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Again, the spring mount arms are quite a patchwork assembly and need not be; it's what I had on hand. I'm asking this design to provide up to 1000/lbs of additional lift to the rear of my coach. Applying this amount of lift at a point on the chassis 3-ft behind the torsion bar tubes should hopefully help mitigate the extra 400 lbs the Cummins brings to the party. If there are any strength issues (ie. flexing/bending) in service, I'll change out the arms for some 3"x3" heavy box channel. One thing I think I got right with this design is the ease of removal of the assembly for repair and/or access to the shocks and wheel hub assemblies. | Scored all the fittings & 20 ft of 1/4" airline for under $40 bucks. Ready to install and test for leaks. | ||
To figure what I thought could be right place to weld the upper spring mount I decided to use the point on the chassis frame where the radius from the center of the torsion bar tube (center of rotation) out to the center of the air spring disk. Then it was a simple matter to transfer that distance up onto the chassis. | Forgive me my Cummin's brethren for I have sinned...all I had handy was some 'Caterpillar yellow' rust paint! | The bolt holes are more or less in a straight line on 4 1/4" centers. My laser came in handy for aligning the holes (which are also the centerline of the air-springs and the 3ft long mounting arms) which all had to position correctly (plumb) beneath the upper spring mount on the chassis. As is shown in the pics following, the 6" dia. circular 1/4" upper spring mount disc needs to be offset from the chassis beam enough to allow access to the mounting bolts and air-line hardware. | |
Here you can see the weld on the radius of the outer torsion bar tube. Had to grind off a bunch of what appeared to be asphalt black undercoating to expose clean steel. | Ignore the extra hole in this view; it was already in the beam material I used. | Added two 5/16" small gussets to the angle bracket to beef it up some. Drilled 3 x 11/16" holes for the 3 x 5/8" (gr.#8)bolts that will secure the air-spring mount arm to the mount. Note: I made the bolt holes 1/16" larger for two reasons (1)I'm not a machinist and only have a simple drill press to drill these holes in correct alignment and knew I'd be off a bit so this would provide some wiggle room. (2)slightly larger holes would also provide useful horizontal adjustment to help correctly align the lower spring mount with the upper one on the chassis. The following pics show the mount in place and the welding tracks where it's attached to the trailing arm. | |
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