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Old 05-05-2007, 07:22 AM   #31
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Originally Posted by xtaiji
Just $40 for 4 scales.

where?
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Old 05-05-2007, 07:27 AM   #32
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Originally Posted by mooony
Gonzo,

I found this on a german site and the cost 325,00 EUR:

http://www.rc-cars.de/

Search for this code: CSE-J30030 in search box on left.

Here is the site that makes them:http://www.jrp-technology.de

The price seems very high but it looks good.

Ronald
that's $441.72 . that's way to much money. thanks though, it looks awesome
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Old 05-05-2007, 09:23 AM   #33
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Originally Posted by gonzo416
where?
Not US. South Korea. It's made in China. Surely they aren't accurate, but I don't care about 0.01g difference.
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Old 11-29-2007, 03:22 AM   #34
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Bringing this back up...

I have finally been able to do some proper tests with corner weights, with 4 of the Much-More 500g scales (one under each wheel). These were placed on a level surface and give consistent results.

It is very interesting to see the weights on each wheel for real.

It is a very useful tool in determining weight distribution.

It is also a useful too for determining tweak, although if I manually tweak the car I end up with the same result anyway.

Here are a couple of examples from my TOP Scythe.

Basically kit setup with plastic bulkheads, 6-cell EP4200, Atlas 19T, Keyence Speedo, Futaba S9550.

Measurements taken without bodyshell so don't read anything more into this than what is written.

Scenario 1: Shock preload equal on each side, race ride height.

FL 361.5 FR 304.9

RL 295.1 RR 378.9

Note that the corner weights are well out, I think in part that is due to inconsistent spring length, as the weight distribution is actually quite uniform on the car.

What this also tells me is the following...

Front axle weight = FL+FR = 666.4
Rear axle weight = RL+RR = 674
Left side weight = FL+RL = 656.6
Right side weight = FR+RR = 683.8

These four measurements by definition will remain constant as you adjust preload, the only things that will change are the crossweights (FL+RR and FR+RL).

What you can see is that the Scythe has almost perfect 50/50 front rear weight distribution. This is interesting as the Scythe is known to have a LOT of steering.

Surprisingly the right side is less than 30g more loaded even with the heavy 6-cell pack, shows how the more central cell position (compared to the motor which sticks out) helps to balance the car. I also did a quick 5-cell mockup and that makes the right side approx 5-10g lighter than the left side, so a much closer balance.

Scenario 2: Tweaked to give equal front corner weights

FL 333.0 FR 333.2

RL 321.5 RR 352.9

By adding approx 1mm of pre-load to the FR (which adds weight to both the FR+RL crossweight) you can get even weight on the front wheels.

I believe that in theory this should give optimum off-power stability. Also the crossweights are significantly closer than when the car was untweaked which must be a good thing for handling.

Scenario 3: Tweaked to give equal rear corner weights

FL 319.4 FR 347.0

RL 336.7 RR 337.4

Acheived by adding a further 0.5mm pre-load to the RL. Should be best for on-power stability.

Acheiving equal crossweights (where FR+RL = FL+RR) should be somewhere in between those two settings. This should give the best overall balance, although the car will never be wholly balanced due to the unequal left/right weight distribution.

Scenario 4: Tamiya TT-01

In comparison I dragged out my TT-01 which also has a pack of 4200s in it. The shocks have limited adjustment so I did not attempt to tweak it. No body.

FL 316.5 FR 345.6

RL 343.3 RR 417.2

Front axle weight = FL+FR = 662.1
Rear axle weight = RL+RR = 760.5
Left side weight = FL+RL = 659.8
Right side weight = FR+RR = 762.8

Now, the TT-01 has a much more rearward weight distribution, with nearly 100g MORE weight than the Scythe on the rear axle. It is closer to a 47/53 proportion. Also the battery side is nearly 100g heavier than the motor side (compared to a 30g difference on the race-bred Scythe).

The TT-01 is acknowledged as being a more stable, understeer oriented type of car, this rearwards weight distribution probably has a lot to do with it.

Anyway, sorry for the long post, but I hope someone finds something of interest in it. I hope to check the weight distribution on a couple of other cars if I get the chance. If you have any questions please ask away.
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Old 11-29-2007, 11:54 AM   #35
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Did you check your ride height, left to right as well as front and back?

Adding preload is OK but you are affecting the ride height, not the actual weight distribution.
i.e. the corner with added preload will have more tension on it going over any bumps and this may affect the handling. How does it look on the tweak board after the loading etc?

I also use a set of wheels without tyres which removes any possible inconsitency with the tyres.

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Old 11-30-2007, 03:30 AM   #36
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Originally Posted by Skiddins View Post
Did you check your ride height, left to right as well as front and back?

Adding preload is OK but you are affecting the ride height, not the actual weight distribution.
i.e. the corner with added preload will have more tension on it going over any bumps and this may affect the handling. How does it look on the tweak board after the loading etc?

I also use a set of wheels without tyres which removes any possible inconsitency with the tyres.

Skiddins
The point of corner weighting is not individual axle ride heights, it is about using shock adjustments to spread the load across the wheels. It may not affect the static weight distribution but it certainly does affect the way the weight is spread across each wheel as you can see from the measurements above.

Springs will not have more tension if they are preloaded. Spring behaviour is constant within normal limits. Bump handling will not be affected.

Tweak checked by hand is the same as tweak determined through corner weighting after these tests.
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Old 11-30-2007, 07:17 AM   #37
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Springs will not have more tension if they are preloaded. Spring behaviour is constant within normal limits. Bump handling will not be affected.
Trouble is spring rates are not constant, they are rated as such for ease of use but it is easier to move a spring the first 5mm of travel than it is the last 5mm. As the spring is compressed the tension builds.

Have you tried the car on the track after making those adjustments, how did it do?

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Old 12-03-2007, 11:07 AM   #38
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Trouble is spring rates are not constant, they are rated as such for ease of use but it is easier to move a spring the first 5mm of travel than it is the last 5mm. As the spring is compressed the tension builds.
You are mistaken. You are confusing the total amount of force exerted on a spring with the amount of force required to compress a spring a given amount.

Regardless of the preload on a spring, if I wish to compress it an additional 5mm it will always require the same amount of additional force to do that.

The only exceptions to this is where the spring is so compressed that coils are starting to touch, or where the loads on the spring are so far in excess of the capabilities of the spring material that the spring is failing.

I suggest you do some reading on Hooke's law, the spring constant and coil spring behaviour in general.

I always make sure my car is manually tweaked before running. If it is not it is easy to tell. Using corner scales is another way of acheiving the same result.
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Old 12-03-2007, 04:25 PM   #39
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I have used the scales to setup wedge on an oval car and 2 scales on the rear of a 1/12 scale for tweak. I remember downloading a small software that when you input the weight from the scales into the software, it shows the front/rear split as well as the left/right split.
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Old 11-30-2017, 06:26 PM   #40
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Just want to get some advice here, i got my car on the SKYRC scale, i manged to get L & R side balance , but i mess up the ride height.. When i tune my spring colar to disturb the weight on the corner, i ensure i did adjust 4 corner with the same turn (same across the wheel), for example, i turn 1/4 in front left, i will add the same 1/4 in my rear right, and take away 1/4 both front right and rear left. I suppose by doing that, the ride height will stay the same, but i found out it is not the case..
any advice would be appreciated, thanks.
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Old 12-01-2017, 12:37 AM   #41
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Originally Posted by uakel View Post
Just want to get some advice here, i got my car on the SKYRC scale, i manged to get L & R side balance , but i mess up the ride height.. When i tune my spring colar to disturb the weight on the corner, i ensure i did adjust 4 corner with the same turn (same across the wheel), for example, i turn 1/4 in front left, i will add the same 1/4 in my rear right, and take away 1/4 both front right and rear left. I suppose by doing that, the ride height will stay the same, but i found out it is not the case..
any advice would be appreciated, thanks.
Adjusting shock collars is what adjusts ride height. So turning collars will change ride height on that corner, regardless if you adjust another collar. They won't cancel each other out.

For RC you should not worry about setting corner weights in this method. It works in real cars, but adjusts ride height in them ever so slightly. For RC you should focus more on balancing the electronics L to R, and balancing the chassis at all 4 corners using electronics placement and balance weights.

This is all contrasted by full size cars, because full size cars are inherintly designed so that the weight distribution will be roughly 50-50 side to side from a design standpoint. RC's weight distribution heavily depends on electronics brand and placement, and is the big variable to getting 50-50 distribution. On the full size car once ride height is set, corner weights can be adjusted by changing the ride height. On a full size car these adjustments may change the ride height a few millimeters to balance the car, changing only 5-10lbs of weight. So for a similar analogy on the RC, you are looking to change rideheight by the 1/10ths of millimeters to adjust corner weights, roughly 1-5g differences. When a car rides many inches above ground, a few mm's difference doesn't matter. RC's ride at 5mm's, so changes should be in the 1/10ths of mm's at most for the same desired effect.

So you should first start by ensuring that your electronics add up to the same weight L to R. Add lead weight to whichever side is lower. Then with all 4 shocks the same length, set the car on scales. Adjust any extra lead on the chassis until you reach a desired cross weight, then screw/glue/tape the weight to your chassis. (Remember that whatever material used to secure the weight also adds weight). This means that the weight distribution will be as close to 50-50 as possible. Now setup ride-height for your car as you would normally. Then place the car back on the scales. Adjust the shock collars to reach the desired cross weight distribution. If you distributed the weight correctly, this cross weight adjustment should not be over 5ish grams. Which would likely equate to much less than a 1/4 turn on the shock collar.

Also ensure anti-roll is not connected when setting corner weights, the sway bar can influence the values and cause them to be off.

On my RC's I ensure the electronics and chassis are all balanced before setting up ride height. It allows me to then set my F and R dampers to the same length settings and mark it on the shock. That way I can make quick adjustments with an easy reference point, knowing the corner weights will never be affected.

TL;DR (Step 1)Balance the weight on your chassis before corner weighting. Adjusting the shock collars for corner weight does affect ride height. The change should be very small. If change is large, repeat step 1.

Sorry for my mix of metric and Freedom units.
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Old 12-01-2017, 02:54 AM   #42
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Quote:
Originally Posted by mschumi101 View Post
Adjusting shock collars is what adjusts ride height. So turning collars will change ride height on that corner, regardless if you adjust another collar. They won't cancel each other out.

For RC you should not worry about setting corner weights in this method. It works in real cars, but adjusts ride height in them ever so slightly. For RC you should focus more on balancing the electronics L to R, and balancing the chassis at all 4 corners using electronics placement and balance weights.

This is all contrasted by full size cars, because full size cars are inherintly designed so that the weight distribution will be roughly 50-50 side to side from a design standpoint. RC's weight distribution heavily depends on electronics brand and placement, and is the big variable to getting 50-50 distribution. On the full size car once ride height is set, corner weights can be adjusted by changing the ride height. On a full size car these adjustments may change the ride height a few millimeters to balance the car, changing only 5-10lbs of weight. So for a similar analogy on the RC, you are looking to change rideheight by the 1/10ths of millimeters to adjust corner weights, roughly 1-5g differences. When a car rides many inches above ground, a few mm's difference doesn't matter. RC's ride at 5mm's, so changes should be in the 1/10ths of mm's at most for the same desired effect.

So you should first start by ensuring that your electronics add up to the same weight L to R. Add lead weight to whichever side is lower. Then with all 4 shocks the same length, set the car on scales. Adjust any extra lead on the chassis until you reach a desired cross weight, then screw/glue/tape the weight to your chassis. (Remember that whatever material used to secure the weight also adds weight). This means that the weight distribution will be as close to 50-50 as possible. Now setup ride-height for your car as you would normally. Then place the car back on the scales. Adjust the shock collars to reach the desired cross weight distribution. If you distributed the weight correctly, this cross weight adjustment should not be over 5ish grams. Which would likely equate to much less than a 1/4 turn on the shock collar.

Also ensure anti-roll is not connected when setting corner weights, the sway bar can influence the values and cause them to be off.

On my RC's I ensure the electronics and chassis are all balanced before setting up ride height. It allows me to then set my F and R dampers to the same length settings and mark it on the shock. That way I can make quick adjustments with an easy reference point, knowing the corner weights will never be affected.

TL;DR (Step 1)Balance the weight on your chassis before corner weighting. Adjusting the shock collars for corner weight does affect ride height. The change should be very small. If change is large, repeat step 1.

Sorry for my mix of metric and Freedom units.
Thank you mschumi101 .. i will give it a try on your steps advised. work on the L & R balance first.. put on the scale.. level on both side L&R.. do the ride height and back on the scale for fine tune adjustment on weight distribution. I got some follow up questions to ask:

1. Before i put on some weight on the chassis for measuring up the balance from L & R side, how would you set the spring pre-load, does that mean i have to turn the same amount of turns in the spring collar? for example (8 turns for each spring collar regardless of the ride height not aligned)


2. For the weight amount, does any website or link has those information listed out how many grams for each brand electronics (motor, esc and servo, or battery)?

Thanks again.
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Old 12-01-2017, 06:32 AM   #43
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Here is a note of caution guys. It has to do with the scales themselves. I bought a Sky set and where they are accurate with a test weight they are not all equal in height which affects what you are doing with the setup. Heck they are not even close. Before you use any set of scales make sure that they are all equal in height as close as you can measure them. I do mine by setting them up and taking a weight reading for each scale. I will then swap one end side to side (RR to the LR as an example). If they if the RR shows the same weight the as the previous scale (within 5g) then that pair should be good. If it reads less, then the scale is short, if it reads more, then the other scale is short. Only do one end at a time. Correct the short scale with tape and test until you get the scales to read the same when they are under a specific wheel. Then do the same thing to the other end set. A set of individual scales (no central box) should have the same thing done to them and mark them as front and back or take the time to match all four.
If you don't do this you are chasing yourself on the setup of your car.
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Old 12-01-2017, 07:49 AM   #44
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Holy cow yes! If the scales are not even, the taller scales are essentially preloading that corner and you’ll be adjusting to a non-level surface. I also have a tweak board for at-the-track adjustments, but the initial setup is done at home on scales on known flat and level surface for consistency.

But I will also verify the car’s balance on the tweak board right off the scales, they should be fairly close if my scales are set up correctly.
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Old 12-01-2017, 08:43 AM   #45
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Here is a note of caution guys...
Yes! I use the one scale method, with 3 precisely measured wood blocks under the other 3 wheels. Took a while to get it right, and even now I take 3 measurements of each wheel and average, resetting the suspension between each measurement.
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