Racers, Are You Making This Slipper Clutch Mistake?
This article was originally published in RC Driver’s February 2016 issue.
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.
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.
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.
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. For more, check out this RC Driver article on setting your slipper clutch: http://www.rcdriver.com/setting-your-slipper-clutch/