Frequently Asked Questions – RC Drifting
What is a Drift Box or Dbox? What does it do?
A Drift box is a gyro that is set-up between the ESC and the steering servo. This gyroscope is used to automatically balance the steering response of the RC car so that it does not spin out. The HPI dbox is one of the most common examples of a drift box. The gyroscope is commonly used tool in the RC Helicopter industry to stabilize flight, where constant stabilization is always needed otherwise the helicopter would be extremely difficult to fly. The gyro can be set up such that it keeps the user from spinning out and losing complete control of the car. The dbox sensors detect the tail sliding of a car and automatically counter-steers to correct itself from spinning. That is the function of a dbox or drift box.
In the RC Drift community, using a drift box or gyro is frowned upon. The gyro is capable of doing a good job that anyone can drift without much effort at all. In the art of drifting, the user is expected to maintain control during the chaos of drifting and sliding. What is the point of drifting with a dbox when you are not actually the one in control? It is highly recommended that everyone goes without it, it is an overpriced and costly option part that does not teach you anything about driving. Why not learn the proper way? Practice makes perfect after all!
What offset should I use for my body?
First, you need to know the width of your body:
Tamiya, Yokomo, and some ABC bodies = 190 mm
HPI bodies = 200 mm (with the exception of the Trueno and Levin).
Of course there are certain bodies such as the BMW Z3 and S2000 that are slightly smaller.
The larger the body width, the bigger offset rim you can use. Most tamiya and yokomo bodies can only use up to 6mm. HPI’s can take 9mm. Of course, if you add a little camber, you can probably use a bigger offset. Also, look at the body and the shape. Take the yokomo supra for example. It’s technically a 190mm body, but since it has really wide fender flares, you can use deeper offsets. Before you buy rims to match your body, keep in mind the width. Or just ask on the forums. We’ve run just about every single body you can imagine… The last thing you want are wheels that stick out.
Now I mentioned before that deep offsets change how the chassis drifts. How? A bigger offset means that the tires stick out more. When the tires stick out more, you are changing the track width of the car. Now it can be contested that a couple of mm won’t make that much of a difference. But depending on the surface, it can. Just something to keep in mind in case you’re wondering why your Chaser body with 12mm offset rims is under steering a little.
What does it mean by offset?
The offset of the rim is basically how much the lip of the rim sticks out from the face. Offset is measured in millimeters. The bigger the number, the “deeper” the rim. Common offsets are 0,3,6, and 9mm. Rims from speedway pal in Japan sometime come in offsets greater than 10 mm.
How much camber do I need?
Again, it depends. In my opinion, unless your set for countersteer, 3 degrees is enough. A lot of guys use 3 degrees front and rear, which is typical on yokomos. My TB03 has 1 in the front and 2 in the rear, and my TT01 runs 0 camber all the way around (it weight shifts a lot). So test it out and figure out what suits you the best. Remember that more camber increases traction in a turn and less camber decreases traction.
The one thing you have to remember about camber is that eventually the inside tire wear will “flatten” out eventually. So even though you have cambered wheels, the initial contact of the tires will be completely covering the ground as if you were running 0 camber. So watch your tire wear and replace the wheels if needed.
What is camber?
Basically, it’s changing the angle of your wheels so that they lean in towards the center of the chassis (measured in degrees). Note that for some weird reason camber is positive in the RC world, but negative in 1:1 racing…don’t ask. We all just call it negative since it’s what we’re used to. Camber is achieved by shortening the suspension upper arms on your chassis by turning the turnbuckle. What camber does is help create more contact between the tire and road when turning.
Here’s a little physics. When you drift there are several forces acting on the car. First there’s the inertia at which the car is travelling due to acceleration and momentum (remember that a body in motion will stay in motion unless acted upon by an unbalanced force..Newton’s 1st law). Then there’s friction at the tires that is working opposite of the inertia. The result is that when you go hard into a turn and slide, weight shifts towards the outside of the turn laterally (again, watered down physics lesson). And when that happens, due to the weight transfer and how suspension works, the chassis will “lean” into the direction you are travelling, and the inside of the tire will lift slightly. See below.
Ever wonder why old school 1:1 drifters used oni-kyan or “demon-camber” (a lot of camber in the front) when they drift? It’s to reduce front tire slide and improve steering in the front (more traction) for an underpowered car, reducing understeer. Although this doesn’t apply RC as much since your chassis is 4WD, the concept is similar.
So with camber, you can see that your initial contact patch with the ground is minimal when standing still. But in the middle of a turn, the car leans, and the contact patch increases. This gives the leaning side a little more traction and grip which is important when you are exiting the turn, or trying to pull in on a clipping point.
How long do tires last?
Tire wear depends on how you drive, the setup of your chassis, and the surface. Obviously, a chassis with a big aggressive motor is going to eat up tires on asphalt, while cambering your wheels will create inside tire wear. For the most part, your tires will last several months depending on how often you drift. But it’s always a good idea to stock spares if you can. You can also rotate your tires every now and then to even the tire wear out.
Which tire is better?
Every brand/Type reacts differently depending based on the compound of the tire, hardness, and the type of surface you run on. HPI T-drifts (smooth) and Tamiya driftechs are pretty much your all weather, all surface tire. Plus, they are easy to find. Yokomo rings usually do better on smooth slick surfaces like polished concrete, while something like PVC (Sushi) piping is a little more difficult on asphalt, but works better on carpet. Which ever tire you use, consider the surface that you drift on the most. Note, that at a lot of RC drift comps, there usually is a tire restriction.
Can I run Nimh on a brushless system?
Yes. Although keep in mind that depending on how fast your brushless motor is, it can drain a nimh pretty fast. Also, once a Nimh hits that point where the charge is low, you’ll notice it on the throttle. Lipos deliver a more consistent output and the power drop off when the charge is low isn’t as dramatic.
How is lipo capacity measured?
Lipos are rated in mAh (2400, 3800, 5400, etc..). The higher the number, the higher the capacity, and the longer the run time (depending on motor size). Also, lipos can be 2 cell or 3 cell (2S or 3S). Note that IMO, a 3S lipo is a bit much for drifting. Also on a lipo is the “C” or discharge rate. This is how fast the battery can be discharged safely. The higher the C rating (10C, 15C, 20C, etc), the faster the battery will discharge. So in other words, more “punch” at the throttle.
Do I need to balance my battery every time I charge?
No. Although it’s highly recommended to balance when you can. Put it this way, the better you take care of your electronics, the longer they’ll last…
What are “CVD’s”?
Constant Velocity Drive-shaft
CVD’s replace the “dogbones” that fit between the differential cups and the the outer drive cups at the wheels. Unlike dogbones, the outer drive cups are connected to the dogbone on a CVD unit. This prevents the dogbone from slipping out (especially in the front when turning) and provides a better transfer of power from the differential to the wheels. Those who have lost or thrown a dogbone know that it’s a good thing to get, and makes life much easier when taking things apart.The only drawback it that the nut holding the drive cup to the dogbone can come loose, shredding your wheel hub. So be sure to add a little thread lock to keep it in.
What is Torque Steer?
Torque steer occurs in all shaft driven chassis’ due to the layout of the drivetrain in relation to the motor and pinion. Without getting too technical, since the rotation of the drive shaft is perpendicular to the wheels of the car, the rotational force (torque) delivered from the motor has to change direction several times before it gets to the wheels. This causes the chassis to have the tendency to slightly “steer” itself and favor one side. If you have a shaft driven car, set it down and floor it without steering. You’ll notice that the car will eventually start to drift to one side automatically, or you can tell that it’s easier to drift one way compared to the other.
Belt driven cars do not suffer from this because the drivetrain is inline with the wheels. The pulleys are parallel with the wheels and motor rotation. Torque is delivered evenly and in the same direction (front to back), and only needs to change direction once (at the pinion and spur).
It’s possible to reduce torque steer by adjusting your setup. Most of us just live with it since it’s not that big a deal unless the torque steer is really bad (usually with big motors).
What are Toe-in/out adjustments for?
Toe will help stabilize your car in a straight line. Generally RC kits come setup with rear toe in to help with straight line acceleration. More rear toe will stabilize the car, but increase tire wear. Less rear toe will make it more tail happy. Its a little bit different for the front toe. Running toe-in will again help with stability in straight line, but you lose turn-in capability (less turning angle, on the tire closest to the corner), and also lessens the ackerman angle. Toe-out will add stability and increase the turn-in, but increases ackerman angle. As far as what works best, its really up to your car and how you drive.
Shaft vs. Belt?
A hot topic of conversation in the RC world for racers and drifters. Both have their respective advantages and disadvantages. It all comes down to personal preference.
1. Easier to drive; smoother power delivery, little to no torque steer due to layout and orientation of the motor
2. Quieter than shaft driven counterpart; more efficient and smoother drive system
3. More options for countersteer modifications
1. Belts stretch over time and needs replacing
2. Unsealed or exposed differential; small debris like pebbles can get into the drive line and cause damage
1. Instantaneous power delivery, throttle on demand
2. Sealed differential; low maintenance and less prone to damage, great for parking lot bashing or any un-prepared surface
1. Torque steer; the torque created from the motor that influences the steering of the vehicle
2. Minimal options for countersteer modifications
What is the difference between CS Percent and CS Ratio?
It is common to see 50%, 80%, 100% CS and 1.5, 2.20, 2.52 CS, so what do the percent and ratio mean?
- 50% CS and 1.5 CS ratio are equivalent (50%CS == 1.5CS Ratio). It means that the rear wheels are spinning 50% more for every revolution of the front wheel. So 1.5CS Ratio means for every 1.0 revolution the front wheels make, the rear will revolve 1.5 revolutions.
- For 80% CS/1.80 CS ratio. The rear wheel will spin 80% more than the front wheel. For every 1.0 revolution of the front wheel, the rear wheels will revolve 1.8 times.
- 100% CS == 2.0 CS ratio; Rear wheels will spin 100% more than front wheel. For ever 1.0 revolution of the front wheel, the rear will turn 2.0 times.
- 2.20 CS ratio == 120% CS; Rear wheels will turn 120% more than front wheels. For ever 1.0 revolution of the front wheel, the rear will make 2.2 revolutions.
- 2.52 CS ratio == 152% CS; Rear wheels will turn 152% more than front wheels. For ever 1.0 revolution of the front wheel, the rear will make 2.52 revolutions.
What is Countersteer (CS) RC drifting?
Countersteering is the act of turning the tires of your car into the direction of the skid to prevent the car from oversteering or spinning. Even in 50/50 drifting there are situations that require some countersteering technique to keep the car in control. In the RC drifting world, CS drifting refers to changing the drive ratio of the front, rear or both differential. By changing the drive ratio, the power distribution of the car will no longer be 50% front and rear. If the power distribution is differed by for example: 30% front and 70% rear, then the car behaves more like a RWD car; similar to a real drift car. This makes the car more difficult to drive due to the rear wheels trying to out-drive the front wheels of the car. This leads to more countersteering and also adds to the realism of scale drifting.
CS is achieved by a couple of methods:
Underdrive (UD): Increasing the drive ratio of the front differential, the front ratio is larger than the rear.
Overdrive (OD): Decreating the drive ratio of the rear differentail, the rear ratio is smaller than the front.
What is 50/50 drifting?
The traditional way of drifting. In an all wheel drive on-road touring car, the power is distributed evenly to drive the front and rear differentials of the car. 50% of the power drives the front wheels and 50% drives the rear. This can be accomplished with any on-road AWD touring car. It is recommended that newbies start here and then move on the Countersteer setup after mastering 50/50.
Too much Oversteer on your RC Drift car?
This can be a common problem, especially for newbies. Here is a suggestion, it comes from one of the members on Driftmission forum, JustSideWayz. It offers some good suggestions and things you can do to mitigate the oversteer problem. Check it out.
One thing I think you might try is messing with the back end of the chassis. If the car is oversteering while on throttle soften the rear springs and thinner damper oil. This should take away some of the forward grip the rear has causing the excess on throttle rotation. If the problem is the opposite the oversteer or over rotation while off throttle you might strengthen the rear damper oil and spring. This should slow the cars rotation while off throttle by increasing the grip while the tires are sliding. This is my general tuning for over rotations. You also have to consider how your front end is doing too. Try to make the adjustments by only 1 turn or less on the shock preloads, and go thru the ranges before completely changing springs. I have found that as I get close to the point of a good tune I can feel a smaller movement like a 1/4 turn one way or the other might just hit a sweet spot. Yes I know its hard to believe you can notice a 1/4 of a round on spring preloads, but you can. In the end you want to balance the forward on throttle grip to the off throttle slide of the rear end. Well anyways I hope this helps… Others may have different methods, and that’s fine, just sharing what I do.
Here is a little info on adjusting the front.
Once you have the rear ok, you just have to balance the amount of grip the fronts have. More spring pressure should provide more grip, Too much front grip will try and make you switch when you don’t want to. While less front preload will start letting the back end come around too easy. You have to find just enough grip to keep the front ahead of the rear. Its all a balancing act between grip traction and weight.