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Old 12-29-2014, 12:20 AM   #1
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Default Corner weight system

I have bought a SkyRC corner weight system to play with (http://www.skyrc.com/index.php?route...product_id=194).

The system measures the "balance" in the car by displaying front/rear weight percentage and the left/right side balance by measuring the cross diagonal weight balance (FR+RL / FL+RR).

First I was wondering if tweak in the car would affect the balance measuring, but does the cross diagonal measuring of the left/right side eliminate the effect of possible tweak in the car when the system meaures and displays the balance percentages?
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Old 12-29-2014, 06:19 AM   #2
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Yes, a tweaked chassis will affect the balance measuring. Make sure your chassis is "tweak free" before making any set up adjustments.
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Old 12-29-2014, 10:52 AM   #3
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The biggest benefit to this system is checking for tweek between runs.

You know what the weights were before you hit the track, when you get off, if the scales have changed you've hit something or something in the car is coming loose.

I've used four small scales for years, but I could do the math in my head to calculate the l/r and f/r splits and the wedge. And I had a photographic memory to remember it. I lost that about six months ago, and I had to switch to writing them down on a note pad, so I bought one of these units to take some of the mental pressure off after my wife and I seperated.

Just make sure the surface is dead flat, and level before you scale anything. I used a bubble level to make sure the board was true.
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Old 12-29-2014, 03:31 PM   #4
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Misc observations from messing with corner scales:

- Suspension tweak doesn't make much difference in getting the total left/right and total front/rear weights. Your cross weights will be way off if it's tweaked, of course.

- An un-level setup board doesn't seem to move much weight around. It makes a difference, but not a huge one. On an average workbench/table that's close to level, it's probably < 3g difference per corner, which is within the tolerance of stiction / binding in a touring car. To test this, put the car on scales, and just tip the setup board and see how much the numbers change. Your results might be different from mine.

- Steering angle makes a big difference, at least with setup wheels and 6* caster blocks, when looking at what's going on with the front. Just being a few degrees left / right from center, I was seeing variances of 10-20g on the front end, which is pretty big. I'm pretty sure this is from the weight jacking effect of the caster. So turn on your transmitter / car, and make sure your steering is trimmed straight, before you start messing with preload.

- Scales alone will not tell you which end of the car has suspension tweak. Something I tried recently that seems to work, is to stack my two droop blocks and put those under one end of the chassis to keep the car flat to the setup board, while the other end is on the scales under the wheels. This will let you check tweak at that end of the chassis in isolation.

At the end of the day, I've found ways of checking everything without using the scales, as long as the car is balanced left to right. I only use the scales during initial setup to balance the car left to right, or when I've got a weird tweak going on that I just can't get figured out. I leave them on my workbench at home, and just use the simpler techniques for checking things trackside.

Also, IMO, it's not enough to get the cross weights even. You really need to get the car balanced left to right to make it handle properly. If it's unbalanced, it will do weird things when it pitches on throttle / brakes.

-Mike
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Old 12-29-2014, 04:33 PM   #5
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I totally disagree with most of what Mike wrote, but I used to race a lot of oval and I can tolerate a car that doesn't handle perfect in the slow speed corners of it goes faster in the high speed ones. Indy cars have been running asymmetrical setups on road course cars for at least 30 years. F1 was slow to catch up, but they do it now too. That means the driver has to be on board with having the car like that. If you can't handle it don't try.

That doesn't mean he's wrong. Only that I disagree.

The corner weight scales are just another tool. Assuming the car isn't tweeked, I can make my car right with just a camber gauge, a steel rule, a ride height gauge, and a flat surface, and an exacto knife. The scales are just another tool I use. Most who try them wind up hating them because they don't understand what they can and can't do.
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Old 12-29-2014, 05:59 PM   #6
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Originally Posted by grippgoat View Post
Scales alone will not tell you which end of the car has suspension tweak. Something I tried recently that seems to work, is to stack my two droop blocks and put those under one end of the chassis to keep the car flat to the setup board, while the other end is on the scales under the wheels. This will let you check tweak at that end of the chassis in isolation.
That's more or less how I was taught to do full scale corner balances, raise the lighter end of the chassis and balance the heavier end. Then set the lighter end down and adjust the spring perches to eliminate tweak.
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Old 12-29-2014, 06:23 PM   #7
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Originally Posted by CraigMBA View Post

I've used four small scales for years, but I could do the math in my head to calculate the l/r and f/r splits and the wedge. And I had a photographic memory to remember it. I lost that about six months ago, and I had to switch to writing them down on a note pad, so I bought one of these units to take some of the mental pressure off after my wife and I seperated.
What happened 6mo ago!?
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Old 12-29-2014, 06:31 PM   #8
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I also agree with Mike for the most part. My full time job is working for a race team in Indy cars, and a prototype car. So I use intercomp scales all the time.

These scales I see being another good tool for balance and weight transfer. That said, I recommend the surface as mentioned to be as flat as possible. 4 grams might not be a ton, but in translation that could mean a lot, in scale terms.

Steering input does have a rather important effect on the numbers up front. On Real cars, we use steering locks. Basically, aluminum blocks we insert between the toe/steer Link and the rack housing. You could come up with your own version of this on your car, based on platform, or as mentioned always check with the wheels perfectly forward. Up to you.

I will say I don't agree with set Up wheels. I scale cars with this in mind. Do it as close to track ready as you can. If you can see the numbers, even do it with a body on that you'll run. Stickers, paint, etc all can change weight bias on the body forward or back, even side to side. Also, scale with the wheels and tires on, each corner as it will be run. Some plastics might weigh or behave differently. Charged battery in, bumper on, etc. We even ballast weight for Driver and fuel.

All depends on how critical you want to be. But I've always gone for as close to track ready as possible. Keeps it consistent.
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Old 12-30-2014, 12:48 AM   #9
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Originally Posted by samnelso View Post
What happened 6mo ago!?
My marriage was ending after 20 odd years. I was trying my damnedest to hold it together, and combined with my super demanding farm job I wasn't sleeping much and taking adequate care of myself.

If you really want a steering lock, turn the transmitter and the car on.
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Old 12-30-2014, 03:31 AM   #10
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Corner balancing, sometimes referred to as "corner weighting," "weight jacking," or "scaling," involves adjusting the spring perches of a car to get a balanced diagonal weight on the tires. Ideally the car should have 50% of its weight on the Left Front and Right Rear tires, and 50% on the Right Front and Left Rear. If your car's diagonal corner weights are not equal then its handling will be unbalanced--it will turn better in one direction than in the other (all other things being equal). If your car has coil over adjustable shocks you should consider renting/borrowing/buying some scales and corner balancing your car. It's a lot of work but in the end it's worth it. Keep in mind the stiffer your springs the more important corner balancing becomes. You can use this custom essay writing service for completing your essay works in a easiest way.
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Old 12-30-2014, 06:54 AM   #11
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Originally Posted by Walterrruiz View Post
Corner balancing, sometimes referred to as "corner weighting," "weight jacking," or "scaling," involves adjusting the spring perches of a car to get a balanced diagonal weight on the tires. Ideally the car should have 50% of its weight on the Left Front and Right Rear tires, and 50% on the Right Front and Left Rear. If your car's diagonal corner weights are not equal then its handling will be unbalanced--it will turn better in one direction than in the other (all other things being equal). If your car has coil over adjustable shocks you should consider renting/borrowing/buying some scales and corner balancing your car. It's a lot of work but in the end it's worth it. Keep in mind the stiffer your springs the more important corner balancing becomes. You can use this custom essay writing service for completing your essay works in a easiest way.
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Old 12-30-2014, 07:12 AM   #12
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So lets take this one step further in our discussion as I think it will help a lot of people.

So lets play through this scenario and see where people start.
I have measured the down stroke on the shocks and the fronts are equal to each other and the rears are equal to each other.
The springs, as rated by the manufacturer, are equal for the front and for the rear.
The shock collars are screwed down an equal distance from their shock caps (used as a point of reference).
Ride height is set
Camber is set
Droop screws are not touching the chassis
Chassis, to the best of our knowledge is not tweaked but how would you verify?
Body installed
Left and right relationship is how you would be sitting in the car.

I believe my car is ready to race so I scale it. I find that I my left rear has 1 ounce more than the right rear. I find the right front is 1.5 ounces lighter than my left front.

Where do you start to get the same amount of weight across the rear tires and also the front tires?
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Old 12-30-2014, 07:37 AM   #13
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Just adding on to the OP, I'm not sure if his question is answered or not.

I also own the same scale system and mainly use it for reference after using Hudy tweak station. Besides using the scales for reference the only thing I do is shift the balance front to rear or vice versa but never cross balance.

Point is, I use this tool as a reference check after balancing my car left to right and very slight adjustment on tweak station. Is this wrong to do so in that order or should I not use the Hudy tweak station at all and just use the scale?
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Old 12-30-2014, 07:51 AM   #14
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Quote:
Originally Posted by Kraig View Post
So lets take this one step further in our discussion as I think it will help a lot of people.

So lets play through this scenario and see where people start.
I have measured the down stroke on the shocks and the fronts are equal to each other and the rears are equal to each other.
The springs, as rated by the manufacturer, are equal for the front and for the rear.
The shock collars are screwed down an equal distance from their shock caps (used as a point of reference).
Ride height is set
Camber is set
Droop screws are not touching the chassis
Chassis, to the best of our knowledge is not tweaked but how would you verify?
Body installed
Left and right relationship is how you would be sitting in the car.

I believe my car is ready to race so I scale it. I find that I my left rear has 1 ounce more than the right rear. I find the right front is 1.5 ounces lighter than my left front.

Where do you start to get the same amount of weight across the rear tires and also the front tires?
Start with small adjustments on the spring adjusters, the art of getting weight were you want comes from playing with the spring adjusters.
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Old 12-30-2014, 08:18 AM   #15
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Quote:
Originally Posted by Kraig View Post
So lets take this one step further in our discussion as I think it will help a lot of people.

So lets play through this scenario and see where people start.
I have measured the down stroke on the shocks and the fronts are equal to each other and the rears are equal to each other.
The springs, as rated by the manufacturer, are equal for the front and for the rear.
The shock collars are screwed down an equal distance from their shock caps (used as a point of reference).
Ride height is set
Camber is set
Droop screws are not touching the chassis
Chassis, to the best of our knowledge is not tweaked but how would you verify?
Body installed
Left and right relationship is how you would be sitting in the car.

I believe my car is ready to race so I scale it. I find that I my left rear has 1 ounce more than the right rear. I find the right front is 1.5 ounces lighter than my left front.

Where do you start to get the same amount of weight across the rear tires and also the front tires?
If both Left side tires are heavy then you need to make the left side of your car lighter or add weight to the right side. It's almost impossible to fix left to right or front to rear weight differences with spring perch adjustments.

Have you tried balancing your car on balance posts? You should try to get the car to balance with static weight before you try adjusting it with your springs.
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