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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 11-27-2012, 11:37 AM   #38656
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wingman2, Sexy looking car. If you don;t mind I'd like to see how the rear pod attaches to the alum Chassis.

Looks really nice
Thanks Jason. I used the carbon pivot plates from a 12M as a base for my ones, which I shaped to help keep the LiPo in place. So, from the bottom of the chassis upwards, each screw (4 in total) goes through the chassis, then a washer (which acts as a spacer), then a nut and then through the carbon plate. A stand-off then screws down on the top of the same screw and then the carbon top plate screws down onto that stand-off. There are 4 of the screws to keep everything tight and keeps the whole setup quite stiff. If you notice in the pics, you'ull see the 4 screws going through the chassis that line up with the 4 screws that go down through the top plate.

Cheers, Chris.
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Old 11-27-2012, 11:39 AM   #38657
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Thumbs up

Nice car Wingman
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Old 11-27-2012, 11:50 AM   #38658
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Nice car Wingman
Thanks mate, Chris.
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Old 11-27-2012, 07:33 PM   #38659
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Originally Posted by Radio Active View Post
There was a competitor using that combination at the NSW Championships at SMA last month. It seemed to be working pretty well for him, but this was only after the grip came up from 2 days running.
The purple/magenta combo was working for me at the nats until the rained ruined the traction.

Anyone else tried purple fronts magenta rears on asphalt?
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Old 11-27-2012, 07:35 PM   #38660
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I am tempted to try purple fronts, double pink rears.

I always thought magenta's were 35 compound, not 32, in the BSR/CRC range.
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Old 11-27-2012, 08:42 PM   #38661
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I have a design/set-up question for you all. The Associated car standard uses 10* of reactive caster, the default setting on the Serpent car is 7.5*, other cars with upper arms look similar. I've noticed that the CRC car looks to have a lot less. I've tried the Associated car with the 5* setting, and it had a *lot* less mid-corner steering in this configuration. So, I'm wondering how the CRC generates mid-corner steering. What else is different in the CRC to compensate?

Also, can someone explain to me how the "Old School" front end with fixed camber and caster behaves in comparison?
On the CRC I have found 10 degrees of reactive castor makes the car extremely twitch on initial turn in then immediately pushs. Its horrible to drive. 0 degrees makes its stable initially (and down the straights) and gives alot more steering mid corner.
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Old 11-30-2012, 07:46 AM   #38662
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Default SpeedMerchant Rev 7 Quad Link Rear Suspension

I thought some of my fellow racers/engineers might find this interesting. It's my quad-link rear end conversion on the SpeedMerchant Rev. 7. I used the same arrangement on my homebuilt link cars back in the late 1980's, and it worked quite well. The design is also currently used on the German RC Devil cars, and on full-scale F500 racing cars.

There are several positives to this design. There is no inherent binding with roll, unlike the usual arrangement using a single fixed center ball. The roll center is the point where lines drawn through the down-links cross, and on this car it is nominally at ground level to eliminate weight jacking due to cornering forces. The roll center is easily modified by changing the aluminum "roll center plate" that anchors the lower pivot balls at the center of the chassis. Roll center and anti-squat are independently adjustable (the anti-squat is set by the height of the side link pivot balls). Wheelbase is easily changed by varying the length of the side links, or changing their pickup locations on the main chassis.

This particular execution required that the center "tab" on the lower pod plate be removed. The chassis is stock. I used the right-angle brackets at the top front corners of the motor pod because there didn't seem to be quite enough material to tap holes directly into the aluminum bulkheads. Ideally, the design of the bulkheads would be (slightly) modified to include these holes. The roll center plate and its associated right-angle brackets could be a single piece of machined aluminum or sheet steel.





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Old 11-30-2012, 08:16 AM   #38663
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Looks real neat. But i can see one differance. The rearpod cant pivot in relation to the chassis with the 2 links, if i am not mistaken it needs just one ball on the main chasis to let it pivot and have the side tube`s expand when cornering. Now it only pivots forward and rearward.

I think

You could look for the CRC 10th post (old) wich has a rear conversion with links and dampers on it.

EDIT, from John stranahan with a 3 link rear

Last edited by djiewie; 11-30-2012 at 08:38 AM.
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Old 11-30-2012, 08:22 AM   #38664
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I am tempted to try purple fronts, double pink rears.

I always thought magenta's were 35 compound, not 32, in the BSR/CRC range.
Purple front with double pink rear has been very good for me if the traction is good.
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Old 11-30-2012, 08:23 AM   #38665
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Interesting idea

In a back to back test, how much quicker does it get around in a lap ?
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Old 11-30-2012, 08:23 AM   #38666
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That's mint. Love to see video of the rear pod side to side action
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Old 11-30-2012, 08:26 AM   #38667
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I am tempted to try purple fronts, double pink rears.

I always thought magenta's were 35 compound, not 32, in the BSR/CRC range.
Our Track is medium traction and I find Pink rears and double pink fronts are awesome but when the traction comes up double Pink rears keep the rear from being too locked in and I just run harder springs with the double pink fronts
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Old 11-30-2012, 08:32 AM   #38668
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Looks real neat. But i can see one differance. The rearpod cant pivot in relation to the chassis with the 2 links, if i am not mistaken it needs just one ball on the main chasis to let it pivot and have the side tube`s expand when cornering. Now it only pivots forward and rearward.
It will pivot laterally just fine...
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Old 11-30-2012, 10:32 AM   #38669
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In a back to back test, how much quicker does it get around in a lap ?
I don't have any comparative lap times for this design versus a fixed center pivot. To do proper testing, I would need to buy a stock lower pod plate (or modify the one I have to add the center tab back), change it, remove the down-links, add the center pivot ball, and make any changes necessary to the roll springing and damping to get the handling right. In the time it takes to do this, the tracks I race on can easily pick up over 0.1 second per lap in traction if other cars are present, so the swap must be done several times back and forth to generate reliable lap time data. I'm far too lazy for that.

Subjectively, the lower roll center does pretty much what one might expect: It increases rear lateral grip and reduces the tendency for the inside tire to lift on high-traction surfaces.

I mostly did this for fun, for "old times' sake", and to have something different. I like it for the elimination of the binding which is inherent in a fixed center pivot design (which may be immaterial, despite my distaste for it). And the stark contrast between the overly complicated rear suspension and the stone-age front suspension appeals to my strange sense of aesthetics.
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Old 11-30-2012, 10:38 AM   #38670
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I don't have any comparative lap times for this design versus a fixed center pivot. To do proper testing, I would need to buy a stock lower pod plate (or modify the one I have to add the center tab back), change it, remove the down-links, add the center pivot ball, and make any changes necessary to the roll springing and damping to get the handling right. In the time it takes to do this, the tracks I race on can easily pick up over 0.1 second per lap in traction if other cars are present, so the swap must be done several times back and forth to generate reliable lap time data. I'm far too lazy for that.

Subjectively, the lower roll center does pretty much what one might expect: It increases rear lateral grip and reduces the tendency for the inside tire to lift on high-traction surfaces.

I mostly did this for fun, for "old times' sake", and to have something different. I like it for the elimination of the binding which is inherent in a fixed center pivot design (which may be immaterial, despite my distaste for it). And the stark contrast between the overly complicated rear suspension and the stone-age front suspension appeals to my strange sense of aesthetics.
Just inquiring from a "racer" pov

Cool build though
nice to see the hobby aspect of 12th scale is alive and well
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