If you drive a heavy-duty truck, trailer, or bus for work, those big vehicles couldn’t get around without air brakes. The air brake system uses compressed air to apply the friction brakes when you press down on the brake pedal. A key component is the air brake chamber, a cylindrical gadget that converts the air pressure into mechanical force to engage the brake pads or shoes.
After years of use, the diaphragm inside the chamber can weaken or develop tiny leaks. That leads to problems like a drop in braking power, uneven braking, or the brakes dragging. To keep your rig in safe shape, you’ll need to swap out those aging air brake chambers for new ones. Don’t worry, you can tackle this repair job yourself in your own garage, if you’re handy with tools.
Let’s run through everything involved so you can replace those worn-out air brake chambers like a pro.
Here’s a step-by-step guide:
- Chock tires and release air pressure from the brake system. Vent pressure from air tanks using the drain valve.
- Disconnect the air hoses and brake linkage rods from the chamber to be replaced. Loosen fittings with the proper wrenches.
- Remove mounting bolts securing the chamber using hand tools like sockets and wrenches. Pry it loose if stuck.
- Install the new replacement chamber, inserting fresh mounting bolts hand tight. Apply threadlocker compound.
- Use a torque wrench to tighten the mounting bolts in a crisscross pattern to specification.
- Reconnect air hoses and brake hardware to the back of the new chamber. Use thread tape or sealant on fittings.
- Refill the air tanks and test brake operation before driving. Watch for leaks.
What Exactly is an Air Brake Chamber?
First, a quick 101 in what an air brake chamber is and how it works its magic.
The chamber itself is a metal cylinder capped on one end. A flexible rubber diaphragm stretches across the inside. The diaphragm has a push rod connected to its center that leads out the other end of the cylinder. That push rod attaches to the brake mechanism on your axle or wheel hub assembly.
When you press the brake pedal, the air brake valves route compressed air into the chamber. The increased air pressure expands the rubber diaphragm outwards. That movement pushes the push rod out further from the chamber. When the push rod extends, it activates the brake mechanism to stop the wheels from turning. Step on the brake pedal harder, and more air flows in to apply more force.
Why Replace Your Air Brake Chambers?
The rubber diaphragm inside those chambers doesn’t last forever. After years of pushing and flexing, it fatigues and weakens. Tiny cracks or pinholes can develop, allowing small air leaks. That cuts down on your braking power. A stretched out or warped diaphragm can also cause uneven wear or pulling when you apply the brakes. Either way, worn diaphragms mean it’s time to put in new chambers.
What You’ll Need for This Job
Replacing air brake chambers isn’t difficult, but having the proper tools on hand makes the work easier:
● Socket set with both standard and metric sizes
● Adjustable wrench set for tight spots
● Pry bar for extra leverage
● Torque wrench for tightening bolts accurately
● Tube of threadlocker compound
● Clean rags and brake cleaner spray
Of course, you’ll also need the new replacement brake chamber for your specific vehicle. Check the manufacturer’s guidelines to match it correctly. Don’t forget new mounting bolts sized to the holes on your axle assembly.
Safety Tips Before You Start
Any time you work on a vehicle’s brake system, safety should be your priority. Follow these rules whenever servicing your air brakes:
● Block the wheels so the vehicle can’t roll either way. For an extra margin of safety, engage the parking brake too.
● Bleed all the reserve air pressure from the brake system. Open the drain valve to vent pressure from the air tanks.
● Use jack stands rated for the weight of a commercial vehicle. Make sure your truck or trailer is solidly supported.
● Wear OSHA-approved safety glasses to shield your eyes from dirt and debris. Good leather work gloves also help avoid skin cuts.
Once you’re prepped with all your tools and materials, you’re ready to tackle removing and replacing that worn-out air brake chamber:
Step 1 – Familiarize Yourself
Study your vehicle’s brake system layout so you understand which chambers operate which axles. Diagram how the air hoses route from control valves to each chamber.
Step 2 – Inspect for Problems
Before tearing anything apart, check your brake mechanisms for issues like stuck slack adjusters, worn camshafts, or contaminated brake shoes. Fix any underlying problems before replacing parts.
Step 3 – Bleed the Air System
Use the manual petcock valves to vent air pressure from the system. Leave valves open so air won’t build up pressure while you work.
Step 4 – Loosen Fittings
Use appropriate wrenches to loosen the air hose fittings from the worn chamber you’ll remove. Also loosen any brake mechanism rods or air lines attached to it.
Step 5 – Remove Mounting Bolts
Use your socket set and wrenches to unbolt the obsolete air chamber from its mounting bracket surface. Applying penetrating oil ahead of time can help loosen stuck fasteners.
Step 6 – Detach Old Chamber
With no hoses or bolts holding it in place, the depleted chamber should detach easily. Use a pry bar if needed to work it loose.
Step 7 – Install New Chamber
Line up the replacement chamber’s holes with the bolt holes on the axle bracket. Insert mounting bolts with a dab of threadlocker compound on the threads. Hand tighten them in a crisscross sequence.
Step 8 – Snug Bolts
Once all new mounting bolts are started, take a final pass with your torque wrench. Tighten bolts to the manufacturer’s specifications in the same crisscross pattern.
Step 9 – Reconnect Fittings
Reattach any detached air hoses, brake rods or electrical connectors to the back of the new chamber. Use fresh thread tape or sealant on pipe threads.
Step 10 – Refill and Test
Close manual vent valves so air pressure can recharge the system. Test brake actuation on each axle to confirm proper operation. Give the new chambers a road test before extended driving.
Some Common Air Brake Chamber Problems
While you have those brake mechanisms exposed during your repair work, it’s smart to check for other potential trouble areas:
● Corroded electrical connectors can cause solenoid valves to malfunction. Clean contact pins and apply dielectric grease.
● Air hoses can crack, leak, and bubble under the stress of heat and vibration. Replace any suspect hoses.
● Inspect brake shoes for oil contamination or excessive wear. Sand or replace shoes outside factory specs.
● A bent or frozen slack adjuster will prevent full brake shoe contact. Rebuild or replace slack adjusters as needed.
How Much Does Replacing Air Brake Chambers Cost?
If you can handle some basic wrenching, replacing your own air brake chambers will save you money over paying for shop labor:
|Type of Vehicle
As you can see from the FAQ below, with some mechanical know-how and the right tools, replacing your truck’s air brake chambers is a maintenance project you can take on yourself. Just work methodically, follow manufacturer’s torque specs, and remember – safety first!
Frequently Asked Questions
How often should you replace air brake chambers?
There’s no set replacement interval. Have a mechanic inspect your chambers during annual DOT inspections or any time you notice a performance drop. Catching problems early saves money.
Can I replace air chambers myself?
With some mechanical experience and the service manual for your specific truck, you can replace simple spring brake chambers in your garage. Consider letting a shop handle tandem chambers or trailer ABS brakes.
What happens if I crack an air brake hose?
Cracked or cut hoses during a brake service allow air leaks that prevent building pressure. Replace any damaged hoses before attempting to recharge the system. Use thread sealant and ensure tight connections.
Should I replace all chambers at once?
Not necessary. Typically, the chambers wear at similar rates. Replace individual units as their diaphragms fail. It’s smart to replace all chambers on one axle to prevent braking imbalance.