Frequently Asked Questions About Freightliner FLC112 Air Springs & Level Valves

What are the signs that my FLC112 air springs need replacement?

Common indicators include uneven ride height between sides of the truck, frequent air compressor cycling, visible air leaks around the spring bellows, excessive bouncing or harsh ride quality, and the truck sitting lower than normal when parked. If you notice any sagging after sitting overnight or hear hissing sounds near the air springs, it's time for an inspection. Most air springs on FLC112 models last 100,000-150,000 miles under normal conditions, but harsh environments and heavy loads can reduce lifespan.

Will these air springs fit my specific year FLC112, and are there different part numbers I should know about?

FLC112 models from 1986-1999 use primarily two air spring configurations depending on your suspension type. For Hendrickson HAS suspensions, you'll need part number W01-358-9910 for most applications. Neway AR suspensions typically use W01-358-9622. Models with air-ride cabs require additional cab air springs (part number 1R11-221). Always verify your suspension type by checking the tag on your axle or consulting your VIN-specific build sheet, as some FLC112s came with specialty suspensions that require different components.

Can I replace just one air spring, or should I always replace them in pairs?

While it's possible to replace a single failed air spring, we strongly recommend replacing them in pairs (both sides of the same axle). Air springs wear at similar rates, and mixing new with old can cause uneven ride height and premature wear on the new spring. If one spring has failed, the opposite side has likely endured the same mileage and conditions. Replacing in pairs ensures balanced performance and prevents return trips for the second spring failure, which typically occurs within 3-6 months of the first.

What's involved in installing level valves, and can I adjust ride height myself?

Level valve installation requires proper linkage adjustment and careful attention to mounting angles. The valve must be mounted perfectly level when the truck is at proper ride height. Adjustment involves setting the linkage length so the valve maintains correct air pressure at your desired height - typically 11.5-12 inches from frame to ground on most FLC112s. While adjustment is possible with basic tools, improper setup can cause constant air cycling, premature compressor wear, or unsafe ride heights. Initial setup should reference your truck's specific ride height specifications found in the door jamb sticker.

Why do my new air springs keep losing air, and what else should I check?

If new air springs are losing air, the problem often lies elsewhere in the system. Check all air line connections for leaks using soapy water - even small leaks will deflate springs overnight. Inspect the height control valve for internal leakage or sticking. Examine air lines for cracks, especially near heat sources like the exhaust. Don't forget to check the quick-release valves and dump valves if equipped. On FLC112s, corroded fittings at the spring top plates are common culprits. Always use thread sealant rated for air systems and ensure fittings are properly tightened to specification.