How to: Off-road Suspension Tune-up

Words: Nick Malato

5 steps to de-slop and smooth out your suspension system

In off-road racing, your car or truck is only as good as its suspension, and all the suspension components get a heavy workout each time you hit the track. Neglect your machine, and it won’t be long before performance suffers noticeably. But it’s never too late to get your car back up to spec. Just follow these steps, and your suspension will be swinging like its old self again.


It’s much easier to inspect the suspension when the parts are clean and the wheels and shocks have been removed.
 
1

Strip and clean

Strip the car down to get to the suspension. Remove the body and tires, the shocks and even the tie rods. Next, clean the suspension parts with a toothbrush and compressed air. Get all the dirt out of the works. A good cleaning gives you the opportunity to look at all the parts of the suspension to make sure that nothing is cracked, bent, or worn out. Replace any parts that look questionable; it’s better to do it now than waste time at the track.


Lift each arm and release; it should fall under its own weight. If it doesn’t, start wrenching.
 
2

Check for free movement

Make sure that all the suspension arms move freely through their complete range of motion. The arms and uprights should drop under their own weight. Suspension arms that bind or don’t move properly can cause handling problems when you hit the track. But also make sure that they don’t move too freely: they should swing up and down easily but not have excessive free play on the hinge pins. If the arms wobble on the hinge pins, it’s generally best to replace them. If there is extra room on your hinge pin between the arm and the E-clip, it’s a good place to put a couple of motor washers. These washers can take up the slack so the arm won’t slide back and forth.


Left: a pin may look straight, but the roll test will help you to spot when it’s slightly bent.
Right: pitted or rusty hinge pins are easily revived with a little metal polish.
 
3

Free up Tight Hinge Pins

If the arms do not move freely, remove the hinge pins and check whether they need to be cleaned or replaced. Roll your hinge pin on a flat surface; if it wobbles, it’s obviously bent. Bent hinge pins will bind and won’t allow the suspension to move freely. Dirty or rusted pins can also cause hang-ups. Put a dab of metal polish on a rag, and use a rotary tool or a power drill to spin and polish the pin. Use the slowest setting, and be careful not to get the rag caught in the chuck of the tool.


A piece of plastic bag under the ball cup (left) or an O-ring over the ball stud (right) will tighten a loose ball cup.
 
4

Restore The ball-cup fit

Your vehicle’s ball cups should operate freely but with as little “slop” as possible. If your ball cups have a lot of play, they won’t be able to hold precise camber and toe settings. If that sounds like your car, it’s best just to replace the cups, but that isn’t the only fix. You can shim the cup by placing a piece of plastic bag over the ball and snapping the cup over it. Some bags are thicker than others, so you might have to experiment to get the perfect fit. Or you can slip an O-ring over the ball stud before you snap the ball cup onto it. Just make sure that the suspension still moves freely, as described in step 2.

1. Excessive wetness around the seals means it’s time to rebuild.
2. Shaft should be shiny, not scuffed.
3. Is the shaft straight?
5
Shock check

Remove the shock springs so you can get a good look at the seals and shafts. Obviously, a bent shaft should be replaced, but even a straight shaft should be replaced if it’s heavily scuffed. A shiny shaft seals better, wears the seals less and operates with less drag. Take a good look at the bottom of the shock; if it’s wet with fluid, the seals should be replaced. Last, compress the shock shaft. The piston should move smoothly throughout its travel range. If you feel any tight spots, check the shock body for dents, and have another look at the shaft to be sure it isn’t bent. If the shock seems to operate smoothly but you feel air bubbles in the fluid, pump the shock shaft. If the air emulsifies in the fluid, the shock will smooth out. If you still feel the bubbles in the piston stroke, it means there isn’t enough fluid in the shock. Refill the shocks with fresh fluid; don’t just top them off.

Factory preparation

We spoke with Team Losi driver Todd Hodge for his factory suspension tips.

RC Car Action: Do you rebuild your cars or trucks for a big event or run brand-new ones?

Todd Hodge: I like to rebuild my cars. This way, I am totally familiar with the car. I find when I do run a new car, it takes a good day of running it to get acclimated to it. At a national or regional event, you don’t have a day to waste.


RCCA: Do you build several spare sets of shocks, each with different setups to try?

TH: I try not to. In the past, I’ve tried two or three setups, and I just end up wasting time testing all of them instead of getting used to driving the car. Lately, I’ve just run my races without overly wrenching to get used to the track. This is one thing Ryan Cavalieri does ... he never changes his car. He practices lap after lap and learns how to dissect the track and find the fastest way around it.


RCCA: What sort of shock maintenance will you do during a day of practice at a national event?

TH: The shocks are important and require the most attention. All of the silicone oils we use tend to make the O-rings in the cartridges swell, so I usually change those every day at a big event, or every other day depending on how dusty the track is. If it’s really dusty, then you should rebuild the cartridges every day. I also check my bearings to make sure they are free, and I clean out my ball cups with a Q-Tip and some Simple Green to ensure free movement.


RCCA: At the Worlds, some guys completely rebuilt their cars the night before qualifying. Is that standard practice, or just for the Worlds?

TH: Many racers tend to go overboard. I think as long as you make sure that all the car’s bearings and hinge pins are clean and the suspension moves freely, everything will be fine. In the 4WD class at the Worlds, it rained during practice, so it was a must to tear your whole car down to clean it, since it was caked with wicked sandy clay.

RCCA: Any final tips?

TH: Yes—practice, practice, practice. Many of the topnotch racers aren’t there simply because they’re talented. They also practice and race as much as they can. Also, it’s important to pay attention to details and be meticulous when building your cars.

Source:

Car Action