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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 10-05-2011, 10:15 AM   #36631
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Quote:
Originally Posted by Serzoni View Post
The steering block and spring still have the same relationship, so the leverage put on the spring when the wheel moves up and down should remain the same, right? If the springs were mounted inboard and somehow still attached to the upper arm then it would probably soften the rate
The longer to arm gives the car more leverage on the spring, but I know that widening the front track seems to increase front roll stiffness so I don't know the actual facts here. I have played around with the Speed Merchant Formula front end and with the top arm in the longest position the car definitely has less steering, and the most obvious difference is in camber gain as the car rolls.

Quote:
Originally Posted by Infinite 12th View Post
Sweet ride however since we're on topic of what things do I know that crc usually sets servo on angle like it says here in the crc page yet here the servo is flat and steering rods straight

"Also, the Gen-XL comes stock with the servo mounted "up". While some put the servo down and flat, that configuration leads to terrible bump steer as the geometry of the front suspension is compromised in such a position. With the servo up on mounts, the steering tie rods are parallel to the upper suspension arm. As the car rolls in the corners and hits bumps, this parallel position keeps the steering angle consistent. With servo down, each bump and weight transfer initiates a drastic change in the steering angle"

So I won't do a cool drawing but what do you guys think about the different steering setups
On my BMI CH12, I started with the servo up, following the kit instructions, and the car was very twitchy, especially exiting corners. When I laid the servo down it became much smoother with more controllable power delivery. This varies from car to car though, as my Rug Rat and my Serpent S120L are both more to my liking with the servo up. I'm not sure bump steer is a serious problem in 1/12TH; most tracks are fairly smooth, and careful adjustment of pivot balls and linkage angles can minimize it with either set up.
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Old 10-05-2011, 10:16 AM   #36632
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Originally Posted by HarryLeach View Post
The availability of lots of shims pretty well take the bump steer element out of the equation these days, if done correctly.

Servo angled or flat comes down to personal preference on akermann, and steering aggression.

Since you see both so often, it's safe to say they both work when matched to an individuals preference.
Ok thanks

I saw at the worlds jilles and elliot had angled and Naoto had flat but to me Naoto car seemed way more aggresive in fact more aggressive than any of the other cars

Would that fit to what you we're perhaps implying with steering akermann/aggression

Isn't akermann if the tires turn the same throughout full range of steering vs. the inside with little akermann turns more?

Thanks

Quote:
Originally Posted by LonnyJ1950 View Post
On my BMI CH12, I started with the servo up, following the kit instructions, and the car was very twitchy, especially exiting corners. When I laid the servo down it became much smoother with more controllable power delivery. This varies from car to car though, as my Rug Rat and my Serpent S120L are both more to my liking with the servo up.
So there's definitely something up with the difference

I guess I'll just have to try both back to back to find out
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Old 10-05-2011, 10:29 AM   #36633
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Ackerman refers to the difference in steering angle between the inside and outside front tires. We used to try to eliminate it in the '90s. but that was mainly on asphalt where rear traction is more critical, on carpet most people run some to help steering response.
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Old 10-05-2011, 10:50 AM   #36634
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Quote:
Originally Posted by LonnyJ1950 View Post
Ackerman refers to the difference in steering angle between the inside and outside front tires. We used to try to eliminate it in the '90s. but that was mainly on asphalt where rear traction is more critical, on carpet most people run some to help steering response.
As I'm starting to remember the:

flat servo/straight rods = More point and shoot hence easier to drive

Angled servo/angled rods = More precise smooth steering
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Old 10-05-2011, 11:12 AM   #36635
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Yes, akermann is the turning difference of the outside versus inside tire.

The below is just my impression, the actual facts could differ.

When I say steering aggression, I'm referring to the arc the toe links take on the servo. With the servo flat, the outside wheel's tie rod inner ball is going down. That means, with the same speed servo and all other things being equal, the initial steering speed off center is quick, and is then slowing down, and the inside wheel is turning at a fairly constant rate.

With the servo angled, the outside toe link is rising, so the initial turning speed is a bit slower, but finishes turning more aggressive. The inside wheel can get to a point where it just stops turning while the outside still has some turning angle left to go, in certain configurations, usually with a lot of akermann apparent.

Of course, there's exceptions, special cases and a lot of variables that can change everything all around as well. Depending on the chassis and front end you're running, it's still trial and error, with a handful of shims to see if you can get exactly what you want.
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Old 10-05-2011, 03:43 PM   #36636
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Has or does any one run single cell with brushed motors? We have a blinky 17.5 class at my local track, but I want to try running brushed. Which turn motor is comparable to 17.5? Thanks
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Old 10-05-2011, 03:46 PM   #36637
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Originally Posted by gashuffer View Post
Has or does any one run single cell with brushed motors? We have a blinky 17.5 class at my local track, but I want to try running brushed. Which turn motor is comparable to 17.5? Thanks
I played around with it in the early days of 1s. 19t was SLOW! It seems brushed motors were hurt more by the voltage reduction. Previously I had been running that 19t against 10.5 boosted with all of us running 4 cell and winning with it but 1s, it was more like a 17.5.
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Old 10-05-2011, 03:52 PM   #36638
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Thanks.
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Last edited by gashuffer; 10-05-2011 at 04:27 PM.
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Old 10-05-2011, 05:03 PM   #36639
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Hi Trev, here's a pic of the basic chassis:



This is with the battery in the furthest forward position (slightly further forward than the standard forward position).

Got a couple more tweaks since I made this, just tweaks, nothing revolutionary!

Cheers mate!
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Old 10-05-2011, 07:05 PM   #36640
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Quote:
Originally Posted by JamesL_71 View Post
Better pic... looks to be a new CRC:

http://rc50.com/modules/coppermine/a...1/IMG_1377.JPG

That chassis looks much longer than the current one with the battery across. What's the wheel base on that compared to the current car? To me it has to be longer because how else can you have the battery mounted lenghwise and still have all that room for electronics behind the servo like it did with the battery across?
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Old 10-05-2011, 08:19 PM   #36641
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Originally Posted by YR4Dude View Post

That chassis looks much longer than the current one with the battery across. What's the wheel base on that compared to the current car? To me it has to be longer because how else can you have the battery mounted lenghwise and still have all that room for electronics behind the servo like it did with the battery across?
It certainly could have a longer wheelbase... but Im pretty sure that is a different size battery than the standard 1S lipos. Maybe shorter but wider?
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Old 10-06-2011, 06:05 AM   #36642
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Cool Speed drop's after 3 rounds Hobbywing & Speed Passion

Hi,

I have an 1/12 CRC XL with an 1S 120A esc Hobbywing and a 13.5t Speed Passion motor. But I have a problem, after 2 or 3 rounds the speed drop's quite fast and the temp. of my motor is hot (80/90*Celsius). But if I go smaller in pinion or bigger in spur it doesn't change.
If I look at my settings in the Hobbywing 1S it is quite normal, I guess.
But when I change my settings, my car is going slower, so I have to have a perfect setting in my esc.
Can somebody tell me what settings I have to have in my Hobbywing?
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Old 10-06-2011, 08:19 AM   #36643
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How exactly are you geared?
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Old 10-06-2011, 08:30 AM   #36644
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Originally Posted by Serzoni View Post
How exactly are you geared?
I have spur 80 and I tried several pinions from 26 to 35 (64 pitch)
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Old 10-06-2011, 10:16 AM   #36645
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Yep. Turns out CRC is released a "shorty" 1S lipo.

And it is a new car:

http://www.rc50.com/modules.php?name...bum=67&pos=278

Last edited by JamesL_71; 10-06-2011 at 10:29 AM.
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