have had to dial in less, which would then be unequal when I get in. Not good for autocross. Might be okay for Nascar, though.

[Cosmo77]

most of us will set our adjustments and then hang off the car from under the car to see the geometry change to get an idea of what things will be like with a driver in the seat....or maybe thats just me

[-|CHECKMATE2012|-]

What type of tires your using also affects the alignment as well, as I've been told.

[notthesnail]

Tires are engineered for a purpose. If that purpose is racing, then they're likely engineered to work best within a certain range of camber. Manufacturer's will have those recommended specs available for you.

Street tires are usually designed to work within typical street car range of adjustment.