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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 09-15-2010, 11:29 PM   #34516
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Anybody a LRP X12 13.5? Have you played around with the endbell timing? We're running out here with no boost (0 timing on the esc). Rollout is between 85-88mm between all drivers; just wanted a bit more infield grunt. I'm running a LRP SXX v.2 btw....

Thanks guys
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Old 09-16-2010, 03:02 AM   #34517
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edit: posts here and here.
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Last edited by kjoer; 09-18-2010 at 05:37 PM.
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Old 09-16-2010, 04:18 AM   #34518
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Quote:
Originally Posted by DPowell View Post
If we could convince them to produce that pack with bullet connectors instead of Deans plugs it would be even better.
How are you ?

Like this

http://www.facebook.com/photo.php?pi...&id=1374897830

Alf :-)
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Old 09-16-2010, 04:29 AM   #34519
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Originally Posted by InspGadgt View Post
Since just about every 17.5 motor has a different timing value at the 0 mark you should rethink the timing on the motor part...
Hope you got back home safe.

Nice to meet you.

What about Hand out motor for 17.5

Alf :-)
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Old 09-16-2010, 10:38 AM   #34520
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Default 1S vs. 4 cell

Just wondering what the consensus is on 1/12th

Has everyone switched to 1S lipo or are there still many who are still using 4 Cell NiMh?

So far the new 1S compatible speed controls have just trickled out on the market. I know the Tekin RS can do it and so can the newly released SXX V2, but what about Novak and any others? I know Novak had the Havoc 1S but that is dated in technology compared to the Tekin and SXX.

Also while I'm on the subject of 1S vs. 4 cell. What about T-bar vs. Link. Is the link style rear end a better handler than the good old T-bar?
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Old 09-16-2010, 11:05 AM   #34521
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Originally Posted by YR4Dude View Post
Just wondering what the consensus is on 1/12th

Has everyone switched to 1S lipo or are there still many who are still using 4 Cell NiMh?

So far the new 1S compatible speed controls have just trickled out on the market. I know the Tekin RS can do it and so can the newly released SXX V2, but what about Novak and any others? I know Novak had the Havoc 1S but that is dated in technology compared to the Tekin and SXX.

Also while I'm on the subject of 1S vs. 4 cell. What about T-bar vs. Link. Is the link style rear end a better handler than the good old T-bar?
1S is the current ROAR spec, with that said, a link car is pretty much the best option for battery placement.

There are many speedos that work with 1S, perhaps a year ago they were "trickling" in, but the floodgates have opened on the 1S / Link racing now.

At our local races there are still a few round cell racers, some use them for a voltage advantage in the Cirtix Spec class, while others have t-bar cars, and older equipment that work best with that type of cell.

search these speedos for more info

The LRP SXXv2 is more for mod type racing.
SXXSS is a pure bred spec boost speedo.

Tekin RS

AEBD

Novak Kinetic

Speed Passion

Mamba
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Old 09-16-2010, 11:34 AM   #34522
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Originally Posted by kjoer View Post
Hi,


I've raced electric off-road from 1988 to 1999, had an eleven year break from RC and I'm now getting into 12th scale. I went to a local club and recently ordered some stuff . I went for a Team Associated 12R5.1.

  • Team Associated #4019 RC12R5.1 Factory Team
  • Protoform #1611-21 AMR-12 Light Weight Clear Body
  • LRP #50682 Vector X12 Brushless Modified - 5.5t
  • LRP #80905 SXX Competition Version 2 Brushless ESC
  • Ko Propo #30048 PDS-951ICS ICS 6.0V Digital FET Servo
  • MYLAPS RC4 Hybrid Transponder
  • 4x LRP #79877 LiPo Competition Car Line 1S Hardcase 5400 - 50C - 3.7V
  • Ko Propo #80400 EX-10 Eurus 2.4GHz SS (Tx/Rx with setting module)
  • Graupner #6444 ULTRA DUO PLUS 50


So, I'm totally green when it comes to 1:12 and current technologies. I built the car, which was fun, apart from sanding/glueing/sanding CF parts. That takes about as much time as actually building the car, if not more .

However during building I noticed some things, I've got some questions:


- The pivot brace is under an angle when adjusting it for for free lower rear pod plate movement.One side is sitting to the front, while the other is sitting to the rear. I guess this is normal/intended.
My car is the same as this

- One of the holes in the left & right rear pod links binds slightly without even having inserted a M2 screw. Its not bad, but its not optimal either. It seems to be mold related, since its the same hole that slightly binds for both links. What is usually done to fix this? Polish the ball? This would remove the coating, wouldn't it? Enlarge the hole somehow?
Try squeezing the plastic part with pliers around the ball to indent it around the ball and free it up slightly

- The pivot balls in the lower front suspension arms bind very badly, they don't move freely at all. Is this normal? Should I fix it somehow? Polish the ball? Enlarge the hole somehow?
Same as last post squeeze the plastic of the arm around the ball to free it up.

- With default settings, the pod is sitting upwards. With the wheels from the ground, shouldn't the rear pod rest downwards (some droop), so one could adjust the center shock preload to make the pod aligned to the chassis under static load (car resting on its wheels with full mass)? I used the (default) center shock droop spacer. The center shock aluminum rod end is all the way onto the shaft. Shouldn't it be? Should I unscrew the ball cup a few millimeters? Or shorten the droop spacer in the shock? How much droop should I aim for?
Check you droop spacer is trimmed to the correct length and trim to suit, i run 1mm of pod droop on my car

- Which Ackermann servo spacers should I use by default? ( Ko Propo #30048 PDS-951ICS ICS 6.0V Digital FET Servo ). At the moment I used one thick spacer per side. In a top view with steering centered, the turnbuckles are sitting colinear.
my steering links run inline with each other

- How am I supposed to use the tiny receiver antenna with the solid antenna mast? Use shrink wrap around the mast with the antenna inside?
just try and run it up the mast as far as possible without touching any other electrics

- Do people position LiPo's to the front or rear? My assumption with LiPo's being lighter than sub-C cells, people would move LiPo's to the front to retain some front end weight. However, pics from the recent worlds show this:

Marc Rheinard: LiPo to the front
Ronald Völker: LiPo to the back
Juho Levanen: LiPo to the front, the ESC is turned 90 degrees to make room for the LiPo
I have used my car since last winter and it was cells at the time so the lipo guys may be able to help you with this

Don't know if the pics were I got this info from were taken during similar track conditions. Or maybe it just comes down to driver preference. I guess I'll install electronics in a way so I can strap the LiPo either to the front or rear (or somewhere in between). Is it true positioning the LiPo to the back actually gives more steering? Is moving it to the front used to reduce grip rolls?

- Just have to install electronics now. I must say, its pretty tempting to trim all receiver channel wires to custom length as well. Not sure if that would void the warranty of the ESC/servo/transponder. Its a bit of a handfull to fit the standard length receiver wires into the car, it doesn't look very tidy either.
Most people either shorten the wires or just fold them up and black heatshrink them so they are slightly neater

- Oh, how many guys replace some of the not-so-stressed steel screws with blue anodized aluminum/titanium ones? Seems a bit iffy to me, but i guess its doable for some screws. On the other hand, better to snap a screw than rip a chassis plate on heavy impact.


Thanks in advance to anyone taking the effort to answer these questions!


( Sorry, I can't link URL's yet for pictures: "You are only allowed to post URLs to other sites after you have made a certain number of posts. You have not reached that limit yet." )
hope this helps
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Old 09-16-2010, 12:19 PM   #34523
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Originally Posted by alf.skaar View Post
Hope you got back home safe.

Nice to meet you.

What about Hand out motor for 17.5

Alf :-)
Hi Alf,

Great to meet you too. It was very interesting seeing your car up close.

Hand out would work but adds to the cost of racing considerably.
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Old 09-17-2010, 04:06 PM   #34524
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hope this helps
Thanks :).
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Old 09-17-2010, 05:00 PM   #34525
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Originally Posted by kjoer View Post
Hi,

- Do people position LiPo's to the front or rear? My assumption with LiPo's being lighter than sub-C cells, people would move LiPo's to the front to retain some front end weight. However, pics from the recent worlds show this:

Marc Rheinard: LiPo to the front
Ronald Völker: LiPo to the back
Juho Levanen: LiPo to the front, the ESC is turned 90 degrees to make room for the LiPo

Don't know if the pics were I got this info from were taken during similar track conditions. Or maybe it just comes down to driver preference. I guess I'll install electronics in a way so I can strap the LiPo either to the front or rear (or somewhere in between). Is it true positioning the LiPo to the back actually gives more steering? Is moving it to the front used to reduce grip rolls?
It's an adjustment just like anything else. Forward, more stable and less likely to traction roll. Back, more steering, more aggressive. I know it sounds backward but that's the way it is and there is good physics behind the reason. The only thing switching to lighter lipos really did is reduce how dramatic an adjustment it is.
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Old 09-18-2010, 03:14 PM   #34526
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It's an adjustment just like anything else. Forward, more stable and less likely to traction roll. Back, more steering, more aggressive. I know it sounds backward but that's the way it is and there is good physics behind the reason. The only thing switching to lighter lipos really did is reduce how dramatic an adjustment it is.
It indeed does sound weird, my guess is it being backwards generates more overall roll? :)
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Old 09-18-2010, 04:02 PM   #34527
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It indeed does sound weird, my guess is it being backwards generates more overall roll?
more weight transfer to the front tires on decelleration.
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Old 09-18-2010, 04:47 PM   #34528
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more weight transfer to the front tires on decelleration.
Alright :).
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Old 09-18-2010, 08:24 PM   #34529
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I guess it depends on what you prefer the feel of. If the pro's all run different settings then that alone tells you its more a preference than outright pace. I have tried forward and backward and much prefer the feel of the car with it forward. I found no real difference in lap times (possibly a tenth) but the car is much better over a run with it forward. In fact I have found concentracting all the weight towards the center of the car means where ever I go I drop the car on the track and turn good times from the get go before I bother doing any tuning. I can only see this as a good thing.
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Old 09-18-2010, 11:12 PM   #34530
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It indeed does sound weird, my guess is it being backwards generates more overall roll?
Nope. Let me see if I can explain it. There are two reasons for the effect.

When you add vertical load to a tire, it gains traction. But if you put them both on a graph, you will see that the traction goes up less than the load is going up. For example, take a tire with a 1 pound vertical load on it, let's say it can take 1 pound of lateral load before it slides. Now double the vertical load to 2 pounds. Does it now take 2 pounds of lateral load to make it slide? No, it will slide at a lesser load, let's say 1.8 pounds.

Secondly, if you move static weight forward in the car, you are putting more vertical load on the front tires but you are also moving the center of gravity forward. Obviously I am talking about the fore/aft position of the cg, not the height. The cg is the point on the car where centrifugal force pushes on it to try and push the car towards the outside of the corner. Let's see an example of how this might affect things.

Imagine a 1 pound car. It has the exact same tires all the way around and its weight distribution is exactly even, 1/4 pound of weight on each tire. Its fore/aft cg position will be right in the middle of the car between the tires. Now let's say skid pad tests show this car can take a 1 pound lateral load before skidding, meaning it can corner at 1g and it's perfectly balanced handling wise so when it skids, it's a four wheel drift out of the circle, not a spin out or an understeer out of the circle. If you doubled the car's weight to 2 pounds, the tires will gain more traction but not as much as the weight will increase the lateral load so the car will now skid with a 1.8 pound lateral load which is LESS than 1g with a two pound car.

Now let's go back to the one pound car but let's move some component forward so that the front tires now have more weight on them. This would initially seem to increase front traction so now this car will spin out when it skids instead of a nice, balanced, 4 wheel drift right? No, that's wrong. Remember, traction goes up more slowly than the vertical load does. So what happens is that the now more lightly loaded rear tires have lost less traction than the fronts have gained. But this alone is only part of the story since we are still seeing a loss of rear traction and a gain in front, even if it isn't an even trade.

That's where fore/aft cg location comes in. Imagine the original, balanced car is stationary on the skid pad and you are in the middle of the skid pad with a pool cue to use to try and push the car from the side out of the circle. The end of the pool cue is placed right on the cg (middle of the car) and the tires and load are the same so when you push on the cue, the car just slides all four tires. Now move the weight forward. The cg moves forward so you have to move the spot on the car that you push with the cue forward. This means you are now pushing harder on the front tires than on the rear. This would be balanced out by the increase in front traction and the decrease in rear traction resulting in another perfect, four wheel slide except that as I said before, the rears have lost less traction than the fronts gained. So the front tires are going to slide first. The car will now understeer.

I hope that makes sense. I am not the best at clearly explaining complex concepts of vehicle dynamics but I have studied it extensively and this is the basic consensus of ALL well informed engineers on the subject. This is why nose heavy front engined cars fight understeer issues while tail heavy rear engined cars like 911s fight with oversteer.

Also, this subject can get even more confusing due to another effect. As I described above, moving the weight to the rear should make the car oversteer but there is a situation where this could be backward. Moving the weight back will make the car looser in a steady state corner but with a rear wheel drive car, the increase in rear weight could reduce wheel spin under power, improving rear traction. This is why offroad dirt cars have such a high rear weight distribution. So in this situation, moving the weight to the rear could result in more steering off power but less on power. Especially when powering off of a slow corner, but might have even MORE on power steering exiting a fast corner.
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