What’s the Difference?

In the world of rear axles for light-duty 4WDs, full floating and semi floating axles reign supreme. These two types of axles play a crucial role in transmitting power from the differential to the wheels, but they do so in distinct ways.

Semi-Floating Axles

Semi-floating axles are the simpler and more common type. In this design, the axle shaft carries both the weight of the vehicle and transmits torque to the wheel. It rests on a bearing at the end of the axle housing.

Full-Floating Axles

Full-floating axles, on the other hand, separate these functions. The axle shaft transmits torque only, while a separate spindle and wheel hub assembly, supported by tapered roller bearings, carry the vehicle’s weight. This design offers several advantages.

Advantages of Full-Floating Axles

• Higher Load Capacity: Full-floating axles can withstand greater weight and torque, making them suitable for heavier vehicles and off-roading.
• Stronger Axle Shafts: Since they don’t bear the weight of the vehicle, full-floating axle shafts are stronger and less prone to damage.
• Easy Removal: Broken axle shafts can be replaced without affecting the wheel’s functionality, allowing you to keep moving in an emergency.
• Unlockable Hubs: Full-floating axles often have unlockable rear hubs, making it possible to disconnect the wheels for towing or flatbed transport, reducing wear and tear on the drivetrain.

Types of Differential Assemblies

Cast Center Housing

In cast center housing differentials, the differential carrier is held by bearing caps within the cast axle housing. This design is common in semi-floating axles.

Third Member (Drop-out Center Section)

Third member differentials feature a removable housing that bolts to the axle housing. The differential carrier is mounted within this housing, making gear setup and swapping more convenient.

High Pinion vs. Low Pinion Differentials

Low Pinion

In low pinion differentials, the pinion gear engages with the ring gear below the centerline of the axle housing. This design is common in semi-floating axles and offers better ground clearance.

High Pinion

High pinion differentials have the pinion gear engaging with the ring gear above the centerline. This design is often used in full-floating axles and offers better protection for the pinion gear.

C-Clip vs. Pressed Bearing Axle Shafts

C-Clip

C-clip axle shafts are secured within the differential assembly by a C-clip. This design requires access to the differential area for disassembly.

Pressed Bearing

Pressed bearing axle shafts are retained by a bearing pressed onto the shaft at the wheel end. This design is easier to disassemble but requires brake line work and bleeding.

FAQs on Full Floating and Semi Floating Axles

What is the difference between a full floating axle and a semi floating axle?

Answer:
* Semi-floating axle: The axle shaft carries both the vehicle weight and transmits torque to the wheel.
* Full-floating axle: The axle shaft only transmits torque, while a separate spindle and wheel hub assembly carries the vehicle’s weight.

What are the advantages of full floating axles?

Answer:
* Higher load capacity
* Stronger axle shafts for off-road use
* Ability to remove broken axle shafts without losing functionality
* Possible to unlock rear hubs for towing or flatbed transport

What are the different types of differential assemblies?

Answer:
* Cast Center Housing: The differential carrier is held by bearing caps in the cast axle housing.
* Third Member (Drop-out Center Section): The differential carrier is mounted in a removable housing that bolts to the axle housing.

What are the advantages of third member differential assemblies?

Answer:
* Convenient gear setup outside the vehicle
* Easy trail swapping if necessary

What is the difference between high pinion and low pinion differentials?

Answer:
* Low Pinion: Pinion gear mates with the ring gear below the centerline of the axle housing.
* High Pinion: Pinion gear mates with the ring gear above the centerline.

What is the difference between C-Clip and pressed bearing axle shafts?

Answer:
* C-Clip: Retained by a C-clip inside the differential assembly.
* Pressed Bearing: Retained by a bearing pressed onto the axle shaft at the wheel end.