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.