Norm Peterson

That would be a rather wild arrangement. Might have to be some sort of active suspension.

Quote:

Could you elaborate on this ? I assume you are talking about actual camber measurement during body roll. and when you say "not evenly divided about the straight ahead position." are you talking about during body roll or sitting still in the garage?

I'm talking about how the camber measurements compare when you steer the wheels (as you do to compute caster). If you have 6.0° caster with 0.0° camber with the wheels pointed straight ahead, you will not get +3.0° camber on one wheel and -3.0° camber on the other when you steer the wheels 30° to the right.

The reason for this asymmetry is the "Steering Axis Inclination", or Kingpin Inclination as it may be alternatively known. The reason you steer to equal angles right and left is to cancel out the effects of SAI.

Quote:

Can we take both of these measuring methods and come up with a Graph function or formula to give us an estimate of- (wheel turn degrees = % of camber change )

[Factor] = 1 ÷ (2 x sin(AngleSteered))

The Hunter paper gives a formula that's essentially the same thing but avoids the trig function by using 180/pi.


Close approximations here are good enough for most anything you're likely to get involved with in a Mustang. Theory that's an order of magnitude or two more precise than what the measurement method can determine or is a similar level smaller than the minimum adjustment resolution - or which corresponds to negligible differences in tire capabilities for that matter - is really useful only on an academic level. Or if you were to design and build your own alignment measuring equipment.


Norm

clintster77

OK Norm I think I get what your saying about not getting +3 degrees camber on one side and -3 degrees camber on the other side with a 30 degree wheel turn because of (SAI). SAI is pure in the sense that it is the opposite of caster . The bad effect(or side effect) of SAI is that it always produces positive camber on both wheels no matter which way you turn them. How much is directly effected by how much caster you have.
If you have a car with +6 degrees caster and turned the wheels 30 degrees , the difference in camber of the right and left wheels would be 6 degrees. something to the tune of what you said. -1.5 on one wheel and +4.5 on the other wheel. Whatever the number ,it would add up to 6 degrees difference in camber.
If a car was set up with 0 camber and 0 caster when you turned the wheel the SAI would cause nothing but positive camber on both wheels. Luckily steering geometry has given us front ends that actually add negative camber as g forces are added into the mix.

Cool. feels like I'm getting a handle on this caster thing.(get it ."handle"

I need another book on this kind of stuff. The only book I have is
Chassis Engineering -By Herb Adams
There are some holes in this book and now a few of them have been filled . Any suggestions on a good book for some one who wants to know everything about this kind of stuff. Technical ,but with good explanations of the formulas and such.
Throw me another monkey wrench so I can learn something else.

Norm Peterson

Here's a list of what I had as of a few years ago. Latest version of the list isn't on this computer, so I tracked this much down on another forum. Some are probably out of print.

Chassis Engineering (Herb Adams)
Performance Handling (Don Alexander)
Chevrolet Power, 5th Edition (GM)
Basic Chassis, Suspension & Brakes (Hot Rod)
Chassis Brakes Suspension (Hot Rod)
Hot Rod Yearbook No. 11 (Hot Rod)
Mustang Performance Handbook 2 (William Mathis)
Race Car Vehicle Design (William & Doug Milliken)
Mopar Chassis (Mopar)
The Car and its Wheels (Jan P. Norbye)
Honda Builder's Handbook, Volume II (Joe Pettit)
How to Make Your Car Handle (Fred Puhn)
Camaro Performance Handbook (David Shelby)
Prepare to Win (Carroll Smith)
Tune to Win (Carroll Smith)
Race Car Engineering & Mechanics (Paul van Valkenburgh)


Norm

clintster77

I like new up to date books but the older books have ideas and tricks probably not in any of the new books . Maybe I can find an out of print book on the net if I keep looking long enough . I forgot I also have Honda and Acura Builders Handbook. Even though it mostly pertains to Front wheel drives a lot of the information can be used on a RWD. Especially If you have a RWD that has a tendency to under steer .

Out of your list Norm. What is the one or two books you would recommend as the best chassis tuning books you have?

Norm Peterson

Best introductory book is Fred Puhn's, hands down IMO. Enough math to actually be useful, without being so much as to overwhelm somebody who's new to the whole topic.

At the other end is RCVD - my understanding is that it's used as a college-level textbook.


van Valkenburgh has some stuff I don't think I've seen elsewhere.

Mathis is pretty good too, especially if you've got a Fox-body. But there are a couple of errors in it (IIRC, one of them has to do with SVIC and anti-squat).

The more complete list is on my computer at work . . . and there's two or three more that I want to add to the collection.


Norm