the more vertical you go the faster the spring will react, but you dont want to necessarily tune your springs that way as your shock angle make a major difference in the handling. find your approximate angle first and then tune the spring freq.

Got a question, you kinda went over it and I don't feel I understand. What is the diffrence say if on a 2wd shortcourse if you run the same camber link length but move it from middle inside to outside outside or vise versa? Also what would the diffrence be if you run inside outside or outside inside. I run on a high bite very technical track with tight turns and I have the shocks set up but just wondering about camber links, and understanding camber gain and how it affects diffrently and what you want with certain type of tracks.

is anyone still on this thread?

Has camber and toe been covered? If not could some one explain it. My understanding is toe out in the front makes the car have more turn in at the price of stability. Toe in makes the car more stable. I read less camber in the rear of the car gives the rear end more traction while more camber in the front of the car gives the front more traction.

i think Fred started a new job this week so i can imagine he is covered up right now!

i dont notice much of a difference by switching the location of the same size link unless i change the roll center. i do know that if the outermost mounting point is too close to the some point as the lower you get dramatic camber gain under roll conditions and on the rear that make it wash out bad. this is why in the rear normally the upper mounting point is always inward by at least 5mm.

your assumptions with camber are correct.

Yup I've been busy. It wouldn't look good to a new boss if I take the time during the workday to type up something as long as this is going to become! So here goes...

When it comes to camber link location, you need to remember that any change in length or position affects roll centers. Roll center is not a static location in space. It changes with suspension movement. You can change the rate at which roll centers change meaning you could have 2 setups with the same roll center at ride height but entirely different roll centers at either extreme of travel. If you do any reading about roll centers and how to determine your instant center then it shouldn't be hard to figure out where this theoretical point is for any amount of suspension movement.

I personally don't like to think of roll centers as a point in space that the car rotates around because that very concept is quite irrelevant. Nevertheless we use the term roll centers anyways. I think about changes in the link locations in a more relevant way. Some refer to this as camber gain. This is a byproduct of roll centers and ultimately tells you if yours is higher or low. I think of upper link length and location in terms of roll resistance or stiffness as that's what we are using it to control.

Here's an example of something that happened to me this week. My car had pretty nice handling with the links where they worked very well. I ended up changing the rear links over to a captured link setup because I'm tired of ball cups popping off. Due to clearance reasons I ended up moving the rear link locations. However I ended up lowering the rear roll centers quite a bit. This is visually seen as less camber gain with suspension compression. The effect was a car that understeers heavily. The rear end seems soft in corners and the inside front wheel comes off the ground. You are much faster with all your wheels on the ground! In corners it behaves as if the rear shocks need to be stiffened quite a bit. Don't do this! Shocks and springs were done to control bumps and jumps, not cornering ability! By raising the rear roll center I can add rear roll stiffness in corner which will keep the front end down and will increase cornering power. I just need to fix this. If I used the rear shocks to take care of this, now the car would handle horribly everywhere else.

Now it seems logical that raising the instant roll center to gain roll resistance is the obvious choice. It is certainly the easy thing to do. However this is where learning how to read your tires comes in handy. You see, your tires tell you what is going on where it counts, where the tread touches the track. With the higher roll centers I was getting greater wear on the inner half of the face of the tread and far less on the outer half. A roll center that is too low will have the exact opposite result. In a perfect world you would be using all of your available tread. With my new low roll center and hence low roll resistance, a byproduct is that my tire wear is now quite even across the face of the tread. So do I raise the roll center and potentially lose some performance from not using all of my tire or do I keep the roll center low but lose cornering ability from not having enough rear roll rate stiffness? The answer is neither.

This is where another trick comes in. It's called a sway bar. Yes they do have a purpose and no they aren't necessarily always needed. I can clearly tell that my tires like my low roll center setup but rear roll stiffness prefers the higher roll center. By adding a sway bar I can have both. How thick of a sway bar? The simple answer is as thin of one that you can get away with and still get the results that you desire. The thicker the sway bar gets, the more and more the suspension behaves less and less like an independent suspension and more like a solid axle. This is an exaggeration but hopefully the point is made. The front of my car shows fairly even tire wear across the tread with the roll center that I have set there so no changes are made. A sway bar is sometimes needed at only one end, sometimes needed at both ends, or sometimes is not needed at all. If I were going only off of performance I'd be tempted to set the rear roll center high and be done with it. By learning how to read my tires, I can see the solution plain as day. It's obvious.

Now back to those upper links. The question was asked earlier what happens if you have the exact same length links but move them over either inward or outwards. Even if you keep the same length and they are always pointed the same with suspension movement, you are still altering your roll centers. By moving the links outwards but keeping them the same length, you are slightly raising your roll center but you are doing it evenly across the suspension range of motion. It is always going to be higher an even amount across the range of motion.

Sometimes you want to alter the roll centers evenly across the entire range of suspension travel. Other times you may want it low at some places and higher at others. Perhaps you want the stability of a low roll center during a long smooth straight but have very tight corners that require a greater amount of roll stiffness. In this case you'd want to shorten your upper links rather than merely move them over. Only you can tell for sure based on how your car handles and what your tires say.

I guess what I am asking is I run on a high bite clay track that sometimes gets dry and almost blue groove, I run a b4.1 with suburb MC's and everybody runs the rear and front camber links on the inside hole on the shocktower and on the front inside on the caster block and the back it varys from inside to middle. It has a average streight with tight corners and they are all offset so what I am asking is what would happen if I went to the middle hole on the shock tower instead of the inside, would it feel lazier or more planted and therefor letting me push it harder. Also I balanced it and ended up with the front spings brown inside inside and the rear green's inside on the shock tower and outside on the arms. 35wt oil in the front and 30 wt in the rear.

If you are only wanting to try to move the front outwards a little bit with no change to the rear, you are going to raise the front roll center a little bit which will add front roll stiffness. This will give you a bit more understeer. If your shocks and springs are balanced, don't touch them regardless of how it corners. Play with those camber links.

Try a few things. Experiment at the extremes even if you don't intend to keep them there. Run those front links all the way in and see what happens. Then you'll know what effect changes within those extremes will probably have.

if you shorten the front link( no change in RC) it will make that end of the car more aggressive, once the weight transfers to that end of the car you will have more traction at the same end. not neccesarily a good thing but would work better in loose conditions. generally when you have high grip you look for a good overall balance in feel. Like Fred says, try the extreme first so you have a definitive difference in feel.

to add to this if you want to have the ability to push your car harder oversteer is a bad thing. you want a smooth balanced car that transitions well with slight turn in push. 2wd is dependent on setup more so than any other class and are very sensitive to small adjustments. if i were you i would play with front tire choices first and then fine tune. everyone drives different so you cant depend on a standard setup if you want to go faster than the person next to you!

Actually any change in location or length of the upper link will have a change on roll center (man I hate that term!). Let's say at ride height just shortening the upper link still results in it pointing in the exact same direction at the same angle. The roll center at this ride height is the same and hasn't changed so in this regards you are correct. You didn't change the roll center. Here. However as the suspension compresses, the angle of the shorter upper link gets greater and greater at a faster rate than the longer link meaning the shorter link is changing to a higher roll center/faster camber gain/increasing roll stiffness at a greater rate than the longer link so at full suspension compression the end result is a higher roll center than the longer link has at this location.

...

Camber gain is a term that seems to make more sense and is more obvious to behold on the car. Fred, I can understand why you don't like the term roll center. I spent a lot of time in my younger racing days attempting to get the camber gain eliminated from the rear end of my RC10. FOOL! If only I knew then what I know now. At least I was a good driver back then, as opposed to now.

Fred,

I just started reading this thread today and havent read past this post yet. I just had to stop and tell you that I appreciate you taking your time and having the ability to explain lessons that usually are only explained in higher level class rooms for a good bit of money. It is super nice to be educated in Apllied Physics 501?

Here's a quick one that I don't think I read on camber links. We were discussing it at the track today...let's take the rear link of a SCT as an example.
What is the effect if you add 2mm ballstud washers under the ballstud on the shock tower AND 2mm under the ballstud on the hub? I realize that the RC was lowered on the inside and raised on the outside. So it would appear that nothing changes but I'm assuming there is more to it than that

It does the same thing as moving the links inwards slightly. A 2mm change vertically is so small that you probably won't detect a difference but technically you have ever so slightly lowered your roll centers everywhere.