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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 10-25-2008, 10:29 AM   #29596
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Looks like they're using the same rear suspension idea of a BMI DB12R, but keeping the T-bar instead of having seperate flex plates.
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Old 10-25-2008, 02:31 PM   #29597
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Originally Posted by Scottrik View Post
Do yourself a favor and spring $5-6 for a proper spur gear and another couple bucks on enough diff balls to fill it. You will feel the difference as soon as it's built even if you don't sand the diff rings, etc.
Lets not forget the importance of having balls of all the same size. It is better to reaplace all the balls at once than one-by-one should you lose a few cleaning the diff.

If you have 12 balls and rings that have a few months of runs of them. heaven forbid that two rolled off the table when reaplacing the worn spur gear. Don't just slap in two new balls. You'll be better off to just leave those holes unfilled or totally replace the balls and rings. The reason being is that with two new balls, those balls will be slightly larger than the remaining 10 balls and the contact pressure will be more on those balls than the others. Resulting in a hard to tune diff. A little too tight, diff is sticky from those two balls digging in, little too loose, diff slips.
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Old 10-25-2008, 05:22 PM   #29598
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Thanks for the comments. I will pick up the right spur gear and some new diff balls.

Scottrik you mentioned sanding the the diff rings. What am I using to sand them with? I never realized there was this much to 1/12 scale. I'm wondering if I'm over my head here.
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Old 10-25-2008, 05:24 PM   #29599
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I always used 600 grit sandpaper on a flat surface to polish my rings. 1/12 cars are easy to get running but there's ALOT of small things you can do to make them either faster or easier to drive.
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Old 10-25-2008, 05:26 PM   #29600
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matt you are not in over your head just keep asking questions and you will be alright...the devil is in the details
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Old 10-25-2008, 06:49 PM   #29601
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Originally Posted by TonyK View Post
Scottrik you mentioned sanding the the diff rings. What am I using to sand them with? I never realized there was this much to 1/12 scale. I'm wondering if I'm over my head here.
Nah...just a lot of little things that can be done to make your car work better. The neat thing is that it really doesn't cost anything to do 'em...unlike TaxiCabs.

The reason sanding diff rings helps is that when they're punched out they end up a bit bowed on one side and cupped on the other. You sand them by holding sandpaper on a very flat surface (a set up board, or I use a piece of tempered glass that I build cars on) and swirling the diff ring on it. You do both sides of each ring until the sanding marks are all the way across the faces from inner edge to outer edge. I like to use #400 until I have "cross-hatching" all the way across, then do a minute or two on #600 for a slightly smoother finish (no need to obsess here).

This can be done with your bare hands, though sanding through your finger tips makes 'em a bit sore for a day or two (done that plenty). IRS makes a diff ring sanding tool which is a machined aluminum holder with a raised ring that engages the inside of the diff ring. These were tooled up prior to the advent of "D"-rings but can be easily modified with a Dremel tool to make a straight side for the D. MUCH easier on your finger tips.
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Old 10-25-2008, 07:41 PM   #29602
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Quote:
Originally Posted by Scottrik View Post
Nah...just a lot of little things that can be done to make your car work better.
The reason sanding diff rings helps is that when they're punched out they end up a bit bowed on one side and cupped on the other. You sand them by holding sandpaper on a very flat surface (a set up board, or I use a piece of tempered glass that I build cars on) and swirling the diff ring on it. You do both sides of each ring until the sanding marks are all the way across the faces from inner edge to outer edge. I like to use #400 until I have "cross-hatching" all the way across, then do a minute or two on #600 for a slightly smoother finish (no need to obsess here).

This can be done with your bare hands, though sanding through your finger tips makes 'em a bit sore for a day or two (done that plenty). IRS makes a diff ring sanding tool which is a machined aluminum holder with a raised ring that engages the inside of the diff ring. These were tooled up prior to the advent of "D"-rings but can be easily modified with a Dremel tool to make a straight side for the D. MUCH easier on your finger tips.
I use to do it that but now it's MUCH easier to just use the outer diff hub
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Old 10-25-2008, 08:27 PM   #29603
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I use a bit of thin double sided tape on a spray paint can cap and stick the diff ring to that for sanding.
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Old 10-25-2008, 09:54 PM   #29604
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Thanks guys, you have given me alot of ideas to get the diff smooth.
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Old 10-26-2008, 12:43 AM   #29605
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1 set of carbides + $1.50 D rings + Slapmaster Thrust Kit = Smooth for life!
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Old 10-26-2008, 07:22 AM   #29606
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1 set of carbides + $1.50 D rings + Slapmaster Thrust Kit = Smooth for life!
I can confirm this statement - purchased - installed - VERY HAPPY!!

I used a set of steel balls for the first 2-3 runs and then changed to carbide. Have not touched them except for replacing spurs in 18+ months.
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Old 10-26-2008, 01:40 PM   #29607
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Originally Posted by trailranger View Post
Lets not forget the importance of having balls of all the same size. It is better to reaplace all the balls at once than one-by-one should you lose a few cleaning the diff.

If you have 12 balls and rings that have a few months of runs of them. heaven forbid that two rolled off the table when reaplacing the worn spur gear. Don't just slap in two new balls. You'll be better off to just leave those holes unfilled or totally replace the balls and rings. The reason being is that with two new balls, those balls will be slightly larger than the remaining 10 balls and the contact pressure will be more on those balls than the others. Resulting in a hard to tune diff. A little too tight, diff is sticky from those two balls digging in, little too loose, diff slips.
Due respect, this isn't quite accurate...

The diff works by ensuring there is no slip between the balls and the rings. Things only wear is there is some differential movement between them, so if there is no slipping there is no wear. If your theory holds, the wear rates would be different, and the balls would be out after just a couple of runs.

The hardness of the balls exceeds that rings, which we see as grooves worn into the rings, not flats worn onto the balls. Truth is, the balls are dependent on the grade used, and that the general grade used has a tolerance of about 0.0001" - there's more flex in the plates than that.

Scottrix and Slapmaster have the recipe we all find gives the smoothest diff for the longest time
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Old 10-26-2008, 02:29 PM   #29608
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Due respect, this isn't quite accurate...

The diff works by ensuring there is no slip between the balls and the rings. Things only wear is there is some differential movement between them, so if there is no slipping there is no wear. If your theory holds, the wear rates would be different, and the balls would be out after just a couple of runs.

The hardness of the balls exceeds that rings, which we see as grooves worn into the rings, not flats worn onto the balls. Truth is, the balls are dependent on the grade used, and that the general grade used has a tolerance of about 0.0001" - there's more flex in the plates than that.

Scottrix and Slapmaster have the recipe we all find gives the smoothest diff for the longest time
Well I'm right and I'll stick to it. Take a pizza cutter wheel and cut some slices. The wheel didn't slip yet the contact pressure between the wheel edge and the pizza was great enough to indent and slice the pizza. Since the pizza is being moved by the slicing wheel it can be assumed that wear will happen to the slicing wheel. Yes this is an example of extremely hard and soft materials, but to some degree the softer diff-ring will yield to the harder diff balls at every pass and create wear. The same approch to pizza slicers is how the Chunnel and many other tunnels were bored through hard rock. This is why a diff with minimal slipping will still create a indentation where the balls were running. As long as there are one or two off sized balls, the contact pressure will increase for those balls and increase the wear to the diff ring.

The harder your diff balls and tighter the grade tollerance the less worry about wear. Some racers like me, just run the diff rings for months and months since the secret I found in a smooth diff is, high quality balls, good thrust bearing and cone washers.
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Old 10-26-2008, 03:56 PM   #29609
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I'm having a massive memory failure right now. what is the size of the arm hinge pin? trying to find a reamer!
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Old 10-26-2008, 07:22 PM   #29610
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Typically when I lose a diff ball I'll replace all of them as well...not necessarilly because of the size issue, but because by then the diff balls are usually pretty beat up by the outdoor racing environment. Plus they are so inexpensive to replace (unless your running ceramics) that it's no strain on the pocket book.
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