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Old 10-18-2016, 07:08 PM   #1
seidcon's Avatar
Join Date: Nov 2015
Location: So California
Posts: 8
3" lift for FR 5th wheel - Torflex axle

Forest River Rockwood 8280WS 5th wheel

Dexter Torflex Axle lift kit

After upgrading my tow vehicle to a new 2500 HD GMC 4 X 4, the 5th wheel towed nose high. It also reduced the clear space between the top of the tailgate and the underside of the 5th wheel deck. This made the decision to add the 3” lift easy.

After reviewing other lift kit installations, and being mechanically inclined, I elected to fabricate my own kit and do the installation in my driveway.

Of the lift kits I found on line and in the forum, one kit consisted of rectangle tube and one kit used angle iron bracket. The angle iron installation appeared to put the weight of the trailer on the bolts, causing the bolts to be in constant shear and did not provide full bearing of the trailer weight on the axle saddles. This looked a little flimsy and light weight. I opted to use the rectangle tube design.

Because we plan on traveling to Alaska via the Alcan Highway, I wanted the strongest adapter possible. My kit uses Ό” rectangle steel tube. 3/16” tube would be more than strong enough but I didn’t want the lift kit to be the weak link. It’s the same reasoning why I went with load range E tires.

I was able to order cut tube on line and the layout and drilling was done on the work bench using a small drill press. After de-burring, cleaning and painting, the brackets were ready for installation.

I did the installation solo, so I elected to do one wheel at a time. Using a bottle jack with a built-in jack stand, I started on the rear axle, and then moved to the front axle. I repeated the process on the other side. When completed, I used touch up spray paint to cover any bare metal and rust spots. Using this method I was able to leave all of the tires mounted and worked from the inside. I was on a flat level surface and lying down under the trailer was not a problem, there was lots of room to maneuver around.

Both the fabrication and the installation required only the basic tools and ability. There is no welding involved. To save some time and energy, a fabrication shop could cut and drill the holes for you.

1. Make a vertical mark on the axle saddle and frame so the alignment of the axle can be maintained during re-installation. See step 8.
2. Remove the two (2) 5/8-18 bolts holding the axle saddle to the frame member flange. This requires a 15/16” box end wrench and a 15/16” socket with an impact wrench or ½” drive ratchet wrench.
3. Place the jack under the box frame of the trailer.
4. Jack up the trailer to a point where there is approximately 3-1/4” clearance between the box frame and the axle saddle. Be sure to check the brake wiring to prevent binding and/or damage. (Additional slack may be pulled from the underside of the trailer).
5. Slide in the rectangle tube with the bolt holes facing down and in.
6. Using the 2 bolts removed in step 2, bolt the rectangle tube to the axle saddle aligning the inside face of the saddle and the inside face of the adapter. (Note: Do not use the washer on the inside of the tube. Clearance is needed to install the side bolts).
7. Install the new 5/8-18 hex bolts (Nut will be on the inside of the tube) into the side flange and the adapter and tighten only enough to allow some movement of the axle saddle. The box frame flange is slotted to allow some movement up and down.
8. Check the vertical alignment of the mark from step 1 to keep the axle alignment in the same position. Lower the jack to put the full weight of the trailer on the axle.
9. Finish tightening the side bolts and torque to 75 ft. lbs. (In lieu of nylon lock nuts, standard Grade 8 hex nuts and thread lock compound (Locktite) may be used).
10. Torque the bottom bolts to 75 ft. lbs.
11. Spray paint any bare metal and/or rusty areas.
12. Move to the front axle and repeat the process.

½” drive Impact wrench or ½” drive ratchet wrench.
½” drive torque wrench.
15/16” - ½” drive socket (6 point preferred).
15/16” - box end wrench (The open end wrench does not fit inside the tube).
Bottle Jack
Jack Stand (Safety First)
Pencil or marker pen

4 pcs. 2” x 4” x 10” rectangle tube adapter.
8 pcs. 5/8-18 X 1” Grade 8 Fine Thread Hex Bolts (Machine bolts).
8 pcs. 5/8-18 Grade 8 Nylon lock nuts.
8 pcs. 5/8” flat washers.
Re-use the 8 - 5/8-18 hex bolts and washers.
1 can black spray paint. (Spray undercoating or spray truck bed paint works the best).
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seidcon is offline   Reply With Quote
Old 10-18-2016, 07:19 PM   #2
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B and B's Avatar
Join Date: Jun 2013
Location: Wilmot Twp, Ontario, Canada
Posts: 8,123
Nice write up and good work!!
B and B is offline   Reply With Quote

5th wheel, axle, lift, wheel

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