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Old 01-26-2010, 03:58 AM
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Default 1/12th Balancing

Hi,

I would like to know how you guys balance out your car ?

I used two hudy pins to balance the car left/right. But this weekend I bought 4 scales and when I place the car on it , the left front tire weighs more as the front right, and vica versa at the back end.

Could someone tell me what is the right way to do balacing with scales ?

The last methode I used : Turn the T Bar as loose as possible. Place one end (read/front) on a flat elevated surface, and place the scales on a flat surface under the opposite wheels. With a water level I made sure the wheels on the elevated surface are completely level. Then I added extra weights untill the scales read the same. I this the way to go ?

Any help would be appriciated... thanks

PS : Sorry for my poor english, hope you guys understand what I mean
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Old 01-26-2010, 05:16 AM
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First of all measure from the rear of the car on the 1st step.

1: I use a tweak station. If you have one, put the rear pod on the bubble and just center. Some may disagree but I put the tweak screws all the way down on the pod so when I tip one side or the other. The bubbles pops back to center somewhat fast. Once that is done then you could knife check the front. If one tire raises fast by 1mm or a bit more that should be fine.

2: The old knife method. It is super simple and cheap. put your car on a smooth and flat surface. Just place the knife in the center of your rear pod. (some kits have a hole in the center for this) Once the knife blade is in place. slowly raise the pod. watch to see which wheel raises first. Then make the proper adjustments with tweak screws. Until they both raise even.
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Old 01-26-2010, 05:42 AM
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You need to distinguish between "balance" and "tweak".

Balance is the static weight distribution, this is what you measure with the Hudy pins or with the corner scales. For the corner scales, ignore the individual wheel weights - instead, sum the left-side and right-side weights to get the left/right weight distribution. You want these two sums to be as close as possible by moving the electrics/ballast around.

Tweak is determined by the suspension setup (or sometimes a bent chassis part). I'm not sure of the preferred way to set it on a 12th car, but basically you want to get the individual wheel weights on each axle as even as possible - the sum of the weight across the axle will stay constant. Given a choice between an evenly tweaked front axle and an evenly tweaked rear axle, I would go for the rear axle every time as it makes the car more confident on power.

But the knife trick is as effective as anything else at tweaking and a lot easier to do trackside!
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Old 01-26-2010, 06:04 AM
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Before buying the scales I had balanced my car using the hudy pins.

When I place my car on the scales their is only a 0.4 gram difference between the left sum and right sum of the individual wheels. So I guess I have the car balanced as sosidge explained, but I was just wondering if i should also try to balance out the left/right front and left/right rear weight distribution.

FL : 175.6 gr FR : 152.3 gr
BL : 211.3 gr BR : 234.2 gr

LEFT : 386.9 gr RIGHT : 386.5 gr

So LEFT/RIGHT is balanced (0.4grams difference) but there is an imbalance on the front wheels and on the rear wheels.

Since I am quite new to racing 1/12th... Can the front wheel imbalance and rear wheel imbalance be solved by correctly tweaking the car ?

My idea was to start out with a perfectly weight balanced car with the same weight applying on each front wheel / back wheel. And that the tweaking was to resolve uneven wheel diameters etc... But I am wrong on this point ?

Thx
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Old 01-26-2010, 07:38 AM
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Originally Posted by Patpop01
Before buying the scales I had balanced my car using the hudy pins.

When I place my car on the scales their is only a 0.4 gram difference between the left sum and right sum of the individual wheels. So I guess I have the car balanced as sosidge explained, but I was just wondering if i should also try to balance out the left/right front and left/right rear weight distribution.

FL : 175.6 gr FR : 152.3 gr
BL : 211.3 gr BR : 234.2 gr

LEFT : 386.9 gr RIGHT : 386.5 gr

So LEFT/RIGHT is balanced (0.4grams difference) but there is an imbalance on the front wheels and on the rear wheels.

Since I am quite new to racing 1/12th... Can the front wheel imbalance and rear wheel imbalance be solved by correctly tweaking the car ?

My idea was to start out with a perfectly weight balanced car with the same weight applying on each front wheel / back wheel. And that the tweaking was to resolve uneven wheel diameters etc... But I am wrong on this point ?

Thx
You said you are trying to resolve a "uneven wheel diameter" by balance. First I am not sure what wheel diameter you are starting with. I recommend you use a tire truer to keep the tires close to the same size. It also helps to rotate your tires often. This keeps the tires close to the same size. You may be doing this already but you did say you are new.
As for a perfect balance you are fighting a very tough battle. As the tires wear they change the balance of the car. It is best to check the balance (tweak) of your car about every 2/4 runs. Also I find the digital scales way to much trouble. It seems like I am always chasing the numbers from one tire to the next.
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Old 01-26-2010, 07:43 AM
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Not sure about the correct way of going about this, but personally, I try to make the install as neat as possible and then set the tweak with a set of setup wheels that I made. They are a set of large CRC rims with a large o-ring glued onto them (after finding a set of 4 that were the same size!). Use these to set the tweak with the scalpel trick, but I lift the front end with a coin on each front rim. This seems to do the trick just fine. I'll see if I have some pics of what I am on about somewhere.....

Cheers!
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Old 01-26-2010, 07:55 AM
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Setting up the weight is critical to how a 12th scale performs and it was my first mistake.

I have found John Stranahan guild !! very !! helpful.

http://www.rctech.net/forum/4524031-post99.html
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Old 01-26-2010, 08:29 AM
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anyone use quarters on the front wheels to tweak their car? That is the method I have been using and it seems to work.
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Old 01-26-2010, 09:21 AM
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Originally Posted by pakk
anyone use quarters on the front wheels to tweak their car? That is the method I have been using and it seems to work.
I use the rear to tweak and just look at both wheels to make sure they come off the ground and the same time
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Old 01-26-2010, 10:29 AM
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This should help. Be sure to read the whole thing. It will be worth your time.

http://www.markpayneblog.blogspot.com/
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Old 01-26-2010, 11:12 AM
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Originally Posted by pakk
anyone use quarters on the front wheels to tweak their car? That is the method I have been using and it seems to work.
Pakk..

I was at the Stock Euro's, and at the European Pancar Series. And the only thing you hear besides the Stock motors, is falling quarters....
I'm using it for several years and its a pretty fast, easy, simpel and effective way! Only be sure that your front end is in good condition, as well as the rest of the car's set-up (ride hight, droop,....)

As for the balancing thing... I would die for a 0.4g difference (well.. it's pretty good, and I wouldn't bother) I'm balacing my 12th scale with a small peace of lead, on the four scales, when it's needed, but that's not often...

Best Regards

Robert
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Old 01-26-2010, 07:08 PM
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You may be over thinking it a little as your left/right balance is better than most already. Critical check is the tweak and you can use just about any of the methods mentioned so far. I personally use a tweak board as I find it quicker and easier than coins and you will drive yourself nuts trying to get two digital scales to read the same. Using coins takes longer for me as each time you make a minor adjustment, you place the coins on the tires again, lift and repeat until equal. A tweak board lets you see the results as you adjust. Different stroke for different folks.

Tire wear will affect tweak so I tend to check it before each run even though it usually won't need adjusting but every 3-4 runs if you don't rotate the tires but by that time the rear tire taking most of the load in a sweeper will have worn a milimeter or two anyway and should be rotated or swapped out for a different set that are trued the same.
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