GMC / CHEVY 4500/5500 Series Trucks RW-1019 Supplementary PDF Installation Instructions

GMC / Chevrolet no longer offers the 3500HD pickup truck. There is still a dual rear wheeled 3500, but its maximum GVWR is only 11,400lbs. The Class 4 & 5 GVWR ranges (14,001 to 19,500lbs) that used to be covered by the 3500HD are now part of the GMC / Chevrolet TopKick / Kodiak (4500/5500 family) line of trucks. The TopKick / Kodiak line of trucks is much more similar in overall construction to its heavier GVWR cousins than it is to the old 3500HD pickup trucks. Therefore, the DMF RW-1019 railgear has been modified to better suit this line of trucks. The redesigned RW-1019 for TopKick /Kodiak trucks is very similar to the larger DMF RW-1212 and RW-1420 railgear. The only difference between this RW-1019 for the Chevy /GMC 4500 / 5500 series trucks and the RW-1212 and RW-1420 line is the size of the rail wheels, bearings, axle and the pivot arms.

FAMILIARIZATION:
Please take some time to familiarize yourself with the terms in this diagram prior to proceeding with installation. The following instructions will be much clearer if you’re familiar with the terminology. Furthermore, if you need to contact DMF for assistance, we will be better able to understand your questions if you use the same terms we do.

ATTACHING GEAR TO TRUCK:
1) Remove front bumper and store for re-installation later.
2) Bolt on front frame extensions provided with railgear.
3) Slide Railgear under truck.
4) Raise the rear of one pair (passenger or driver’s side) of long arms so that the two sections of threaded rod straddle the leaf spring. Continue to raise the spring hanger until it comes in contact with the lower most leaf. This can be made easier by inserting an appropriately sized bolt through hole marked “A” in BOTH inner and outer long arms. Then slide a long lever (e.g: 1-1/2” tube steel) OVER the bolt and UNDER the rear pin / spring hanger (see picture below)
5) Measure the height of the rear pin as the spring hanger is in contact with the spring. Add or remove spacers as necessary so that the centerline of the pin will be at approximately 9-3/4” when secured in place.
6) Install rubber pad over the top of the leaf springs and then the top 1” spacer. Thread 2 nuts on EACH of the threaded rods of the spring hanger. Tighten until the rubber just starts to deform. Do not overtighten.
7) Repeat steps 4&5 for the opposite side of the railgear. Both spring hangers should now be clamped around the leaf springs.
Raise the railgear until the spring hanger just touches the frame or frame extensions. The easiest way to do this is to actually connect the truck hydraulics, remove the safety pin offs, and “lower” the railgear. This will force the long arms up toward the frame / frame extensions. When the cross tube just contacts the frame stop and measure the height of the front pin. The height should be about 22-1/2 to 23-1/2” inches. If it is higher, you will need to space the cross tube down with flatbar. If it is too low you will have decreased road clearances in the highway position. Please see following diagram for proper highway position pin heights.

Proper clearances will allow the railgear to move up and down with the truck front suspension. As the truck tire hits bumps in the road, the truck spring allows the front axle to move upward (see following figure). Since the railgear is attached to the spring just in front of the axle, sufficient clearance must be allowed to prevent interference with other parts on the truck (i.e. frame, steering boxes, shocks, oil filters, spring hangers, hydraulic lines, etc.). The Front Mounting Pin does not move in relation to the vehicle frame because it is fastened through the Frame Extension (or directly to the truck frame). As the Front Mounting Pin does not move and the Rear Mounting Pin (at the axle) does, the rail gear effectively rotates about the Front Mounting Pin. Therefore, the part of the rail gear near the Rear Mounting Pin moves more than the part near the Front Mounting Pin, and attention needs to be paid to the possible clearance problems that can be caused by this movement.

Download GMC / CHEVY 4500/5500 Series Trucks RW-1019 Supplementary PDF Installation Instructions