funked1

iTrader: (10)

This site is pretty awesome if you are just using four $10 Harbor Freight scales like I am.
http://robrobinette.com/corner_weight_calc.htm

wingracer

iTrader: (24)

I use that all the time when setting up a new ride.

CraigMBA

iTrader: (22)

The first thing I do is check chassis tweek. If the chassis is twisted, and you can't get it out, and it's the middle of a race day, it's not the end of the world. But the car is never going to be as "right" (which means it's easier to work on) than it will if you got it square to begin with.

You can check chassis tweek by setting the car on setup blocks, on the screws where the front and rear suspension mounts pass through, and then see if the car lies dead flat or "rocks". If it rocks, it's not square and you need to try and get it straight before you move further forward.

In order to untweek it, you are going to need some tools. You can buy something to untweek the car that's really fancy like this:

http://www.redrc.net/2014/06/zen-rac...is-tweak-tool/

Or, you can home brew something. My "home" rig is a piece of 1" x 2 1/2" x by 13" billet aluminum remnant stock I got from a local industrial stainless and aluminum company and the biggest anodized aluminum knitting needle you can find at Hobby Lobby.

(This space reserved for a picture of my $7 setup when photobucket stops being a grump)

At the track, I just use my setup board and the knitting needle because I don't want to haul around this block and my Marc Reinhart setup board is already pretty robust.

At the track, I check it on setup blocks between rounds.

My standard setup regimine is:

- Check/fix chassis tweek
- Set droop (I usually use 20mm blocks and an off-road 20-30mm ride height block, but can use a steel rule and my eyes)
- Put race tires back on in their appropriate wheel positions (I mark my tires in sets, never seperate them and never rotate them) and set the ride height.
- Check cambers and toe, recheck/set ride height.
- Put the car on the scales and see what the L/R, F/R, and split weights look like. There is a way to get the car unwedged/us tweeked without scales using an exacto knife. If you KNOW the car is 50/50 left and right, you can pick up one end with the exacto knife and see which tire comes up first.
- The way you adjustment you make to fix it is remove a small amount of preload the shock DIAGONAL on the chassis to the heavy tire, and add the same amount to the DIAGONAL tire that is light. That way, the ride height isn't disturbed, but you fix the split on the other axle.

Real life MBA case study problem:

The RF and LF tires weight the same. The RR is 30 grams heavier than the LR.

Solution:

Add 1/8 of a turn to the RF (taking weight off the LF and RR, moving it to the LR), remove 1/8 of a turn from the LF (adding weight off the RF and LR, reducing weight on the RR). Recheck and do it again till you are happy.

If I get the car within a couple of grams, I usually quit. If you bump a curb, a board, or another car, it's going to be wrong, especially if you use a plastic chassis car.

Important note:

The above mentioned car is not exactly 50/50 left to right, the math indicates it's 30 grams heavier on the right side. Assuming the car isn't 30 grams underweight or have 30 grams to be relocated, it's probably never going to be. The best you can do in a situation like this is get the cross weights equal (LR+RF = RR+LF) and hope all the high speed sweeper corners are right hand.

IMO the f/r bias is more important than the l/r bias. Moving the weight forward and backward on the chassis has a far greater effect on the car having appropriate handling characteristics getting in the corner and making grip off the corner (slow corners) than having the car be exactly perfect left and right.

CraigMBA

iTrader: (22)

After posting, I found this older but still valuable article via X-ray. If you got this far, you should take three minutes and read it. It's clear, concise, and has pictures.

http://www.teamxray.com/teamxray/sho...p?file_id=2919

grippgoat

iTrader: (8)

Put the car on droop blocks, or directly on the setup board if you don't have battery tape / screws protruding. Make sure it doesn't rock at all. If using droop blocks, you can put a finger on each end of the block and rotate it under the car, to feel where it wants to rotate around. If the chassis is flat, they'll both feel like they're rotating around the middle of the car. If the chassis has a slight tweak, you'll be able to feel the front block rotating around one side of the car, and the rear block rotating around the other side. If they're both rotating around the same side of the car, that side of the car is heavy.

This should be done with battery in, and with a clean setup board, and clean bottom side of the chassis.

Note that many modern TC's have so much flex that they will sit flat on the board / droop blocks, but can still be holding a tweak or uneven flex, which will show up on track, and possibly when the sitting on the tires.

So, you've got the right front and left rear that are heavy. This is an indication that there's a suspension tweak, and is exactly the situation I was referring to when I said that scales don't tell you which end is tweaked. It's also the situation you can resolve by putting one end of the car on droop blocks (stacked up to match height of the scales as much as possible) with the other end on scales. Tighten the spring on one side while loosening the other side by the same amount, until the weights match. Repeat for the other end of the car, and then re-measure with all 4 wheels on the scales.

This of course assumes the car is balanced left to right. If the car isn't balanced left to right, then you may be able to get left and right to read the same with two scales and blocks, but when you put it back on 4 scales, one side will read heavier on both ends, and the ride height on side of the car will likely be higher. I don't really have experience in what's the best way to set things if the car isn't balanced left to right, because I've only run Mi4's with the motor clamp that makes left/right balance easily adjustable, and Xray T4s which have always balanced well with my electronics.

Also note that a mis-adjusted swaybar can cause a suspension tweak. If you're seeing a lot of tweak, it's worth disconnecting the swaybars to see if it's coming from the springs or the swaybars.

-Mike

CraigMBA

iTrader: (22)

Generally, the sway bar shouldn't ever get bent if you went to the trouble to get the preload (tweek) out of it when you built it. Anytime I have the shocks off, I always try to check this because you never know.

Everything else you wrote is correct. I think.

tmail55

iTrader: (61)

This thread is getting GOOD!!!!

Started offroad March 2004, added onroad May 2014 so this tweeking is some what new to me.

Know the blade tweek bit had a AE 12L (white chassis), have a 18" x 24" floor title as a setup board and now four $8 scales from ebay.

The Xray info is a GREAT read!!

THANKS!!!!!!!! :-)

CraigMBA

iTrader: (22)

You can still set tweek with a hobby knife. Just make sure if the car has the same tweek left and right. That is, if you are tweeked a little to the left front, make sure the left rear has the same amount.

tmail55

iTrader: (61)

So important and so simple!!!!!

grippgoat

>>>> a clean setup board, and clean bottom side of the chassis. <<<<

CraigMBA

>>>> If you really want a steering lock, turn the transmitter and the car on. <<<<

"It's the little things that makes a Difference" Stan Brower

Rich Panganiban

iTrader: (72)

Sorry to revive an old thread but I just picked up the Sky RC corner weight system.

I would like to resuscitate the conversation on balancing our RC cars.

I am currently running a Tamiya M05 in the TCS races. I already knew that the weight would be biased to the front left being a fwd car and the motor being mounted on the left. I would like to shift a little of that weight to the right rear and ultimately better balance the left & right weight distribution.

Any input would be appreciated.

mooby64

iTrader: (3)

Lead weights will be your best bet to adjust the balance. It is almost impossible to "Move" weight in a mini. Smaller and lighter servo's, esc's and receivers might help.

Rich Panganiban

iTrader: (72)

Thanks for that.

I am definitely going to swap what side my esc and receiver are currently mounted. That will help a bit.

I really like the fact that my Mini is within 5 grams of minimum race weight, which I think is a "plus" for spec racing. I would prefer to not add lead, but I think you're right since there's not a lot of weight to move around.

Boostinswifty38

iTrader: (6)

Balance the car side to side on pins to get a static weight balance. Doing it dynamically with suspension allows for more error. Spring rates (even if the same printed spring rate-they are not all the same!), spring preload, squareness of the car with caster and toe,etc all take an effect on the cars balance. Do it on balance pins side to side first, thenuse on one of these setup weight systems. Also measure Atleast ride heights and the spring preload you have at each corner from two like positions on the shock body-make sure the fronts match, and the rears match.

Skiddins

Haven't read every single post, but so far haven't seen anyone mention checking the pivot blocks aren't twisted.

I put the chassis on flat surface, with removed top deck.
Gently tap each corner of the chassis with one of your hex drivers, pretty close to where the droop screws are. If the chassis is flat, tapping it will make a 'dead' sound, if that corner is bent up at all it makes a much thinner 'tapping' sound (this sound seems a little more obvious if performed on a glass surface, but again, must be dead flat)
In extreme cases you can even see the chassis move down when tapped.
If you get a difference in sound, or get the movement.
Go underneath and loosen the bulkheads at that end, then try again.
If you still get it then try loosening the pivot block mounts and see if it goes away.

This is a process of elimination.
The most common bent alu part I get is the FR block (Xray) as this takes most of the strain during any sort of front crash.

If you think a particular block is bent, remove it and lay it on the flat surface and perform the 'tap' test on each end, rotate the block 90deg and repeat. Again, if the part is bent you'll see it rock slightly as well as seeing a gap under it at one end.

Rich Panganiban

iTrader: (72)

So after moving the ESC to the other side of the chassis, I was able to get the L/R balance pretty close. Still need to tinker with a couple of things but very encouraging thus far.

Thanks for the tips everyone.