alignment math, all you numbers guys check my math!! Options

[jaybird840]

OK,

I'm working on a home alignment on my teener, and am trying to calculate my camber adjustments. I can't use the bird board measurements because I'm running 18" wheels. So, in order to get an adjustment measurement, I calculated the circumference of my wheels--outer lip to outer lip (this is where I take my measurements). C=diameter x pi--right? So if my wheels measure 19.5", then the circumference = 19.5 x 3.14159 which gives a circumference of 61.26". If you divide the circumference by 360, then 1 degree = .17". In order to run 30" of negative camber, I divide by three again to give me .05" or 1.43mm. Now, in order to achieve that number, I must multipy by two to get the actual measurement from the bottom of the rim to the top of the rim, right? Long story short, my measurement needs to be 2.86 (call it 3mm) greater at the top of the rim than the bottom of the rim, right? I'm a cop, not a math genius, so you engineers feel free to chime in.... thanks tons!!!!!

While on the subject of alignments.... What should the toe in measurements be in degrees? Am I right that a 32nd on 15's is different than a 32nd on 18's?

--jaybird

[jaybird840]

I agree on -3 being excessive... that was what Jim D. used for his calculations. I'm actually shooting for 30 min of negative camber (one third of a degree). It's a street application... If I weren't a CSOB, I'd buy the pegasus goodies... 8^)

--jaybird

[jd74914]

I agree on -3 being excessive... that was what Jim D. used for his calculations. I'm actually shooting for 30 min of negative camber (one third of a degree). It's a street application... If I weren't a CSOB, I'd buy the pegasus goodies... 8^)

--jaybird

Oops, my mistake. I thought that seemed excessive (IMG:style_emoticons/default/laugh.gif)

For 1/3 degree the number is .057 (instead of .51) which is about 1/16 of an inch. So the horizontal difference from bottom to top would come out to about an 1/8 on an inch. (IMG:style_emoticons/default/smile.gif)

[jaybird840]

I agree on -3 being excessive... that was what Jim D. used for his calculations. I'm actually shooting for 30 min of negative camber (one third of a degree). It's a street application... If I weren't a CSOB, I'd buy the pegasus goodies... 8^)

--jaybird

Oops, my mistake. I thought that seemed excessive (IMG:style_emoticons/default/laugh.gif)

For 1/3 degree the number is .057 (instead of .51) which is about 1/16 of an inch. So the horizontal difference from bottom to top would come out to about an 1/8 on an inch. (IMG:style_emoticons/default/smile.gif)

Cool,
Looks like my math was right, I just went through a couple of extra steps. It's only been 21 years since my last college trig or geometry class... (IMG:style_emoticons/default/cheer.gif)
Thanks!!!!!
--jaybird