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Top 5 Key Elements of a Top Performing Crawler

Whether you’re talking about drifting, short course racing or–as we are here–about rock crawling, nothing can replace talented driving. You should work on you far more than you work on your equipment. Practice often. Become intimately familiar with what your rig can and cannot do. When you get to the point that you believe that your rig is holding you back, don’t start changing everything at once. If you do, you’ll often waste money and only make matters worse. Instead, check out these five aspects that all top performing crawlers have dialed in and start there. Also take in these expert tips from champion crawler and Axial team drive Jake Wright. Jake is the 2011 USRCCA Overall National Champion and, in addition to being sponsored by Axial, also runs for Futaba and Holmes Hobbies.

 

1. TIRES
You’ve probably heard the phrase “Location, location, location.” It’s used to describe everything from real estate to restaurants. The point is nothing matters as much as location. In RC, it’s tires, tires, tires. If your tires don’t work for you, nothing else really matters. Before you spend money on anything else, spend money on the right tires. If your truck can’t climb the same rocks as some of your competition, take a look at what tires they’re running.

Consistency. Competitions are held on a wide variety of terrain, so I want a tire that will work great no matter where I go. Knowing how a tire will react on your rig is key.–Jake Wright

2. CENTER OF GRAVITY
You don’t need to calculate your exact center of gravity, you just need to know lower is better. Mount all of your major components as low as possible. If you’re competing, you’re probably running a motor-on-axle rig such as the Axial XR10. That means you don’t have to worry about the motors, but you should still work to get the battery, speed control (or speed controls) and even receiver as low as you can. Lower is better. Even lower is even better. Get the body as low as possible too. Most people fail to appreciate how much the body influences the center of gravity of their vehicle.

On my latest Axial XR10 build, I have put a lot of effort into lowering the CG and working with the link geometry to keep the rig planted. I have moved all the electronics to the front axle (unsprung weight) and switched to lightened hardware throughout. For a relatively stock rig, things like battery and electronics placement can make a big difference.–Jake

3. DURABILITY
Rock crawling may be slow, but most people quickly learn how tough it is on equipment. When a crawler loses grip and falls, it falls hard. Make sure you electronics are mounting securely. Aluminum knuckles are a must-have hop-up. Be warned: not all aluminum parts are created equal and you get what you pay for. Aluminum shocks are also a wise move as the they are far less likely to pull apart. If hardened steel gears are available–get them.

Steering durability is usually my #1 concern. Nothing is worse than having a truck with sloppy steering, especially when trying to sneak past a tight gate in a competition. On my current rig, I am running a Futaba servo with Vanquish Products knuckles and axle C’s.–Jake

4. WEIGHT DISTRIBUTION
When rock crawling first took off, the common school of thought was to build tanks. People commonly built rigs that you could throw your back out lifting up. More important than weight is weight distribution. In addition to getting everything low as was described in the section on center of gravity, it is essential that the weight is properly distributed. Most crawlers work best with the weight distributed approximately 60/40 with 60% of the weight forward of the center of the vehicle. A 50/50 split can also work, but it is highly unlikely a truck will crawl well with the majority of the weight in the rear.

I’ve found that a 60/40 front to rear weight bias usually works the best for most obstacles. For courses with a lot of climbs or breakovers, I usually add extra weight to the front to help the rig up and over. I have focused a lot on reducing the sprung weight of the rig, and it has made a huge difference in performance.–Jake

5. POWER
Again, things have changed from when rock crawling first took off. Initially, everyone was only concerned with torque. It didn’t take long for people to catch on to how much having some wheel spin on tap would help. Sometimes momentum (achieved via some wheel speed) is need to be able clear an obstacle. Heck, sometimes you just have to launch the thing. Don’t throw away that 55-turn motor just yet. For a variety of reasons, wheel speed is best achieved by increasing voltage as opposed to changing motors (lower turn) or gearing (higher count pinion). The big benefit is what is commonly known as a “high volt/low Kv” setup will be easier on the electronics equipment. so, if you haven’t gone with a 3S LiPo setup, do so now.

I am using Holmes Hobbies Crawlmaster motors with a variety of small 3S LiPo batteries. Most competition courses are under six minutes long, so I chose packs that will give me 8-10 minutes of run time. The small packs can easily be mounted on the front axle instead of in the chassis, which helps weight bias and CG.–Jake

 

Links

Axial

Futaba

Holmes Hobbies

Vanquish 

 

 

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10 Comments

  1. I would like a 4s lipo set up because I have extra 4s lying around and I would like to use them with a axial truck for crawling. I was wondering is any brushed motto can handle that and if its possible.

    1. 4S is a pretty high voltage pack for a crawler. You can try it, but gearing will be very important. Also, it will have to be a fairly high turn motor or the setup may get too hot. Even with a small pinion, the motor may simply not be able to handle the voltage. I’m not saying it won’t work, but be warned. Be sure to check your speed control specs too–very few brushed speed controls can handle 4S.

  2. Thank you very much for your respond and sharing your great knowledge about rc. I would think if in not at full throttle the motor won’t get the full voltage of the 4s? I know it’s a lot of voltage for the axial truck set up lol. It’s just a have so many 4s lipos around I’m I’m getting in to the axial trucks now to climb that I want to make good use of the lipos for it if I can. I found a few ESC that can handle the 4s. The mamba max pro and torque master from holmes hobbie. Of you can answer this question too sir what would be better to climb rocks and dirt a 27 turn or a 55?

    1. I prefer a 55-turn for climbing rocks. The 27-turn motors will work, but the power curve of the typical 55-turn will allow for precise control and slow speed finesse. The 27-turn will give a lot of wheel speed for a crawler, but may be a little too low of a turn. A 45-turn is a good compromise.

      Back to the 4S subject, if you go with a speed control, like the ones you mentioned, you can go with 4S. You won’t be the first person to run 4S in an Axial SCX10. More than a few guys running in Top truck Challenge events seem to love the power. Even if the motor survives, the drivetrain will be abused. Many people replace the axle gears with Axial’s heavy duty replacements, replace the transmission gears with metal gears, replace the drive shafts and even the motor plate. I run 3S in a SCX10 and have never had any problems that I thought were out of the ordinary.

      1. there is a viable alternative to compromising on motor turns. 2 speed tranny with shifter on the tx.

        Just thought id throw that in since thats the way my scx10 is setup. but mine is also a hybrid monster. 3s with evx2 and titan 775 and summit tranny.

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