Ideal Geometry

[pro-tour79]

your questions can't realy be answered because those values are different for different vehicles, there is no "one best" and most importantly is the driver's confidance in the seat is what makes a car handle well.

[ccracin]

Originally Posted by pro-tour79

your questions can't realy be answered because those values are different for different vehicles, there is no "one best" and most importantly is the driver's confidance in the seat is what makes a car handle well.

Good suspension geometry is not different for different vehicles per say. My question was for what folks would call ideal without the confines of a particular body style. This comes down to physics and dynamics. The way a suspension system works has nothing to do with what sheet metal is wrapped around it. (Except for how that sheet metal affects weight and balance) So to clear this up a bit more. Lets just say we are all able to build a tube chassis ACME Hot Rod (Think Old Road Runner Cartoons Here!) What would the ideal front geometry be for the 3 areas I listed in the first post? Oh and to some degree I agree with driver skill and confidence, but a confident driver does not make say...........an old Willys Jeep handle "WELL" at Road Atlanta or on an autocross course. But I get your point.

[ccracin]

Maybe I should get this started. These are all guesses on my part to get this going. I am by no means an expert, obviously based on me asking the question. At least these numbers may garner a B... Sh.. or Yeah that will work. Lets see if we can keep this going.

Street
Roll Center location Static +4"
Roll Center Migration In Roll <1" / Degree of Roll
Roll Center Height in Dive and Lift <= The Amount of Dive or Lift
Roll Center to Center of Gravity relationship Short as Possible ** This one is somewhat dependent on the vehicle.
Caster +4 Deg.
Camber -1 Deg
Camber gain per inch of travel 1/2 Deg More Neg. / Inch of Travel
Caster gain per inch of travel 1/4 Deg More Pos. / Inch of Travel
Toe 1/16" In
Ackerman for a given steering input 2 Deg. Per 20 Deg. Of Steering
Bump steer ( amount of toe in or out per unit travel) .015 / Inch Of Travel
King Pin angle 8 Deg.
Scrub radius 1" - 3"
Anti-dive 3 Deg.
Ideal amount of body roll to design for at max lateral-g 3 Deg.

Track
Roll Center location Static +3"
Roll Center Migration In Roll <.75" / Degree of Roll
Roll Center Height in Dive and Lift <= The Amount of Dive or Lift
Roll Center to Center of Gravity relationship Short as Possible ** This one is somewhat dependent on the vehicle.
Caster +5 Deg.
Camber -2.5 Deg
Camber gain per inch of travel 3/4 Deg More Neg. / Inch of Travel
Caster gain per inch of travel 1/4 Deg More Pos. / Inch of Travel
Toe 1/16" In
Ackerman for a given steering input 1 Deg. Per 20 Deg. Of Steering
Bump steer ( amount of toe in or out per unit travel) .015 / Inch Of Travel
King Pin angle 8 Deg.
Scrub radius 0"-1"
Anti-dive 4.5 Deg.
Ideal amount of body roll to design for at max lateral-g 2 Deg.

Auto - X
Roll Center location Static +3"
Roll Center Migration In Roll <.75" / Degree of Roll
Roll Center Height in Dive and Lift <= The Amount of Dive or Lift
Roll Center to Center of Gravity relationship Short as Possible ** This one is somewhat dependent on the vehicle.
Caster +2 Deg.
Camber -3 Deg
Camber gain per inch of travel 1/2 Deg More Neg. / Inch of Travel
Caster gain per inch of travel 1/4 Deg More Pos. / Inch of Travel
Toe 1/16" In
Ackerman for a given steering input 2 Deg. Per 20 Deg. Of Steering
Bump steer ( amount of toe in or out per unit travel) .015 / Inch Of Travel
King Pin angle 8 Deg.
Scrub radius 0"-1"
Anti-dive 4.5 Deg.
Ideal amount of body roll to design for at max lateral-g <2 Deg.

[chevyIIpost]

I would venture to say that anyone on this site understands that there is not going to be One correct answer to each item listed. But there has to be a narrow range of good and a much wider range of bad to the list of items mentioned that started this thread.

Roll center location and migration specs. in dive and roll
Roll center to center of gravity relationship
Caster
Camber
Camber gain per inch of travel
Caster gain per inch of travel
Ackerman for a given steering input
Bump steer ( amount of toe in or out per unit travel)
King Pin angle
Scrub radius
Anti-dive
Ideal amount of body roll to design for at max lateral-g

And even if that range is wide than the discusson and opinions that will follow will be interesting and may educate and enlighten. This is a black magic area to most beginners and as you learn more about suspension design and function you will realise that it is less black magic but requires a whole lot of knowlege and understanding of a very dynamic system. So I hope some of you more educated suspension guys will lift the magic spell and throw out your opinions and points of veiw for the rest of us to learn form.

That Acme Road Atlanta Car could go from having a 1969 camaro front clip and be upgraded to a C6 set up and we discuss what changed and/or improved as a result.

[ccracin]

Thanks for helping with this Ted. You are definitely catching what I am pitching. This thread is meant to educate us all as the discussion builds. Hopefully we will get some takers.

[Silver69Camaro]

I'll bite. I actually have no problem sharing our data, because somebody can't really just take the numbers and copy it. If you could, you wouldn't need us because you clearly have the knowledge and know-how to be doing it yourself. Trying to copy the whole package is very difficult. Anyway, I've shared this information before on and off topic.

Anyway, per your listings:
Roll Center location Static: +1.9"
Roll Center Migration In Roll: 0.258" / Degree of Roll
Roll Center Height in Dive and Lift: 1 to 1 ratio
Caster: +6 Deg.
Camber: -0.5 Deg (Street alignment, but adjustable to stupid amounts)
Camber gain per inch of travel: 0.6+ Deg Neg. / Inch of Travel
Caster gain per inch of travel: 0.5+ Deg Pos. / Inch of Travel
Toe: Up to end user
Ackerman for a given steering input: 1 Deg. Per 20 Deg. Of Steering
Bump steer: .014 / Inch Of Travel
King Pin angle: 9.2 Deg.
Anti-dive: 6.5 Deg.
Ideal amount of body roll to design for at max lateral-g: Rougly 2 to 3. I wont give the exact answer here.

We also have exact models of C6 suspension parts that allow us to accurately locate pivot points and ball joints. No dial calipers and measuring tapes here.

Like everyone has said before, this is a system that we believe works best for these vehicles. We have lots of time under our belt to give us priceless experience and know-how.

[ccracin]

Matt,

Thanks very much for jumping in. You are one of the "Heavy Hitters" I was hoping would jump in. Just to be clear again, I am not trying to garner anyone's secrets to copy their product. That's I why I say "ideal", knowing that compromises have to be made sometimes for packaging. If you didn't have to package it in an F, A, G ..........body, would you be looking for something else to make it better? I give you great respect for publishing "actual" numbers for your products. In fact I already had great respect for your products, enough that I used your stuff on our project and did not try to re-invent the wheel. Anyway, back on task. If the numbers you posted are for your street set-up, what tweeks would you recommend for high speed track days and lower speed auto-x stuff? Thanks again Matt, you and the rest of the Morrison team are top notch.

later,

[Silver69Camaro]

Thanks for the kind words.

The only things I would change are simple alignment basics; camber and toe. I generally try not to increase caster (doesn't really need much more anyway), because it raises the outer tie rod pivot location and can increase bumpsteer. Not much, but it's there.

For camber, obviously that depends on your tires. The camber gain is fairly aggressive in this suspension, so 0.75 to 1.5 degrees is all you need (static) unless if the tires spec more. Toe is fun to play with, and I like to have slight toe out, as little as possible. Works very well.

We also carry a line of stuff to "fine tune" our suspension. Solid rack mount bushings, adjustable flow steering pumps, custom rack torsion bars, etc.