I've been working on dialing in my friend's Evo2. I think I've got a really good setup for smooth asphalt. I will update here when I get it all typed out.
Front:
40W, Tamiya yellow, no rebound sponge
center hole for shock, 3mm spacer under inner upper link
gearbox shaved and 1.5mm spacer underneath rear hingepin (less caster)
no swaybar, 6mm droop with TC3 gauge
wheelbase spacers fwd (arms back)
Rear:
30W, Tamiya yellow, no rebound sponge
center hole for shock, 4mm spacer under inner upper link
outside hole on hub carrier
1 dot rear hingepin block (414M)
stock swaybar, 7mm droop with TC3 gauge
wheelbase spacers fwd (arms back)
Tires: CS32R
One of the primary problems I see with the Evo 2 is weight distribution and overall weight. First of all, the thing is a porker. If you get rid of the old TB01 style battery tray and use strapping tape, you can run lighter electronics like a GM, LRP, or KO ESC and still come up 50/50 L/R. It also drops off over an ounce from the weight. After that, do whatever you can: Ti screws, etc to get that thing down to 53 oz. I remove the center post and the 2 central screws in the front top deck to get a little more chassis flex.
The next order of business is F/R weight distribution. The stock settings of the Evo 2 are something ridiculous like 6X/3X. By running the arms full rearward in front and rear the ratio is something like 5X/4X. Not optimal, but still better. One of my friends is experimenting with the 414M rear arms, but they make the wheelbase BARELY illegal (261mm) even in the forward setting (Same guy is also using 414M caster blocks with torque rods - something for me to try next). I would rather shave the rear section of the Evo 2 arms to get a little more room for adjustment. The other benefit of this is that the front universals are almost straight and the rears are closer to being straight. This greatly affects power transmission/efficiency, outdrive and universal life, and handling. This is one reason that I feel that the Evo 2 drivetrain is inferior to my mutant TB01. Like the Yokomo which has forward swept universals, the outdrives will wear very quickly if not lubed. If an outdrive develops a notch, CHUCK IT. Even the slightest notch will make your car hop under acceleration. I would still like to rework the gearboxes to see if any more efficiency can be freed up. Rear diff maintenance is CRUCIAL on this car. The driveline is so brutal that diffs don't even last that long in STOCK. Using the old David Jun trick of a Tamiya 5x11 bearing will make things last longer because the thrust goes out before the rings. Only use Tamiya bearings for this application because even Boca bearings do not hold up as well under the sideload.
The main problem that I found with the Evo 2 was a lack of corner speed. The car just wanted to stop and pivot instead of carve. Adopting Surikarn's method of raising roll-center, the chassis becomes more progressive at the limits, breaking away smoothly instead of suddenly. Take out a little caster for sharper turn-in. Rear swaybar for the rear to come around a little harder and get rid of some of the on-power looseness. Bingo. It could still use some tweaking, but it's not my car.
