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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.

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

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!


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 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 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.

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:



JFT (Japan Foam Tire)


Enneti (Xceed)

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 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.

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!
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


Reflex Racing/RSD:


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Old 05-25-2003, 02:46 PM   #3016
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Ok...... but I still don't know where you can get any of those servos from. On the speedmerchent, what are the different ways the instructions say you can mount it? Does it tell you how to drill holes or tell you how to use shoe goo or what? How come the geometry would be messed up if you didn't use a Kimbrough small servo saver? Do either of the cars come with a servo saver? Probably not because the size of the external gear on servos usually very a bit . One reason I don't want to use shoe goo is because if I strip out a servo gear, than I probably wouldn't have my car working again for the next race because shoe goo doesn't dry super fast. Thanks for all the help! It's all very helpful.
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Old 05-25-2003, 03:34 PM   #3017
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your LHS might have them, or most larger online shops have them (tower hobbies almost always has them in stock). As far as the KO propo, from what i've heard from Ko team drivers is that its way to fast for even them (and thats in mod), lol.

in the speedmerchant manual it tells you to line up the front of the servo case with the arm or something like that (sorry i cant tell you specifcally since i dont have the manual and havent done it in a long time). and with the servo saver its phyically impossible pretty much (except if maybe you took a dremel or hammer to the servo) to break servo gears, and messing up the servo saver almost ALWAYS takes place when you remove it or put it on.

it would change the steering geometry because of the height of the ball stud, and thus mess up your ackerman (or at least i am pretty sure thats what it does, also it could rub the chassis since the servo sits on it, and the servo gear sits very close to the ground (since the servo is smaller to begin with).

it may seem like alot of annoying crap right now, however running 12th scale is alot simpler than sedan, just hold in there!
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Old 05-25-2003, 03:47 PM   #3018
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So in the manual it does tell you how to properly drill holes? Or just how to properly mount the servo with shoe goo or servo tape? Yer right, this DOES seem like a lot of annoying crap right now. I've changed my mind about cars, or components so many times. Ugh. So I should get a small Kimbrough servo saver if I get either car, right? If my servo turns out to be too fast I can just dial out some speed with my transmitter , so no worries here. So I think I'm gonna get the Airtronics 94143 for the servo and a couple small Kimbrough servo savers. Who else has run both the Carpet Knife and the Rev 3, do you guys not mind having to use servo tape of shoe goo for mounting your servo in the Rev 3? Just trying to get a couple more opinions before I make my big ol decision on which car to get. Thanks for helping me through all this stuff!
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Old 05-25-2003, 03:57 PM   #3019
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Is this the servo you guys were talking about, it's a 94145Z. It's not compatible with standard Airtronics recievers I think from what it said, but I have Futaba recievers and things, and it said it was compatible with Futaba . Unfortunaitly it won't be in stock until late June , any other ideas of palces besides tower? My track might have it, but it will cost more and I will have to pay tax which I don't really want to do.

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Old 05-25-2003, 04:04 PM   #3020
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Here's the smallest servo safer from Kimbrough that would work on Airtronics:


It doesn't say "mini" but it says mid-sized, would it be small enough?
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Old 05-25-2003, 04:49 PM   #3021
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The Airtronics servo that most people use for 12th scale is the 94145. It will work with Futaba. Make sure you check the plug wires so that the plus, minus and signal are in the right order. Plus=red, minus=black, signal=blue. It's a metal gear servo, although not all the gears are metal (?).

The mid size servo saver is too big (like huge)- you need the small one.

Drilling holes for the servo mounts is not that difficult. The way I do it is to attach the mounts to the servo then position the servo on the chassis as the instructions state. Then mark around the mounts where they touch the chassis. Then take the servo off and mark the center of the holes you need to drill based on the servo mount marks. Then just drill the holes. Servos in mounts are sturdier than tape or goo, and it's easier to take the servo on and off.

I have and race both a Rev3 and a Carpet Knife. There's not that much difference between them. They are both great cars, each with thier good and bad points. You won't go wrong with either one.
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Old 05-25-2003, 04:51 PM   #3022
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Default 94145

oh yeah-Sheldon's Hobbies carries the 94145 for about $60.00.
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Old 05-25-2003, 05:14 PM   #3023
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Exclamation Rev 3. manual

Stormperson, I bought a previously owned (sounds better than used) Rev 3. I got a set up sheet with it, but no manual. Is their such a thing as an actual Rev.3 manual. I looked on the speed merchant Web site, but didn't see anything about a manual. Unfortunately I didn't get it before the end of the carpet season and I am going to have to wait until Oct. to try it out.

Thanks for any help,
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Old 05-25-2003, 06:38 PM   #3024
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Our carpet season goes year round . If it's not raining on saturdays during the "good weather" season we race outdoors. So I'll be able to use my new 1/12 all summer, once I get it . Does Sheldon also carry the the Kimbrough mini servo saver for the 94145? Does the Rev 3 come with servo mounts? Or do you have to purchase them sepretly? If I got the CK with the "old skool" front end seperatly, would I also get instructions on how to install the old skool front end with the kit? Or do I have to find some instructions for the Rev 3? Or I could just figure it out my self on how to put it together. Since the CK mounts the servo pointing up slightly, do you need the mini servo saver, or could I use the mid-sized one there? For drilling holes to mount the servo on the Rev 3, I would need a counter sinking drill bit right.......? Where can I get a counter sinking bit, what size would I need?
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Old 05-25-2003, 07:02 PM   #3025
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Default new servo from futaba

Salutations Earthlings!
its a digital mini servo from futaba : S9650
case size: 35.5 X 15 X 28.6mm, 26gms
torque: 3.6kg.cm @ 4.8V or 4.5kg.cm @ 6.0V
speed: 0.14sec/60 @ 4.8V or 0.11sec/60 @ 6.0V
do we need this kind of speed or holding power?
Attached Images
File Type: jpg futabas9650.jpg (13.4 KB, 95 views)
During heats, i use durex for both front and rear, with Hard inserts.

Sorex, i meant Sorex.
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Old 05-25-2003, 07:09 PM   #3026
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On the CRC website I found something that said:
The Carpet Knife V3.1- Professional Four Cell 1/12th Scale Multiple On-Road Champion. With Retro-Front End + 3 bolt rear wheels
What do you suppose a retro-front end is? Because the other CK's they advertize just say "with 3 bolt rear wheels" and nothing about the front end. I wasn't able to find out what they ment by retro-front end. They sell the "retro-front end" seperatly for 20 bucks, thats the same price that Hobby ect. sells the "old skool" front end. Could the retro-front end possibly be the same as the old skool front end? I'm really leaning towards the Carpet Knife over the Rev. 3 because of the servo thing. I really like how the Rev. 3 has the adjustable battary mounts, but I feel like I could just screw up my nice new chassis. I know they're both good cars too so I'm sure I'll be happy with the CK. It would make building the car much more fun not having to worry about the servo mounting thing .
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Old 05-25-2003, 09:00 PM   #3027
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Default i do like the that too...

Salutations Earthling racerdx6,
i do prefer the rev3 myself, especially if it uses the old skool front end.
b'cos ....its simple beyond words!
easy to build, setup n maintain.
and there is very little chance settings being altered in a scrap.
as a matter of fact, when i purchased my carpet knife, i installed the old skool front end right away!
1/12 should be run on smooth prepared tracks , so i feel a strut sus shld never really be neccesary.
During heats, i use durex for both front and rear, with Hard inserts.

Sorex, i meant Sorex.
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Old 05-25-2003, 11:14 PM   #3028
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I think I'm going to definetly get the standard Carpet Knife and buy a "old skool" front end for it. Unless the Carpet Knife with the "retro-front end" is the same as the old skool front end. What replacement parts should I also order, I know I should get some parts for the front suspension. What front suspension parts break often? Do any other parts break very often or wear out very often that I should consider buying extras? I'm also going to get a foam bumper to try trimming to fit and also a plastic bumper to see how I like that. What extra parts like springs should I also get, should I buy springs for the center shock and a side spring set? What about a front spring set? Thanks again for all the help!
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Old 05-26-2003, 12:24 AM   #3029
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Hi, which set up is better, the "old school fronts" or the ones by AE? Or they are just the same? I got my CK Team Red with AE Fronts. Thanks
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Old 05-26-2003, 01:38 AM   #3030
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Default Rollout

Howdy fellow 12th scale racers,

I'm sorry if this question's been asked already... I asked it on the corally thread and other forums, but to no avail.

Can somebody please recommend a rollout for 6 cell mod (12x2), with 3000HV's, on a moderately tight, extremely grippy asphalt track? We're running 12th scalers for kicks when it's rainy outside and we can't run 8th scale onroad, so I'm more focused on lesser motor maintenance with adequate performance, than squeezing these last 50mAh out of my packs to run 8 minutes and one lap, but having to rebuild the motor every couple of runs.

Also, what's the rule of thumb for rollout per wind? Say, you're going from a 12 turn to a 13 turn, shall you lengthen rollout by 1mm? 2mm? Or anything else?

Rollout advice, anybody?

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