3rd Gen Tech: Crossmember and Skid Plate
#1
12-07-2008, 01:11 AM
3rd Gen Tech: Crossmember and Skid Plate
Lately in my spare time, I’ve been working on a cross member designed for multiple use.
It will be used as a platform for a Transfer case skid plate, a fuel tank skid plate, and possibly down the road as a frame mount for traction bars. As far as the skid plate platform goes, I wanted something a little more durable than the factory offering, since I didn’t think it would hold up to my off road driving in this truck.
First thing I did was define my project goals, which in no particular order were:
Something that would actually hold up to more than one or two high centers without folding up into a twisted pile of metal.
The cross member had to be capable of being a platform for a transfer case skid plate, a Fuel tank skid plate, and possibly later, something I can use as an upper mounting point for traction bars for the rear axle. Strength obviously is a major concern.
It also had to be removable, without any bulky brackets left on the frame, and without any excessive welding to the frame.
I also wanted the cross member to line up with the factory transmission/transfer case cross member and the bottom of the fuel tank, so that simple, removable flat pieces of steel could be employed for the skid plate portion.
As a side benefit I wanted the cross member to add strength to the frame, although the frame is plenty strong as it is, I didn’t want the fabrication of this to weaken that structure.
In summary, I wanted a simple bulletproof structure anyone with some mediocre fabrication skills (Like myself) could build.
If you like the idea, but feel you lack the fabrication skills, you could always print this post out and take it to a fabrication shop in your area. I have no idea how much something like this would cost, however. All you probably need them to build would be the cross member, I think most people could cut their own plates and drill some mounting holes.
This is what I came up with. As always, questions and comments are welcome.
First, in case you haven’t seen the stock cross member and transfer case skid plate, I took a picture of one with my camera phone. I’ll probably edit this post later with a pic from my digital camera of one from the Dodge dealership.
The raw materials necessary for the Cross member I built are:
2”X3”X3/16” rectangle tube.
4”X1/8” flat plate
8- 1 ¼” X ½” Grade 8 bolts
8- ½” flanged metal self locking grade 8 nuts (NOT Nylon lock nuts!)
4- prefabricated tabs (If no one in your area sells them, you could make these out of your leftover flat plate)
The tools required would be:
Wire feed welder (I used a Flux core Lincoln wire feed)
Angle Grinder (Soft grinding pad, knotted cup brush)
Sawsall (14 TPI blades)
Right Angle Drill and Drill bits (A Unibit is a “Nice to have”)
Tape measure
Combination Square
Vise (Not really required, but nice to have)
In this pic, the 2X3 tube has been cut to length and the 4” flat plate has been trimmed down to 3” and tack welded to the tube for test fitting.
After test fitting, the plates are fully welded to the tube, and the welds and spatter cleaned up (Flux core)
A close up of the inner weld.
The cross member was put into place, traced in red permanent marker on the frame. This was to provide a measuring reference for using the stock hole locations as mounting points. Measuring points were then transferred to the plate for drilling. Once the holes were drilled, I found some 3/8” bolts to use to temporarily hold the cross member in place for the remainder of the fabrication.
Here is a pic of the tab that I used for the lower cross member mount.
Since a hole is going to be drilled into the bottom of the frame, and a flanged nut is going to be welded into it, I used a washer to space off the tab from the frame to compensate for the flanged portion of the nut, to get it in the right spot on the cross member, before marking the hole on the frame.
The next step is to tack weld the tabs onto the cross member. I used one of the bolts and a washer (Between the frame and tab, not seen in this pic) to line up the tab on the cross member.
After tack welding, the cross member was removed for welding the tabs. Here’s what it looks like so far
It will be used as a platform for a Transfer case skid plate, a fuel tank skid plate, and possibly down the road as a frame mount for traction bars. As far as the skid plate platform goes, I wanted something a little more durable than the factory offering, since I didn’t think it would hold up to my off road driving in this truck.
First thing I did was define my project goals, which in no particular order were:
Something that would actually hold up to more than one or two high centers without folding up into a twisted pile of metal.
The cross member had to be capable of being a platform for a transfer case skid plate, a Fuel tank skid plate, and possibly later, something I can use as an upper mounting point for traction bars for the rear axle. Strength obviously is a major concern.
It also had to be removable, without any bulky brackets left on the frame, and without any excessive welding to the frame.
I also wanted the cross member to line up with the factory transmission/transfer case cross member and the bottom of the fuel tank, so that simple, removable flat pieces of steel could be employed for the skid plate portion.
As a side benefit I wanted the cross member to add strength to the frame, although the frame is plenty strong as it is, I didn’t want the fabrication of this to weaken that structure.
In summary, I wanted a simple bulletproof structure anyone with some mediocre fabrication skills (Like myself) could build.
If you like the idea, but feel you lack the fabrication skills, you could always print this post out and take it to a fabrication shop in your area. I have no idea how much something like this would cost, however. All you probably need them to build would be the cross member, I think most people could cut their own plates and drill some mounting holes.
This is what I came up with. As always, questions and comments are welcome.
First, in case you haven’t seen the stock cross member and transfer case skid plate, I took a picture of one with my camera phone. I’ll probably edit this post later with a pic from my digital camera of one from the Dodge dealership.
The raw materials necessary for the Cross member I built are:
2”X3”X3/16” rectangle tube.
4”X1/8” flat plate
8- 1 ¼” X ½” Grade 8 bolts
8- ½” flanged metal self locking grade 8 nuts (NOT Nylon lock nuts!)
4- prefabricated tabs (If no one in your area sells them, you could make these out of your leftover flat plate)
The tools required would be:
Wire feed welder (I used a Flux core Lincoln wire feed)
Angle Grinder (Soft grinding pad, knotted cup brush)
Sawsall (14 TPI blades)
Right Angle Drill and Drill bits (A Unibit is a “Nice to have”)
Tape measure
Combination Square
Vise (Not really required, but nice to have)
In this pic, the 2X3 tube has been cut to length and the 4” flat plate has been trimmed down to 3” and tack welded to the tube for test fitting.
After test fitting, the plates are fully welded to the tube, and the welds and spatter cleaned up (Flux core)
A close up of the inner weld.
The cross member was put into place, traced in red permanent marker on the frame. This was to provide a measuring reference for using the stock hole locations as mounting points. Measuring points were then transferred to the plate for drilling. Once the holes were drilled, I found some 3/8” bolts to use to temporarily hold the cross member in place for the remainder of the fabrication.
Here is a pic of the tab that I used for the lower cross member mount.
Since a hole is going to be drilled into the bottom of the frame, and a flanged nut is going to be welded into it, I used a washer to space off the tab from the frame to compensate for the flanged portion of the nut, to get it in the right spot on the cross member, before marking the hole on the frame.
The next step is to tack weld the tabs onto the cross member. I used one of the bolts and a washer (Between the frame and tab, not seen in this pic) to line up the tab on the cross member.
After tack welding, the cross member was removed for welding the tabs. Here’s what it looks like so far
The following users liked this post:
Oilfield_Mafia (12-07-2008)
#2
12-07-2008, 01:12 AM
Continued
The next step was to enlarge the holes in the bottom of the frame to accept the flanged nuts, and weld them into the frame. Here is what it looks like with them welded in and the surface ground flush.
Here’s what it looks like with the cross member in place.
The upper mounting holes are still 3/8” and are now drilled out to ½” while the cross member is in place. Proper hole alignment is critical. Once the holes are drilled, the cross member is dropped down and the frame holes are enlarged to accept the flange nuts, and they are welded in.
Cross member after painting
Cross member installed and ready to start on skid plate
Skid plate done and installed. From this angle, it doesn’t look like it protects the transfer case, but it does. I’ll have to get another picture from a more rearward angle.
Here’s what it looks like with the cross member in place.
The upper mounting holes are still 3/8” and are now drilled out to ½” while the cross member is in place. Proper hole alignment is critical. Once the holes are drilled, the cross member is dropped down and the frame holes are enlarged to accept the flange nuts, and they are welded in.
Cross member after painting
Cross member installed and ready to start on skid plate
Skid plate done and installed. From this angle, it doesn’t look like it protects the transfer case, but it does. I’ll have to get another picture from a more rearward angle.
