Technically you are both right.

Your test is legitimate as long as you placed all of the batteries in the same spot.

To make it as accurate as you can, the batteries should be placed where they normally would be. This would better simulate real world conditions.

I would guess that your numbers would change but the end result wouldn't.

Edit: if you really wanted to nitpick, a person could argue that the suspension wasn't readjusted to accommodate the added weight.

A 1S lipo, a 2s lipo, a 6 cell nimh, and a 12 cell nimh are all very different. The test would need to be performed with all batteries secured in a manner that is realistic in actual use. Even then the test is to determine the battery configuration effects on adhesion where weight is just one factor in the difference rather than the sole factor. Cg height absolutely affects the end result as a higher cg will lose traction first.

Agreed and I still believe the most accurate test won't use a car at all it would be a tire held perfectly 90* to the test surface with the weight being added to the exact center of the tire. It takes a lot of time and possibly money to make a test like this perfect, time that i would rather put somewhere else (ex. Racing) for the purpose we need I believe this to be sufficient, in fact the curve is most likely flattened because I was adding stick packs to the higher side thus making it have a l/r weight balance closer to 50/50 when angled if you decide to change the test and play with it more that is up to you, ideally this would have been done with a 2wd buggy so all the weight was added to the centerline of the chassis but I do not currently own a 2wd buggy as I'm just getting back into racing and I like 4wd more.

I absolutely applaud the effort to test this and I don't want to take anything away from that. As I've pointed out several times though, changing only one thing rarely results in only one thing actually being affected.

Anyways to sum op the past couple of pages I think after tuning roll centers you need to adjust antisquat because weight moves. Does that about sum it up:lol:

It would be real neat if we could dynamically test the adhesion of our tires, suspension setup, and weight distribution. For 1:1 scale I think they perform what's called a skid pad test. A test vehicle is driven either in a circle or a figure eight. They then measure the G's generated which reflects the adhesion of the tires.

All we need is a G meter small enough to stuff in our rc cars and a way to record the data. EagleTree Systems offers a setup but it's pricey.

m.motortrend.com/wot/best-handling-cars-weve-tested-motor-trends-top-figure8-performers-3095.html

Actually if you draw out a circle for the car to follow and you can find the speed of the car, you can use the cars speed, the circles radius, and the cars static weight (I think)to calculate g force. I've got the formula somewhere if anyone is interested in it.

Edit now that I think of it I don't think you need the cars velocity, I think you need to time how long it takes to complete one revolution

There's somewhere a tutorial about doing a mini-z tire testing machine. I'll search it and post it here.
Oh it was in my bookmarks. http://www.mini-z-guide.com/tires.htm

Just wanted to say that im sooooo happy that this thread has sparked up again:), I first came across it about 5-6 months ago and couldnt stop reading it, and then it just went dead for a while:cry:. fredswain, (and the others that have made helpful posts) thanks so much for all your input here, it was awesome to find a thread that is helping people understand all these concepts and how/why they affect their cars. Im a total gear head and LOVE all this technical stuff!!!

Can some one elaberate on bump resistants vs PAC I would like to Beter understand why I drop 2sec of my average lap times just by going to mip pistons with no pac

Hideeho
Most of the people on this thread have one. I'll bet a good number of the posts to this thread were done with one.

The Iphone has a fairly sensative g meter & there are several programs out there to do exactly what you are wanting. There are several apps that will gather this info into data, including some that will generate a track map.

Either with or with out an Iphone/g meter, a good way to test what added weight does to handling would be to drive in circles. Use the EPA on the transmitter to set a base speed for driving at a set diatmeter with the wheels at full lock. Once you have set a circle the car drave around all day long at never slide out of at full (EPA adjusted) throttle, start adding throttle until it eather slides or pushes out of the circle. I.e. at full lock & 50% EPA the car won't spin or push out of a 4' circle. For the 1st test add 1% at a time until the buggy exits the circle. Note down where the EPA was & reset to the base line. Add some weight & start going around & adding EPA until the buggy leaves the circle, note the EPA & reset again. Repeat, repeat, repeat until the weight is obviously WAY excessive. After going as far as you wish with the weight, I would recommend doing it 1 more time with no weight again to verify nothing has changed dramaticly that would alter the results.

For consistancy I would think doing this on very smooth concrete, like what you probably have in the garage, would be best. This won't be a "real world" comparison to what we experience on track, but that is not really desired for this type of test. Inconsistancies in the surface, changing water content during the test, wearing down of the surface of the test area will all lead to skewed results. The tires probably need to slicks to avoid wearing out pins on offroad tires & changing the results. Circling left & right would be nice also to remove any inherent weight bias. It would also be interesting to see the difference between adding the weight up high vs down low (added to the top brace of a b44 vs added to the chassis). Similarly adding weight in the middle of the car vs to the ends of the car.

Got to thank you guys all the help you gave me.
Now my low-spec 2wd buggy is fun to drive,no more plow nor occasional mid corner spin out. Still not 100% there but now I have quick turn-in, corner speed and on-power steering. The track got 2 weeks of rain and because of inexistent draining pipes ruts are everywhere except the main straight, small stones and sand on bends and this buggy just powers and steers on any condition. Only non-stock parts where shock oil and RB5 pistons. Only "issue" now is too much steering off center (I'm dialing out dual rate) and average rear traction(attributed to really worn Double Dees). Expect some photos from track tomorrow :)
Wear mark @ approximately 0 degrees camber.

Any one on PAC

MIP Bypass 1's essentially makes your shocks dampen only in one direction. If you have the thin disks on the bottom, you soften up the dampening in the upward travel of the suspension, and vice versa if you flip it over.


So...

With the disks at the bottom...the setup becomes softer absorbing shocks. The car will tend to bottom out easily with a slow rebound.

With the diskes at the top....the setup becomes stiffer absorbing shocks. Packing will occur sooner since the disks block the holes as the piston moves upwards.

I have these on my TLR 22, and they are very tricky and difficult to setup. Use Fredswains' method of balancing out the suspension to setup them up properly.....the disks just adds another variable to adjust, and they are difficult to get to :-(

A few months ago I saw a blurb on a new shock design that does away with packing. By the way, as I've understood it packing occurs when the piston is traveling so fast that the fluid (shock oil) does not have enough time to get out of the way. At this point the piston's motion basically stops and this can occur along any point of the pistons travel distance. So at times you might only be getting partial shock travel that can upset the weight transfer of the car and thus causing you to lose control or cause the tires to lose contact more often. Anyhow these new type of shocks have oil passages that provides the oil another escape route, and packing never occurs. Unlike the MIP's the fluid action is progressive. I hope I got that correct since I'm going from memory. Hopefully someone can dig up the blurb.

Are you talking about ADS