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Old 01-29-2011, 03:11 AM   #1
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Default Balancing car

Hi,

Trying to get my car balanced with equal weight on each corner or best I can. With no weights my car (T3 2011) is balanced left to right but only weighs 1285g including body. I put it on four small scales and I get FL 304.4g, FR 303.2g, RL 315.0g and RL 317.6g this is with weights added. I need to add 25g to the RL and 35g to the FR this gets the FL and FR close and the RL and RR close to each other but this is with me adding the weights on top of each wheel while on the scales. So my car is still not quite balanced front to back and still slightly under weight BUT I'm never going to fit all those weights on so how do you balance yours ? I don't want to start moving electronics around as I happy with how they are placed.

Thanks.
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Old 01-29-2011, 03:24 AM   #2
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I know there is a special putty you can add to the inside tires. I think it's for Balancing tires, but it will add weight to the car without having to add weight to the chassis.
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Old 01-29-2011, 03:29 AM   #3
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You use the spring pre-load to even out the corner weights. Use the ballast to get the base weight and weight distribution correct.

First of all, put your (unballasted) car on one scale and take its weight. This will let you know how much ballast you need to add.

Then, put the car on the four scales. Ignore the four individual weights for now, just take the sums of the FR+RR (right side) and FL+RL (left side),FR+FL (front axle), RR+RL (rear axle).

You can use these sums to calculate the left/right and front/rear weight distribution.

Arrange your ballast on the chassis to get an even left/right weight distribution (essential), and the desired front/rear weight distribution (normally somewhere between 50F/50R and 49F/51R). Try to keep the ballast close to the centre of the car if you can.

Once the car is ballasted, you can use the pre-load adjusters on the shocks to even out the corner weights. Adding pre-load to a shock will add weight to both that wheel and the diagonally opposite one. You need to make these adjustments in a balanced way so as not to affect the ride height.

It all makes a lot more sense when the car is in front of you on the scales!

Having said that, corner weighting is quite a precise science, and RC cars are quite imprecise in comparison, so you can get different results each time you put the car on the scales. I wouldn't be too obsessed with corner weighting - but measuring weight distribution is very useful.

HTH
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Old 01-29-2011, 04:49 AM   #4
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Originally Posted by Foxxrocket View Post
I know there is a special putty you can add to the inside tires. I think it's for Balancing tires, but it will add weight to the car without having to add weight to the chassis.
The wheels are the absolute worst place to put weight. Slows the car down in every possible way.
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Old 01-29-2011, 05:32 AM   #5
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For balancing out the car by using weights I wouldn't suggest putting the car on four scales but one axle on the scales and one on a Hudy pin.
This eliminates the variables like chassis straightness which can cause a false reading.
If you want to do it perfectly you should also replace the shocks with a set of turnbuckles.
First you will dial in the left/right balance on both axles and then the front/rear balance.
When you set it up like this and build your shocks properly you don't have to balance out the car by changing the spring preload. This gives you a very good handling car.

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Old 01-29-2011, 10:33 AM   #6
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how exactly do you do it with turnbuckles instead of shocks?
how would you balance front and back
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Old 01-29-2011, 11:22 AM   #7
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The idea is to make turnbuckles at the approx ride-height length of the shocks, and clip them on in place of the shocks.
When you place your car on scales with shocks on, the car won't settle properly due to stiction etc, and so will have some shocks loaded more than others, giving false readings of the weight distribution.
The same effects are why all the guides say to push down on your car a few times before checking ride-height.
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Old 01-29-2011, 12:26 PM   #8
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heres a thought for ya..lololol just put heavy weight shock oil in the shocks....lol thats gotta addmore weight to the car since its heavier.. na dont do that.. do what he said with thechassis thenwhen u tweak it out it will conter react the weightright
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Old 01-29-2011, 04:02 PM   #9
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@digitrc,
I tried your method with my car ready to go without and weights it weighs 1285g so I need 65g and then stuck it on four scales and this is what I got rounded up
FR+RR 631g
FL+RL 655g
FR+FL 617g
RR+RL 667g

so does that mean I need 24g on the left and 50g up front once this is added I would then need to put it back on the four scales and use the spring pre-load to get the four corners equal or close enough ?

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Quote:
If you want to do it perfectly you should also replace the shocks with a set of turnbuckles.
Do these need to be the length of the assembled shocks or the length of the shocks when on the car at the correct ride height ? shouldn't matter should it ?
Quote:
First you will dial in the left/right balance on both axles and then the front/rear balance.
Would you use four scales for the front/back ?

Thanks.
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Old 01-29-2011, 04:30 PM   #10
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ok, weights in the tires are a major mistake for two reasons: you add unsprung weight which is only gonna make your ride much rougher and secondly, you add to the force needed to turn or stop the wheels and thus acceleration and deceleration suffer.
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Old 01-29-2011, 05:18 PM   #11
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Quote:
Originally Posted by S.A.W View Post
@digitrc,


@DS Motorsport

Do these need to be the length of the assembled shocks or the length of the shocks when on the car at the correct ride height ? shouldn't matter should it ?

Would you use four scales for the front/back ?

Thanks.
I have the set of links made so it has the same rideheight all around, normally you will have the rear setup higher but when you're figuring out the weight distribution you don't want this as this will give you false readings.

For the front/back measurement I use four scales.
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Old 01-29-2011, 11:36 PM   #12
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I would suggest using the balancing holes in your chassis to get weight balance. As long as it is very close to 50/50 front and rear and also left and right the car will run fine. The rest of the balancing is done when you tweak the car during setup.
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Old 01-29-2011, 11:51 PM   #13
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Quote:
Originally Posted by S.A.W View Post
@digitrc,
I tried your method with my car ready to go without and weights it weighs 1285g so I need 65g and then stuck it on four scales and this is what I got rounded up
FR+RR 631g
FL+RL 655g
FR+FL 617g
RR+RL 667g

so does that mean I need 24g on the left and 50g up front once this is added I would then need to put it back on the four scales and use the spring pre-load to get the four corners equal or close enough ?
Obviously it's about balance in the weight placement. Certainly your car needs a bit more weight on the right side to get the balance. Front/rear balance is more of a tuning setup - I'm assuming that XRAY have designed the car to have a rearward weight balance, so try and keep the same sort of proportion front/rear to start with, move the ballast around if you feel the car lacks overall grip at one axle.
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Old 01-30-2011, 10:37 AM   #14
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you wouldn't add 50 grams there, as any weight gets applied to ALL corners, just not evenly
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Old 01-30-2011, 11:52 PM   #15
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is that you adjust the length of the shocks same as the link measured on scale ?
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