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Old 07-05-2015, 10:21 PM   #1
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Default Build Complete: Tamiya FF-04 Evo

I wanted something different when I bought an FF-04, and boy, I sure got it.



Normally I lead with a picture of my new vehicle with the body installed, but as nice as the body looks, that's not what makes this car special; what makes it special is the fact that it's a front-wheel-drive car with a limited-edition carbon-fiber-and-aluminum chassis.

It was a really straightforward build; I was able to assemble most of the chassis during a weekend visiting my brother. I didn't have to tweak anything except for the gear cover, which required some trimming to clear the front-right camber link, but everything else just bolted together. Tamiya knows how to write good instructions for their kits. (of course, I say "write", but it was really all diagrams to avoid the need for translation, but the detail was still very helpful.)



Having the motor hanging off the front end of the car like that seems like it should ruin the handling, but it actually handles amazingly well. With no push from the rear axle like all 4WD and most AWD cars have, the car just goes exactly where the front wheels are pointing.

The axles, which you can see above, are double-cardan joints, which means they have two mirror-image pin-and-barrel joints stuck right next to each other inside a metal sleeve. The two mirror-image pin-and-barrel joints cancel each other's hysteresis when the wheels are turned, so the drivetrain runs incredibly smoothly, even at full steering lock.

Acceleration is traction-limited, of course, and the drivetrain is super-simple because there's no need for a slipper clutch -- if the drivetrain gets overloaded, the front wheels just spin.

Braking is also interesting; if you lock the front wheels, the car just skids in a straight line, because sliding friction is always weaker than static friction, and the rear tires still have grip while the front tires are sliding. So it's the exact opposite of a RWD vehicle that wants to spin around backwards if you lock the brakes.



Speaking of steering, this car has fantastic Ackerman. (also, I love the Max Speed Technology color-matched servo saver I found on eBay; it works great, and the adjustability means I didn't have to worry about whether it would work right with this specific car.) This is probably fairly common among touring cars intended for racing, but I personally have never owned an RC car with a steering setup like this, and it works fabulously.

On the off-chance you don't know what Ackerman is: The wheel on the inside of a corner is supposed to turn more sharply than the outer one so it can follow the outline of a smaller-radius circle than the outside front wheel, which this setup does an excellent job of accomplishing. Combined with the front-wheel-drive powertrain, the vehicle steers like it's on rails.

It's of course possible to understeer or oversteer with the right combination of too much speed and a sudden change in throttle input, but I have yet to spin-out the car without intending to. And this is my first FWD RC car and my first touring car that wasn't built for rough terrain, so it's not like I have a lot of experience to help me drive it well. The handling is still at least 90% the setup of the car at this point.



The rear of the car is totally different from what I'm used to; there's nothing going on here at all, just simple suspension parts and a couple freewheeling stub-axles. One interesting change is the kit came with a rear swaybar, but no front swaybar, because putting a swaybar on the non-drive axle of a 2WD vehicle tends to help it handle more neutrally. This car would probably understeer like crazy if there were no rear swaybar, or if both axles had swaybars, because the FWD drivetrain requires that the front tires maintain maximum contact with the ground at all times.



What you see in the picture above is actually the most difficult problem I had to deal with in this whole build: the ESC. I went through three ESCs before I got one that works the way I want. I originally used a $50 Dynamite ESC, which worked fine until I drove across some wet pavement and splattered some water droplets on the chassis. Then the ESC forgot that brake commands meant it should slow down instead of speed up. I returned that and got a $70 Castle Sidewinder 3, which would've been great except that Castle has apparently forgotten how to detect if a brushed motor is spinning (pro tip: a spinning brushed motor is an electrical generator), so if I let it coast for more than two seconds, it would engage reverse while the car was still moving forward. So that wasn't going to work. What I ended up with was this $100 Tekin FX-R (I still have the Sidewinder 3 that I need to sell, btw), which still isn't perfect, but it does a much better job of detecting when the car is coasting and won't engage reverse until the car is at least moving slowly.



The battery-retention mechanism is one of two things I actually changed from the original spec. This being a racing chassis, Tamiya didn't include a battery box, or a battery clamp, or even a battery strap. What they included was instructions to go buy a roll of battery tape, which didn't appeal to me at all. So instead I went to my hobby shop, got a long Velcro strap to hold the battery in-place, and used some leftover foam tape included with the kit to make the surface the battery sits on both flat and high-friction. As long as I make sure to tighten the Velcro strap as much as possible, the battery stays right where I put it.

The other thing I changed, you can actually see in the pictures of the front and rear axles above. I installed optional longer lower-eyelets on the front shocks, and I slightly unscrewed the lower-eyelets on the rear shocks and moved the lower mounts as inboard as possible, to increase the ride-height. So now it has ground clearance of somewhere around 1/2", lower than my RS4 but still high enough to survive driving on pavement covered with pebbles without having the pretty underside all torn up.

Speaking of the pretty underside, here's what the underside looks like:



That's a nice chunk of carbon fiber. Stiff as all-get-out, too. The aluminum chassis on my RS4 *might* be stiffer, but it's way heavier. This chassis weighs almost nothing; when I install the motor, the balance point moves from just barely front-of-center all the way up to the steering posts.

Okay, and now for some pictures of the body I ended up putting on it:









(you might notice the wheels and tires look different in these pictures; I took them back when I was testing foam tires, and I didn't feel like re-taking them just because I switched to rubber tires.)

That body was death by decals, but it sure looks good. I'm not confident the race-spec decals will look good for much longer, since the body has so many curves it was nearly impossible to get the decals to stick, and even minor scrapes causes the decals to start peeling away, but even if I have to remove the race-spec decals it will still look great. I'm glad I chose pearl-white instead of gloss-white; the pearlescence gives the paint a nice sparkle.

Last edited by fyrstormer; 07-05-2015 at 10:48 PM.
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Old 07-06-2015, 02:17 AM   #2
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Awesome!
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Old 07-07-2015, 01:40 AM   #3
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Thanks!

It's funny, after a talk with a couple friends, I'm now entertaining the possibility of a minivan body, just so I can say I built an RC minivan.
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Old 07-07-2015, 03:42 AM   #4
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That sounds great! Maybe I'd do the same in the future. But where can those bodies be found?
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Build Complete: Tamiya FF-04 Evo-7497_img_2150ahp-3p_800_600.jpg   Build Complete: Tamiya FF-04 Evo-rc-custom-body-contest-63.jpg   Build Complete: Tamiya FF-04 Evo-rc-custom-body-contest-45.jpg  
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Old 07-07-2015, 03:45 AM   #5
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Looks great and that Honda body is awesome.
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Old 07-07-2015, 03:53 AM   #6
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If I get around to buying one, I'll paint it electric blue and mount it on my TB04 Pro 2 with 6mm offset wheels.
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Old 07-07-2015, 11:18 AM   #7
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Video please...
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Old 07-07-2015, 12:20 PM   #8
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Quote:
Originally Posted by SagadSetup View Post
That sounds great! Maybe I'd do the same in the future. But where can those bodies be found?
ABC Hobbies makes a Honda Odyssey body kit.
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Old 12-07-2015, 07:45 PM   #9
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Hi can you tell me what is the part number or from witch tekno model it came from that you put on your ff04 evo I am in search of that kind of thing it give me headache to fit my battery.Thanks have a nice day.
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Old 12-07-2015, 07:54 PM   #10
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hi what is your combo esc/motor and the gear ratio could be great too .Thanks have a nice day.
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Old 12-07-2015, 11:10 PM   #11
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Don't bother with the velcro strap, it doesn't hold the battery tight enough. The battery fell off the chassis every time I ran this car. Tamiya Glass Tape is the only solution that works well.

I used the stock gear ratio with a 12-turn brushed motor and a brushed ESC. It didn't work very well, because the 12-turn motor made too much power and spun the wheels too easily. If I were going to build this car again, I would use a 27-turn motor, or maybe even a rock crawler motor, with the highest gearing I could fit.

By the way, Tamiya pinion and spur gears are Mod 0.6, so you'll have to buy Mod 0.6 pinions to change the gearing.
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Old 12-17-2015, 10:26 AM   #12
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Hi again this is because I got the same chassis with a 102t/44t gear ratio and my castle side winder 3 4600kv motor at 80% of power and is was near freezing zero outside and I can feel the motor heating .now I am 6.02 about the gearing should I go for 7 or get lower like 5.8 thats where I am I got the setup I want it drive perfectly but it seem because of the heating motor that I got the wrong gearing .Thanks alot for the advice.
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