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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 10-04-2011, 03:32 PM   #36601
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Quote:
Originally Posted by Geforcy View Post
to bump my question up again...

am I correct rollout for mod is around 34 mm? and 13.5 turns boost around 58mm?
what pinions and spur range i can use? what is the smallest spur i am able to use? crc has 72teeth 64dp.

I am also interested 13,5 no boost and 17,5 turns rollout... in case i ever gonna drive that
That 72 tooth spur is WAY too small for anything other than blinky 13.5 or 17.5 classes, and probably not ideal there as you want to get the motor a bit more forward in the cage. 58mm isn't bad for 13.5 boosted, but unless you run bare rims for tires that will be impossible to achieve with with that 72, get a spur somewhere in the mid to upper 80's for boosted 13.5, low 90's for mod, and 70's for blinky classes.
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Old 10-04-2011, 04:40 PM   #36602
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Here's a question for you guys.

I am in the middle of making up a experimental front end for myGen XL car.

Basically, the existing crossbrace will have a few extra sets of holes for mounting the castor blocks closer to the centre line of the chassis (they can almost touch in the very centre holes!).

My friend has already made up some top links that extent to that point but what would you expect from a handling point of view?

Cheers,

Chris.
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Old 10-04-2011, 05:38 PM   #36603
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Originally Posted by wingman2 View Post
Here's a question for you guys.

I am in the middle of making up a experimental front end for myGen XL car.

Basically, the existing crossbrace will have a few extra sets of holes for mounting the castor blocks closer to the centre line of the chassis (they can almost touch in the very centre holes!).

My friend has already made up some top links that extent to that point but what would you expect from a handling point of view?

Cheers,

Chris.
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Old 10-04-2011, 05:41 PM   #36604
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Based on my experience, increasing the length of the upper arms decreases steering. The thought is that you get less camber gain as the car rolls with a longer arm, which reduces the contact patch and lowers the traction limit.
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Old 10-04-2011, 11:57 PM   #36605
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Originally Posted by LonnyJ1950 View Post
Based on my experience, increasing the length of the upper arms decreases steering. The thought is that you get less camber gain as the car rolls with a longer arm, which reduces the contact patch and lowers the traction limit.
SPOT ON. Excellent description of the effect the geometry has on handling......
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Old 10-05-2011, 12:34 AM   #36606
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So the last 30 years of racing weren't entirely wasted? Thanks, I really do appreciate that.......... Really!
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Old 10-05-2011, 01:04 AM   #36607
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Nice one fella's!

So, would you expect to run a little more camber to get the full contact patch on the front tyres through high speed corners?

And what about the castor settings?

Got the brace being made right now so will take a few pics once it is all together.

Cheers!
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Old 10-05-2011, 01:32 AM   #36608
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So the last 30 years of racing weren't entirely wasted? Thanks, I really do appreciate that.......... Really!
25 years here, and yes, your efforts have been most fruitful!!!! I just love when someone states things so succinctly.
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Old 10-05-2011, 01:35 AM   #36609
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Originally Posted by wingman2 View Post
Nice one fella's!

So, would you expect to run a little more camber to get the full contact patch on the front tyres through high speed corners?

And what about the castor settings?

Got the brace being made right now so will take a few pics once it is all together.

Cheers!
A bit more static camber will cover you in Hi-speed corners.

Caster is less affected by upper arm legnth, Since the sweep angle in the caster blocks is unchanged by upper-arm length........
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Old 10-05-2011, 03:37 AM   #36610
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Hi guys I just built my first 1/12 scale so this is a bit new to me.
I'm not sure how to adjust the front ride height. The car is a Yokomo R12 and if you look at the pic the:
Yellow circle is where the spring is.
Green circle is the screw that adjusts the value achieved in the red circle. However it also puts pre-load on the front spring (Yellow circle) Is this bad?

Im coming from a TC background so this is very new to me. Is what im doing correct or way off?

Thanks
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Old 10-05-2011, 05:15 AM   #36611
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Originally Posted by wingman2 View Post
Nice one fella's!

So, would you expect to run a little more camber to get the full contact patch on the front tyres through high speed corners?

And what about the castor settings?

Got the brace being made right now so will take a few pics once it is all together.

Cheers!
I expect the longer arms will effectively soften your spring rate as well.
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Old 10-05-2011, 05:29 AM   #36612
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Ran 1/12th for the first time yesterday,(10.5 blinky) car (CRC XL with bomb R) seemed good from the start but with a little on power understeer (exceed med fr and exceed soft rear, cs grip addative) swapped to med fr and med rear gave the car much better balance, didn't mess with any other setting to begin with, well impressed so far

Anyway my questions are:-

what is best, a high rev or high torque motor for 10.5 blinky

Ran 3 x 8min runs and tyres wear is totally parallel, is that normal are my castor (5) /camber (1) /toe out angles (.5) correct.

lap times in the second half of run were 0.4sec slower than at the start, is that due to addative, batteries or the motor getting hot (60deg)


Is it normal for for you hands to look like you have just done a oil change on the gearbox of a coal truck.

Bb
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Old 10-05-2011, 05:49 AM   #36613
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Originally Posted by bucketboy View Post
Ran 1/12th for the first time yesterday,(10.5 blinky) car (CRC XL with bomb R) seemed good from the start but with a little on power understeer (exceed med fr and exceed soft rear, cs grip addative) swapped to med fr and med rear gave the car much better balance, didn't mess with any other setting to begin with, well impressed so far

Anyway my questions are:-

what is best, a high rev or high torque motor for 10.5 blinky

Ran 3 x 8min runs and tyres wear is totally parallel, is that normal are my castor (5) /camber (1) /toe out angles (.5) correct.

lap times in the second half of run were 0.4sec slower than at the start, is that due to addative, batteries or the motor getting hot (60deg)


Is it normal for for you hands to look like you have just done a oil change on the gearbox of a coal truck.

Bb
Welcome to the wonderful world of 12th car racing!

I normally find that I adjust the camber angle to suit the wear rate on the tyres. So, looks like you are spot on at the moment if the tyres are wearing flat. You may find though, as you change to either harder, or softer springs, you will have to change the camber angle slightly to get that flat tyre wear (as the spring will be compressing more or less with either the softer or harder spring).

With regards to the lap time dropping off, this could be due to all of the things you mentioned, but probably not the batteries (as the initial higher voltage normally drops off after the first few laps, not half way through the run).

Not too sure whether a high rev or high torque motor would be better. This is due to the size, and layout of the track you are racing on.

I run the original GM 10.5 (that you can not adjust the timing on the end bell) whilst other guys at the club run the LRP/Nosram x12 (with adjustable timing).

There really is not much in it at our club although I find I have to gear higher to get more punch from the bottom end whilst the other guys gear lower and then use the timing.

One thing for sure though, is my motor is the same temp at the end of a run as it is at the start whilst some of the others guy's motors are really, really hot!!

How long do you apply the additive and how much do you put on the fronts?

Cheers, Chris.
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Old 10-05-2011, 06:17 AM   #36614
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Quote:
Originally Posted by bucketboy View Post
Ran 1/12th for the first time yesterday,(10.5 blinky) car (CRC XL with bomb R) seemed good from the start but with a little on power understeer (exceed med fr and exceed soft rear, cs grip addative) swapped to med fr and med rear gave the car much better balance, didn't mess with any other setting to begin with, well impressed so far

Anyway my questions are:-

what is best, a high rev or high torque motor for 10.5 blinky

Ran 3 x 8min runs and tyres wear is totally parallel, is that normal are my castor (5) /camber (1) /toe out angles (.5) correct.

lap times in the second half of run were 0.4sec slower than at the start, is that due to addative, batteries or the motor getting hot (60deg)


Is it normal for for you hands to look like you have just done a oil change on the gearbox of a coal truck.

Bb

Another welcome!

Everything Chris says is correct. It is possible that it is the cells causing the drop off though, I have known it in the past. How much did you need to put back into them when recharging?

Yep, tyre wear and settings are fine. If you are running a new XL keep checking and adjusting for slop in the front end for the first few runs, top and bottom pivot balls. It should settle down quite quickly though.

Yes it is normal for your hands to get like that! Keep a full pack of baby wipes handly and don't be afraid to use them!

Trev
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Old 10-05-2011, 06:22 AM   #36615
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Thanks for that, I'm running a 10.5 HPI at the mo because I already had one.
As for addative, put all over rear, 1/2 front about 10 mins before a run. Not going to bother changing srings battery position, or any of the other stuff just yet because after running 1/10th TC for the past 15 years its nice to be able to plonk a car on the track and have it go pretty much where you want it to go straight out of the box Might need to review that statement after the first race though

Deffo going to invest in a box of these http://www.ace-safetywear.co.uk/stor...wipe-250s.html

Bb
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