Drag Slash Performance Tuning Guide
Part 1: Basic Setup
The Traxxas Drag Slash is much more than a street makeover for RC’s most popular short-course truck. From bumper to wheelie bar, the Drag Slash has been refined and optimized for straight-line performance, and Traxxas Stability Management® (TSM) makes it easy for drivers of all skill levels to make straight full-power passes. If organized no-prep competition is your target, utilizing Drag Race Mode (TSM off) with a refined setup is essential to racing success. The Drag Slash is fully adjustable to help you find the perfect setup for your track, traction level, and skill, and we’ll cover the basics of setting up for the strip in three installments. Let get started with the basic setup techniques you’ll need for taking home wins at the strip.
Which Battery is Best?
The Drag Slash arrives fully set up for the strip and Ready-To-Race, leaving only battery selection to you. If you’re planning on going racing with your Drag Slash, make sure you choose a battery that is allowed by the rules of your local drag racing club and the class you plan to run in. Most organized drag racing is done with 2-cell (“2s”) LiPo batteries, and Traxxas offers three different 2s Power Cell iD LiPo batteries for the Drag Slash. For peak performance on the strip, the 7600mAh pack (2869X) is the best choice as it offers the optimum balance of high capacity and low weight. You may wonder why capacity is important given that a drag race only lasts a few seconds, but battery capacity does more than determine run time. Greater capacity means greater ability to deliver high amperage when your Drag Slash demands it.
The Drag Slash can be operated with a 2-cell (2S) or 3-cell (3S) Power Cell LiPo battery, or a 7-cell NiMH pack. The 2s 7600 shown here is ideal, but other 2s packs like this 2s 5000 (2842X) can also be used.
This chart lists the Power Cell batteries compatible with the model. For organized competition, the 2-cell 7600mAh LiPo battery is best.
If you don’t already have a charger and battery for your Drag Slash, you can complete your model with the safety, performance, and convenience of Traxxas iD technology with a Completer Pack featuring the EZ-Peak Plus iD charger. The 2992 Completer Pack includes a 5800 mAh 2-cell LiPo, and the 2994 Completer Pack will equip your Drag Slash with a 4000 mAh 3-cell LiPo.
Running with 3-Cell Power-Cell LiPo Power
Like all Traxxas models equipped with the VXL-3s speed control and Velineon 3500 motor, the Drag Slash can be operated with a 3-cell (“3S”) LiPo battery for maximum speed and power. If you decide to go with 3S power for fun driving, stick with the stock gearing (22-tooth pinion, 76-tooth spur gear). As an optional step to further safeguard against motor, speed control, and battery heating when using a 3S battery, you can install an 83-tooth spur gear to achieve “lower” gearing. Monitor the motor’s temperature and make certain it does not exceed 200° F (93° C). Overheating can damage and even ruin the motor. You can monitor motor temperature remotely using the Traxxas Link app and your iOS or Android smart device by adding the Traxxas Link Wireless Adapter to the Drag Slash’s TQi transmitter and installing the 6521 temp sensor on the motor (6511 Wireless Adapter and 6521 temp sensor sold separately).
Like all Traxxas models equipped with the VXL-3s speed control and Velineon 3500 motor, the Drag Slash can be operated with a 3-cell (“3S”) LiPo battery for maximum speed and power. If you decide to go with 3S power for fun driving, stick with the stock gearing (22-tooth pinion, 76-tooth spur gear). As an optional step to further safeguard against motor, speed control, and battery heating when using a 3S battery, you can install an 83-tooth spur gear to achieve “lower” gearing. Monitor the motor’s temperature and make certain it does not exceed 200° F (93° C). Overheating can damage and even ruin the motor. You can monitor motor temperature remotely using the Traxxas Link app and your iOS or Android smart device by adding the Traxxas Link Wireless Adapter to the Drag Slash’s TQi transmitter and installing the 6521 temp sensor on the motor (6511 Wireless Adapter and 6521 temp sensor sold separately).
Staying Straight on the Strip
Even if you’re racing with Traxxas Stability Management (TSM), adjusting your Drag Slash for straight launches without TSM assistance will help you achieve lower ETs and notch more wins. Whether the steering inputs are coming from TSM or your own reflexes, the commands required to correct your car’s path and the forces they exert on the chassis represent energy deflected from powering the car down the track. Careful setup to ensure your Drag Slash stays aimed squarely at the finish line will help you win races with or without TSM. Here’s how to make sure your machine is dialed in:
Toe Angle
The factory setting for the front wheels’ toe angle is zero degrees, meaning the wheels are parallel to each other and point straight ahead rather than angling slightly in or out (check out our Suspension Tuning Guide to learn more). As your Drag Slash accrues track time and the steering parts wear-in (and/or you have a few, ahem, “mishaps” on the track) you may find the toe setting could require readjustment via the steering turnbuckles. Note, too, that there is slight play in the steering system. Though you may have set zero toe at the bench, the tolerances of the system may result in slight toe-out when the car is under way. Adding just enough toe-in to account for this sets the car to run with zero toe when powering down the track, and can help improve straight-line stability.
The factory setting for the front wheels’ toe angle is zero degrees, meaning the wheels are parallel to each other and point straight ahead rather than angling slightly in or out (check out our Suspension Tuning Guide to learn more). As your Drag Slash accrues track time and the steering parts wear-in (and/or you have a few, ahem, “mishaps” on the track) you may find the toe setting could require readjustment via the steering turnbuckles. Note, too, that there is slight play in the steering system. Though you may have set zero toe at the bench, the tolerances of the system may result in slight toe-out when the car is under way. Adding just enough toe-in to account for this sets the car to run with zero toe when powering down the track, and can help improve straight-line stability.
Use the included turnbuckle wrench to set front toe. The links are installed so that pushing the wrench forward will lengthen the link and increase toe-in, and vice-versa.
Setting toe so the car maintains one or two degrees of toe-in while underway can further improve stability. The toe-in will also introduce a tiny amount of tire scrub that represents more drag for the car to overcome, but any drag attributable to toe-in is completely insignificant compared to the time cost of a run that requires steering input to stay on track. If a degree or two of toe-in helps you run straighter, it’s well worth any minuscule increase in rolling resistance.
The Drag Slash is set at the factory with zero front toe and rear toe fixed at 2.5 degrees in.
The Drag Slash’s rear wheels also have toe-in for improved stability over a zero-toe setting. A rear toe setting of zero degrees (wheels pointing dead ahead) can make any car feel more loose and “wandery” on the straights. This effect becomes more pronounced as tire width is increased, making it an undesirable setup for a car on drag slicks. The Drag Slash’s rear toe setting is non-adjustable to ensure the setting is precise and won’t drift.
Camber
The Drag Slash’s front and rear camber can be precisely set via the turnbuckle camber links. Our Suspension Tuning Guide explains what camber is and how it affects handling for cars that need cornering traction to win, but a drag car’s priorities are different. Cars that need to make cornering grip may use up to three degrees of negative camber, but since the Drag Slash is optimized for straight-line traction, it stands its rear tires up perfectly vertical at zero degrees.
The Drag Slash’s front and rear camber can be precisely set via the turnbuckle camber links. Our Suspension Tuning Guide explains what camber is and how it affects handling for cars that need cornering traction to win, but a drag car’s priorities are different. Cars that need to make cornering grip may use up to three degrees of negative camber, but since the Drag Slash is optimized for straight-line traction, it stands its rear tires up perfectly vertical at zero degrees.
You can confirm a zero-degree camber setting using any handy object with a true vertical side—in this case, a can of spray paint.
As with steering toe, the rear tires’ camber setting may drift as the suspension parts wear in, or if you roll or otherwise crash the model. Before resetting camber, be sure to install the battery you plan to race with and give the suspension a couple of bounces to make sure the car is at ride height. You can reset camber to zero using any handy object with a flat side that is perpendicular to your work surface—a spray can works well. To measure camber angles of 1, 2, or 3, print the artwork below and mount it to stiff card. Make sure to cut the flat sides precisely for accurate settings.
Print and cut out this handy camber gauge.
Use the gauge to test your camber.
As a drag car launches, it transfers weight to the rear tires, causing the suspension to compress or “squat.” If you compress the rear suspension by hand to simulate squat and note the tires’ camber angle, you’ll see the tires lean in toward the chassis (gain negative camber) as the suspension is compressed. You can experiment with setting the rear tires for slight positive camber (a half-degree or one degree is plenty) at ride height so the squatting effect will tilt the tires to zero camber as the car launches. As with all racecar tuning, be sure to make small changes, adjust one setting at a time, test thoroughly, and keep notes so you can easily go back to your previous setup if you don’t like a new setting.
Putting the Wheelie Bar to Work
For fun-running, you can set the wheelie bar anywhere you like for exciting wheels-up action. Go higher to hold wheelies longer (and look awesome) or go lower to get back on all four tires faster. For competition driving, a low setting is always the way to go. The sooner the front wheels are back on the ground (if they leave the ground at all), the sooner you can make steering inputs to keep your car headed straight down the strip. In fully stock configuration, the second hole from the top of the mount will provide the best starting point for all-around performance.
The wheelie bar’s five height settings and two wheel diameters make it easy to set the bar for ideal power transfer.The wheelie bar should be as close to the track surface as possible (but not touching it) when the car is at ride height. When you launch, weight transfer and rear squat will lower the bar to the contact the track. If the bar is on the track at ride height, it will interfere with weight transfer and reduce traction. If the racing surface is low on traction and you’d like to try increasing rear squat to generate more grip, raise the wheelie bar one position higher than the lowest no-track-contact setting. You can further fine-tune the wheelie bar setting by changing the wheels. The Drag Slash includes wheelie-bar wheels in 18 mm and 26 mm diameters. Install the larger or smaller wheels as needed to adjust the gap between the track surface and the wheels at ride height.
Prevent “Pulling” with Preload
Even if your Drag Slash drives arrow-straight when you check the steering trim, you may find your car pulls to one side when you launch off the line. The extreme weight transfer under full-power acceleration makes the front end very light, so the narrow front tires have little steering power until the car is fully underway. A straight launch is all about the rear tires, and precise rear suspension setup is essential.
From the factory, each rear shock has two 1 mm spacers, one 2 mm spacer, and one 4 mm spacer for a total of 8 mm of preload. You can fine-tune from there with the included additional spacers.
Thankfully, dialing out a “pull” isn’t difficult: all you have to do is increase spring pre-load on the side of the car that matches the direction of the pull. Or, you can decrease pre-load on the “away” side of the pull—as long as there’s more pre-load on the “pull side,” you’ll be tuning in the right direction. Determining exactly how much pre-load change results in perfectly straight launches will require experimentation and testing, but in general a good start will be removing a 1mm pre-load spacer from one of the rear shocks and placing it on the opposite shock. For example, if the car is pulling to the right, take the 1mm spacer off the left shock and place it on the right shock. If a smaller difference in preload from left to right is required, try removing the 1mm spacer from the left shock and leaving the right shock as-is.
To correct a “pull” at launch, you'll want to add additional spacers so there's greater spring pre-load on the “pull side.”
This chart will help you zero in on the best settings for your car and track, but experimentation and testing are always the keys to a dialed setup.
Burnout Basics
A productive burnout is a critical step in getting the most grip from your Drag Slash’s slicks. When done properly, a burnout will give you evenly heated tires without wearing the treads any more than necessary. Here are a few tips to help you warm your tires the right way.
Don’t Mash the Tires
When performing a burnout, you only need to prevent the car from moving forward. Mashing the tires against the pavement will only shorten tire life and unnecessarily strain the motor and drivetrain.
When performing a burnout, you only need to prevent the car from moving forward. Mashing the tires against the pavement will only shorten tire life and unnecessarily strain the motor and drivetrain.
Use Just Enough Throttle to Spin the Tires
Avoid performing burnouts at high rpm, as centrifugal force will expand the tire and concentrate heat and wear on the center of the tread. Burning out at lower rpm minimizes expansion to help the tread stay “flat” for even heating across the width of the tires.
Avoid performing burnouts at high rpm, as centrifugal force will expand the tire and concentrate heat and wear on the center of the tread. Burning out at lower rpm minimizes expansion to help the tread stay “flat” for even heating across the width of the tires.
Avoid Grooving
High spots and sharp points in the pavement can groove the tread if you hold the car completely still during a burnout. Move the wheels side to side for even heating and wear.
High spots and sharp points in the pavement can groove the tread if you hold the car completely still during a burnout. Move the wheels side to side for even heating and wear.
Keep It Short
Five seconds is all it takes to perform an effective burnout. Any longer will only reduce tire life, with no improvement in performance.
Five seconds is all it takes to perform an effective burnout. Any longer will only reduce tire life, with no improvement in performance.
Extend Tire Life by Burning Out on Carpet
A scrap of low-pile carpet makes an ideal “burnout pad” for effective tire warming with minimal tread wear. Check your local home store for free scraps, or hit the dollar store for a carpet doormat—as shown here.
A scrap of low-pile carpet makes an ideal “burnout pad” for effective tire warming with minimal tread wear. Check your local home store for free scraps, or hit the dollar store for a carpet doormat—as shown here.
Burning out on a patch of carpet will extend tire life. Moving the car from side to side helps ensure even heating and wear.
Important Tuning Tips
The Drag Slash is tuned and equipped to win right out of the box and will only get faster as you use its adjustable features to dial-in performance for your driving style and track conditions. Keep these tips in mind as you hone your Drag Slash setup:
Effective tuning is a lot like scientific experimentation, in that controlling the variables is key. Make one tuning adjustment, test it, assess the change in performance, then readjust and test again until you stop seeing a beneficial effect. Only then should you move on to the next adjustment. If you make multiple adjustments at once, you won’t be able to tell which are helping and which are hurting.
The differences in the settings of a poor-handling car and one well optimized for best performance are measured in just a few degrees and millimeters, so your setting changes should always be incremental. A half-degree of camber, two millimeters of preload, or a one-hole position change is plenty. If you adjust your car in big whacks, you may go from too little to too much and miss the perfect setting in between.
After making a change, give the new setting enough test runs to be certain you like the results or not. What may seem less than ideal on the first pass may feel like a winning setup as you adjust to the change.
Whether you make notes on your phone or go old-school with a pen and notepad, putting your settings and their affects in writing is an invaluable tool for zeroing in on a winning setup and getting repeatable results from your machine. Every run is a chance to learn more, go faster, and get closer to that next win.
Part 2: Gearing Your Drag Slash to Win
Part 3: Tuning the Sealed Differential
