Jochim_18

iTrader: (10)

Calibration on your scale is possibly off..

Conrad

iTrader: (3)

I remove tweak in the same way Skiddins and have never had any problems. Remember the corner weights are linked diagonally on the car. So if you have something really heavy on the left rear (passengers side as we drive on the correct side of the road :P) usually the motor then the right front should be heavy as well. So adding half a turn on the left rear shock will increase the corner weight on the left rear and the right front.

I know it's a bit drastic but to eliminate the weight distribution caused by the electronics, you could strip the car back to just a rolling chassis and measure the weights. You would have a good base setting/point of reference then.

6376vette

Remember he is around 100 g different from left to right. You cannot adjust out that much pressure with the shocks and maintain a consistent ride height unless the ride height and shocks are that far off to begin with. The procedure you describe is perfect to fine tune the balance of the car for optimum handling though.

jpk4ud

iTrader: (5)

I think four of these on a set up board might work well.

http://www.gramscales.com/product_in...roducts_id=822

rmdhawaii

iTrader: (4)

... and a round bubble level.

jpk4ud

iTrader: (5)

Yes and there is a nice phone app for that.

Skiddins

Having fiddled around with top deck screws etc I've managed to get it to around 40-50g difference left to right at each end, which is still better than it was. Next up will be attaching the wheel's and shocks

2-Bad

iTrader: (24)

Use setup wheels for accuracy.
Normal wheel & tyres can be different weights, the plastic wheel maybe twisted, etc...

Magnet Top

iTrader: (4)

Hey Skiddins,
Maybe you tried this already... but something that is overlooked is that the shock tower can rotate slightly while tightening the 4 screws that hold the shock tower to the "upper clamps". Xray doesn't use countersunk holes so there is more chance for "shock tower tweak" or so I call it. It is also important which side the screws are on ( depending on which chassis it is ). On the Xray T2 and 3 the screws are on the back of the rear shock tower, and front of the front shock tower. So when tightening the screws it twists the two towers in opposite directions ( clock wise and counter clock wise ) ... compounding this diagonal "tweak". And of course, in a wreck, the shock tower could shift too... so I make sure they are tight once I get it right by using opposing force on each tower while tightening. Hope this helps solve it for you.

Cheers,

Jake D.

old_dude

iTrader: (1)

That rules out the scale calibration as you noted. If the tires are on the car try set up wheels or just bare rims. If you still see the differences then the chassis is tweaked as many are stating. Try the twisting as several have suggested.

2themax

iTrader: (7)

This is the setup I use to corner weight the car, the scales cost me about $8 each delivered on ebay.

Max

sosidge

Corner weighting on RC cars is an imperfect science - I've played with it many times, and it will throw up completely random results at times.

Likely reasons? Domestic-quality scales, chassis flex, and the free play in components - perhaps.

Using the scales to determine Front/Rear and Left/Right weight balance is reliable. Using them to determine corner weights is not. I tweak the car manually if I feel there is a problem.

terry.sc

That doesn't mean they are anywhere near identical in length. Unless the holes are a tight fit on a 3mm pin, and you can guarantee the second hole is drilled absolutely perpendicular, you would have to be extremely lucky to get them all exactly the same length. The amount of play of the screws in the first hole will guarantee they are all slightly different lengths, and any play at all in the links when fitting to the chassis will guarantee even more chance of being out. Due to the positioning of the linkages on the arms, any slight difference will then be amplified at the wheel end - if the link mounts to the centre of the wishbone then 0.1mm link difference will translate to 0.2mm difference at the axle. Whichever corner is slightly lower that corner and the opposite corner will be the ones that give the highest weight reading.

Then assuming all of your home made links are exactly the same length, down to tiny fractions of a mm, and the whole chassis/top deck/suspension mounts/shock mounts are all perfectly flat and square, you would still have to make sure you have exactly the same amount of play in axle bearings, uprights, wishbone pivots, etc. to actually get an accurate reading.

Simple way to prove the difference in numbers is down to tweak and not the actual corner weights, put your car as it is on the scale and measure the corner weights. Now wrap a few turns of tape around one of the axles and try it again. You will notice the taped axle and its opposite corner will be 'heavier' while the others will be lighter. If the scale was only measuring the actual corner weight the difference would be the corner with the tape would be a few grams heavier. As you are using fixed links there is no way for the slight tweak to be taken up by the springs.

It is virtually impossible to have an absolutely tweak free chassis and suspension, you dial it out with the shock length, droop screws and spring collars.

If you want to deal with car balance a simple tweak board is a much easier and quicker way of sorting corner weighting than a set of scales.

2themax

iTrader: (7)

I use my scales to check firstly for tweak, then for front/rear & left/right bias. I have little concern for the actual weight on each wheel, only how it compares with the other scales on the board. As we use a very low racing weight here (1350), I use them to move things on the car to balance it. As a side note, one thing it has shown me is how little impact it takes to tweak the car, and how much it needs to be out to affect the handling. It comes down to one thing for me, you can never have too much information.


Max

blacky2kgt

This is my first post here guys so forgive me (and correct me) if I do something wrong.

DS Motorsport is correct, and don't forget to compensate for variances in SCALE PLUNGER travel (due to the different corner loads). Often times, I find it necessary to shim between tweak board and bottom of scales to get the car back level.
I want to help stress again the point DS Motorsport is making..........THE CAR must be PERFECTLY level (as your referrence) or everything else you do including (but not limited to) caster, camber, and toe settings will be in error.

AGAIN - GET IT LEVEL EVERY TIME!