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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 01-25-2006, 12:54 PM   #17056
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Technically, you should be able to control the bumps and track elevation changes through the suspension and not rely on the the chassis flex.

Here's my theory: Most people don't realize the stock front suspension binds up when you put the kingpin shims on top. This is a design flaw. (See attachment.) I bet that most people haven't used a dremmel to fix this, and therefore are using front suspensions that are nearly useless for the 2nd half of the compression. It took me a while to discover what the problem is.

When the suspension is compressed about halfway, the top shims bind against the upper suspension arm eyelet. To test if you have this problem, remove the front e-clip and spring and move your suspension up and down. It should move all the way up without binding. It should be completely free for the full travel. If you are noticing some binding, remove the top e-clip and shims and see if it becomes free and smooth.

What you will find is the top shims bind against the top inner wall of the upper suspension arm eyelet. This causes the suspension to bind about halfway to 2/3rds of the way up. People don't usually notice this when the spring is on since it can be overpowered by your hand strength.

The solution: take a dremel, and shave off some of the material on the upper wall where the shims start to bind. This only has to be done in one area of the eyelt. If you have a caliper, it's wise to find the smallest diameter shims you have and use those at the top. (I've noticed a small variation from batch to batch.) This has completely solved the problem for me. And now the suspension is buttery smooth all the way up for me.
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Old 01-25-2006, 01:12 PM   #17057
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Quote:
Originally Posted by Chris Reilly
Here is a pic. I know it's a older pic but you can see the upper outer camber link. It's grey. I need a part number if anyone knows. Thanks

Talk to Bud at BRP. He might still have some left. I believe they were cut down rocket city links. I think I have 1 set left if you can't find any.

Tim
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Old 01-25-2006, 01:21 PM   #17058
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Quote:
Originally Posted by Tim Stamper
Talk to Bud at BRP. He might still have some left. I believe they were cut down rocket city links. I think I have 1 set left if you can't find any.

Tim
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Old 01-25-2006, 01:28 PM   #17059
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Quote:
Originally Posted by JayBee
So which grade of carbon fiber are you using with the DB12's?

i went with quasi isotropic 2.5mm.the high modulous was too brittle for a car that is not a double deck car.our chassis on the db12 is rock solid and with ll the testing we did over the past year,it works extremely well in every condition we tested it in.(both high bite carpet and all the way to low bite asphalt)
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Old 01-25-2006, 01:44 PM   #17060
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Originally Posted by Nick-C
I would have to agree with that thinking. Why on earth would you want to put the consistency of your car in the hands of something that flexes?

(cough, t-bar)
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Old 01-25-2006, 01:54 PM   #17061
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for bumpy apshalt fibre glass car were the usally the the quickest tick around the track as they would twist and flex to generate grip and would be more forgiving over the bumps. A opposed to stiff graphite chassis. The supension design on these cars can only cope with conering loading as opposed to bumploading so to cope with the bumps it better to let the chassis deal with the bumps and the supension deal with the corners.
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Old 01-25-2006, 02:12 PM   #17062
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Quote:
Originally Posted by Smoking motor..
for bumpy apshalt fibre glass car were the usally the the quickest tick around the track as they would twist and flex to generate grip and would be more forgiving over the bumps. A opposed to stiff graphite chassis. The supension design on these cars can only cope with conering loading as opposed to bumploading so to cope with the bumps it better to let the chassis deal with the bumps and the supension deal with the corners.
Unless you aren't relying on a hunk of fiberglass to control the side to side and fore and aft roll rates on your car. Maybe if you could vary the spring rate side to side as well as front to rear, the car could be tuned for differing levels of traction , as well as bumps. If only a car like that existed!!!
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Old 01-25-2006, 02:31 PM   #17063
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I think you would find the tyre would be doing the damping over the bump while the chassis flexes. the roll rate you are talking about would only occur when the car corner this where the there is tranfer of load in occuring within the chassis. The bumps are a vertical load not a side to side tranfer the the idea for the flex is to allow the wheel to roll over the bump rather than bounce up then crash over the bump and causing the chassis to bottom out. This causes the chassis to skid and slow down. Keeping the chassis the same height with repect to the road require the wheels to follow the contours of the bump the flex stop the car wheel lifting up of the ground when it intial hit the bump pushes the wheel back down as the chassis return to it normal position.

This is the simplest explaination unless you have driven car with European supension at Speed on english roads. Best one would be to compare the current model audi a4 vs the current model bmw 3 series over industrial used road at speed over 60+mph.

Or drive a Peugeot 205 206 306 at speed and compare it to a VW golf to get the picture.
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Old 01-25-2006, 02:34 PM   #17064
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Quote:
Originally Posted by CypressMidWest
Unless you aren't relying on a hunk of fiberglass to control the side to side and fore and aft roll rates on your car. Maybe if you could vary the spring rate side to side as well as front to rear, the car could be tuned for differing levels of traction , as well as bumps. If only a car like that existed!!!
What car is that? It comes with purple parts?
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Old 01-25-2006, 02:42 PM   #17065
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Quote:
Originally Posted by Smoking motor..
I think you would find the tyre would be doing the damping over the bump while the chassis flexes. the roll rate you are talking about would only occur when the car corner this where the there is tranfer of load in occuring within the chassis. The bumps are a vertical load not a side to side tranfer the the idea for the flex is to allow the wheel to roll over the bump rather than bounce up then crash over the bump and causing the chassis to bottom out. This causes the chassis to skid and slow down. Keeping the chassis the same height with repect to the road require the wheels to follow the contours of the bump the flex stop the car wheel lifting up of the ground when it intial hit the bump pushes the wheel back down as the chassis return to it normal position.
This is why a link car can run softer front to rear to absorb bumps, (as best a live axle car can), and still be sprung stiffly enough side to side to control roll rate while cornering. They're two completely different variables, both easily understood, but only two cars currently available offer the ability to tune separately for each.

TFR: That's a Rev. 2, I don't know if Bruce still carries the Purple goodies or not.
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Old 01-25-2006, 02:52 PM   #17066
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James35,

I just took a look at what you mentioned above and I don't think that your binding would have come from the upper eyelet, as it moves in conjunction with the upper arm and the wheel. The only point at which the king pin moves through the eyelet is the lower arm. If it did move through the upper one, the king pin would hit the inside of your wheel.

One thing I have noticed that can cause some issues is the hinge pins are not round on the end where the upper arm rotates on them. I put mine in a dremmel and polished the ends on a fine grit sharpening stone until they would spin freely by hand before assembly.

Greg
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Old 01-25-2006, 02:59 PM   #17067
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Quote:
Originally Posted by Tim Stamper
Talk to Bud at BRP. He might still have some left. I believe they were cut down rocket city links. I think I have 1 set left if you can't find any.

Tim
FYI. If you do find the Rocket City links, you will need to find some pivot balls to fit. The stock Associated ones do not work. I believe Du-Bro makes some Delrin ones that fit, but I'm not 100% sure about that...
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Old 01-25-2006, 06:01 PM   #17068
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Quote:
Originally Posted by CypressMidWest
This is why a link car can run softer front to rear to absorb bumps, (as best a live axle car can), and still be sprung stiffly enough side to side to control roll rate while cornering.
Could this be why Speedmerchant Rev.4's went 1st and 2nd this year in Cleveland? Two fantastic drivers with two cars that soaked up every bump and still had the ability to scream through the corners. I wonder if anyone there was tempted to run a thinner chassis to help with the bumpier than normal track conditions?
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Old 01-25-2006, 06:54 PM   #17069
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Quote:
Originally Posted by CypressMidWest
This is why a link car can run softer front to rear to absorb bumps, (as best a live axle car can), and still be sprung stiffly enough side to side to control roll rate while cornering. They're two completely different variables, both easily understood, but only two cars currently available offer the ability to tune separately for each.

TFR: That's a Rev. 2, I don't know if Bruce still carries the Purple goodies or not.
Note I respect your knowledge and your probably faster driver than me.
But please look at what I am saying.

It is not a live axle car !!!! (live axle are a stupidly different ball game! and always considered to use eliptical springs,Panhard rods.)
When it uses links or de dion supension it is referred to as a trialing link supension or an de dion axle.Yes I study automotive engineering and have messed around with kit cars etc.
You also need to consider the tyre as the most effiecent point for the damping and springing to occur that why single seater race cars use tall tyres (inflated with nitrogen to ten to 15 psi) and very stiff supension so they can transfer the wings down force to the tyre contact patches. So you can do stupids thing such as pull 4g in braking, in a formula renault when braking from a 160 mph 30 mph in less tham 50meters. This is just data of a black box.
With heavier race cars such as rally cars and touring cars the rules are different and the reliance of Down force is much less so the tend to let the supension do the work rather than the tyres thus the use of low profile tyre the make the car more reponsive in terms of changing direction as they have a reduced slip angle.
It is very much akin to a go kart (t-bar) or a trailing link setup (link car). Any of these cars can be adjusted to cope with roll rate, i.e tweak springs on the carpet knife and the t-fource, changing the t-bar thickness will control roll rate. Chassis thickness won't it but may effect the effiency of the supension by absorbing the bumps of the car, that why you use an flexible chassis. this will not effect the roll rate.
Any way the roll rate is controled by the side damping of the plate or tubes no the fore aft damping of the center shock. That controls the fore and aft transfer of the cars mass around the point of inertia in the accelarating and braking.
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Old 01-25-2006, 07:01 PM   #17070
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Quote:
Originally Posted by brianrice
FYI. If you do find the Rocket City links, you will need to find some pivot balls to fit. The stock Associated ones do not work. I believe Du-Bro makes some Delrin ones that fit, but I'm not 100% sure about that...
I bought some of those links from BRP a while back, and he told me that RPM makes some delrin pivot balls that fit those cups. I believe they were from old losi truck ball ends, but I can't be sure.

-James
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