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This is a place to share knowledge related to 1/12th scale racing. It is not to be used for conversations.

KITS:
Click links to go to manufacturer product page. If any are missing please add them!

TIRES:
Pre-mounted tires readily available in the US:
Pre-mounted tires readily available in the Europe:
  • Hot Race ??

Gluing your own donuts:
https://www.youtube.com/watch?v=hm7z1rz-74s - Special thanks to Edward Pickering!
Truing tires:
https://www.youtube.com/watch?v=8wqHOLWq6Uc - Special thanks to Edward Pickering!

The following information came from HERE, with some editing and information added. Thanks Christian!

THIS MAY NEED UPDATING FOR THE NEW BLACK CRC CARPET

Brands:
BSR, CRC, Jaco:
Pro One is no longer selling to the public, but it and the brands above are all mounted by BSR and use the same foam. The nomenclature of the BSR vs Jaco/CRC is a little different in a few instances but is otherwise the same. The BSR foam consists of three families, and can be identifed as synthetics, naturals, and blends.

Synthetics - The old school, light weight, easy to true "dry feeling" tires. These include tires like CRC/Jaco Yellow (BSR White), Black, Gray, etc. These tires offer the highest wear rate and lowest grip. Many racers continue to use these nder high bite conditions.

Naturals - These tires are usually the best alternative for low bite and asphalt. They include Pink, Magenta, Double Pink, Lilac (BSR Team Purple), Purple, and other tires. These tires provide a ton of grip, but tend to get sticky in high bite conditions. This rubber does not wear as easily, and the cars will pick up gunk and fibers from the carpet under most high bite conditions. This is especially bad if the humidity is high.

Blends - These are the tires most people run today. They were initially called "JFT foam" by some, as it was believed that the tires were the same as the JFT tires. We can divide the blends further into two groups: high rubber and low rubber content. The high rubber would be the new rear Orange and Red from the BSR family, and the low rubber would be the Green and Blue varieties. When, asked about the difference, John Foister from BSR Tires said they came from the same "family" of foam, but they offered different grip. According to John, the Green/Blue has more bite than Orange/Red, but from track testing Oranges offer more bite than Green (being equivalent to in hardness) when the grip is high and absolutely no grip when it is lower. The Orange foam has a denser pore structure and the tire is not as prone to chunking. It is also important to note is that BSR Blue rears are not the same as the BSR Blue fronts!

JFT:
JFT stands for Japan Foam Tire. They started the new wave of foam tires we are all using now (Blue/Blu, Green/Greene, Dbl Blue, etc). These tires are a little different than the BSR tire family, but work in very similar conditions. They offers four varieties A (asphalt), C (carpet), S (???), and R (???). This does not mean that those types only work on that surface, but this is what they recommend.

JFT uses the same foam for fronts and rears if the color is the same.

A: Used on asphalt, considered close to the natural rubber variety and are named consistently with other natural tires.
C: Used on carpet, considered a blend.
S: Used on carpet?, tires are ???
R: Used on carpet?, tires are ???

For setup, the JFT foam seem to generate more bite than the BSR, therefore the car tends to be a little more aggressive.

Ulti:
Ulti is another Japanese brand that offers an array of compounds. They have their own way of rating tires, and are difficult to equate to other brands. They have 4 different varieties, each in varying degrees of hardness.

J: High rubber content tire, similar to Pink/ Magenta. Soft would be close to a pink. These offer the most bite and are great for asphalt/carpet front tire. (J hard being very popular)
X: "Balanced" blend, similar to JFT Blue/ Green. Soft is equivalent to Green, medium to Blue in hardness. Great for carpet!
Y: High synthetic blend with lower grip, and is not a very popular variety.
Z: A very expensive "special" foam that is supposed to be magic on asphalt. Only make it in soft shore.
European tires:
There are many great European foam tire brands that use their own types of foam, as well as traditional foams. SOmeone with more knowledge about them will need to fill this in!

Tire Diameter:
If you are racing on carpet, you have to evaluate how much grip your track has. If your track is low to medium grip, you can run bigger tires. If you are on higher bite you have to cut them smaller, there is simply no way around it. Bigger tires are needed for asphalt, especially in the rear. The larger tires provide much needed lateral bite.

Carpet (mm):
Low - Medium Bite
Front: 42.0 - 42.5
Rear: 42.5 - 43.00
Medium - High Bite
Front: 40.5 - 41.0
Rear: 41.5 - 42.0
Big Race
Front: 39.5 - 40.0
Rear: 40.5 - 41.0
Asphalt (mm):
Parking Lot
Front: 43.0 - 44.0
Rear: 44.0 - 45.0
Prepped High Bite
Front: 42.0 - 43.0
Rear: 43.0 - 44.0

Tire Saucing:
Most facilities have moved towards odorless traction additives such as SXT. Some of additives evaporate very quickly and some do not. This seems to be something that is also dependent on tire compound and ambient temperature. For example, saucing a Green compound seems like it never dries, especially when tjhe temperature is lower. We have found that wiping the tires off 15 minutes before we go run allows the sauce to cure, which makes the car come in much quicker with Green rears. Blue compounds on the other hand, do fine when wiped off right before hitting the track.

Saucing half front and full rear is a good initial starting point. If the front of the car is too agressive you can sauce les than half, or for a shorter amount of time.
Tire Fuzzing:
In conditions of increasing grip, foam tires will somewtimes get sticky and pick up fuzz and debris from the track. This is highly dependent on the rubber sedan tire that is being run at your local track and the compound/ type of foam you are running on you car. The softer the sedan tire and the harder/higher rubber content in your foam tire, trouble with fuzzing seems more likely to occur.

There are ways to get around fuzzing under most conditions, and usually involves the selection of the correct foam compound. The more fuzz you get, the softer/lower rubber content you want to run.

Examples:
Problem: Car fuzzes with Lilac/Team Purple fronts and car starts pushing.
Solution: Use a softer front tire and or different family of foam. Replace it with Blue or Double Blue front.

Problem: Car loses rear bite 6 minutes into the run. Blue rear tires look almost clean but have small carpet hairs.
Solution: Use Green rear tires. The softer compound wears instead of getting sticky, minimizing fuzz.

Tire Selection:
Starting out, pick 2 tire compounds for the front and rear. The following should have you covered 99% of the time.

Front - Green and Blue (BSR) or Green and Light Blue (JFT)
Rear - Blue and Double Blue (BSR) or Blue and Dark Blue (JFT)

You may wonder about other compounds out there and if they might be better, trust me, they probably won't be. Even if there are other tires that can be as fast, the synthetic family wears out really fast and the high natural rubber will probably fuzz on you over an 8 minute run. The blends family seems to be the most versatile foam type available today. They last awhile, and sticking to them will make your process of tire selection simpler.
Tire Charts:
BSR/CRC/Jaco



Contact



Corally



JFT (Japan Foam Tire)



Ulti



Enneti (Xceed)



ELECTRONICS:
ESC:
As of now, ROAR is staying 1S (3.7V nominal; 4.2V fully charged) for 1/12. There are many 1S ESC's with a built in BEC so nothing else is required to power the receiver and servo.

If you don't want to lock yourself into a 1S specific ESC, you do have other options! It is possible to use your 2S ESC without a booster or receiver pack, and the ESC simply supplies the lower voltage. If that does not appeal to you, you will need to use an Rx pack or booster. The Rx pack and booster will both supply the receiver with a higher voltage than the 1S pack.

If you decide to use an Rx pack, MAKE SURE TO REMOVE THE RED WIRE FROM THE ESC PLUG THAT GOES INTO THE RECEIVER!!!

If you choose to use a voltage booster, it works exactly how it sounds. Instead of plugging the ESC into the receiver, it plugs into the booster, and the booster plug goes to the ESC, supplying the higher voltage.

1S ESC:
If there are any missing please add them!!

If anyone would like a need for a chart comparing the ESC's specs PM fenton06 and I'll get one made and put in here!
Voltage Boosters:
If there are any missing please add them!
Servos:
BODIES:
Black Art (CRC - US Dist):
  • Audi R8C - BA002 - .020 Thick



  • Black Market (Mohawk 12) - BA005 - .020



  • Lola B10 - BA006 - .020 thick
  • Toyota TS030 - BA008 - .020 thick

    Lola - black/red, TS030 - green/pink


PROTOForm:

Reflex Racing/RSD:

SUSPENSION ADJUSTMENTS:

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Old 03-02-2014, 08:46 PM   #40486
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What's the reasoning behind running negative steering exponential?

Under what conditions should it be negative and positive?

Also, I'm kinda lost with tire selection for asphalt and carpet for 21.5 blinky.

What's a good starting point for both of these surfaces?

Cheers.

Last edited by EDWARD2003; 03-02-2014 at 10:39 PM.
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Old 03-03-2014, 06:19 AM   #40487
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Negative Exop on the steering reduces the amount the tires turn in the center .

Zero Expo means if you move the wheel 25% of it's travel the servo will move 25% of it's set throw (depending on your epa settings) and for 50% it will go 50% of its throw and 75% is 75% of throw right up to 100%

Now adding expo (negative) as you first start to turn there is less servo travel than wheel so the first 10% might only be 2% on the servo (depending on how much expo you want) then to 25% where you may get 10% throw and say 50% you get 35% and at 75% you are at 70% throw and at 100% you still get 100% throw

for positive it's the other way where a little movement of the wheel makes a larger movement at the servo but it still only can go 100%
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Old 03-03-2014, 10:05 AM   #40488
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Default Best 1S Lipo for GT12 Blinky

Hello, I've just started running a Mardave ac12 in 13.5T blinky 1S class. I'm wondering what peoples recommendations would be in terms of the best performing 1S lipo packs?

I hear LRP 6900 do not fade as much as the Reedy 7000 and these are both readily available from my club shop. I just purchased turnigy nanotech 5600's having tried my friends the week before only to find the performance to be very poor with the cells I have received (new from Hobbyking), poor punch and top end.

Any thoughts on if these are a duff batch? I've heard cycling them may help and have requested an RMA from Hobbyking, though not sure if they will give me a full refund.

Any help appreciated, thanks
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Old 03-03-2014, 11:39 AM   #40489
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Trinity revtech 7100 mah 100c with 5mm bulletts is what I use.
No fading.
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Old 03-03-2014, 12:18 PM   #40490
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SMC race Formula 7000mah packs have a really low IR

With the Nanotech they need to be cycled quite a few times before getting to their top potential. I run weekly a 6000mah Nano-Tech and it's just starting to come alive and not Fall on it's face after about 30 cycles

To cycle I use a old LRP charger that has a cutoff voltage for 1cell at 3.6 (thats as low as it will go) and it discharges at around 8A slowing down as the voltage drops. then I charge at 1C (or 6Amps) to full.


A Simple Test of IR for 1 cell packs is to use any current and Voltage meter. as long as you always use the same one the number will mean something

I use a Digital Multimeter for current and the voltage reading on the discharger.


So to see if your NanoTech Pack is getting better over time use this method. I also like to watch the voltage and the mah removed to see where the voltage will be after a run since I know I usually put back in 1500mah per run it's nice to know

Charge the pack and let it sit for min 20 min to settle the temps.

Have a pen and paper ready. Start the discharge and write down the start voltage ( usually 4.2 ) and then count to 10 and write down the voltage and current measured. the 10 seconds gives the lipo to settle from the instant current.

Now subtract the second voltage number from the First and then divide that by the current

eg. 4.2-4.12 = .08/8A = .01 Ohms or 10 milli Ohms

Don't worry about the number exactly but this gives you a baseline for that pack

my 1s packs are around 4-6 milliOhms by this method and when tested on high end equipment end up around the 3-4 as most testers only draw a small amount of current.
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Old 03-03-2014, 03:59 PM   #40491
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When you get down into the milliohm level, battery resistance becomes less important, let me explain: (wall of text warning)

1 foot of 12 gauge copper wire (solid, not stranded) has a resistance of 2 milliohms. 16 gauge wire, 4 milliohms. A 5mm plug connector to the battery would be another few milliohms as would the solder connections to your ESC/motor. So lets say you really go overboard and wire your car for LOW RESISTANCE. Big chunky wires everywhere... well, in a car that uses 6" of 12 gauge wire and two 5mm connectors, and four well-done solder joints from the battery to the ESC, then 14" (super short motor leads) of 14 gauge wire with six solder joints from the ESC to the motor, you've added up to this:

(2 milliohms from the 12 gauge) + 2(1 milliohms for each plug) + 3(3 milliohms for 14" of wire from the ESC to the Motor) + 10(0.5 milliohms per solder joint... I'm being generous here) adds up to 2+2+9+5 = 18 milliohms in your wiring at room temperature.

Seems kinda high, compared to the claimed internal resistances as low as 2 milliohms I have seen claimed a few places. Not much difference between 0.019 ohm and 0.020 ohm.

To measure resistance in batteries with your charger, it's even worse. I can discharge my packs at 35 amps, but my leads are 12 gauge and if each is 18" long with bullet plugs, there's far more resistance in my leads than my pack. As a result, my measured internal resistance can be quite high.

I think that the best packs are not the ones that fight for the lowest possible internal resistance. The best packs have the highest average voltage under load over a full run.
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Old 03-03-2014, 05:57 PM   #40492
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Quote:
Originally Posted by DesertRat View Post
When you get down into the milliohm level, battery resistance becomes less important, let me explain: (wall of text warning)
.
In my experience, low IR packs, almost always have the best avg v as well
Both test, seem to be a good indication of the packs potential
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Old 03-04-2014, 06:44 AM   #40493
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Good point @DesertRat While the rest of your wiring adds to the resistance the battery with the lowest IR will have a higher voltage vs discharge rate than a battery with a high resistance.

Which is why I discharge a pack down to 3.6 while watching the mah removed vs voltage to get a better Idea on how your pack preforms over time. If you had a v3 hobbywing esc where you can pull out come data after a run that would be a better and realistic view of the packs voltage over the 8min run. as well as Amp draw and also how you are applying the throttle and G forces but I digress.

I used on Sunday my Cheapie nano-Tech had no problem keeping up to the fast guys. Save for a crash or 12 when I was actually putting down clean laps times were about equal.


The biggest thing is to know your gear. How to use it properly and how to know when things are not working properly.

Data is your friend


Cheers
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Old 03-04-2014, 08:45 AM   #40494
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Thanks guys ill try and cycle the turnigy before I fork out for something new.

Do you have any advice on finding the sweet spot between timing and gearing? Running a trinity D3.5 maxzilla and was struggling to get it going quickly (probably the cells) warmest it came off was 40 degrees Celsius with the timing on 55degree (25 on the can) which is maxed out.
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Old 03-04-2014, 11:35 AM   #40495
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I notice on the pro driver setup sheets they always run a smaller front tire. Seems most are one to two mm smaller in the front. Why is this?
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Old 03-04-2014, 11:48 AM   #40496
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It's Called Split, More slpit means more steering to a point. you can tune the size difference to your track and driving style. I like 2mm but when on a really high bite track I go down to 1mm
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Old 03-04-2014, 12:08 PM   #40497
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Quote:
Originally Posted by bama racer View Post
I notice on the pro driver setup sheets they always run a smaller front tire. Seems most are one to two mm smaller in the front. Why is this?
Especially when traction is high, the smaller sidewall of the front tire will help keep the car from gripping too much and traction rolling. Most of all, though, 12th scales just feel dialed on small tires!
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Old 03-04-2014, 12:16 PM   #40498
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Quote:
Originally Posted by LloydLoar View Post
Especially when traction is high, the smaller sidewall of the front tire will help keep the car from gripping too much and traction rolling. Most of all, though, 12th scales just feel dialed on small tires!
Thanks guys. I'll have to try some split. I've always cut the front and rear to the same size. (42.5 mm) I guess its time to cut the fronts on down!
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Old 03-04-2014, 06:46 PM   #40499
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Quote:
Originally Posted by EDWARD2003 View Post
Also, I'm kinda lost with tire selection for asphalt and carpet for 21.5 blinky.

What's a good starting point for both of these surfaces?

Cheers.
It's going to depend on the goop level. Assuming an unprepped but clean track for asphalt try Ulti Hard front, Ulti Soft rear.

Carpet, well everyone else here will know more than me, but if it's a gooped up permanent track I'd go with black front yellow rear, and if it's a rollout carpet track I'd start with purple front, pink rear, and then switch to magenta front as the grip comes up.
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Old 03-04-2014, 06:50 PM   #40500
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Quote:
Originally Posted by DesertRat View Post
I would recommend adjusting your front end to have bump toe-out by angling the ends of the links up with shims or finding a way to lower the mounting point at your servo. If that doesn't work, going to a stiffer, less aggressive front end while saucing more of the front tire to keep steering may help.

Not all cars will react the same to changes, though.
Well, I was running the servo flat to the chassis with the horn above, which meant very little bump-toe, or maybe just a little bump toe-in. So I've now mounted it on an angle, with the horn below, and now there's a lot of bump toe-out. I'll give this a run on Friday and see how I go.

Just to clarify, by the links, did you mean the other end of the steering links at the knuckle?
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