Dampers / Shock Absorbers for Radio Controlled Models Explained

What Do Dampers Do?

   Dampers, Shock Absorbers, Shocks - call them what you will, they are one of the least understood, but most important tools you have for adjusting the handling characteristics of your RC model.

My Mission

   In this article, I will endeavour to explain just what you can achieve by making simple tweaks to your shocks and how these tweaks can keep you ahead of your opposition on the track.

The Dictionary Definition

   In dictionary terms "Damper" is described as - "A mechanical device to absorb the energy of sudden impulses." - In plain language, they stop your car from bouncing all over the track.

How Dampers Work

   Basically what you have is a small amount of silicone oil contained in a sealed cylinder. Through the centre of that cylinder is a metal shaft and on the end of that shaft, a piston with a number of small holes in it. Pulling, or pushing the shaft in and out of the cylinder, your will notice a certain amount of resistance as the oil is forced through the holes in the piston.

Damper Adjustment Options

   To manipulate that resistance you have two options. You could use thicker or thinner oil, or change the size of the holes in the piston. So if you have thicker oil, or smaller holes, you have more resistance. Less viscous oil or larger holes, less resistance. This simple physical relationship, coupled with a good set of tuning springs, is all you need to set-up your car to beat the rest.

Diagnosing your Cars Handling Problems

   Out on the race track, the main thing you want to avoid is your car bouncing around all over the place, sliding, or even rolling over when you negotiate a tight corner. To prevent this you need to make changes, but before you make those changes you need to consider what your problem is for that particular track. How your model reacts when cornering - does it Under-steer? (Slide towards the outside of the corner) or Over-steer (Turns towards the inside of the corner). Does it react differently when you exit the corner to how it did when you entered it?

Use Our Setup Guide

   Once you have decided what your problem is, go to our "Set-Up" page linked below and follow the step by step instructions. But remember to only make ONE change at a time. If the first suggestion isn't enough to cure the problem, add the second - and so on, until you find that perfect setting. Good luck and good racing.

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Or, check out our RC Model Car Setup Guide

A Guide to Damper Pistons

What Do Pistons Do?

   When you first build your RC model, you will sometimes find that there are a number of different pistons in the kit, with varying numbers of holes or hole sizes in them. Generally, the manufacturer will suggest one particular piston in the car manual, and may provide you with a mid range oil weight, but depending on the type of terrain you intend to race your model, their suggestion may not be the best for your needs.

   When it comes to tuning your dampers there are basically two things you need to know about pistons. "Pack" and "Static Damping".

What is Damper Pack?

   Pack, is the speed your damper reacts to any quick compression and can be considered to be a consequence of the size or number of holes in the piston. Smaller holes, more pack, larger holes, less pack.

What is Static Damping?

   Static Damping is the amount of resistance you sense when slowly pulling or pushing the piston rod in and out of the damper. As with pack, this is related to the number or size of the piston holes. Larger holes, less static damping, smaller holes more static damping.

Damper Tuning Tips

   Setting up your dampers is a matter of trial and error. With the car in full race mode, that means with everything installed, place it on a table, then pick up the rear of the car, raising it around six inches and drop it onto the table. The chassis should dip slightly below then back up again to the pre-set ride height, in one smooth movement. If instead, it slaps down onto the table, the pack of your dampers is not enough. In this instance, depending on the setup you are testing, you have two options, thicker oil or smaller holed pistons. If when you do the test the dip is hardly any, then the pack is too hard and you should try thinner oil or bigger holed pistons. Repeat this process for the front of the car. Finally, with both ends adjusted, pick up the entire car and drop it from the same height. Both ends should respond equally when dropped, if not, change your pistons or oil weights until they do.

The all important Track Test and Fine Tuning

   After your basic setup, you then need to test your car on the track. If the rear of the car tends to hop excessively over small bumps, the rear dampers have too much pack. You need to change the pistons on the rear for larger holes, and also use thicker oil to maintain static damping. If the car chassis bottoms through small bumps and landing on jumps, the pack is not enough. In this instance, change for smaller holes and thinner oil.

   If the car lands nose up from a jump, this is indicative of the front dampers having too much pack. These should be adjusted as described above to keep the car static damping in balance. Nose down obviously means not enough pack.

   I hope this article has been helpful. Good luck and good racing.

Dont Ignore your Shock Mount Settings

   The combinations of Shock settings available on the majority of ON and OFF road cars are far too many for this article to cover, so I will endeavour to explain some of the basics, that should give you some idea what these changes might achieve. Some of the settings suggested may not be available on all RC model cars.

Lower Wishbone Damper Settings

   If you look at the lower wishbones of you model, you may see a number of holes alongside where the ball studs for the dampers are positioned. If you were to remove those studs on the rear wishbone and reposition them in the hole further out from the center of the car, the first thing you will notice is the ride height has dropped, this can be corrected by adding C spacers above the springs. The second thing you will notice is the shocks are more sluggish, this can be compensated by using thinner oil. If this adjustment is made on an off-road car, it can be advantageous for landing after big jumps, providing improved stability due to the increased hydraulic pack in the shocks (as described in my previous article). This setting can also improve the way cars handle small bumps and dips in the track, due to the softer static damping.

The Effect of Damper Angle

   Changing the mounting hole positions used by the dampers, on the wishbone or on the shock tower, will always change the angle the dampers lay. This angle is what changes the characteristics of the shocks in that they will react to different track types and conditions. The above example is just food for thought, for those looking to improve their cars handling in relation to any other settings, such as caster, camber, toe-in etc, they may have previously made on their car. The only way to really get to grips with this subject is through trial and error.