On our medium-high grip tight indoor carpet track we run a little harder damper oil and HPI silver springs on our TRF418 and with the center screw in on the top plate to allow for less flex.

Others run a little softer damper oil and Yokomo springs (softer) and the center screw removed, compared to us.

Guess its about driving style, but to us the softer setup with more flex provides maybe an easier car to drive, but also a lazy car, that tends to "hang" in the carpet in med-high grip situations.

The "harder" setup, on our track, provides in our hands, a car that rotates faster.

I currently run a Losi Type R touring car which is very stiff and doesn't seem to be the worse for it. Watching the car go around the track it looks largely the same as other cars. If there is one handling characteristic I would pin on the extremely hard chassis, it would be that the car has a much harder low-speed rotation than most cars where the car pivots right on the nose. This can be adjusted, of course, and I do tend to run a little more front sauce than most TC racers for a given traction level, but I like the car and would not consider the stiff chassis a handicap.

Chassis Flex now there is a subject near and dear to my heart.

What chassis flex does is allow you to change the stiffness of a spring that connects the front and rear suspension. The effect being to either soften or stiffen the overall response of the chassis and affect the distribution of the weight transfer between the front and rear. It does absolutely nothing to increase or decrease the total weight transfer from the inside to outside wheels. What it does affect is how that weight transfer is distributed between the front and rear tires. Depending on how you have your front and rear suspension setup that can be a good thing or bad. So stiffer chassis the more connected the front and rear suspension are and the softer the less… Flex also affects the overall response, stiffer the quicker the car responds, softer well you get the idea.

The biggest reason chassis flex is needed is because these cars we race are so complex most racers do not fully understand how to adjust the handling by changing springs, anti-roll bars, caster, camber, camber gain, roll centres…. There are more than enough ways to adjust the handling using what I just mentioned without throwing in another variable. In reality you can get a much better handling car by leaving the flex alone and adjusting the suspension geometry to achieve the desired result. IMHO

It would be interesting to build a car and tune it by chassis flex alone. I have a hunch that a 4wd touring car could be made into a competitive racer without touching the geometry and shocks.

I thought that another big problem is that our suspension and steering has too much slop compared with the real thing.
On the other hand, try removing all the slop, you'll end up with an undrivable car.

reminds me of the times where I went crazy trying to get all the slop out of my M03. The chassis is pretty stiff for it's size too. After all that, I came to the conclusion that the minis run best with all that slop :lol:

The key seems to be to let the chassis and shocks work together for the surface it is running on. If the chassis reaches its max flex during cornering, the load to the suspension will increase suddenly, and may go beyond the tire's grip. Too soft, and the suspension will not be able to put down the proper load on the tires at the right timing.

Inpuressa, your thoughts on the stiff TRF418 and a flexible chassis car like the ARC R10?

I drove my 418 and a few buddies at my track have the ARC which I drove too. They have different handling characteristics but both handle fantastic, just different feels. Installed the Samix on the 418 and curious how it will be.

imo, the 418 and having the samix conversion will give you the full spectrum to adjust to many situations. I should have gave the stock 418 chassis more time with the 17.5 class on high grip. The samix allowed the car to be driven hard. With faster motors 13.5 and below, the flexibility of the samix should make the car easier to drive. The samix 418 should feel similar to the ARC.

Our asphalt track is a small technical layout, but enough grip to run 1/12th. If the condition is right, we even experienced traction roll. In conditions like this, it seems that a stiffer chassis can get better lap times. That's why I am experimenting on the ARC to get the chassis a little stiffer w/o resorting to an alum chassis.