TinyRC.com - XMODS, XMOD, Micro Flight, ZipZaps, ZipZaps SE, Bit Char-G, MicroSizers, TTTT, Plantraco Desktop Rover, SuperSlicks, Digi Q, Forums, News, Pictures, Parts, and Shop
Forums, XMODS, XMOD, Micro Flight, ZipZaps, ZipZaps SE, Bit Char-G, MicroSizers, TTTT, Plantraco Desktop Rover, SuperSlicks, Digi Q
XMODS Hop-Ups, XMODS Parts, XMOD Hop-Ups, XMOD Parts, Bit Char-G Hop-Ups, Bit Char-G Parts, MicroSizers Hop-Ups, MicroSizers Parts

Go Back   TinyRC.com > Blogs > Color0's Micro RC Blog

Color0's Micro RC Blog -- A technical brain dump from the mind of yours truly...
Rate this Entry

Thinking to Tune

Posted 03-21-2011 at 12:10 AM by color0
Updated 03-21-2011 at 05:46 PM by color0
Good racers know that a good racing setup has to cater to two things in order to win: the driver and the track. No stone can be left unturned either, if you miss a single area where you could improve, you won't be extracting the maximum performance out of your car and it might even cost you the win.

Now, I'm not a frequent racer -- I'm a college student who barely has enough time to go out to eat dinner, going to races usually means skipping meals and subsequent all-nighters to finish all my homework. So when I do go race, I better hope to the powers that be that I can get a good setup figured out on my car, because my driving sure isn't going to be perfect!

So to demonstrate how I get to a good setup, let me take as an example 1) my personal driving style and 2) the RC Kenon Mini-Z track in Baldwin Park, CA (USA).

1) I know how I drive for the most part: smooth on the steering, but not on the throttle. I roll the wheel left and right perfectly fine, but I like to pitch the car back and forth (weight transfer) using the throttle. I don't control my car's trajectory using speed, I control it using weight transfer -- they're not the same and you can't treat them like they are.

2) RC Kenon is notoriously difficult to set up a car for: the track has the two distinct properties of being both very grippy AND very bumpy. Narrow and short cars are at a double disadvantage, you will not only traction roll more but also will be more affected by the bumps and jumps on the track.

So here's one solution to the problem (a little bit out-of-date, but a good example nonetheless while I work out my new setup).









It's long (98mm), it's wide (+2N/+3W), it's low (<45mm tall!), and with some modifications to the GT-R body, it's perfect for a track like Kenon.

Everything about this car setup is soft, to deal with Kenon's bumpiness. The front springs are PN Racing Oranges, the softest available; the T-plate is a PN G10 #3, the 2nd softest; The tri-shock system has 3racing AWD Black springs (the softest) on the sides and a PN Blue (the 2nd softest) on the main damper. During testing I observed that my car, on these springs, was definitely the smoothest car out there, absorbing all the bumps and ignoring tile gaps while flowing from one corner to the next. Seeing this gave me the confidence that I was doing my setup right.

Many people recommend running a harder spring on the main damper, for increased rear traction right as you get on the gas, but recall that I utilize weight transfer heavily: the soft main spring buys me some time to decide where to point the car after hitting the gas, allowing me to shoot out of the corner under traction or throttle steer a little to pick a tighter line. The throttle steering characteristic, for its part, allows me to hit the gas earlier, which nullifies the need for increased rear traction at the corner exit -- by mid-corner I'm already back on the gas, that's just the way I drive.

The wide stance helps me avoid traction roll on the grippy RCP, but during testing I found my car extremely close to traction rolling due to the sheer grip available at Kenon. So to give myself an extra safety margin I raised the PN tower bar by 0.2mm. This has the added benefit of reducing my static camber to 0.5deg and reducing the camber gain upon suspension compression, which matches the wide, low GT-R just perfectly -- even though the car is so softly sprung to promote mechanical grip, it is still so inherently low that it corners quite flat. Toe was left at 0deg to reduce tire drag in a straight line (important for 70t classes), and caster was set to 2deg for some stability without sacrificing turn-in response.

Front tires (PN 20 slick) were trued to 23mm; the shorter sidewall gives better steering response, and the reduced rubber mass lets the tire warm up better during the race (it's winter in SoCal, it does get a little cool!), which gives you more grip to work with. I tried truing the front tires to 24mm in a subsequent race, and although the car was still OK fast, there was definitely a little bit of a push that could not be driven around. Tire wear became negligible at 24mm though, so keep that in mind if you're going to an endurance race where every little bit of wear life matters!

Rear tires (PN 8 slick) were trued only to remove the top coating layer; leaving the soft rears larger saves them from overheating, and allows the sidewall to flex a little more, letting you lay down more power earlier in the corner. For even colder tracks, instead of altering the rear tire diameter, the smarter choice would be to pick a softer compound, such as PN 6 slicks/radials or Kyosho 20 slicks/radials.

Even rim choice matters, btw: I'd been using the PN Delrin rims for a long time just because they're indestructible, but this time I pulled out all the stops and used PN's ABS plastic rims. The material is a little softer and the wheels flex more, to deal with bumps, and in general I feel that they produce more mechanical grip than the Delrin dishes. They're also lighter, which means you can accelerate and decelerate faster (very important for 70t motor classes).

Gearing is an area where I seem to disagree with most of SoCal's Mini-Z racers: on a short (7.6-sec fast lap), tight, technical track, I feel it's most important to gain time in the infield rather than making it up on the straight. Passing people on the straight in Mini-Z is tough, since you get all of 1 second to go down the straight and pass. I find it much easier to pass in the corners, and so I geared my car one tooth lower than everyone else, at 11/53 (64p gears), giving me more power coming out of turns. Sure I hit top speed early down the straight, but it wasn't significantly slower than anyone else and I more than made up for it with corner exit acceleration.

I'm sure I'm not the first to realize this but the paint scheme itself is important to your performance. Mine, with dark extremities and a white front, lets me ignore the front splitter and rear fenders, letting me focus on holding the tightest line possible and not overestimate the clearance my car has with the walls. Trust me, it does work.

You may be wondering why there's no aero on this car when I talk so much about it. To be frank, I had no time to implement the aero on this shell before it was already race day, lol... the only thing I could do beforehand was to cut out the rear bumper to the PNWC legal limit. The lack of downforce meant I had to drive carefully, but that didn't stop this car from taking the overall win (3rd-1st-1st) at Kenon's club race. I was the only Stock driver in the 7.6xx range, laying down 7.69, 7.658 and 7.652 (the new Stock record) over the course of the night, and not counting crash laps I was able to hold an average lap of roughly 7.9. Note that these times were set with no aero aids (other than the useless stock GT-R wing), whilst almost everyone else had a rear wing of some sort (many Reflex wings on the track that night). I was able to take the win without aero due to the car setup being extremely efficient, and optimized to both my hands and Kenon's track surface. As you can see from this article, there are a lot of fine details to cover, and in the end a good setup is all about attention to detail -- you get every part of it right and you will reap the rewards come race night!

As a final note, huge thanks to Dr. Kustom for painting me the new GT-R -- the new paint scheme really draws heads at the track and as I mentioned before, it improves my performance. Cheers my friend!

Setup summary:

Front end:
  • PN Reverse Kingpin Front Suspension
  • Tower bar raised 0.2mm
  • PN steering knuckles, 0.4mm shims above knuckle, 0.5mm below
  • PN MR03 Orange springs
  • Custom spring holder
  • 0 droop
  • 0 toe
  • 2deg caster
  • 1deg camber arms -- ~ 0.5deg static camber
  • 1.5mm ride height
  • PN 20mm ABS rim +2N
  • PN 20deg slick tire, trued to 23mm
Rear end:
  • PN FRP T-plate #3
  • PN Reconfigurable Motor Pod (98mm)
  • PN Tri-shock
  • Side springs: 3racing AWD Black (soft)
  • Side damper grease: Kyosho 15000
  • Main spring: PN Blue (2nd softest)
  • Main rebound spring: PN MR02 Yellow (hardest)
  • Main damper grease: Kyosho 15000
  • Lightweight differential: 53t 64p PN locking spur, 5 balls
  • PN 70t Stock motor: 11t 64p pinion
  • 2mm ride height
  • PN 20mm ABS rim +3W
  • PN 8deg slick tire, trued lightly to scrub surface coating
PCB/ICS:
  • 3x2 AN0113 FET stack
  • GAIN: Strong
  • SPEED: Fast
  • PNCH: 2
  • D.BAND: Narrow
  • DUMP: Over
  • D.FREQ.: 1.2kHz
  • NUTRAL: Mid
  • VINERTIA: Off
  • BAKTIM: 1
  • ST.GAIN: 250
  • TH.GAIN: 250

Tx settings: KO Propo EX-1 UR:
  • Steering Travel: 70
  • Steering Travel: L70/R70
  • Steering Dual Rate: 85%
  • Steering Subtrim: R2
  • Steering Trim Rate (step size): 2
  • Steering Config: Normal (not reversed)
  • Steering Punch: 0%
  • Steering Curve: 0%
  • Steering Quick-Response: OFF
  • Steering Speed: L100%/R100%
  • Throttle Trim: 0
  • Throttle High Point: 60
  • Throttle Brake: 40
  • Throttle Subtrim: 0
  • Throttle Trim Rate (step size): 10
  • Throttle Config: Normal (not reversed)
  • Throttle Punch: F0%/R0%
  • Throttle Curve: F0%/R0%
  • Throttle Quick-Response: OFF
  • Throttle Speed: F100%/R100%

Next week I will be sure to have the results from the TWO RCX races we had this past weekend -- a lot of updated information and very pertinent to our discussion!
Posted in Setup Guides
Comments 0 Email Blog Entry
Total Comments 0

Comments

 

All times are GMT -5. The time now is 04:51 PM.


Powered by vBulletin® Version 3.7.3
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Mini Inferno Sale - Up to $85 Instant Savings!
Micro-T Hop-Ups
RC18R, M18, Micro RS4, Mini-LST, TamTech-Gear, Minizilla, RC18T, RC18B, RC18MT
shop.tinyrc.com Products
Tiny RC Community News
[03/17/10] Kyosho Mini-Z F1 MF-010 SP2... : The Kyosho Mini-Z F1 MF-010 SP2 Carbon Limited ASF 2.4GHz Tx-Less Chassis Set - more»
[10/23/09] Kyosho Mini-Z MR-03 In Stock! : The Mini-Z MR-03 (http://mr-03.com) is now In Stock and Pre-Orders are shipping! - more»
[09/06/09] Labor Day Savings - $5 Off... : Labor Day traditionally marks the unofficial end of summer - but we're not ready to let go! So, we - more»
Mini-Z, Mini-Z Racer, MR-02, MA-010
M18, M18T, RC18T, Mini-LST, Mini-T, Micro RS4, XRay, 1/18, 18th scale
XMODS, XMOD, Micro Flight, ZipZaps, ZipZaps SE, Bit Char-G, MicroSizers, TTTT, Plantraco Desktop Rover, SuperSlicks, Digi Q
Mini Inferno, Mini Inferno ST, half EIGHT, 1/16, 16th scale
Epoch, Indoor Racer, 1/43, 43rd scale
E-Savage, eSavage, eZilla, e-Zilla, HPI
Robots, Bots, Bipeds, Wheeled, Manoi, Roomba, NXT, Lego, Hacking
Crawling, Crawlers, Micro, RC, Losi Mini-Rock Crawler, Duratrax Cliff Climber
Kyosho Minium, Caliber 120, Minium Forums
Mini-Z Hop-Ups, Mini-Z Parts, Mini Inferno Hop-Ups, Mini Inferno Parts, M18 Hop-Ups, M18 Parts