steering and suspension ET and Camber

[SydneyTii]

Hi folks,

 

Is there a calculation that I can use to work out what the different degrees of camber will allow in terms of ET fitment of a wheel under a standard arch? Cheers.

[2002Scoob]

Pi x the radius of the degree of mounting the wheel to the hub, added to the compression of the strut to the 5th power, minus putting a finger between the tire and the fender and seeing if it fits. Squared, of course.

 

Kidding of course. I wouldn't think there would be a calculator for this.

 

You'll be more exact by staying close to wheel sizes that are known to fit, and then massaging your fenders if you need extra clearance. It's also depends heavily on your tire size.

 

I've got BBS RS001's  15 inch with ET25 and Ireland Engineering camber plates, running 205's. The rears clear with zero issues and no massaging. The fronts clear under all strait-line driving circumstances, and will ever-so-slightly rub when hammering tight corners, or if there's a compression. I did roll and do a fair amount of pulling and massaging to my lips thou. 

Edited June 14, 2016 by 2002Scoob

[SydneyTii]

 love that calc, commonly known as a swag...,,. swinging wild arse guess!

the reason I ask is I have a set of very nice ET15 wheels and looking at them I think with some camber and a judicious tyre choice I may get away with them in the front, but how much camber I need is the question? I love my e30 BBS but I would like to return to 13's. Perhaps my Ovtavo's would be better, just need to check the ET of those? Good problem to have though?

Thanks for the reply...

[steve k.]

a² = b² + c² − 2bc*cosA

 

For you b and c are the same (the radius of the tire). assume that your radius is 11 and you are changing camber by 1 degree you will get 

a² = 11² + 11² − 2*11*11*cos1

a² = 121 + 121 − 242*0.9998

a² = 121 + 121 − 242*0.9998

a² = 0.037

a = 0.19

 

So for every degree of camber that you will add at the top of the strut you will gain 0.19" clearance at the fender for a tire with 22" diameter 

[jrkoupe]

steve.....I'm still not sure if that's a joke..

 

 

....Ill say u r serious tho.

 

 

geez.......leave it up to you.....

[steve k.]

21 minutes ago, jrkoupe said:

steve.....I'm still not sure if that's a joke..

 

 

....Ill say u r serious tho.

 

 

geez.......leave it up to you.....

 

The answer is serious  It is a simple calculation. Geometry is fun

[TobyB]

...serious nut job you are, Steve...

 

 

...I calculated it in radians instead.  Then you don't have to worry about the tire OD.

 

hee

 

t

 

[2002Scoob]

 Look at the brains on Steve! That was impressive. 

[xferboy]

same can be use to calculate camber, if you don't have a guage.

 

measure the distance between two point equally above and below spindle (rim works great), then with a square on the floor (assuming flat surface), measure the distance from those two points to the square.

 

find the difference, divide that by the distance between the two points, divide by .017, and that should be your deg camber (close)

 

tan(1) = .017 ish

 

close enough approximation for the accuracy of the measurements I'm doing.  Now if I could borrow the Faro arm from work, it would be different    I'd let the software figure it out.

 

or do the measuring, and use free CAD software to calculate

Edited June 15, 2016 by xferboy

[bento]

If you're lazy, this calculator does the trig for you. Just enter the known values and it'll fill in the rest.

http://www.carbidedepot.com/formulas-trigright.asp

I used it both to estimate camber change needed to clear the fender, and to estimate camber as xferboy described.

 

Doesn't help with camber, but this tool is great for comparing various offsets so you have an idea of how much fender clearance you're losing.

http://www.willtheyfit.com