Rear Winch Install

GMC Rear Winch install

How-to custom fit a Mile Marker SEC9.5 electric winch under the rear of a 2008 GMC 3500HD Dually with a Fab Fours rear bumper

by Bruce W. Smith

Rear winches are rare in the everyday world of pickup owners. They aren’t needed.

But in the world of heavy construction and utility services trucks, winches mounted at the rear are a welcome accessory that serves multiple purposes.  

Rear-mounted winches are great tools for pulling vehicles and equipment on to a trailer, they also allow for the winching vehicle to do so without having the front being put in an awkward, and sometimes dangerous position.

A rear-mounted winch also allows for the recovery of another vehicle without the winching vehicle turn around and face into traffic.

That’s why we turned to Mile Marker’s products and Truck Supply & Outfitter’s expertise to outfit our 2008 GMC Sierra 3500HD Dually with a hidden rear-mounted winch setup.  

MILE MARKER SEC9.5 

Mile Marker SEC9.5 winch and universal channel mount make rear winch install easy.

The winch we chose is the little brother to the 15,000-pound-capcity Mile Marker winch we have mounted in the front bumper, the  Mile Marker SEC9.5.

The SEC9.5 is a strong, reliable planetary-design unit with a maximum pull of 9,500 pounds. It is powered by a 4.8hp series-wound motor that drives a planetary gear setup with a 212:1 ratio. 

It’s compact and light in weight, ideal for rear mounting. 

We also used the Mile Marker universal channel mount ($110) for the winch to save time on the fabrication process. 

BASIC WINCH INSTALLATION

Installing the winch in the Fab Fours rear bumper is a straight-forward process:

Remove the spare tire, fabricate a mounting plate so the winch can be located behind the spare tire cross member and above the receiver hitch, mount the winch, cut a hole in the rear bumper for the winch cable and fairlead, and install the winch control box with new cables.

Utilizing a Mile Marker wireless remote control will make the last part of the installation go smoother–and be valuable in the field.

The entire winch installation should take about four hours in a well-equipped shop by an experienced installer.

Parker re-installs mounting bolts to sandwich the new winch mounting plates between the hitch bracket and the GMC’s frame rails.

Utilizing a Mile Marker wireless remote control will make the last part of the installation go smoother–and be valuable in the field.

STEP-BY-STEP

Here’re my shop notes taken when Truck Supply & Outfitter’s Daniel Parker handled the rear winch upgrade for Project Big Red:

1. Remove the spare tire, loosen (don’t remove) two bolts holding receiver to the bumper step, and remove the two bolts on each side of the receiver frame brackets so the hitch can be angled downward from frame rails.
2. Measure, mark and fabricate two 9”x9” ¼-inch steel plates to extend the universal winch mount so it bolts to the frame rails utilizing the hitch mounting holes. (Distance between the outside of the GMC frame rails is about 42 ¼”.)
3.  Cut a 2”x2” notch in “forward outer “corner of each plate to clear the spring hanger brackets.
4.  Remove winch control box and cables from the winch (it will not fit with control box attached because of OEM wiring harnesses in that area.)
5.  Center and bolt winch plate/winch to the new mounting plates.  Use floor jack to lift winch assembly into place.
6. Sandwich one side of mounting plates between factory receiver hitch brackets and frame. Run hitch-mounting bolts through the plates and hitch frame brackets. Attach bolts finger-tight.
7.  Center winch assembly between the frame rails.
8.  Drill a hole in each plate so a third bolt can be used to attach each plate to the rear of the spare tire crossmember.
9.  Now tighten all bolts.
10.  The winch control box needs to be mounted in a protected location near or on the driver’s-side frame rail or inside the bumper. This will require making longer control box cables.
11.  The receptacle for the hand-held control cable will need to be moved/re-mounted somewhere convenient, like on the side of the license plate inset on the rear bumper.
12.  Or, you can do as we did, and install Mile Marker’s wireless remote control setup before mounting the winch control box under the truck and not worry about the where to place the control cable receptacle.
13. The last step is to cut out the opening in the rear bumper behind the license plate to accommodate the roller-type fairlead. Treat fresh cut edges with rust-preventive paint/sealer.
14.  Mount fairlead. Mount flip-up license plate holder. Run winch cable through fairlead and install hook.
15.  Double-check that all bolts and wires are tight. Check winch for proper operation. Re-mount license plate over fairlead. Job done