All Entries Tagged With: "Tech"
Monster Truck Shock Tuning
Most people, when they get some RC experience, develop a pretty good understanding of how a suspension works. Understanding, however, may not be the ideal word to use as it implies they know exactly what’s going on and are tuning correctly. Read on and see if you’re getting things right when tuning the suspension on your monster truck.
The Basics
There are a lot of moving parts in a RC suspension system, but the key component is the shock. And, almost all RC monster trucks use what is called a coil-over shock design—a coil spring is fitted over the shock body. The shock and the spring work together, but they have very different functions. The spring’s main job is to support the weight of the vehicle. The shock, in turn, is there to absorb energy. Technically, the shock converts kinetic energy (motion) into heat, but the real point is it keeps the truck from bouncing like a pogo after every bump or jump. In addition to the basic functions of the shock and spring, this key component of the suspension greatly influences how a truck handles.
Pre-load
Changes in pre-load are achieved either via an adjustable collar on a threaded shock body or by clip-on spacers. It’s important to note that increasing pre-load does not increase spring stiffness. Again, if you’re looking to increase your suspension’s stiffness, pre-load will not achieve that result. Pre-load is used to adjust ride height. If you have determined your truck is sitting too low, adding some pre-load could be a good fix. So, pre-load is used to set the ride height, and it is often used to compensate for ride height changes that occur when the shock position is changed.
Springs
While the main function of a spring is to support the weight of the truck, springs also greatly influence how weight is transferred while the truck is moving and thus have an important impact on handling. Springs also influence traction even more directly by impacting how easy the suspension moves. That is why it is common to install softer springs on the rear of a race vehicle that needs more rear traction. In contrast, it is common for racers to install softer front springs if more steering is desired.
Shock Fluid
As was said previously, the main job of the shock is to absorb energy. Without the piston inside the shock body having to pass through the shock fluid, your truck would just bounce and bounce after a bump or jump. The thickness of the shock fluid greatly impacts the handling of the truck. If the fluid inside is too thin, the piston will move too freely and the truck will still bounce. It will also most likely have other negative handling characteristics such as excessive body lean in the corners and bottoming out when landing from even small jumps. In the same way that springs impact handling, shock fluid does the same. Racers will often switch to thinner fluid to get increased traction or do switch to thicker fluid at the opposite end that more traction is needed (i.e. thicker front shock fluid for increased rear traction).
Shock Position
How shock mounting positions or locations influence handling is extremely interesting and yet simple. The suspension arm is a simple lever. If the lower shock mount is moved in on the suspension arm toward the center of the truck, the shock will feel softer much the same as installing a softer spring. This is because the suspension is now applying more leverage on the shock. Keep in mind that when moving the lower position in will also impact ride height. In this case, it would increase ride height and this is best compensated by adjusting pre-load.
Shock Angles
While shock position is pretty straightforward and easy to understand, shock angles get a little more complicated. A shock that is straight up and down operates in a linear manner. Huh? This means as the suspension compresses, the shock’s feel doesn’t change. If the shock is angled in at the top, the shock will feel progressively stiffer as it is compressed.
Tuning
On a monster truck that is being run for fun on a variety of surfaces such as dirt, pavement and grass, you shouldn’t have to get too crazy with the suspension tuning and should leave the never ending search for the perfect setup to the racers. That said, if your truck isn’t handling exactly how you would like, you can probably easily fix it with a little shock tuning.
> If your truck is bottoming out when landing from jumps, first check to make sure the ride height isn’t set too low. If the truck doesn’t seem to be sitting too low, try adding thicker shock fluid.
> If your truck is sitting low after adding a lot of aluminum hop-ups, do not add pre-load, use stiffer springs to properly compensate for the added weight of the new parts. You may also need to slightly increase the shock fluid weight.
> If your truck is bouncing excessively over small bumps, try slightly thinner shock fluid to allow the shock to react faster. This should be a minor change.
Big Air & Backflips
Go big or go home! That old saying is used in all sorts of motor sports and action sports, and it most certainly holds true for the addictive nature of jumping a RC monster truck. Once you get started in airborne antics, you will want more. Going big is easy—if you know what you’re doing. Let’s take a look at what it takes to get some really big air and still be able to drive away.
The Basics
One of the most amazing things about RC trucks is that you can control their nose-up or nose-down attitude in the air. And, best of all, this is actually easier in big air situations since you’ll have more time to react compared to a fast on-track jump that’s usually low, fast and over quickly. Here’s how it’s done: If the nose of your truck is too low and it looks like you’re going to nose dive, grab some throttle. If the nose is too high, tap the brakes. The key is to not over correct.
Truck Setup
Big air means big impacts. Before getting airborne, go through your truck and make sure the suspension is working properly and make sure the pinion set screw and motor mount screws are snug. Going up 5wt in shock fluid is also advised to help absorb the force from the landing. Remember, the more energy the suspension absorbs, the less that gets transferred onto the truck. You can also add short pieces of silicone fuel tubing on the exposed part of the shock shaft. This will function as a bump stop of hard landings.
Big Air
Before you go big, take a number of smaller practice jumps to get used to your run-up area and the ramp. Where you stand is also important. It is highly recommended that you stand off to the side so that you can see the approach and also be able to fully see the truck while it’s airborne and landing. Many drivers sacrifice being able to see the landing by standing inline with the jump. They do this so they can easily hit the jump squarely, but completely miss being able to see the important landing and thus can’t make corrections as needed. When you are ready to tap into your inner Tanner Foust and make your first attempt at really big air, approach the ramp under throttle, but let of the trigger as soon as the truck is airborne. This is where you’ll watch the flight path your truck is making and get ready to make a correction for a level landing. As was explained before, if the nose is pointing down, squeeze the throttle. Jab the brakes if the nose is pointing up. These corrections should be smooth and relatively small inputs. Don’t over correct. What I mean is do not give too much of a correction that will require additional inputs. You don’t want your corrections to need corrections.
Backflips
Backflips are fun, impressive and easy. That’s right, I said easy. First, the steps needed to perform a backflip are simple; you just grab some full throttle when in the air. Second, the rapidly spinning wheels act like a gyro and actually help the flying truck track straight. You’ll quickly notice the difference when you try a front flip (more on that later). So, to do a backflip, stay in the throttle as you leave the ramp. You may even go to a quick stab of full throttle if you weren’t already there. This throttle input will take about a second. If you grab full throttle and stay there, you will keep on flipping and probably land on something other than your roof. To stop the rotation and end the flip, simply tap the brakes.
Front Flips
In the same way a nose high attitude is corrected in the opposite way you correct a nose-low attitude, a front flip is initiated in the opposite way you initiate a backflip. To perform a front flip, tap the brakes as your truck is about halfway to its anticipated highest point. A quick blip of the throttle may be needed to stop the rotation and level the truck out. Front flips can be trickier than backflips because you often get some crazy, tweaked rotations without the gyro effect of the wheels spinning.
Key Points
> Nose too high when jumping, hit the brakes
> Nose too low when jumping, hit the throttle
> Perform a backflip by staying in the throttle
> Perform a front flip by hitting the brakes in the air
Short Course Racing Tips—5 Tips For Faster Laps
Anyone with any racing experience will tell you that jumping from class to class isn’t as easy as just selecting a new model on your transmitter and picking up a new truck. And, many people think that because the scale appeal of short course attracts so many newcomers to the hobby that the class is for beginners and thus easy. The point is that short course racing takes just as much skill as any other class and even experienced racers can have a hard time adapting and succeeding. If you want to run at the front of the pack, check out these five tips:
1. Momentum
Racing is all about going fast, right? Well, if you’re constantly flying into corners, spraying dirt everywhere and ripping down the straights, you’re doing it wrong. You might feel like you’re going really fast and that may work to some degree with an overpowered truggy, but it’s the slow way to get a short course truck around the track. This is especially true if you’re in the 17.5-turn class. You can get away with a little bit of a heavy-handed driving style with 4WD class short course truck, but it is essential that you drive smoothly. You should drive like you have an egg strapped to your truck. Drive smoothly and try to keep your truck always rolling.
2. Stay Out of Trouble
I lot of people think short course is the class where it’s OK to beat and bash. Let them think that and let them smash into each other. Just keep your distance and let the action unfold—don’t be a part of it. You’ll lose far less time by slightly hanging back in comparison to getting involved in a wreck. Think about the time you lose when you crash and then have to wait for a corner marshal as compared to when you just ease back a bit and wait for the right time to make a move. We’re talking the difference between ten seconds and a tenth of a second or maybe the difference between first and third.
3. Passing vs. Catching
There’s a difference? There very much is a difference between catching someone and passing them, but you’d never know it watching the typical RC race. Most racers just race as fast as they can try to get around people as they catch them. It sounds good, but catching and passing are simply too different acts. When you catch someone think about whether you’re at a good place to pass. Some slow cars can be blown by down the straight, but keep in mind that a phenomenon called target fixation almost always occurs when you try to pass someone on the straight. They focus on your car and essentially subconsciously drive right into. It looks like they’re trying to squeeze you off the straight, but usually it’s just an unintended rookie type mistake. The point is it’s almost always better to pass in corners. Drivers of equal ability will take some work (that’s what makes racing fun), but there is usually a corner or two they go wide on and most newer drivers are usually easy to pass on the corner going into the main straight as the almost always fly in wide and get back on the gas too soon. Just slow to the inside and out accelerate the on exit.
4. Like a Sports Car
Short course trucks are just like sports cars. Makes perfectly good sense…if you have experience with the racing of full-size cars—either as a driver or an entrenched fan. You see, sports car or road course racers know that you brake in straight lines and accelerate in corners. This is the foundation of proper performance driving. You should be 100% done slowing down before you get to a corner and you should be accelerating through and out of the corner.
5. Practice Smart
There may be no such thing as bad practice, but some practice is definitely better than others. Most racers get their practice in by showing up early on race day. They’ll get there hours before they really need to and then spend most of that time shooting the bull with the other “diehards” that show up at the crack of dawn. When the early birds do hit the track it’s on a dry track that is nothing like the one they’ll race on. Experimenting with tires and setup at this stage is completely pointless as while that practice is valuable, the track is simply nowhere near race shape. It’s far better to stay late and drive on the track after racing has concluded. Check with the race director first, but most don’t mind and you’ll be running on a track in is much closer to race condition. This is the time to try every tire combo you can think of and mess with your shocks.
Loading ...
