This article was originally published in RC Driver’s January 2016 issue.
By Charlie Suangka
Welcome back, fans of all things technical and perhaps considered confusing. This month’s tech topic will touch on an area often overlooked; steering setup and adjustments. Steering settings in your transmitter can literally make or break a setup. Knowing what does what not only helps keep your servo alive longer, but will give you better control as your driving needs or conditions change. So join us for this month’s tech pointers on steering setup.
SQUARE IT UP
First up is, of course, assuming that the steering linkages in the vehicle are set up correctly. The basics are simple: tie-rods should be equal length, steering rack should be centered/square, and the servo horn should be parallel with its counterpart on the steering rack. Consult the vehicle build guide and do a few basic checks if anything looks out of sorts. A little time on the linkages can go a long way toward an easy setup. Check that any servo saver/spring mechanisms are working correctly, and are not overly loose or sloppy.
TRIMS AND TASKS
Next is to see exactly what the radio has to offer beyond servo reversing and basic trim. Some have a simple dual rate, others have independent rate or travel adjustments and more advanced radios allow further tuning to the steering with curve adjustability or sub trims and mixing options. You don’t really need more than simple trim and independent rate/travel adjustments to get the steering set up correctly and live a long, healthy life. Even basic dual rate that lowers both sides of the travel is usable to prevent damage.
Start with the trim centered and then check exactly how the steering looks on the vehicle. Try to make the vehicle have fairly straight steering via the main servo link or adjust the servo horn on the splines of the servo. The closer this is to center now, the more neutral and evenly the servo will operate.
Setting the final straight line trim should always be done before anything further regarding steering adjustments. This can be tricky due the time of the build or conditions to get space to drive a straight line, but it is very important. The steering center point effects the left and right maximum throw points and if not done first, will skew later end point adjustments or at a minimum, create a need to redo the final end point adjustments later.
Once the vehicle is tracking straight, the steering left and right end point maximums can be checked. With the vehicle on a stand with at the least front wheels in the air, slowly turn the wheels in one direction and watch the steering carefully. Watch for the servo to move farther than the steering linkages. This causes a bind and will heat up and damage the servo.
Sometimes, but not often, the servo will not be giving full throw to the steering. Check that the link on the servo arm is correct. Also, the radio may have had the steering travel turned down. This simply limits the travel and should cause no harm or damage beyond reduced steering range.
More on that later. Often, the steering will max out long before the servo does, this bind can damage a servo quickly. Use the transmitter’s left and right end point or travel settings to stop the servo before the bind. This will limit the servo throw to prevent damage. If your transmitter only has dual rate, you’ll want to check each side and adjust to the side that has more bind. If the left and right are not fairly close as far as overall limiting of travel, you should examine your steering linkage setup and make sure everything is correct. Most vehicles will have almost the same left to right servo travel when all linkages are set up right.
The dual rate and travels can be used to help fine tune steering response as well. When traction is low and steering feels overly sensitive, lowering the dual rate will reduce overall steering and calm down the feel. Transmitters that have steering curve and expo settings offer further tuning to the steering feel. Initial response is toned down, but overall travel is retained at full input. It takes off the edge without lowering overall steering travel; great when high and low speed steering needs are drastically different or if initial steering feels a bit edgy. A small amount of curve can help calm down steering.
A servo working too hard at full lock is a common mistake with many setups. A little bit of time spent going over the basics and making a few adjustments will ensure that the servo lives the long, healthy life it was built for!