In the proverbial grand scheme of things, the Slash 4×4 hasn’t been out very long, but veteran Traxxas racer Steve Slayden has already put more miles on his Slash 4×4 than most of us will all year. So who better to get the straight scoop from than this guru of all things Traxxas?
RC Car Action: Which kV brushless motor do you recommend for use in open class racing?
Steve Slayden: First of all, the ideal power needed for any circumstance should ultimately be decided by what the driver can handle and effectively put down on the track. This will vary from track to track and most importantly by driver skill level. I believe rather than pinpointing a specific rating, a range or window of effective kV ratings would be best. With that said, 3000 to 6000kV should be the window of power to focus on, with most situations leaning toward the 3000 to 5000kV mark. The fastest motor doesn’t equal a first-place win. I think this is what sets a lot of racers back. If your motor is so hot that it pulls wheels off the ground, spins them to reduce forward momentum, or keeps you from being able hit your apexes correctly, then you’re clearly over-powered. Stay in a reasonable zone. The Traxxas Velineon 3500kV motor is a great racing motor, with plenty of speed and controllable power. It’s probably even too fast for some. But that’s where practice and understanding setup come in.
RCCA: What is the ideal front, center and rear diff fluid starting setup?
SS: Again, it’s more about a range or window of effective viscosities. Up front, 5K to 10K fluids will suit most drivers; I personally favor fluids closer to 10K. Lighter fluids will help with more steering entering the corners but will fade (scrub) a bit of power coming out of the corners. Find the best balance to get you in and out of the corner as fast and easy-to-manage as possible.
The center diff has the most effect over the truck than the front or rear. It basically dictates how much power is sent to the front of the chassis and also manages brake bias when hitting the brakes. This is also crucial for corner entry. Lighter fluids help with turn in (turns sharper), but slows acceleration a little. Heavier fluids will enhance acceleration but take away a bit of steering entering a corner. With that being said, the range of recommended fluids is between 20K and 75K (100K/50K mix). I’ve been the happiest with fluids around the 50K mark for the center diff.
The rear diff affects how the rear feels rotating into and around a corner, and even more so when exiting the corner under acceleration. If fluid is too light, corner exit under power can get sketchy and make the truck difficult to track straight, especially with hotter motors. Too heavy of a fluid in the back and the rear end will want to push the chassis straight when entering and exiting corners. Range of effective rear diff fluids are between 5K and 10K. I use 7K as a base setup.
RCCA: Do you think the 4WD Short Course class should be open in terms of motor and battery?
SS: Two types of classes can be had here. You can always “spec” a class. This is good for stock racing, cost control, or brand-specific events. Local club racing has seen some benefits here as well. For most of the “open” or “mod” racing programs from club to national-level events, I feel it should be open. There are many reasons and so much to talk on this subject, but I’ll focus on the more important issues. First of all, most consumers want freedom. They don’t like being restricted. It benefits the hobby overall to allow more flexibility with the rules, as it appeals to drivers who want to run want they want to run. Besides, any class of racing that gets popular with the public increases manufacturer involvement and support. That means there’ll be many different products to choose from and lots of different products used by many different consumers. Trying to restrict to just one battery and just one motor alienates a lot of RC racers, and I don’t feel that’s the best answer.
Ninety percent of what makes a winner a winner is individual determination, skill, focus and preparation. All the truck really needs is something that is relative in power, and the driver does the rest. Only those driver who honed their skills and maximized their ability can benefit from the fastest motors and batteries, and they are likely to be the winners anyway. In open class racing, the motors are all fast, and the batteries are all powerful. It comes down to who can control their truck the best. Restricting to a particular motor and battery doesn’t really help in this situation. If someone wants to buy the fastest motor available, they’re likely only hurting themselves and their lap times. This is a common mistake but one that every driver should learn.
RCCA: After finding the right tires, what are some of the first suspension tweaks racers should make?
SS: To me, every adjustment is critical, but to pick a few of the most important suspension settings would probably be springs, damping, ride height and shock position. All of this dictates how your truck feels on the track concerning bump handling, jump landings and overall control of the chassis.
RCCA: Compared with some of the buggy-based 4WD short course offerings, what are the Slash 4×4’s advantages?
SS: I think there are advantages found in both designs and specific conditions where one may shine over the other. What I see as an advantage with the Slash 4×4 is drivetrain layout. I like the rear-mounted motor with just a single center shaft. This helps with efficiency and chassis balance for off-road racing; it’s lightweight, and I believe the Slash 4×4 is on the lighter side, and this helps with acceleration and less strain on electronics. The chassis is extremely easy to work on and take apart. You can literally break this thing all the way down to the chassis between heats if you need to; and it has a slightly higher CG. Even though the CG isn’t much higher than the pan-chassis designs, it does allow for more ground clearance, and this helps with weight transition and traction on slicker surfaces.
Read the full article on Slash 4×4 Tuning Tip in the July issue of RC Car Action