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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 12-03-2011, 08:12 PM   #37216
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Quote:
Originally Posted by Andy w View Post
Issue one is I am going through bearings like crazy. Mostly front but a few on the rear axle. I went through 4 front bearings today.
When I had a GenXL I blew through CRC Bearings as well. The kit CRC bearings spin really free, but were not that durable for me, when I went to Avid or Bocca bearings they lasted much longer and at $1 a piece they are hard to beat.

Also as others have mentioned, CRC has new steering block and axles that use the 1/8" bearings, which are more durable as well.

Quote:
Originally Posted by Andy w View Post
Second, all the cars seem like they are chattering around the sweepers at full speed which is making it hard to stay in the groove and maintain the speed I want on sweepers.
1. Check your body to see if it is rubbing on the carpet, trim it, or raise it.
2. Check under the chassis if there is any gummy stuff on it, means your rubbing the carpet probably in high speed corners.
3. If the track is bumpy, your car might be too stiff and jumping around.

Quote:
Originally Posted by Andy w View Post
Third, my diff feels inconsistent during qualifiers. I will have it set then a couple mins in it starts to slip then feels like it gets tighter a couple mins after that
If it is diffing out .. that one thing, if not .. then it might be the way you are building your diff. I hope you are not using black grease as diff lube, I use Associated Stealth Differential Lube and won't use anything else. Also, you should break in the diff by hand, set it and recheck after the first couple of runs as it will naturally loosen up a bit, reset it and it should be good to go.
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Old 12-03-2011, 08:40 PM   #37217
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Thanks for all the help so far. I really like this class but its just so frustrating when I am running great for 5 minutes then my car goes to crap for the last 3. I can learn to drive a bad car but when it is unpredictable I just want to boot it across the room.

On the diff grease I use the regular clear silicone diff grease.

The "diffing" might make sense. The best way I can explain what is going on is when going through the infield I will be trying to carve a chicane pretty aggressive then it feels like the diff slips and spools up then it catches and launches me. And since it is slipping or diffing the car over steers and shoots me off the line I am on. And not being in the groove on our carpet in not fun.

I don't know if all that makes sense, but I will try rebuilding the diff and cleaning the threads and all that was suggested to try to isolate if it is the diff slipping or diffing. Also I'll try some different bearing brands.

If it is diffing that would that be due to setup or driving style, or just the effect of a solid axle?
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Old 12-03-2011, 08:50 PM   #37218
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Good call from Wing, definitely sounds like it's diffing, or lifting up the inside rear.

Post a pic of the car, and your setup, and let's see what the CRC guys have to say.
Seems as if you have the wrong tires for your track, should be consistent for 8 mins.
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Old 12-03-2011, 08:56 PM   #37219
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Originally Posted by Andy w View Post
Thanks for all the help so far. I really like this class but its just so frustrating when I am running great for 5 minutes then my car goes to crap for the last 3.
Part of 1/12 scale is getting the car to last for 8 minutes.

Tire Compund & Prep.

How are your tires coming off the track? Clean, Fuzzy, Tacky, Gummy, Normal?

Quote:
Originally Posted by Andy w View Post
The best way I can explain what is going on is when going through the infield I will be trying to carve a chicane pretty aggressive then it feels like the diff slips and spools up then it catches and launches me.
You can hear when the car is "diff'ing out", usually happens in tight 180's or when driving too aggressively, the rear inside tire is lifting off the ground. Listen for it next time. Either change your driving style or change the setup to accomidate your style.

Quote:
Originally Posted by Andy w View Post
If it is diffing that would that be due to setup or driving style, or just the effect of a solid axle?
Both setup and driving style.
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Old 12-03-2011, 09:23 PM   #37220
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Quote:
Originally Posted by ByteStream View Post
Part of 1/12 scale is getting the car to last for 8 minutes.

Tire Compund & Prep.

How are your tires coming off the track? Clean, Fuzzy, Tacky, Gummy, Normal?



You can hear when the car is "diff'ing out", usually happens in tight 180's or when driving too aggressively, the rear inside tire is lifting off the ground. Listen for it next time. Either change your driving style or change the setup to accomidate your style.



Both setup and driving style.
Last for 8 minutes? My wife says the same thing about me.

My fronts have a little fuzz. The rears feel normal, at least what I would think is normal.
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Old 12-03-2011, 11:35 PM   #37221
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One technique in sanding your diff ring is do a figure 8 when sanding it, not circular or up and down. You will find it more even that way.
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Old 12-04-2011, 01:05 AM   #37222
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Since were on the diff questions. How often should you replace the diff rings?

Last edited by Josh-n-ya; 12-04-2011 at 07:35 AM.
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Old 12-04-2011, 01:33 AM   #37223
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http://www.multiverse.jp/QTEQ/englis...ringtruer.html

The ultimate diff ring sander
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Old 12-04-2011, 08:14 AM   #37224
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Who sells that tool ?
Great idea.
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Old 12-04-2011, 08:47 AM   #37225
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simple , low cost diff ring polish method

http://www.rc10talk.com/viewtopic.ph...=11937&start=0
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Old 12-04-2011, 12:29 PM   #37226
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Is the trend in 17.5 non-ramping still to run the largest spur/pinion combo you can fit on the car(that yields the correct rollout, of course)?

I see most people are running 76t spurs with 52-58t pinions. The larger gears push the motor further inward, away from the axle.

I have a couple 70t spurs laying around. Are these usable in a competitive environment? Obviously I can practice with them, etc... but do any of you hardcore 17.5 12th guys actually use spurs this small?
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Old 12-04-2011, 08:23 PM   #37227
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I like to use the biggest combo I can. The more forward the motor the better the car handles.
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Old 12-04-2011, 08:34 PM   #37228
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I believe that running the motor further forward does good things, but is hard to test back-to-back. I currently run 13.5 blinky at my local track and I am running a 47/88 gearing with tires that actually have some meat on them, but in order to test it I would a have to have somehow assembled the diff exactly the same with a new spur and that just doesn't happen

You do need to keep in mind it puts more weight effectively on the center shock and reduces unsprung weight (the rear pod of a 1/12 scale car is a massive amount of unsprung weight), so springs are changed accordingly.
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Last edited by DesertRat; 12-04-2011 at 08:46 PM.
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Old 12-04-2011, 10:22 PM   #37229
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Quote:
Originally Posted by DesertRat View Post
I believe that running the motor further forward does good things, but is hard to test back-to-back. I currently run 13.5 blinky at my local track and I am running a 47/88 gearing with tires that actually have some meat on them, but in order to test it I would a have to have somehow assembled the diff exactly the same with a new spur and that just doesn't happen

You do need to keep in mind it puts more weight effectively on the center shock and reduces unsprung weight (the rear pod of a 1/12 scale car is a massive amount of unsprung weight), so springs are changed accordingly.


Wouldn't be too hard to test back to back with an axle built with each combination you want to try...
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Old 12-05-2011, 09:07 AM   #37230
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Default Metal lathe to true tires

Just got my first 12th scale car and I'm hooked. Also my wallet is a lot lighter, so I'm thinking of using a old Sherline lathe to true the tires. I intend to mount a SaburrTooth burr in the tool post at a similar angle as the Hudy burr. I haven't made the arbor or the burr mount yet. Before I spend time on this, I have a few questions.

I has anyone measured the run out at the arbor on a quality tire truer? Depending on how my 3 jaw chuck closes I could have as much as 5 thous. run out.

Is the foam dust corrosive or likely to melt when sticking to oil and grease on the lathe?

What rpm do tire truers run?

Thanks
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