HPG Explains: Geared Hub Spindle Nuts

Posted by David Oberer on 10/1/2021 to HPG Explains

AM General Geared Hub Spindle Nuts

AUTHOR NOTE: The comments, instructions and recommendations posted here are meant to enhance the AM General Service Manual with "real life experience" (not to replace it)...As always you should reference that for proper torque specs and step by step repair guides. If you aren't comfortable doing these repairs or feel this HPG Explain article doesn't fit your specific needs then DON'T DO IT and contact somebody that you feel is qualified.

Overview of the Spindle Nut

The spindle nut is located at the geared hub (1 per wheel) inside the steering gear cover, where the braided line screws into the back of the geared hub. To access the spindle nut you remove the four bolts that hold on the steering arm cover to the geared hub. This is a VERY IMPORTANT nut that holds the wheel onto the geared hub. If the spindle nut is not properly installed the spindle WILL LOOSEN UP and the spindle WILL FALL OUT while driving down the road (yes very scary stuff) so take precaution when messing around with this nut and follow the service manual procedures for properly pre-loading and applying the correct torque to the spindle nut during installation.

The three types of spindle nuts

Type 1: Civilian PN# 6001735

This is the only style nut used on the Hummer H1 (1992-2006). It requires the Kent Moore Tool PN# J-42545. There is a small socket-head capscrew that holds the nut in place by pinching the two halves of the nut together after it is tightened onto the spindle threads. The screw it installed in the same direction as the threads of the spindle. The screw is PN# 6001757.
(View/Purchase on HPG Website)

Type 2: Military 8 Slot PN# 01-382-5031 *superseded from original 4 slot version

This is the primary version used on the Humvee's until the REV B geared hub was created for the ECV Humvee. The original 4 slotted nut version was changed to an 8 slotted nut to allow for more washer "ears" to bend over the nut during installation. This nut uses Kent Moore Tool J-33144. The washer is installed first, then the nut is installed. Once the final torque sequence is applied the washer "ears" are bent over into the open slots in the nut thereby not allowing the nut to loosen up.

GENUINE AMG FORGERY IDENTIFICATION TIP Watch for the black paint marks on the washer to identify the correct length (ALL Genuine AMG washers have this) Fake washers have too short of washer ears and the nuts back off. Washers will also be very shiny metallic, almost mirrorlike in finish. The Genuine AM General ones will have black paint marks and be a dull satin color.

(View/Purchase on HPG Website)

Type 3: Military REV B Spindle Nut PN# 01-595-4956

This version was released with the upgraded ECV Humvee (Expanded Capacity Vehicle) and the REV B geared hub. The REV B hub introduced some of the changes seen in the H1 Alpha hubs (helical gears, 2 piece input and output seals) but it also introduced larger steering arm covers and added this newer style spindle nut. The advantage of this nut, in my opinion, is that you don't need a special Kent Moore tool to install it...just a big old deep well socket. You follow the normal torque sequence but at the end you install the 3 setscrews INTO the face of the nut, thereby pinching the threads against each other due to the slot cut into the side of the nut. The advantage of this design is you don't have a washer to keep replacing like in the Type 2 version because the nut is re-usable.
(View/Purchase on HPG Website)

Special Tools

The Kent Moore tools are no longer available from AM General but some owners have luck using Ebay, Google and other places online to locate them. We used to have loaner tools for customers but they turned into "permanents" and never were returned.

Will it fit on my H1?

The Type 2 (Military 8 slot) will 100% fit your Hummer H1 without any modifications because it uses the same steering arm covers. When you purchase these spindle nuts from HPG we include the proper military tech manual pages for reference during installation.

The Type 3 REV B spindle nut fits on the spindle but there is a clearance issue with the stock Hummer H1 CTIS enabled steering arm covers (they rub due to the larger size of the hex nut) so modification of the steering arms is required. The ECV steering arm covers are available but they will not work properly due to the changes in geometry of the steering/suspension of the front end (bigger steering arm covers). If you "really" wanted to use this type of spindle nut you could machine out the inside of the existing Hummer H1 steering arm cover slightly to allow for more room as the nut turns inside.

So what does HPG use?

I personally use the Type 2 military 8 slot version on all my geared hubs. It is actually easier to install than the civilian style nut. In my opinion at least 50% of the phone calls we get everytime somebody touches a spindle they have issues with the civilian nut due to the torque and testing procedure (it always fails). The first time I rebuilt my geared hubs and saw the design of the civilian spindle nut I threw them away. I prefer the captive washer type of the military spindle nut...plus over 200,000 Humvee's used this design (close to 1M geared hubs).

Geared Hub Spindle Nuts