We've talked a lot about maximizing the forward grip of your car, but what happens when the power plant within your vehicle overcomes the weight-transfer physics of your chassis or the ability of your tires to make grip? Now we have to make changes to harness the extra power to prevent wheel spin and again maximize the available forward grip. This can be done easily through your slipper clutch if your vehicle has one. A slipper clutch is a relatively simple traction control system that allows your transmission to absorb excess power from going to your wheels and creating spin. To set your slipper, place your car on one of the lower traction areas of the racing surface and hammer the throttle. If your tires spin, then loosen your slipper slightly. Keep doing this until you can grab a handful of throttle and launch from your starting position without fishtailing everywhere. This is your perfect starting point; now you can make minor changes to fine-tune your slipper for the rest of the track.
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There are few components on your RC car or truck that have as direct an impact on the overall durability and life of your transmission as the slipper clutch. This often under-utilized and misunderstood component of your RC car or truck has long been used to improve traction and reduce wheel spin on slippery surfaces. However, that's only part of the picture. A slipper clutch can also help extend the life and performance of your transmission as a whole. We recently dove into the workings of the slipper clutch on the Losi Strike to point out the innermost workings of the design, how to maintain your slipper and how to properly adjust your unit. Come along with us as we show you how to be a slipper clutch master.
One of the most underrated tuning options on any off-road vehicle is the slipper clutch. This system helps protect the drivetrain from damage due to sudden jolts or excessive loads. The process of setting the slipper clutch to work properly seems easy, but most people still don’t have a clue how to do it. Too much slip and you can overheat the slipper; too tight and you can do damage to the spur gear (or the gears inside the transmission).
In my years of track time, I have seen different ways to set the slipper and this is by far the most effective method I’ve used. Follow along with the steps below.
1. Tools Required
Most buggies and trucks come with a four-way tool or something similar that allows you to adjust the slipper clutch. If not, you’ll need to pick yourself up a hex driver that will fit your slipper nut.
2. Initial Setting
If you own an RTR, the slipper clutch was probably set close to the correct position from the factory. You can use this as your initial setting. If you own a kit, go ahead and tighten it down as shown in the instruction manual. This should also set you close to the correct position for an initial setting.
3. Initial Test
Turn your transmitter on, followed by your vehicle. Now, with the vehicle facing away from you, place your left forearm on the left rear tire and your right hand on the right rear tire. Hold firmly! Now apply full throttle, but only a short burst. The front of your vehicle should lift off the ground approximately five to six inches.
4. Make Any Adjustments
If the front of your vehicle doesn’t lift off the ground, your slipper is too loose. Tighten it approximately ¼-turn and repeat step three. If the front end jacks up higher than six inches, your slipper is too tight. Loosen it approximately ¼-turn and repeat step three. Once you have the front end lifting approximately five to six inches, the slipper is set in a good starting position.
5. Hit the Track
The true test of how well your slipper is set will be on the track (against the track conditions). Take a few laps and see how it feels; if you feel you need to make further adjustments, do so in smaller, 1/8-turn increments.
Racers, Are You Making This Slipper Clutch Mistake?
Many new racers will set their slipper too loose to help eliminate the punch of a faster motor. This is not a good idea as it will only cause your motor to run hotter and wear out faster and cause your slipper components to wear out quicker too.
A loose slipper may help you get around the track more smoothly, but it will not make you a better driver. The only way to become a better driver is practice.
Let’s look at why your slipper clutch setting is important.
WHAT DOES YOUR SLIPPER CLUTCH DO?
Attached to the transmission of almost all 2WD electric off-road vehicles, many 4WD electric monster trucks and some 4WD electric off road buggies is a slipper clutch.
The slipper clutch has several useful purposes.
It helps reduce wheel spin as your vehicle accelerates, something very useful on low traction surfaces. This is helpful as your vehicle will be less likely to spin-out as it speeds up exiting a corner or any time you punch the throttle quickly.
It also helps your vehicle perform better after taking a jump or on rough choppy spots on the track, absorbing the impact that can cause your transmission gears to wear out and fail.
SLIPPER DESIGN
Basic slipper clutches consist of a backing plate that connects directly to the top shaft of the transmission. Here you’ll find a slipper pad followed by the spur gear and then another slipper pad, then another backing plate.
Depending on your slipper, a spacer or washer comes next followed by a spring, then a washer and finally, a locknut that when tightened down sets the adjustment.
Many of these components come keyed and need to fit together in a specific way so make sure you have everything aligned before you tighten the spring down.
Some newer, more complex slipper units have a third plate and pad on the outside of the spur gear to help smooth out acceleration more and because it remains more consistent over long runs. While this does increase rotating mass, the pay off in performance in modified racing more than makes up for it.
SLIPPER TUNING
Now that we have established what the slipper clutch is used for and its basic design, let’s discuss how to properly set and adjust it.
Many instruction manuals will tell you to tighten down your slipper all the way so the spring is fully compressed and then back it off three to four turns for your initial setting. From there you should bring your vehicle to the track and give it a true test.
Ideally, when you punch the throttle from a stand-still you should hear your slipper clutch slipping for about one to two feet. To test this you would place your vehicle on the track, facing away from you, and punch the throttle.
If your vehicle pulls the front wheels off the ground or if it spins out before you even get going, it is too tight and you need to loosen it and try again.
If you hear the clutch making a whining sound or it seems sluggish with a lacking power, it is too loose and you need to tighten it.
A general rule of thumb it to tighten or loosen your slipper no more than 1/8 of a turn at a time and test again.
On a very low traction surface you may want to loosen your slipper just a touch to further reduce wheel spin. Conversely, you may want to tighten up the slipper on high-grip tracks as to not wear the pads prematurely and to put as much power down as possible.
ADDITIONAL CONSIDERATIONS
With the advent of fully programmable electronic speed controls that have features like punch control to help lessen wheel spin automatically, some people who run 2WD buggy will opt to run their slipper clutch completely locked to get as much power to the ground as possible.
Others, instead of tightening down the slipper and locking it have installed direct spur gear mounts from manufacturers like Exotek. This eliminates the spring, slipper pads and backing plates so there is absolutely no chance of slippage and this helps reduce rotating mass.
Hopefully this clears up any confusion about setting your slipper clutch too loose.
