Can Someone Explain Corner Balance?
 

I've read many threads about corner balancing the car and I've also seen many threads about "stance" and lowering the front, etc.

I'm wondering: how is a corner balance done and how does this affect ride height? Also, will any alignment shop understand how to do a corner balance? Are there any specific specs for a 911?

Thanks for any input.

When you sit in your car, clearly there is more weight on the driver's side, than on the passenger's. This alters the car's overall center of gravity. Thus, there will be effects on the car's handling in left-handed turns vs right-handed turns. Ideally (assuming your car will be turning both right and left), there is even distribution of weight so that the car will behave similarly in left-hand and right-hand turns. Corner balancing is changing suspension settings and/or the location of items in a car to try to achieve that equal distribution of mass.

Ohh Ohh, very clearly in my case.

Thanks for the explanation, that helps.

Corner balancing does not move mass or change the distribution of mass.

The idea behind corner balancing is too adjust the load on all four tires to maximize grip and increase handling performance.

There are different schools of thought on what is best. You can corner balance to optimize cornering, to optimize braking, or a compromise that tries to do both.

Scott

Compensating for the driver's weight is only a fraction of the equation. The way to think of corner balancing is to imagine a 4-legged chair that has different length legs. The chair teeters back and forth on two of the legs that take most of the chair's weight. Corner balancing a car is like adjusting the chair's legs so that it's stable, with all 4 legs sharing the weight equally. In the car's case, the weights at the corners should be the same right vs. left, and in the 911's case, approximately 60% carried by the rear and 40% by the front. The weights at each corner are adjusted by changing the ride heights. It's a somewhat complicated affair, as adjusting the height at one corner affects the weight of the corner being adjusted as well as the opposite corner, and to some extent the weight at the other two corners as well. Corner balancing is supposed to be done with the driver's weight in the driver's seat (using sand bags or whatever), and normally with about a half tank of fuel. The goal is to end up with a car that is balanced squarely and will exhibit the same handling characteristics when cornering right or left.

Very nice analogy Porschenut!

I will add that 'no' not every alignment shop will know what this is or have the scales to do it.
The car really needs alignment and corner balancing done in tandem.
You want to find the right shop in your area. This takes extra time and the regular bit of "get it in the acceptable range" that most alignment places use isn't acceptable in this case.

The way ride height and "stance" are affected are also a common confusion point.

When many lower their 911 they are after the look. To lower and corner balance your car means that from a visual standpoint the car might not "look" exactly right.

In the case of my SC, the ride heights are up to 1/4" to 5/8" different as measured at wheel center to fender edge. This will bother some, but the car is balanced.

My $ .02
Cooper

Great Info from all.

I'm lucky to work at a factory that has giant scales for weighing bins of almonds. I'm thinking that I might just set up an area with 4 scales and do a quick check of where I'm at. However, I'm going to look for a shop that actually does this. Luckily, I have adjustable spring plates in the rear so adjusting the height is easy. Right now, left and right sides are identical (as measured at the torsion tubes) but as far as weight....I have no idea. It probably doesn't help that I weigh 200 lbs. Dammm, I promised to lose 6 lbs when I put in power windows and I think I gained instead.

Find a race shop that does 911's. They will have the tools and "secret sauce" to get you car set up right.

I am fortunate that Rothsport Road and Race is near me and they do a superb job of chassis setup.

Vern,
You are just a fast road trip away from some of the best 911 suspension guys(Jerry Woods and Chuck Moreland) on the left, if any coast. I would offer my Intercomp Digitals, but the area is a mine field of deer and tweakers. But I digress. After I corner balanced both my cars, the handling was much more balanced and precise, whereas prior brake applications were almost squirrely, and afterwards heavy braking can be done hands off!
Enjoy the CIS stuff!

Is corner balancing really necessary for non-tracked cars?

It needs to be close at least. If not, you can end up locking up brakes. Mine used to lock the left front, even when it was the outside tire on a downhill right turn.

Only if the right conditions occur:

From the FSM

http://forums.pelicanparts.com/uploa...1389937070.jpg


http://forums.pelicanparts.com/uploa...1389937105.jpg

Another condition, if the car is handling unusual, it might need to be corner balanced. A well balanced car is actually very pleasant to drive fast.

Corner balancing is relevant for non tracked cars. And +1 for Chuck Moreland's outfit for suspension tweaking.

My car used to do exactly that only it was the right front and it was at the end of a straight like entering T1 at Summit Main or at the bottom of the hill just after bridge straight on Lightning at NJMP. I destroyed so many tires when my car had this problem. At first I thought it was me being too aggressive on the brakes, so then I started backing off the brake and would carry too much speed into the turn. That problem used to make my car go all over the place. I'm surprised the track steward never yanked me. I found the problem on a whim when I mentioned the problem to one of the mechanics at work. The before measurements were reading at something like 330# on the r/f and like 1125# on the l/r and the l/f was somewhere in the 600# range and the rear was just a little over 800#. This is when I learned about balancing, only the old timer taught me to imagine the center of my car on a pole and the idea is to try and make the car balance on the end of the pole. Everyone here is correct, not every alignment shop can do this, in fact, most are not even interested in correct set up. To many techs, an alignment is setting the toe and letting it go as long as it shows green on their computer screen. You will be amazed at the results after your car has been balanced but what will be more eye opening is the before measurement.

I borrowed a set of scales and did my own. I got pretty lucky when I bolted my car back together and was close, but a little fine tuning never hurts.

Before and after shots below. Photos are of without me in the car, but the cross percentages didn't change significantly with me in there.

http://4.bp.blogspot.com/-n0haRHgC9t...403_173914.jpg
http://4.bp.blogspot.com/-ciEehzjAla...403_182802.jpg

For a street car, you would have to be pretty far off to notice a difference. For a track or competition car, it's worthwhile to do because it gives you more consistent behavior in turns.

Just to be clear, my car was locking the brakes in the canyons, and I was not going more than about 7/10ths as I had a passenger onboard. I don't know what the before measurements were, but the big suspension refresh fixed things and I had an alignment and corner balance thrown in there.

a good alignment is necessary before doing weight balance(camber and toe can have a significant effect and caster less so) but you will also need to check your alignment after the balance just to confirm the settings and so that you dont significantly lose your way doing the balance. You can never get street car or race car built from a street car perfectly balanced since you are fighting physics and design elements. Allowances have to be made even when you are dealing with an almost perfect chassis such as a Miata much less a 911.
You will never get the corners to be equal but you do want the diagonals to be as close as possible. Take your time and dont make big adjustments or you again may lose your way. It helps to have notes from similar cars. When we built the first Spec Miata, we put the donor car on the scales and then just tried to duplicate the same numbers when the car was done. We still made minor adjustments but the car drove very well from the very first day.