Brushless & Nitro RC Cars Trucks | HPI | Traxxas

Axial Exo Terra Buggy : Now the Rock-crawling Masters are on the Short Course Buggy SCB Bandwagon!

The Professional Bum — Fri, 10 Feb 2012 03:21:17 +0000

Let’s see what happens when the masters of rock-crawling suspension design, Axial, can get up to when they put up a tough short course- type buggy…. or would this be a terrain buggy? Apparently the weight is also well balanced and that makes it good for landings.

These ones are running Novak Havoc Pro ESC’s, with 4.5 turn motors and Thunder Power 2S lipos.

Check out the official video right here on http://hpisavagex46.wordpress.com

Jared Tebo Neo11 Race Inferno MP9 Setup Sheet

The Professional Bum — Sun, 29 Jan 2012 02:41:46 +0000

This is Jared Tebo’s winning setup for the Neo11. I was looking this up because I need to get a new clutch bell for my MP9, and thought I might want to see what he’s up to. I’m quite surprised at the 13/48 ratio though. It’s really high!

Is this Kyosho ST-RR Evo Body – Original Kyosho? J-Concepts? Proline

The Professional Bum — Sat, 28 Jan 2012 15:22:27 +0000

I’d like to get one of these low profile body designs for my newly-acquired Kyosho Inferno ST-RR Truggy.

Sanwa High Torque Servos Crazy Test

The Professional Bum — Fri, 27 Jan 2012 02:46:18 +0000

I just busted a Sanwa Servo Yesterday. Gears stripped. I heard that I could simply replace the stripped gears in the servo, and it’d have a new lease of life. The previous owner spent alot on them back then, and hence it’d be a very worthwhile few-dollar repair. When checking out repair videos, I came across this cool video which I thought I’d share.

RC SETUP GUIDE – BASICS TO EXPERT – TheToyz Forums

The Professional Bum — Thu, 12 Jan 2012 07:22:08 +0000

Quick Tire Basics

Tires are always the first element in setting up a car. If you’ve got the right tires, you’re 90% there.

Here is a quick basics on tire and insert choice

Compound(Tire Material)

Harder

Less wear
Less grip
Less sidewall movement

Softer

More wear
More grip
More sidewall movement

Foam tires offer large amounts of grip, but also large amounts of wear. Any imperfections in the track will badly effect the life of a foam tire.

Inserts

Harder

Less grip on harder surfaces
Less sidewall movement
More predictable tyre wear

Softer

More grip on harder surfaces
More sidewall movement
Less predictable tyre wear

Choosing the right combination of Compound and inserts is important, too harder compounds will reduce the effect of softer inserts, and harder inserts will reduce the effects of a soft compound.

Sidewall movement can help increase the cars grip at the start and end of turns, but will slightly effect the response of steering as the car moves around on the tyre.

Tread Pattern

Pins

Extremely high wear on hard surfaces
Low traction on hard surfaces
Gives even traction in all directions on the tyre
Traction greatly reduced by too much loose surface (such as sand)

X Pin

Medium-high wear on hard surfaces
Relatively low traction on hard surfaces
Gives even traction in all directions on the tyre
Traction less effected by loose suface material (such as sand)

Paddle

High wear on hard surfaces (especially during accelleration)
Extremely good traction on loose surface material (such as sand)
Can drastically reduce steering on RWD vehicles

Grooved

Medium-low wear on hard surfaces
high side-to-side traction
Low traction on acceleration on loose surfaces

Smooth/Slicks

High traction on hard surfaces
Gives even traction in all directions on the tyre
drastically reduces traction on loose surface material

V-Groove (onroad)

improved traction in wet conditions during accelleration

Z-Pattern (onroad)

can help improve traction in loose surface material (such as dirt on track)

slightly decrease overall traction

more tyre wear

Springs

Stiffer

Stiffer springs make the car feel more responsive, more direct.
They also help the car jump a little better and higher.
Stiff springs are suited for high-traction tracks, which aren’t too bumpy.

Softer

Softer springs are better for (mildly) bumpy tracks.
They can also make the car feel as if it has a little more traction in low-grip conditions.

Stiffer Front

The car has less front traction, and less steering. It’s harder to get the car to turn, the turn radius is bigger and the car has a lot less steering exiting corners.
The car will jump better, and maybe a little further.
On very high-grip tracks, it’s usually beneficial to stiffen the front, even more than the rear. It just makes the car easier to drive, and faster.

Softer Front

The car has more steering, especially in the middle part and the exit of the corner.
Front springs that are too soft can make the car hook and spin, and they can also make it react sluggishly.

Stiffer Rear

The car has more steering, in the middle and exit of the turn. This is especially apparent in long, high-speed corners.
But rear traction is reduced.

Softer Rear

The car has generally more rear traction, in turns as well as through bumps and while accellerating.

Damping

Heavier

Thicker oil (heavier damping) makes the car more stable, and makes it handle more smoothly.
It also makes the car jump and land better.
If damping is too heavy, traction could be lost in bumpy sections.

Softer

Soft damping (and springing) is better for shallow, ripply bumps.
It also makes the car react quicker.
Damping should always be adapted to the spring ratio; the suspension should never feel too ‘springy’ or too slow.

Heavier Front

The turn radius is wider, but smoother. The car doesn’t ‘hook’ suddenly.
The car is easier to drive, and high-speed steering feels very nice.

Softer Front

The steering reacts quicker.
More and better low-speed steering.

Heavier Rear

Steering feels quick and responsive, while the rear stays relatively stable.

Softer Rear

Feels very easy to drive, the car can be ‘thrown’ into turns.
More rear traction while accellerating.
If one end of the car has slightly heavier damping than the other, then that end will feel as if it has the most consistent traction and the most stable when turning in and exiting corners.
A car with slightly heavier rear damping, or slightly lighter front damping will feel very stable turning into corners on bumps or whoops sections. It won’t feel ‘touchy’ at all.

Caster

More More caster aids stability, and handling in bumpy sections.
Less Less caster increases steering drastically.
Steering feels much more direct, the car turns tighter and faster.

Ride Height

Higher

The car feels better in bumps, and jumps better.
It can feel tippy, or even flip over in high-grip conditions.

Lower

The car feels more direct, and it can potentially corner a bit faster.
It’s also harder to flip the car over.
Lowering one end of the car, or putting the other end higher up, gives a little more grip at the lowest end, but try to avoid big differences in ride height between the front and the rear.

Wheelbase

Shorter

A short wheelbase makes the car feel very nimble, and good in tight turns.
This is a good idea for very small and tight tracks, without big jumps or bumps.

Longer

The car becomes a lot more stable, adn better in wide, high-speed turns.
This is good on wide-open tracks.

Anti-Squat

This refers to the angle of caster on the rear wheels. Raising the front of the hinge pins of the rear arms gives a caster (anti-squat) angle and helps to transfer the power more evenly, keeping the front of the vehicle from lifting under heavy acceleration.

More anti-squat generally makes the rear of the car more sensitive to throttle input.
The car has more steering while braking, and also a little more powering out of corners.
On high-traction tracks, it may feel as if the car momentarily has more rear traction accellerating out of corners.
A car with more anti-squat can also jump a little higher and further, and it will soak up bumps a little better, off-power.
A lot of anti-squat (4° or more) can make the car spin out in turns, and make the rear end break loose when accellerating.

Less

Less anti-squat gives more rear traction while accellerating on a slippery or dusty track.
It also gives more side-bite.
Less anti-squat will make the car accellerate better and faster through bumpy sections.
Very little anti-squat (0° or 1°) makes the rear end feel very stable. It also makes power sliding a lot easier.
Note that anti-squat only works when you’re accellerating or braking, it does absolutely nothing when you’re coasting through turns.
The harder you brake or accellerate, the bigger the effect of anti-squat is.

Shock Pistons

The assumption is made that if pistons are changed, the viscosity of the oil is also adapted, to give the same static feel. (Same low-speed damping)

Smaller Holes

Smaller holes mean more ‘pack’. Pack means the damping gets very stiff, or almost locks up, over sharp bumps, ruts, or landing off jumps.
Small holes are good for smooth tracks, with big jumps or crummy jumps with harsh landings.

Bigger Holes

Bigger holes mean less pack. The point at which the damping gets stiff (where the shock ‘packs up’) occurs a lot later, at higher shock shaft speeds.
Big holes are very good for bumpy tracks. The car is more stable and has more traction in the bumpy sections. It won’t be thrown up over sharp bumps, the suspension will soak them up a lot better.

Smaller holes in front

The car jumps very nicely, a little more nose-up.
It feels easy to drive.

Bigger holes in front

Can give a subtle feel of more steering and more consistent front end grip if the track isn’t perfectly smooth.
Always use the same, or about the same shock pistons front and rear. Big differences in pistons make the car feel inconsistent, and not very smooth.

Lower Shock Mounting Location

Bear in mind that changing the lower shock mounting location changes the lever arm of the shocks on the wheels.

So mounting the shocks more inward makes the suspension softer at the wheel, and mounting the shocks more towards the outside makes the suspension stiffer.

Front more inward

More low-speed steering.
Usually makes the car very hard to drive.
Front more outward
Makes the car very stable, but it has a lot less low-speed steering.

Rear more inward

Makes the car soak up bumps a little better, and can make the car corner a bit faster.
Can be good for bumpy, low-grip tracks, but general stability is greatly reduced.
Rear more outward
Feels very stable.The way to go for high-grip tracks.

Upper Shock Mounting Location

More Inclined

Has a more progressive, smoother feel.
More lateral grip.
Less Inclined (More Vertical)
More direct feel;
Less lateral grip. (side-bite)
generally a bit better for jumps and harsh landings.

Front more inclined than rear

Steering feels very smooth.
A little more mid-corner steering.
Mounting the rear shocks very upright can result in the rear end sliding in the middle of the turn, especially in high-speed turns.

Rear more inclined than front

Feels agressive turning in.
The car has a lot of side traction in the rear, and the turn radius isn’t very tight.

Roll Center / Camber links

Long Link

A long link gives a lot of body roll in turns.
It feels as is the body is willing to keep on rolling, until in the end, the springs prevent it from rolling any further.
The car has more grip in corners, especially the middle part.

Short Link

A short link makes that the body doesn’t roll as far, its tendency to roll drops off as it rolls.
This can stabilize a car in bumps and curved sections.
It feels as is the car generates a little less grip.

Parallel Link (Parallel to lower arm)

A parallel link gives a little more roll than an angled one.
It feels very smooth, and consistent as the body rolls in turns.

Angled Link(Distance between arm and link is smaller on the inside)

An angled link makes it feel as if the car has a tendency to center itself (level, no roll), other than through the springs or anti-roll bar.
It gives a little more initial grip, steering into corners. It makes it very easy to ‘throw’ the car.
The body rolls a little less than with parallel links.
On bumpy tracks, it could be possible to use softer settings for damping and spring rate than with parallel links, without destabilising the car.
Beware that you should always keep an eye on the balance of your car; large differences in roll center front vs. rear will make the car feel less consistent and less confidence-inspiring.

Longer Front

The front rolls and dives more in turns.
Lots of steering in mid-corner.
Could make the car hook.

Shorter Front

The front feels very stable.
A little more turn-in, but less steering in mid-corner.

Longer Rear

More rear traction in turns, and coming out of them.
Rear end slide is very progressive, not unpredictable at all.
Make sure that there’s enough rear camber though, or you could lose rear traction in turns.

Shorter Rear

The rear feels very stable. It breaks out later and more suddenly, but if it does, the slide is more controllable.
It makes the front dive a little more, which results in more steering, especially when braking.

More Angled Front

Turn-in is very agressive.
The front feels as if it wants to roll less than the rear.

More Angled Rear

The rear end is rock-solid while turning in. It feels very confident.

Camber

Camber is best set so the tires’ contact patch is as big as possible at all times. So with a stiff suspension you’ll need less camber than with a soft one.
If the tires wear evenly across their contact patches, camber is about right.
On really bumpy tracks, adding a little more negative camber (2 to 3 degrees) can help traction and reduce the chances of catching a rut and flipping over.

Toe

Front Toe-in

Stabilizes the car in the straights, adn coming out of turns.
It smoothes out the steering response, making the car very easy to drive;

Front Toe-out

Increases turn-in steering a lot.
But can make the car wandery on the straights;
Never use more than 2 degrees of front toe-out!

Rear Toe-in

Stabilizes the car greatly. It makes the rear end ‘stick’, but more toe-in makes the difference between sticking and breaking loose bigger.

Rear Toe-out

Rear toe-out is never used. It makes the rear of the car very, very unstable.

Anti-Roll bar

Anti-roll bars are best used on smooth, and high-traction tracks only.
If you must use one on a bumpy track, try to use a very thin one.
Adding an anti-roll bar, or stiffening it, reduces traction at that end of the car. So it feels like the opposite end has more grip.
If the track is smooth enough, it also makes the grip level feel more consistent.
Anti-roll bars reduce body roll in turns, so they make the car feel more direct, and make it change direction quicker.

Stiffer Front

An anti-roll bar at the front of the car reduces low-speed steering. The turning radius will be larger, but very consistent.
It reduces ‘hooking’ by preventing front end roll.
The car will have more rear traction in turns.

Stiffer Rear

Adding an anti-roll bar to the rear of the car gives more steering. the car steers tighter, also at low speeds.
On a very smooth track, it can make powersliding easier. It can also make powering out of turns and lining up for jumps a little easier.

Ackermann

More(Bigger difference in steering angle between the two font wheels)

More Ackermann makes the steering more consistent, and smoother.
It just feels right, also at low speeds and in tight turns.

Less (Smaller, or no difference in steering angle between the two font wheels)

Less Ackermann makes the steering more agressive at high speeds.
The car turns in more agressively.
It doesn’t work well when either traction or cornering speeds are low.

Internal Travel Limiters / Droop / Downtravel

More (less droop/downtravel)

The car changes direction faster, and corners flatter. It feels generally more responsive.
Adding a lot of travel limiters is only advisable on smooth tracks.

Less (more droop/downtravel)

Less internal shock spacers give better handling on bumpy tracks, and more and more consistent traction on difficult tracks.
The car also land better after jumps.
The end with the least downtravel will feel the most stable, and the most direct. But try to keep a balance (front and rear end droop about the same), especially on low-grip tracks.
Adding more internal travel limiters is a very effective way of reducing traction rolls, if not the most effective way.

Wings

Front

Adding a front wing, or increasing front downforce increases steering at speed, which almost always makes the car feel very, very agressive and difficult to drive.

Rear

Adding rear downforce by changing to a bigger wing, or mounting he wing higher or at more of an angle increases rear traction at speed.
This can be very useful on slick tracks with fast, sweeping corners.

Pinion/Spur

Smaller Gear Ratio (bigger number means smaller ratio)

More punch and accelleration.
More runtime.
Lower top speed.

Bigger Gear Ratio (smaller number means bigger ratio)

Less punch, but more top speed.
Less runtime.

How Gear size (tooth count) effects gear ratio

Smaller Pinion Gear = Smaller gear ratio
Bigger pinion Gear = Bigger gear ratio
Smaller Spur Gear = Bigger gear ratio
Bigger Spur Gear = Smaller gear ratio

Overall Ratio

Overall Ratio = (Spur/Pinion)*Internal Gearbox Ratio

Rollout (mm/rev)

Rollout = (Pi*Tire Diameter)/Overall Ratio

Motors

More Turns(e.g. 13×2 or 14×3)

More runtime.
Less power, and smoother response.
Easy to drive.

Less Turns (e.g. 9×2 or 8×3)

Less runtime.
More power.
Harder to drive.

More Winds (e.g. 11×4 or 12×5)

Slightly more runtime.
Feels very smooth, has a nice powerband. Very useful on slippery tracks.
More top-end.

Less Winds (e.g. 12×1 or 11×2)

Slightly less runtime.
Feels very punchy, but has less top-end.

More Timing Advance (e.g. 6 to 8mm)

Less runtime.
More punch, and more top speed.
More wear on the comm and brushes.
Motor gets hotter.

Less Timing Advance (e.g. 4 to 6mm)

More runtime.
Easy on the comm and the brushes.
Less punch and top speed.

Stiffer Brush Springs

More power at low revs.
Slightly lower top speed because of increased friction.
Better for high currents and bumpy tracks.

Softer Brush Springs

More power at hight revs, but less punchy.
Higher top speed.
Good for low current draw.

TIP: You get slightly more punch and a slightly more efficient motor if you use a slightly stiffer brush spring on the + side.

The easiest way to do this is to hold one leg of the spring with pliers and gently bend the leg 5 to 10 degrees more.

*I copied this from a public domain forum a long time ago. Can’t remember where from. Not original work.

via RC SETUP GUIDE – BASICS TO EXPERT – TheToyz Forums.

A Complete Guide to Sussing Out Those Finicky Camber, Caster and Toe?

The Professional Bum — Thu, 12 Jan 2012 06:28:39 +0000

via Caster, Camber, Toe.

The following article is reprinted with the permission of Grassroots Motorsports magazine. For more information from this fine publication, please point your browser to Grassroots Motorsports magazine.

Pointed the Right Way

story by john hagerman

Camber, Caster and Toe: What Do They Mean?

The three major alignment parameters on a car are toe, camber, and caster. Most enthusiasts have a good understanding of what these settings are and what they involve, but many may not know why a particular setting is called for, or how it affects performance. Let’s take a quick look at this basic aspect of suspension tuning.

UNDERSTANDING TOE

When a pair of wheels is set so that their leading edges are pointed slightly towards each other, the wheel pair is said to have toe-in. If the leading edges point away from each other, the pair is said to have toe-out. The amount of toe can be expressed in degrees as the angle to which the wheels are out of parallel, or more commonly, as the difference between the track widths as measured at the leading and trailing edges of the tires or wheels. Toe settings affect three major areas of performance: tire wear, straight-line stability and corner entry handling characteristics.

For minimum tire wear and power loss, the wheels on a given axle of a car should point directly ahead when the car is running in a straight line. Excessive toe-in or toe-out causes the tires to scrub, since they are always turned relative to the direction of travel. Too much toe-in causes accelerated wear at the outboard edges of the tires, while too much toe-out causes wear at the inboard edges.

So if minimum tire wear and power loss are achieved with zero toe, why have any toe angles at all? The answer is that toe settings have a major impact on directional stability. The illustrations at right show the mechanisms involved. With the steering wheel centered, toe-in causes the wheels to tend to roll along paths that intersect each other. Under this condition, the wheels are at odds with each other, and no turn results.

When the wheel on one side of the car encounters a disturbance, that wheel is pulled rearward about its steering axis. This action also pulls the other wheel in the same steering direction. If it’s a minor disturbance, the disturbed wheel will steer only a small amount, perhaps so that it’s rolling straight ahead instead of toed-in slightly. But note that with this slight steering input, the rolling paths of the wheels still don’t describe a turn. The wheels have absorbed the irregularity without significantly changing the direction of the vehicle. In this way, toe-in enhances straight-line stability.

If the car is set up with toe-out, however, the front wheels are aligned so that slight disturbances cause the wheel pair to assume rolling directions that do describe a turn. Any minute steering angle beyond the perfectly centered position will cause the inner wheel to steer in a tighter turn radius than the outer wheel. Thus, the car will always be trying to enter a turn, rather than maintaining a straight line of travel. So it’s clear that toe-out encourages the initiation of a turn, while toe-in discourages it.

With toe-in (left) a deflection of the suspension does not cause the wheels to initiate a turn as with toe-out (right).

The toe setting on a particular car becomes a tradeoff between the straight-line stability afforded by toe-in and the quick steering response promoted by toe-out. Nobody wants their street car to constantly wander over tar strips-the never-ending steering corrections required would drive anyone batty. But racers are willing to sacrifice a bit of stability on the straightaway for a sharper turn-in to the corners. So street cars are generally set up with toe-in, while race cars are often set up with toe-out.

With four-wheel independent suspension, the toe must also be set at the rear of the car. Toe settings at the rear have essentially the same effect on wear, directional stability and turn-in as they do on the front. However, it is rare to set up a rear-drive race car toed out in the rear, since doing so causes excessive oversteer, particularly when power is applied. Front-wheel-drive race cars, on the other hand, are often set up with a bit of toe-out, as this induces a bit of oversteer to counteract the greater tendency of front-wheel-drive cars to understeer.

Remember also that toe will change slightly from a static situation to a dynamic one. This is is most noticeable on a front-wheel-drive car or independently-suspended rear-drive car. When driving torque is applied to the wheels, they pull themselves forward and try to create toe-in. This is another reason why many front-drivers are set up with toe-out in the front. Likewise, when pushed down the road, a non-driven wheel will tend to toe itself out. This is most noticeable in rear-drive cars.

The amount of toe-in or toe-out dialed into a given car is dependent on the compliance of the suspension and the desired handling characteristics. To improve ride quality, street cars are equipped with relatively soft rubber bushings at their suspension links, and thus the links move a fair amount when they are loaded. Race cars, in contrast, are fitted with steel spherical bearings or very hard urethane, metal or plastic bushings to provide optimum rigidity and control of suspension links. Thus, a street car requires a greater static toe-in than does a race car, so as to avoid the condition wherein bushing compliance allows the wheels to assume a toe-out condition.

It should be noted that in recent years, designers have been using bushing compliance in street cars to their advantage. To maximize transient response, it is desirable to use a little toe-in at the rear to hasten the generation of slip angles and thus cornering forces in the rear tires. By allowing a bit of compliance in the front lateral links of an A-arm type suspension, the rear axle will toe-in when the car enters a hard corner; on a straightaway where no cornering loads are present, the bushings remain undistorted and allow the toe to be set to an angle that enhances tire wear and stability characteristics. Such a design is a type of passive four-wheel steering system.

THE EFFECTS OF CASTER

Caster is the angle to which the steering pivot axis is tilted forward or rearward from vertical, as viewed from the side. If the pivot axis is tilted backward (that is, the top pivot is positioned farther rearward than the bottom pivot), then the caster is positive; if it’s tilted forward, then the caster is negative.

Positive caster tends to straighten the wheel when the vehicle is traveling forward, and thus is used to enhance straight-line stability. The mechanism that causes this tendency is clearly illustrated by the castering front wheels of a shopping cart (above). The steering axis of a shopping cart wheel is set forward of where the wheel contacts the ground. As the cart is pushed forward, the steering axis pulls the wheel along, and since the wheel drags along the ground, it falls directly in line behind the steering axis. The force that causes the wheel to follow the steering axis is proportional to the distance between the steering axis and the wheel-to-ground contact patch-the greater the distance, the greater the force. This distance is referred to as “trail.”

Due to many design considerations, it is desirable to have the steering axis of a car’s wheel right at the wheel hub. If the steering axis were to be set vertical with this layout, the axis would be coincident with the tire contact patch. The trail would be zero, and no castering would be generated. The wheel would be essentially free to spin about the patch (actually, the tire itself generates a bit of a castering effect due to a phenomenon known as “pneumatic trail,” but this effect is much smaller than that created by mechanical castering, so we’ll ignore it here). Fortunately, it is possible to create castering by tilting the steering axis in the positive direction. With such an arrangement, the steering axis intersects the ground at a point in front of the tire contact patch, and thus the same effect as seen in the shopping cart casters is achieved.

The tilted steering axis has another important effect on suspension geometry. Since the wheel rotates about a tilted axis, the wheel gains camber as it is turned. This effect is best visualized by imagining the unrealistically extreme case where the steering axis would be horizontal-as the steering wheel is turned, the road wheel would simply change camber rather than direction. This effect causes the outside wheel in a turn to gain negative camber, while the inside wheel gains positive camber. These camber changes are generally favorable for cornering, although it is possible to overdo it.

Most cars are not particularly sensitive to caster settings. Nevertheless, it is important to ensure that the caster is the same on both sides of the car to avoid the tendency to pull to one side. While greater caster angles serve to improve straight-line stability, they also cause an increase in steering effort. Three to five degrees of positive caster is the typical range of settings, with lower angles being used on heavier vehicles to keep the steering effort reasonable.

Like a shopping cart wheel (left) the trail created by the castering of the steering axis pulls the wheels in line.

WHAT IS CAMBER?

Camber is the angle of the wheel relative to vertical, as viewed from the front or the rear of the car. If the wheel leans in towards the chassis, it has negative camber; if it leans away from the car, it has positive camber (see next page). The cornering force that a tire can develop is highly dependent on its angle relative to the road surface, and so wheel camber has a major effect on the road holding of a car. It’s interesting to note that a tire develops its maximum cornering force at a small negative camber angle, typically around neg. 1/2 degree. This fact is due to the contribution of camber thrust, which is an additional lateral force generated by elastic deformation as the tread rubber pulls through the tire/road interface (the contact patch).

To optimize a tire’s performance in a corner, it’s the job of the suspension designer to assume that the tire is always operating at a slightly negative camber angle. This can be a very difficult task, since, as the chassis rolls in a corner, the suspension must deflect vertically some distance. Since the wheel is connected to the chassis by several links which must rotate to allow for the wheel deflection, the wheel can be subject to large camber changes as the suspension moves up and down. For this reason, the more the wheel must deflect from its static position, the more difficult it is to maintain an ideal camber angle. Thus, the relatively large wheel travel and soft roll stiffness needed to provide a smooth ride in passenger cars presents a difficult design challenge, while the small wheel travel and high roll stiffness inherent in racing cars reduces the engineer’s headaches.

It’s important to draw the distinction between camber relative to the road, and camber relative to the chassis. To maintain the ideal camber relative to the road, the suspension must be designed so that wheel camber relative to the chassis becomes increasingly negative as the suspension deflects upward. The illustration on the bottom of page 46 shows why this is so. If the suspension were designed so as to maintain no camber change relative to the chassis, then body roll would induce positive camber of the wheel relative to the road. Thus, to negate the effect of body roll, the suspension must be designed so that it pulls in the top of the wheel (i.e., gains negative camber) as it is deflected upwards.

While maintaining the ideal camber angle throughout the suspension travel assures that the tire is operating at peak efficiency, designers often configure the front suspensions of passenger cars so that the wheels gain positive camber as they are deflected upward. The purpose of such a design is to reduce the cornering power of the front end relative to the rear end, so that the car will understeer in steadily greater amounts up to the limit of adhesion. Understeer is inherently a much safer and more stable condition than oversteer, and thus is preferable for cars intended for the public.

Since most independent suspensions are designed so that the camber varies as the wheel moves up and down relative to the chassis, the camber angle that we set when we align the car is not typically what is seen when the car is in a corner. Nevertheless, it’s really the only reference we have to make camber adjustments. For competition, it’s necessary to set the camber under the static condition, test the car, then alter the static setting in the direction that is indicated by the test results.

The best way to determine the proper camber for competition is to measure the temperature profile across the tire tread immediately after completing some hot laps. In general, it’s desirable to have the inboard edge of the tire slightly hotter than the outboard edge. However, it’s far more important to ensure that the tire is up to its proper operating temperature than it is to have an “ideal” temperature profile. Thus, it may be advantageous to run extra negative camber to work the tires up to temperature.

(TOP RIGHT) Positive camber: The bottoms of the wheels are closer together than the tops. (TOP LEFT) Negative camber: The tops of the wheels are closer together than the bottoms. (CENTER) When a suspension does not gain camber during deflection, this causes a severe positive camber condition when the car leans during cornering. This can cause funky handling. (BOTTOM) Fight the funk: A suspension that gains camber during deflection will compensate for body roll. Tuning dynamic camber angles is one of the black arts of suspension tuning.

TESTING IS IMPORTANT

Car manufacturers will always have recommended toe, caster, and camber settings. They arrived at these numbers through exhaustive testing. Yet the goals of the manufacturer were probably different from yours, the competitor. And what works best at one race track may be off the mark at another. So the “proper” alignment settings are best determined by you-it all boils down to testing and experimentation.

John Hagerman is a mechanical engineer who works for the U.S. Army as a vehicle test engineer at the Aberdeen Proving Grounds in Maryland. John started autocrossing at the age of 16 in a Triumph Spitfire and switched to road racing a few years later. Lately, he has been playing with a Sports 2000.

Ever Wanted More Run-time During Nitro Buggy Races? O.S. Engines Speed Tuned 19XZ-B ABC

The Professional Bum — Thu, 12 Jan 2012 05:55:50 +0000

Finesse and fuel economy for tight, twisty 1/8 scale tracks!

Ever wanted one or two less pit stops during a main to extend your lead over your competitor? The O.S. 19XZ-B Speed offers 10% better fuel economy over the current 21XZ-B Speed with the 21J2 carburetor and 6mm carburetor reducer and still has all the performance you need to win.

The 19XZ-B Speed also incorporates a DLC (Diamond Like Carbon) coating crankshaft to reduce friction and improve wear life and durability and also prevent corrosion. The crankshafts passageway is silicone filled to direct the air smoothly into the tuned cylinder assembly and crankcase.

The ceramic bearings reduce rolling resistance throughout the power performance.

A square bore/stroke (1:1) short stroke provides stress free performance and sharp acceleration.

The ultra light weight cylinder head is smaller and weighs 8 grams less than the current 21XZ-B Speed head; overall weight is 12 less.

The black anodized crankcase with fins helps direct air flow over crucial parts of the engine and helps dissipate heat to keep it cooler.

SPECIFICATIONS
Stock Number: OSMG2035
Displacement: 0.19 cu in (3.1 cc)
Bore: 0.62 in (15.8 mm)
Stroke: 0.62 in (15.8 mm)
Practical rpm: 4,000-40,000
Output: 2.4 hp @ 34,000 rpm
Weight: 12.1 oz (343 g)
Includes: glow plug, 6 mm carb restrictor

via O.S. Engines Speed Tuned 19XZ-B ABC.

The Best Truggy Got Better : The Kyosho Inferno ST-RR EVO

The Professional Bum — Wed, 11 Jan 2012 08:35:14 +0000

This is post was originally from http://www.infernosonly.com/Kyosho_Inferno_ST_RR_EVO_is_Launched_s/1040.htm

The Best Truggy in History Is Now Better!

Kyosho has made it official now, the Inferno ST-RR EVO details have been released! (well most of the details)

The Kyosho ST-RR EVO is an assembled and unpainted kit rolling chassis, so these pictures just represent what yours can look like once completed!

Some History First
Ok let’s examine what’s going on here! With all the time since the last ST-RR version, about 3 years ago… there has been an evolution happening with the team driver’s kits. With Cody King, Jared Tebo and others taking items from the MP9 buggy and adopting them to the truggy as well as trying some new things, Kyosho finally decided to update the truggy to this new level its being raced at in a new kit!

The ST-RR has been the trend setter all along in the truggy scene, much like the 1/8th buggy scene. The last version of the truggy, the ST-RR set new standards by using a lengthened wheelbase and wider track.than every other truggy. It has been almost unbeatable ever since. Remember also that the Inferno ST-R was the very first officially created truggy kit on the market for competition racing and it was designed byYuuichi Kanai, of coarse!

The Kyosho Inferno ST-RR EVO
Looks like Cody King’s Truggy! (Click for a bigger image)

Well then, here we are! The new EVO! (Short of coarse for EVOLUTION) and that is exactly what this truck is, an evolution. Through great care, racing and winning, just like the big car manufactures, Kyosho has again developed the ultimate competition racing Truggy on the market!

What’s New on the Inferno ST-RR EVO?
Well at first glimpse there does not seem to be all that much, but upon further inspection… a lot!

……………… for the rest of this post, do visit the original review at:

http://www.infernosonly.com/Kyosho_Inferno_ST_RR_EVO_is_Launched_s/1040.htm

Hi Everyone, it’s been awhile!

The Professional Bum — Wed, 11 Jan 2012 04:29:18 +0000

Hey! Happy New Year 2012 everyone. It’s been awhile since I last posted. It’s interesting that even in this long absence, my blog readership has been getting better and better.

I’m having a little more time on my hands now, and I will be back to regular posting.

Thanks for staying tuned!

Julian Wong

Used Traxxas Revo for Sale

The Professional Bum — Wed, 23 Nov 2011 07:44:05 +0000

Used Traxxas Revo for Sale

Roller- without engine, optidrive module, push rods n other bits. What you see is what you get. Letting go $140.