IslandBwoy

LOL. LOL. LMAO! THAT WAS A GOOD ONE.

robk

iTrader: (22)

Hmmm, Ill factor = bitter after an ESL class??

STLNLST

iTrader: (32)

Man do I have one hell of a response but I'm taking a back seat to this because I was the one that wanted it squashed. I just feel that if you don't like being told it's 8:30......DON'T ASK WHAT TIME IS IT!!!!!

HarshGuy

iTrader: (6)

What time is it?

STLNLST

iTrader: (32)

So cal homies are coming up this weekend. Too bad you gotta miss it. Should be fun

HarshGuy

iTrader: (6)

Well look at it this way, at least you get to move up a spot

STLNLST

iTrader: (32)

This weekend will be an eye opener for sure. Ya'll stay tuned.

IslandBwoy

ANy of you guys run the futaba s9451 by chance? The guys sold me on this servo over my regular airtronics and had nothing but praises to say about it. but they run RDX's.

And how critical is the rare brace on the EC? The one that replaced where the rear bumper would normally be mounted on the MI2? Apparently my kit was missing 2 parts.

STLNLST

iTrader: (32)

On the regular MI2 I never ran anything in that spot. I had my body posts on the shock tower so the rear bumper wasn't put on. It shouldn't make that much of a difference. If anything it may act as a reinforcement brace of some sort.

IslandBwoy

K. Im thinking it shouldnt make much of a difference either but wanted to be sure. Maybe i can convince Paul or Adrian to sell me one of theirs before they goes back home from the birds.

Fred Perkins

iTrader: (264)

Ok, Im sure this has been answered before, hell, I probley asked it!! but to get the rear end to rotate more I would raise or lower the inner piviot/roll center?

cornerspeed

Raise it(roll center) so, the rear lower arm pivot blocks up, and/or lower the rear camber link on the tower or shim up the ball stud on the hub carrier for the camber link.

Fred Perkins

iTrader: (264)

Thats what I thought! Thanks

BATT_MAN

To get more roll, you want to RAISE the inner pivot.

There is a misunderstanding in the r/c lingo...
When you LOWER the camber link at the inner pivot, you RAISE the roll center. The steeper the angle of the camber link (toward the center of the car) the HIGHER THE ROLL CENTER (you raise the RC...it comes closer to the CG of the car)...and less roll.

To get a car to roll more you LOWER THE ROLL CENTER. To lower the roll center you RAISE the camber links (raise them at the inner pivot). The higher the roll center the lower roll you get (the closer to the CG, the lower weight transfer and roll). To achieve more roll you want the weight transfer to take effect through the springs and less through the roll center. As the roll center approaches the ground, yoy develop more transfer through the springs. At ground level, ALL WEIGHT TRANSFER TAKES PLACE THROUGH THE SPRINGS.

You can also increase the length of the camber links to achieve more roll through the corner.
By moving the camber link to the outside position on the hub carrier you gain two things.
A) You increase the length, thus more roll through the turn (once you are in the turn) The chassis rolls for a prolonged period.
B) If you do not add any spacers at the hub, you will LOWER the roll center by a few thousands and gain more roll.

You do not need huge adjustments to change the RC position.

If you decrease the track, the chasis will roll more. Take out the spacers in the rear hubs (and front too if needed) to achieve more roll.

Shock position also causes differences, you can lean the shocks and achieve a slight increase in roll.

The Mi2CE comes with 1.6mm raisers for the hinge pin carriers. If you lower the hinge pin carriers and keep the same chassis clearance you will LOWER the roll center.

By lowering the rear end of the car by 0.2 to 0.5 mm and that will also lower the RC and cause more chassis roll in the rear end. This will change the angle of the A-Arms and camber link.

Camber, tire shape, well there are many things you can do to add chassis roll.

The Mi2EC is under weight so you can add more weight at the rear corners. Contrary to popular believe, this will cause the rear to roll more. Roll is weight transfer, so if you bias the weight at the rear end you can gain weight tansfer, thus more roll.

One critical thing with FOAM tires is the contact patch and camber. You need to see how the tire contact patch changes as the chassis rolls. I have found that if you trim your tires at 1.5* from the center of the tire towards the edge it will help the car roll and go at faster speeds through the corner.
When using pneumatic (real cars) or rubber tires, the tires give and add to the actual chassis roll. This effect is minimal with foam. One solution is to trim the tires like I mentioned above. BY trimming them from the center patch line to the outside at a 1.5 to 2.5 degree you will make it easier for the chasssis to roll and carry speed through the turns. Excessive trimming is contraindicatory and will reduce traction and stability.
The idea behind this is to allow the tire to turn a few degrees without adding undo pressure at the edges. This is a modification that if used the right way will change the dynamics of the car through the turns.

One more thing, the Mi2EC has a very stiff chassis, so in order to gain more rear roll you will have to add some front roll. The front will need to roll more in order for the rear to roll. (can some of you see now why in r/c cars chassis flex is necessary under certain circumstances) Although for foam we do not like the chassis to flex, if you need to add roll at one end of the car (depending on how much) you need to do it at both ends to achieve it. The entire chassis will roll the same amount, front and rear...

When we measure chassis roll, we look at the overall roll since a car rolls through the center of gravity (we measure the roll in degrees). You can have different front and rear roll centers, and finding the right balance between them is the trick. If you draw a line from the rear RC to the front RC and cross it at the CG, that is the point where the forces are taking effect on the chassis.
For touring cars you can have as much as 2.5 to 3 degrees of roll. For example, in F1 cars, we limit roll to 1 degree.
You can simulate the chassis roll by placing thecar on a flat table and applying a force equivalent to 1.5 to 4 times the weight of the car through the CG. Watch the chassis roll and take the necessary measurments. A critical thing to look for is the TIRE CONTACT. You want to make sure that the edge of the tire/wheel does not LIFT the chassis (when the chassis rolls). If this happens, you may get errotic handling, drag, and tire wear. That is why I recommend trimming the tires. If you ever look at a racing tire, you will notice that they are not flat.
Foam tires have a flat foot print and it does not help. Contouring the shape of the tire can help you avhieve greater speeds through the turns.

As any one can see, there are many changes that can be made to achieve this. Some work better than others, and only by trial and error you will find which one works better for you. The thiong to remember, NEVER do more than one change at a time, and if it does not work, return the previous setting and try something else. Once you figure out how this works, then you can do multiple changes to achieve what you want.

I hope this will help.

Wirre

I've been running an S9451 for about 9 months now (first mi2 then mi2ec) and it's working perfectly.

I doubt the rear brace does that much of a remarkable difference, I haven't noticed any difference when removing it / mounting it. Though remember it's a part of the entire calculation when it comes to designing the car, so it is probably valuable for the chassis to work properly.