Monotube Maintenance

Just a few years ago, a shock that was smashed off the car was sent to the trash. These days racers are sending their high-dollar, but rebuildable monotube (nitrogen charged) shocks back to the manufacturer for repair. And when they do, the two or three pieces (or in extreme cases, shock dust) that come out of the box indicate that they weren’t being properly maintained. Many of these shocks haven’t been properly functioning for a while. You can avoid racing on shocks that aren’t working by inspecting them on a regular basis.

Like any maintenance program there’s a schedule. “Think of your shocks like an engine,” says Afco’s Bill Workman. “They have many of the same parts, a piston, cylinder wall, and they have oil, so put shocks on the same maintenance program that your engine is on.”

Like your engine, there are weekly checks as well as more involved procedures at larger intervals. “If you race often enough where your engine is getting overhauled twice a year, the shocks on the car should be getting overhauled when the engine is being rebuilt,” says Workman. “If you’re a guy who races 20 times a year and your engine is getting overhauled in the winter, that’s probably all your shocks need, unless you’re racing every week at a place that’s like a plowed cornfield.”

Maintenance should be as elaborate as your time and resources allow. “I have teams that don’t check them from race to race and others that check everything on them each week,” says Penske’s Dave Reedy. “There’s never enough time to do all the maintenance because there’s always something that can be done.”

At minimum, incorporate your shocks into regular procedures. “When you wash the car and its components, wash the shocks and inspect them then,” says Reedy.

Removing the dirt helps the shock do its job. “Keep the shock clean to help dissipate heat,” says QA1’s Karl Hacken. “I wipe them down with soapy water and a rag.”

Some manufacturers prefer to clean with a do-all like WD-40 while others prefer a cleaner like Formula 409, but all suggest avoiding brake clean-type products. “If your shock is covered with oil from the engine, you can spray some brake clean on a rag and wipe down the shock,” says Reedy. “But I would stay away from using brake clean regularly on the shocks.”

One reason is to avoid damaging the wiper seal where the shaft goes into the body. The seal must keep oil in the shock while preventing ambient items from entering the body as the shaft moves in and out. “Soaking the shock in brake clean or sometimes even spraying around the seal can cause problems,” says Reedy. “Even paint overspray on the shaft can damage the wiper seal.”

Regardless of what damages the seal, problems aren’t always immediately apparent. “It may not take the seal out right away, but it can eventually cause a leak,” says Hacken. A shock that’s leaking oil can be the source of many handling headaches, but there are ways to identify a leaking shock. “Watch for oil residue on the shaft around the wiper seal,” says Bilstein’s Rex Merritt. “If it’s mounted with the body up, you’re going to see residue around the monoball on the shaft and if it’s mounted body down you’re going to have oil around the wiper.”

There are clues for subtle leaks too. “If there’s dirt stuck to your shaft, the shock is probably leaking,” says Workman. “Something has attracted the dirt to that shaft. The only catch is when guys are sloppy with the WD-40 since it can run right down the shaft and collect dirt.”

Oil can also escape an undamaged seal. “I see many shocks where the shafts have a pit in them because they’d been hit by a rock,” says Workman. “That causes a leak because the pit acts like a scooper. The shaft goes into the shock, fluid sits in that dent, and oil comes out every time the shaft comes back out.”

Guys protected their shafts by slicing an old piece of radiator hose and wrapping it around a shock so it extended down to protect the shaft. However, they’re heavy (including the clamp) and can be awkward and hard to fit in some applications, especially coil-over ones.

Shock bags are considered an effective alternative for coil-overs, but it wasn’t always that way. “We used to discourage their use because heat is the shock’s enemy and shock bags trap heat,” says Workman. “But, if you’re pitting shafts, get some bags and cover them up. Besides, monotube shocks run cooler compared to older twin-tubes, so bags are less of a problem.”

It is also common for the sharp edge of a shaft-ding to damage the seal. “An important part of your weekly inspection is to look for dents, dings, and shaft nicks that will eventually take a seal out,” says Mike Farr from Genesis shocks.

Losing oil can cause a variety of problems including loss of appropriate nitrogen pressure since decreasing the amount of oil in the shock increases the area for nitrogen and that reduces pressure.

Pressure can also be lost because the nitrogen escapes. “Anybody with a Schrader valve in their shock needs to keep an eye on the gas pressure,” says Merritt. “Check pressure with the shaft fully extended. If the shaft is in the shock body you’ve compressed the volume of nitrogen so it’s going to read more pressure. You can do it compressed as long as you have a reference to the extended pressure, but it’s not going to be what everyone talks about. Also make sure the shock is at the same ride height if you do it compressed. Consistency is everything.”

Pressures should checked done frequently. “Gas pressure should be checked weekly or before every race if you’re running 50- and 100-lap features,” says Farr.

Also give the shock a good visual inspection. “The shock may not be leaking but something may have flown up and dented the shaft or body. Visual checks are important,” says Reedy.

Dented bodies are especially on a monotube shock. “Make sure the shafts are straight and that there are no nicks in the body of a monotube because even the slightest nick can affect where the piston rides,” says Hacken. “Stroke the shock if you don’t have a dyno. It can have a little bind when the piston passes it, but it’s probably not going to affect it too much if you can’t feel it.”

Bilstein’s Merritt says, “Push the shaft of a monotube shock all the way in because if it goes all the way in and comes out at a consistent rate, the shock is more than likely okay.”

The most commonly overlooked maintenance item on shocks is the rod end. In a worst-case, according to Farr happens too often, the rod ends are about to fall off. “Make sure the eye-rings that thread on the shaft are tight,” he says. “I’ve seen a lot of them loose to the point of about-to-fall-off. Some shocks, especially on dirt, require a shock extension and when it’s installed, they remove the [threadlocker] compound that was installed at the factory. Some guys don’t check it until the see they’re loose.

“You should take the shocks all they way off each week,” says Farr. “But if you’re not going to do that, then at least be sure the eye-ring is tight by sticking a wrench on there. If it’s together as a coil-over and it has a jam nut and you can get a wrench on it, turn the eye ring with a ¾”-wrench (it will fit most eye rings). If it doesn’t have a jam nut like our new one, you have to tighten the shaft in a vise’s set of soft jaws to check the rod end.”

Another reason to remove the shocks is rod end maintenance. Merritt says, “I race my car with the shocks hooked up, so I scale it with the shocks hooked up, but I like to unhook the shocks while it’s still on the scales and bounce it to make sure all the [numbers] come back. When I do that, I take the spherical ball in the rod end and make sure it moves all around using my thumb and forefinger. It should have a little drag, but move consistently through its mount. If a monoball binds up in a shock, you’ll have a suspension bind.”

And apparently lots of guys do. “These shocks come in and the rod ends are frozen up solid,” says Workman. “Spray ‘em once in a while. Take ‘em off the car and work them with a screwdriver. They should feel like a regular rod end.

“We don’t use Teflon bearings anymore because they swell when lubricated. And our experience was the races would pop out under heavy loading.”

There are varying levels of concern regarding lubrication of a Teflon-lined bearing. “Lubricant on Teflon-lined rod ends doesn’t hurt, it just doesn’t need it,” says QA1’s Hacken whose company also makes rod ends. “If you take the ball and turn it sideways so you can see into the race of the bearing, it’s either going to be bare metal or look like a maroonish, brown-colored fabric. If you see that weave, that’s the Teflon fabric.

“We use a race that’s an injection-molded plastic that’s actually Kevlar and some other materials. The outside of the bearing is plastic, it has no metal in it at all. That’s a variation of the Teflon. We’ve been doing it for a year and a half. It’s self-lubricating and dampens the shock so there’s no metal on metal. If you’re in a high-load situation, it will compress that fabric so it doesn’t have much of a memory so it tends to pound out quicker where with the plastic, it can compress and spring back to normal. It can swell, but not that much.”

Maintain your shocks, but don’t let maintenance such as rod end lubrication cause problems. “Wipe the excess off so you are not collecting dirt because that tends to get into the bearing and act like sandpaper in there. It can chew them apart.”


P.O. Box 548
Boonville, IN 47601

Bilstein Motorsports
195-5 Raceway Drive
Mooresville, NC 28115


14102 Stowe Drive
Poway, CA. 92064

Genesis Shocks
5020 Old Ellis Pointe
Suite 200
Roswell, Ga. 30076

50 Franklin Street
Reading, PA 19603

21730 Hanover Avenue
Lakeville, MN 55044

Story by Karl Fredrickson