Semi Truck Inter-axle Driveshafts

Semi-Truck Inter-axle Driveshafts: Everything You Need to Know

A semi-truck inter-axle driveshaft is a short driveshaft that connects the forward and rear axles in a tandem axle truck. It transfers torque between axles, allowing power to reach all drive wheels. Built for heavy torque and constant load, inter-axle driveshafts are critical for performance, uptime, and safety in Class 8 trucks.

What Is an Inter-axle Driveshaft?

An inter-axle driveshaft (sometimes called a jackshaft or center shaft) is the component that links the two drive axles in a tandem axle setup.

• Location: Between the forward and rear axle differentials.
• Length: Shorter than the main transmission-to-axle driveshaft.
• Strength: Designed for extreme torque, especially in heavy haul, over-the-road, and vocational trucks.
• Common Series: Dana/Spicer 1710, 1810, SPL170, SPL250, with Neapco and Meritor equivalents also widely used.

Without the inter-axle shaft, the second axle in a tandem configuration couldn’t receive power, making it one of the most important pieces of the drivetrain.

Why Are Inter-axle Driveshafts Important?

• Torque Distribution: Ensures equal power delivery to both drive axles.
• Durability: Handles shock loads from heavy cargo, uneven terrain, and sudden torque spikes.
• Smooth Operation: Absorbs axle movement to reduce stress on differentials and bearings.
• Uptime & Safety: A failure can sideline a truck, create costly downtime, or cause dangerous driveline separation.

For fleets, keeping inter-axle driveshafts in top shape means fewer breakdowns, lower maintenance costs, and longer vehicle lifespan.

Common Questions

How long does an inter-axle driveshaft last?

With regular greasing and inspection, many inter-axle shafts last 500,000+ miles. In severe duty cycles (mining, construction, heavy off-road), lifespan may be closer to 250,000–300,000 miles.

What are signs of inter-axle driveshaft failure?

• Vibration at highway speeds
• Clunking or banging during acceleration or gear shifts
• Excessive U-joint play or visible movement
• Grease leakage around caps or slip yokes
• Dented or twisted tubing
• Spline wear or binding in the slip assembly

Ignoring these signs risks catastrophic driveline separation, a major safety hazard.

What U-joint series are most common?

• 1710 series (standard for many Class 8 trucks)
• 1810 series (heavier torque loads)
• SPL170/SPL250
• Meritor RPL series (common on some OEM builds)

Can an inter-axle driveshaft be rebuilt?

Yes. Most are serviceable with:

• New tubing (cut/weld/balance)
• Replacement U-joints
• Slip yoke or flange yoke replacement
• High-speed balancing to OE spec

At Action Machine, we rebuild and balance inter-axle driveshafts to tighter tolerances than OEM for maximum uptime.

How much does replacement cost?

• Rebuild/Repair: $400–$700 depending on damage.
• New Inter-axle Driveshaft: $800–$1,400 depending on series, length, and components.
• OEM dealer prices may be higher, but aftermarket builders like Action Machine can often provide faster turnaround and stronger balancing tolerances.

Do all semi trucks use inter-axle driveshafts?

No. Single drive axle trucks don’t use inter-axle shafts. They’re only needed in tandem axle configurations (the vast majority of modern Class 8 tractors).

Maintenance Tips for Longer Life:

1. Grease on Schedule: U-joints and slip yokes should be greased per manufacturer recommendations, often every 15,000 miles or oil change interval.
2. Check for Play: Any movement at the U-joints beyond spec means it’s time for replacement.
3. Balance After Repairs: Any tube or yoke replacement requires high-speed balancing.
4. Inspect After Impacts: A rock strike, road debris, or bottoming out can dent tubing, weakening the shaft.
5. Record Service: Tracking mileage and maintenance intervals helps fleets catch wear before failure.

Action Machine’s “Fast Shaft” Program

At Action Machine, we know downtime kills profitability. That’s why we launched the Fast Shaft program, quick lead times on the most common 1710 series inter-axle driveshafts for Class 8 trucks.

• 100% USA-sourced tubing and welds
• Dana Spicer and Neapco components in stock
• Precision high-speed balancing to under 0.002" runout
• Custom builds available for Peterbilt, Kenworth, Freightliner, International, and more

Fast-Shaft
Inter-Axle Driveshafts

FAQs 

Q: Can you upgrade an inter-axle driveshaft to aluminum or carbon fiber?
A: Not recommended, the shaft is short, torque loads are extreme, and steel is the industry standard for durability.

Q: What happens if an inter-axle driveshaft fails on the road?
A: Loss of power to the rear axle, potential driveline separation, and severe safety risks. Always stop and inspect at the first sign of failure.

Q: Do OEMs make their own driveshafts?
A: Most OEMs (Peterbilt, Kenworth, International, Freightliner) source from Dana/Spicer, Neapco, or Meritor. Dealers typically resell these components under proprietary part numbers.

The inter-axle driveshaft may be short, but it’s one of the hardest-working components on a semi-truck. From distributing torque between tandem axles to withstanding constant heavy loads, its role is critical to uptime and safety.

For fleets, knowing the signs of failure, maintenance schedules, and replacement options can prevent breakdowns and save thousands in downtime. And when it comes time to rebuild or replace, Action Machine’s Fast Shaft program delivers precision-balanced inter-axle driveshafts faster than OEM channels, keeping your trucks on the road where they belong.