Removing the Front Hubs on a Marmon Herrington MT-14H Axle
Upgrading Wheel Studs for Aluminum Wheels on the PUG Truck
As part of the ongoing PUG Truck (Grapple Saw Truck) build, we recently tackled an important—but often overlooked—detail: wheel stud length. Thanks to the generous donation of Northstar aluminum wheels from Buy Truck Wheels.com, we needed to upgrade the front wheel studs on our Marmon Herrington MT-14H front steer axle to ensure proper thread engagement and long-term safety.
Aluminum wheels typically require longer studs than steel wheels, and after verifying our setup, it became clear that a full hub removal was required to do the job correctly. Below is a step-by-step breakdown of the process we followed.
Why the Hub Needed to Come Off
Before tearing anything apart, we confirmed a few critical things:
- The original wheel studs were too short to safely run aluminum wheels.
- The studs could not be pressed out with the hub installed on the truck due to clearance limitations.
- The only proper solution was to remove the entire hub assembly and service it on the bench.
We sourced the correct replacement studs directly from Marmon Herrington:
- Marmon Herrington PN: MT931631 (longer wheel studs designed for aluminum wheels)
Step-by-Step: Removing and Rebuilding the Front Hub
1. Verifying Stud Length
We test-fit the aluminum wheel and confirmed that the factory studs did not provide sufficient thread engagement. This step is critical—running aluminum wheels with undersized studs is unsafe and can lead to wheel failure.
2. Confirming Hub Removal Was Necessary
With limited clearance behind the hub flange, there was no way to safely press out the studs on the truck. Hub removal was unavoidable.
3. Designing a Custom Spindle Nut Socket
The Marmon Herrington spindle nut required a special socket that we didn’t have on hand.
- We designed a custom spindle nut socket
- 3D printed a prototype to verify fitment
- Once confirmed, we fabricated a steel version for final use
This step saved time and ensured we could properly torque and reassemble the hub later.
4. Disassembling the Hub Assembly
Following the Marmon Herrington MT-14H service manual, we carefully disassembled the hub, removed the bearings, and pulled the hub assembly from the spindle.
5. Removing the Old Studs
With the hub on the bench, we pressed out the original studs without issue.
6. Cleaning and Refinishing the Hub
While the hub was apart, we took the opportunity to do some preventative maintenance:
- Cleaned all mating surfaces
- Removed surface rust
- Repainted the hub with POR-15, a corrosion-resistant coating ideal for heavy-duty applications
7. Installing the New Studs & Test Fitment
The new Marmon Herrington studs were pressed into place, and we test-fit the Northstar aluminum wheel to confirm proper engagement and seating.
8. Reinstalling the Hub & Setting Bearing Preload
The hub was reinstalled on the axle, and we carefully checked bearing end play to ensure proper preload per the service manual specifications.
This step is critical for bearing life and safe operation.
9. Final Assembly & Oil Fill
With everything torqued and verified:
- Hub was fully reinstalled
- Oil was refilled
- Wheels were mounted
And just like that, the truck was ready to roll with its new aluminum wheels.
Stronger, Safer, and Built to Last
This project may seem small compared to installing a crane or designing a subframe, but details like proper wheel studs matter—especially on a heavy disaster response vehicle that will operate in extreme conditions.
Thanks again to Buy Truck Wheels.com for supporting the PUG Truck build. Every upgrade like this brings us one step closer to putting this truck into service where it matters most: helping families recover after disasters.
Stay tuned for more updates as the build continues.
IMPRESSIVE!
GOO JOB WARREN AND TEAM!!!