rpsinc Posted March 14, 2023 Report Share Posted March 14, 2023 Working on some modifications on my bed and need info about the clearance needed for a box I will place behind my tandem rear tires. Some of you that have designed and built your beds, what is minimum distance from the ground to the bottom of a box for clearance to prevent hitting the box. I plan on using a box I already own and making accomodation for my Smart ramps which will facilitate moving my hitch back about 20" for clearance to the Smart with our new to us NH. Any input from the voices of experience is appreciated. Quote Marcel Link to comment Share on other sites More sharing options...
Steve from SoCal Posted March 14, 2023 Report Share Posted March 14, 2023 My truck is singled but, the issue is the same, approach angle. How far behind the axle centerline is box? My rear boxes extend 46" from the centerline of the axle and at ride height are 15" from the ground. I have a rather steep driveway entry and, use a drive on grain scale with quick riseing ramps. With my suspension dumped there is 12" clearance and plenty of room on these. The longer the overhang the more height you will need. I don't recall what angle I used but 12-14 degrees seems in the ball park. Quote 2005 Peterbilt 387-112 Baby Cat 9 speed U-shift 1996/2016 remod Teton Royal Atlanta 1996 Kentucky 48 single drop stacker garage project Pulls like a train, sounds like a plane....faster than a Cheetah sniffin cocaine. Link to comment Share on other sites More sharing options...
phoenix2013 Posted March 14, 2023 Report Share Posted March 14, 2023 Integrated the rear fender skirt into the box front, cut out the door from the skin. Two front and two rear skins attached to real boxes The rear boxes were quite big. Quote Link to comment Share on other sites More sharing options...
rpsinc Posted March 14, 2023 Author Report Share Posted March 14, 2023 Very helpful guys. Thanks. This will provide a good start to my design. Its raining here in So Cal so have some time to do inside work. Quote Marcel Link to comment Share on other sites More sharing options...
rpsinc Posted March 14, 2023 Author Report Share Posted March 14, 2023 Will be repurposing 1 of the 2 of these that I already have. My doors open the other way and I will have those opening to the rear. 78" long will allow for 10" boxes on each side to house the lights. The top tray will be modified for ramp storage, either in front of the box(which will be toward the cab) or on top of the box, which is built for chain storage on rollback tow trucks. Henry-what did you use to extend the frame for the hitch support. I am thinking some 3/8" roll formed Cs made long enough to bolt to existing frame or weld to end and splice plate. Quote Marcel Link to comment Share on other sites More sharing options...
Darryl&Rita Posted March 14, 2023 Report Share Posted March 14, 2023 We're about 6" or 8" off the ground, 50" behind the tires. We drag, we knew we would drag, we built for it. Hammer down, power through. I can get exact measurements in a month, if I remember. Quote I have been wrong before, I'll probably be wrong again. 2000 Kenworth T 2000 w/N-14 and 10 speed Gen1 Autoshift, deck built by Star Fabrication 2006 smart fourtwo cdi cabriolet 2007 32.5' Fleetwood QuantumPlease e-mail us here. Link to comment Share on other sites More sharing options...
rickeieio Posted March 14, 2023 Report Share Posted March 14, 2023 We're a bit more conservative than Henry's drawing, but not much. Bumper is 12" off the ground and roughly 40" from rear of tire to extreme rear of bumper. Quote KW T-680, POPEMOBILE Newmar X-Aire, VATICAN Lots of old motorcycles, Moto Guzzi Griso and Spyder F3 currently in the front row Young enough to play in the dirt as a retired farmer. contact me at rickeieio@yahoo.com Link to comment Share on other sites More sharing options...
phoenix2013 Posted March 14, 2023 Report Share Posted March 14, 2023 2 hours ago, rpsinc said: Henry-what did you use to extend the frame for the hitch support. I am thinking some 3/8" roll formed Cs made long enough to bolt to existing frame or weld to end and splice plate. 1/4 inch plate rolled with the same radius as the frame, attached at the end of the slope. V grove both sides, weld both sides, grind inside flush to slide the hitch mounting angles in. Frame is about 1/4 inch thick so it works. Used to order it in two two footers or one four footer and cut these to length depending on the bed design. Finished and painted Quote Link to comment Share on other sites More sharing options...
rpsinc Posted March 15, 2023 Author Report Share Posted March 15, 2023 4 hours ago, Darryl&Rita said: We're about 6" or 8" off the ground, 50" behind the tires. We drag, we knew we would drag, we built for it. Hammer down, power through. I can get exact measurements in a month, if I remember. No need but thanks. I will do what works for my situation but now I have a much better idea of what my min/max is. Quote Marcel Link to comment Share on other sites More sharing options...
Darryl&Rita Posted March 15, 2023 Report Share Posted March 15, 2023 It should be noted that when I say that we drag, it's not every day, or even every trip. It does happen, but only barely occasionally. Mostly when one of us hasn't been paying attention. Probably once per year. Quote I have been wrong before, I'll probably be wrong again. 2000 Kenworth T 2000 w/N-14 and 10 speed Gen1 Autoshift, deck built by Star Fabrication 2006 smart fourtwo cdi cabriolet 2007 32.5' Fleetwood QuantumPlease e-mail us here. Link to comment Share on other sites More sharing options...
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