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Corner balancing strategies

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Old 07-18-2018, 01:34 AM
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NSFW
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Default Corner balancing strategies

There are (at least...) two common strategies for corner balancing:

1) Try to get the left-front + right-rear weight to match the right-front + left-rear weight.

2) Try to get the left-front weight to match the right-front weight.

If you optimize for one, the other will probably suffer, unless you have ballast to offset the driver's weight. (Or you put the driver's seat in the center of the car, but that seems kind of hard with a Corvette.)

What are the strengths and weaknesses of each approach?

If you have tried both, which do you prefer?

If you haven't tried both, why not?
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Old 07-18-2018, 09:24 AM
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Gordy M
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I only use the cross weights to corner balance. That is what Danny Kellermeyer taught us and what he measures every time he races. My car is usually 49.9-50.1 on the scales. Also always weigh the car with the amount of gas you usually run with and yourself or equivalent weight in the drivers seat.
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Old 07-18-2018, 09:48 AM
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96CollectorSport
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You want to set your ride heights first - then adjust as little as possible to achieve the desired cross weight - typically 50/50

Without really jacking up or down one or two corners you're more than likely not going to be able to hit the numbers you want without physically moving weight around the car.

For each set-up you are where you are - without actually moving weight, remember that your cross weights move as you burn fuel so don't get too excited if they aren't just where you want them - they are not going to stay "perfect" for long. I've always tried to set my corner weights around 1/2 tank (some people suggest either both tanks full or both tanks empty but how often do you run full or empty?) The way I figure it if you put it at 1/2 tank the car will go from a heavy RR to "perfect" to a light LR.

Honestly there is no "right" or "wrong" way to do it, try stuff out and see what feels best for you - at least the chassis will be balanced and that's the important thing.
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Old 07-18-2018, 01:00 PM
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Originally Posted by NSFW View Post

2) Try to get the left-front weight to match the right-front weight.
Do yourself a favor and forget that you ever read that somewhere.
Follow 100% what 96CollectorSport said.

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Old 07-19-2018, 10:24 PM
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Adrian @ F.A.S.T.
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Originally Posted by 96CollectorSport View Post
You want to set your ride heights first - then adjust as little as possible to achieve the desired cross weight - typically 50/50

Without really jacking up or down one or two corners you're more than likely not going to be able to hit the numbers you want without physically moving weight around the car.

For each set-up you are where you are - without actually moving weight, remember that your cross weights move as you burn fuel so don't get too excited if they aren't just where you want them - they are not going to stay "perfect" for long. I've always tried to set my corner weights around 1/2 tank (some people suggest either both tanks full or both tanks empty but how often do you run full or empty?) The way I figure it if you put it at 1/2 tank the car will go from a heavy RR to "perfect" to a light LR.

Honestly there is no "right" or "wrong" way to do it, try stuff out and see what feels best for you - at least the chassis will be balanced and that's the important thing.
Thats exact same view I have on it. Well stated.
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Old 07-20-2018, 01:59 AM
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fatbillybob
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50/50 cross @ 50 % fuel load. Conventional wisdom is unquestioned. Is that because it is absolutely correct or secret sauce only tasted by the consistent pointy end of the grid?
What happens if your car gets worse as the race progresses? What happens if you are a late brake passer because your brake package is particularly good? What happens if you are a power passer on a right turn bias track? I think the OP is asking important questions.
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Old 07-20-2018, 08:51 AM
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50/50 diagonal, only if your left side weights are the same as right side weight.

If you are left side heavy, 50/50 diagonal is not optimal.
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Old 07-20-2018, 12:28 PM
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Many different approaches.
Will you be readjusting for each track? Trying to maximize setup for a certain section/corner/corners? Compensating for tire temps? Running an oval?
Or just looking for a good, predictable starting point.
50/50 diagonal, with driver and fuel. Barring other issues, the car will behave the same in lefts and rights. It's a nice place to start...
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Old 07-20-2018, 01:40 PM
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Note on fuel... I would balance at 1/4 or 3/4 of a tank. Reason is due to left side constantly being filled, ie:
Full tank... 10 and 10
3/4........... 10 and 5
1/2........... 10 and 0
1/4............ 5 and 0
So you spend more time around 1/4 weight diff between tanks and 1/2 tank is the most extreme. May have to start car for measurement.

Last edited by Joshboody; 07-20-2018 at 01:40 PM.
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Old 07-21-2018, 12:37 AM
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Originally Posted by alextz View Post
50/50 diagonal, only if your left side weights are the same as right side weight.

If you are left side heavy, 50/50 diagonal is not optimal.
OK, so what is optimal? I like where you're going with that, but you stopped way too soon.

Is there some arithmetic that will give you target weights at each corner, or targets for the relationships between corners, when your car's left side is heavier than the right?

Originally Posted by Nowanker View Post
Many different approaches.
Will you be readjusting for each track? Trying to maximize setup for a certain section/corner/corners? Compensating for tire temps? Running an oval?
Or just looking for a good, predictable starting point.
50/50 diagonal, with driver and fuel. Barring other issues, the car will behave the same in lefts and rights. It's a nice place to start...
I'm just trying to understand the advantages and drawbacks of different approaches. I had only heard of the LF+RR=RF+LR method until a few weeks ago, but saw a post where someone said they prefer LF=RF and I've been wondering about it ever since. So I figured I should ask rather than just wonder.

My Corvette is purely for recreational lapping days and I plan to try it both ways just to see for myself, but I'm still curious about which aspects I should pay the most attention to. If anything I'd probably just optimize for whatever is the most fun to drive (if there's a noticeable difference in that respect) or for even tire wear across all four corners.

I also share a dedicated race car with some friends (caged & trailered Mustang) and whatever I learn in Corvette we'd probably apply to that car with the aim of being faster (if there's a measurable difference). I doubt we'd bother trying to optimize the car for either of the tracks we race at though. Unless it makes a huge difference, which seems unlikely.

I just like to understand things. Asking questions sometimes helps.

Last edited by NSFW; 07-21-2018 at 12:38 AM.
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Old 07-21-2018, 12:44 PM
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I've heard the theory of equal LF and RF, to minimize F wheel lockup on cars with very light front ends (formula cars, DSR, etc.).
As I would tell my customers:
This isn't a 1000lb. Formula Ford, and we're not Alain Prost... let's use 50/50 until you know you need something different.
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Old 07-21-2018, 04:35 PM
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50/50 cross first, then look at your front/rear ratios on each side. Unless those are SERIOUSLY out of whack, 50/50 is your goal. If your side bias's (front/rear) are more than about 3% off, then you need to go on a diet, or move some weight to the right side/rear end.

Example:
lf 750 rf 650
lf 650 rr 550

cross weights 50/50, left side 1.15, right side 1.18 (2.6% difference). Car will have more relative front grip on right handers, and more relative rear grip on left handers, but overall 50/50 is best.
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Old 07-21-2018, 11:04 PM
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Originally Posted by davidfarmer View Post
50/50 cross first, then look at your front/rear ratios on each side. Unless those are SERIOUSLY out of whack, 50/50 is your goal. If your side bias's (front/rear) are more than about 3% off, then you need to go on a diet, or move some weight to the right side/rear end.

Example:
lf 750 rf 650
lf 650 rr 550

cross weights 50/50, left side 1.15, right side 1.18 (2.6% difference). Car will have more relative front grip on right handers, and more relative rear grip on left handers, but overall 50/50 is best.
Dave, help me out, you lost me somewhere. Looking at the corner weights, I'm only seeing that this "car" would make a great NASCAR type vehicle (great for left hand turns), as both axles are left side weight biased. What am I missing?
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Old 07-22-2018, 08:21 AM
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that's where the (200lb) driver sits...Unless you don't have a driver, or always carry a passenger, this is how most cars come into my shop. Front bias, and left side bias. If you are building a car from the frame up and have the luxury of adding lead, then you could have 50/50 cross, side and front/rear.

This is just a made up example.....but it's how most cars end up with driver weight. Front bias is often worse.
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Old 07-22-2018, 09:27 PM
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FWIW. While very different than a Corvette, I am in the process of scaling my road race kart. Getting these numbers right is critical for dialing in a baseline setup. Here are the specs:

57% rear/ 43% front
LF and RF within 5 pounds of each other
LR and RF (cross) 50%

In a kart you can move the seat/driver, move ballast, shim the spindles, raise or lower rear bearing cassettes, or even bend the chassis to achieve the desired numbers.

Oval track guys regularly run high cross setups 60ish%.

Last edited by Neil B; 07-22-2018 at 09:28 PM.
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Old 07-24-2018, 02:06 PM
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Here is my car balanced with me in it,
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Old 07-24-2018, 05:59 PM
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Old 07-25-2018, 10:17 AM
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IF car is left side heavy, and you set 50/50 diagonal, the car will be tight turning right and be a little more free turning left.(to a varying degree depending on how whacked the left side weight is to the right side weight).
This is because your left side heavy car will roll more when turning right than turning left.

What I would recommend is add weight to LR/RF diagonal until it balances out (by raising LR or RF).
You have to go by feel, or through data logging of G-levels of how the car handles.

OR move weight from left to right, so that you have close to a 50/50 split between left and right weights.

If you are close left and right (within 1%, then 50/50 diagonal should be ok).

Last edited by alextz; 07-25-2018 at 10:19 AM.
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Old 07-29-2018, 09:05 AM
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Also, set the tire pressure with your hot settings. Disconnect all sway bars. Start out with the 50/50 and run the car and adjust accordingly. Don't forget to jounce all four corners after you make an adjustment. When you achieve your setting, take the car off the scales and run the car up and down the street and put the car back on the scales and check your settings to make sure that you didn't have any corner binding up during your adjustments.

Make sure wherever you set up the scales, all four scale pads are laser/bubble level with each other.
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