Front end height?

[Kromulous]

All other things being the same, tires, shocks / springs. What all would change if you were to rasie the front end up 1 inch, both sides equally? Not via tire size btw.

CG would swing aft, and add more rear % ?

Front roll center would move? higher?

and decrease / increase in camber?

Thanks, Krom.

[MasterSbilt_Racer]

All other things being the same, tires, shocks / springs. What all would change if you were to rasie the front end up 1 inch, both sides equally? Not via tire size btw.

CG would swing aft, and add more rear % ?

Front roll center would move? higher?

and decrease / increase in camber?

Thanks, Krom.

No change in percents.

higher roll center from both raising points and geometry changes

Loss of camber both static and dynamic on rf (loss of negative)

static camber gain on lf (gain of positive)

[Austin34471]

All other things being the same, tires, shocks / springs. What all would change if you were to rasie the front end up 1 inch, both sides equally? Not via tire size btw.

CG would swing aft, and add more rear % ?

Front roll center would move? higher?

and decrease / increase in camber?

Thanks, Krom.

This is too generic of a question. So many variables here that the answer could be either extreme based on what the variables were. If you are just jacking an inch of ride height to it, it depends on your springs as far as what that will do dynamically. If you are running 50 pound front springs with bumpstops, then the static ride height change wont mean much. If you are running 1000 pound front springs, then the car will dynamically be almost an inch higher than it was before the change. CoG woud then be higher, roll center (whatever that means) would be higher, if your car is set up like most modern day late models, you will have less negative camber on the RF, etc.
rather than asking these questions, it would be more beneficial to research what causes camber change, what causes roll center change, what are roll centers even? How does weight transfer work? What actually effects weight transfer? Etc

[Kromulous]

I'll determine whats beneficial to me, thanks.

Just researching something pavement cars run, versus Dirt late Models.

Roll center(s) is a theoretical pivot point created by the mechanical linkage. Theoretical because some believe in force based roll centers, some don't etc etc.

https://www.youtube.com/watch?v=UQ9ocXniUnI

[Bubstr]

If you believe bar angles in the rear can make or decrease hike, you have to believe roll centers can influence weight transfer, side to side. Juggling roll centers and ballast, is how neutral cars are made or un-made. It's the reason you lift the LF or not. It determines if you wear a tire out prematurely. It determines how much side bite you get on the RR compared to the RF. It makes you wonder sometimes, if we don't rely on shocks too much.

[MasterSbilt_Racer]

If you believe bar angles in the rear can make or decrease hike, you have to believe roll centers can influence weight transfer, side to side. Juggling roll centers and ballast, is how neutral cars are made or un-made. It's the reason you lift the LF or not. It determines if you wear a tire out prematurely. It determines how much side bite you get on the RR compared to the RF. It makes you wonder sometimes, if we don't rely on shocks too much.

We have come a long way, but shocks are still used as crutches.

[Mr.Kennedy777]

I'll determine whats beneficial to me, thanks.Just researching something pavement cars run, versus Dirt late Models. Roll center(s) is a theoretical pivot point created by the mechanical linkage. Theoretical because some believe in force based roll centers, some don't etc etc.https://www.youtube.com/watch?v=UQ9ocXniUnI

I think the most accurate model for front end “moment center” style stuff would be using lines of action. While true total lines of actions are in three dimensions that sum up the forces from what guys would call front view, side view and top view swing arms into one line, they can be broken down into two dimension as well. Each link depending on its angle, length and the pick up points location in three dimensions, will try to feed forces between the chassis and the tire differently. As the suspension links undergo motion these lines of action change. If the chassis is compliant that force will become deflected somewhat in that area of the chassis, creating a bit of a cushioning effect. I think that’s why there is a lot of disagreement with moment center, jacking forces etc, however the lines of action are actual magnitudes and direction of force. It makes the entire picture easier to deal with when let’s say one tire is not touching the ground. Your moment center calculation starts to go out the window because you’re using both tires contact patch to find a intersecting plane of the LF and RF “lateral IC”. At the point of lift and beyond the left front doesn’t have that much of an affect on the RF and the way it works, it’s all the lines of action and how much force is acting in what direction into the chassis/tire that way. Lines of action simplify the modeling that way. With the right information, a guy can actually calculate how much force should feed into the chassis at given points by the links. Combining that information with an understanding of structural design and engineering, would allow a guy to determine how much the chassis will deflect under a certain load. Don’t quote me on it, but I do believe there is some software available that is capable of telling you close force numbers for how much tension or compression your links are going through, based on the forces being fed into them from either the chassis and tire, and I KNOW for a fact there is software available on the market that can tell someone the stress and deflection points of a given structure. I don’t know if it’s readily available to the public or not, or that it’s very cheap, but I do know that it does exist. If you wanted to really get an accurate picture, determining the lines of action into the chassis/into the tire, will set you up to better model what’s really going on in the front end. If a guy was a fabricator that type of information is basically priceless.

[Mr.Kennedy777]

If you believe bar angles in the rear can make or decrease hike, you have to believe roll centers can influence weight transfer, side to side. Juggling roll centers and ballast, is how neutral cars are made or un-made. It's the reason you lift the LF or not. It determines if you wear a tire out prematurely. It determines how much side bite you get on the RR compared to the RF. It makes you wonder sometimes, if we don't rely on shocks too much.

Not true. You don’t even need to know roll center at front or rear. It’s not even important. If you calculate the forces going through the links, you are much better off than having the known location of an imaginary point. Geometric moment center dynamics will leave you with unanswered questions. N lines don’t. If you believe making bar angle changes can increase or decrease height, knowing which link is applying more work in what direction and how much will allow you calculate the behaviour of the suspension. Based on input from mechanical linkage. Combine that with the known values of motion ratios and values of spring and dampening forces, you can paint a pretty clear picture of how the rear end behaves without needing to make a roll axis with front and rear moment centers. The rear especially this applies with the j bar, it’s angle, and the way it behaves. While you could say it creates a rear moment center, if you look at what happens as a function of combined spring and dampening forces with jacking forces, the model is very clear. And there’s not much need to decide the “moment” of rotation based on links because you have a known value of how the links act on the chassis. And then, you wanna know moment center height but who has actually measured vertical center of gravity height accurately? Do you really know how long this lever arm is?? Most guys just guess based on a point they were told but they don’t actually know.

[Austin34471]

Well put Mr. Kennedy. After reading 100s of pages of people much smarter than me debate Roll centers, FAPs, N lines, force based roll centers, etc, I have come to this conclusion on how it applies to our sport: It is important to understand the concept, but like you said, it just doesn't matter much. In short, if the LF is on a chain, or has 30 pounds of weight on it, and the RF is on a solid bumpstop...how can the roll center matter? .................................................. .................................................. ....................

On the programs used to show stress and deflection per amount and direction of force applied, there are plenty of cheap programs capable of performing simple finite element analysis that will show how much deflection and to what extent the part exceeds or doesn't exceed its nominal yield strength under load.. that is the easy part. The difficult part is knowing what numbers and what directions to direct the forces. Hard to do when nobody, Hoosier included, has any useful tire data. Easier to just overbuild and spend your time working on something else that has a bigger impact on lap speed. Over built parts don't hurt when the driver decides to smack the RF into the wall either