[{"data":1,"prerenderedAt":583},["ShallowReactive",2],{"navigation":3,"\u002Fdocs\u002Ff550-crew-cab-203\u002Fsub-frame":71,"\u002Fdocs\u002Ff550-crew-cab-203\u002Fsub-frame-surround":578},[4,8,38],{"title":5,"path":6,"stem":7},"Home","\u002Fdocs","docs\u002Findex",{"title":9,"path":10,"stem":11,"children":12,"page":37},"About","\u002Fdocs\u002Fabout","docs\u002F1.about",[13,17,21,25,29,33],{"title":14,"path":15,"stem":16},"Manifesto","\u002Fdocs\u002Fabout\u002Fmanifesto","docs\u002F1.about\u002F1.manifesto",{"title":18,"path":19,"stem":20},"Philosophy","\u002Fdocs\u002Fabout\u002Fphilosophy","docs\u002F1.about\u002F2.philosophy",{"title":22,"path":23,"stem":24},"Principles","\u002Fdocs\u002Fabout\u002Fprinciples","docs\u002F1.about\u002F3.principles",{"title":26,"path":27,"stem":28},"Constraints","\u002Fdocs\u002Fabout\u002Fconstraints","docs\u002F1.about\u002F4.constraints",{"title":30,"path":31,"stem":32},"Roadmap","\u002Fdocs\u002Fabout\u002Froadmap","docs\u002F1.about\u002F5.roadmap",{"title":34,"path":35,"stem":36},"License","\u002Fdocs\u002Fabout\u002Flicense","docs\u002F1.about\u002F6.license",false,{"title":39,"path":40,"stem":41,"children":42},"F550 Crew 84CA","\u002Fdocs\u002Ff550-crew-cab-203","docs\u002F2.f550-crew-cab-203\u002Findex",[43,45,55,61],{"title":44,"path":40,"stem":41},"Overview",{"title":46,"path":47,"stem":48,"children":49},"Sub-frame","\u002Fdocs\u002Ff550-crew-cab-203\u002Fsub-frame","docs\u002F2.f550-crew-cab-203\u002F1.sub-frame\u002Findex",[50,51],{"title":44,"path":47,"stem":48},{"title":52,"path":53,"stem":54},"Installation","\u002Fdocs\u002Ff550-crew-cab-203\u002Fsub-frame\u002Finstallation","docs\u002F2.f550-crew-cab-203\u002F1.sub-frame\u002F2.installation",{"title":56,"path":57,"stem":58,"children":59},"Bed","\u002Fdocs\u002Ff550-crew-cab-203\u002Fbed","docs\u002F2.f550-crew-cab-203\u002F2.bed\u002Findex",[60],{"title":44,"path":57,"stem":58},{"title":62,"path":63,"stem":64,"children":65},"Camper","\u002Fdocs\u002Ff550-crew-cab-203\u002Fcamper","docs\u002F2.f550-crew-cab-203\u002F3.camper\u002Findex",[66,67],{"title":44,"path":63,"stem":64},{"title":68,"path":69,"stem":70},"nuCamp Cirrus 920","\u002Fdocs\u002Ff550-crew-cab-203\u002Fcamper\u002Fnucamp-cirrus920","docs\u002F2.f550-crew-cab-203\u002F3.camper\u002F1.nucamp-cirrus920",{"id":72,"title":46,"body":73,"description":556,"extension":572,"links":573,"meta":574,"navigation":575,"path":47,"seo":576,"stem":48,"__hash__":577},"docs\u002Fdocs\u002F2.f550-crew-cab-203\u002F1.sub-frame\u002Findex.md",{"type":74,"value":75,"toc":555},"minimark",[76,103,111,114,117,120,122,127,130,146,154,168,171,173,177,184,187,204,207,209,213,216,230,233,236,238,242,249,252,266,269,280,282,286,289,292,300,303,317,320,322,326,329,340,343,346,348,352,355,358,369,372,375,377,381,384,387,409,412,414,418,424,427,459,462,464,468,471,474,485,488,490,494,497,505,508,511,513,517,520,523,537,540,542,546,549,552],[77,78,79,95],"tabs",{},[80,81,83],"tabs-item",{"label":82},"3D Explorer",[84,85,91],"model-explorer",{":groups":86,"alt":87,"height":88,"orientation":89,"src":90},"[{\"label\":\"Pendulum\",\"material\":3},{\"label\":\"Chassis Frame\",\"material\":1},{\"label\":\"Sub-frame\",\"material\":0},{\"label\":\"Floor\",\"material\":2}]","F-550 Crew Cab 203 sub-frame 3D model","420px","0 -90deg 0","\u002Fassets\u002Ff550crew-203-84ca.glb",[92,93,94],"p",{},"Interactive 3D model — click and drag to rotate, scroll\u002Fpinch to zoom, right-click (or two-finger drag) to pan. Use the toggles below to show or hide each group.",[80,96,98],{"label":97},"Gallery",[99,100],"placeholder",{"caption":101,"ratio":102},"Hero shot of the F-550 reference build — placeholder until the first finished truck is photographed.","16 \u002F 9",[92,104,105,106,110],{},"The zero-torsion sub-frame for this build. See the ",[107,108,109],"a",{"href":53},"installation guide"," for the step-by-step field procedure and BOM.",[112,113],"hr",{},[92,115,116],{},"This document defines the OpenOverland zero-torsion sub-frame as a standalone architectural object.",[92,118,119],{},"The sub-frame is the structural interface between the truck chassis and everything above it — the aluminum body, the camper, and all attached systems. It is designed first, in isolation, with clear boundaries and explicit intent.",[112,121],{},[123,124,126],"h2",{"id":125},"purpose-of-the-sub-frame","Purpose of the Sub-frame",[92,128,129],{},"The sub-frame exists to:",[131,132,133,137,140,143],"ul",{},[134,135,136],"li",{},"Isolate the body and camper from chassis torsion",[134,138,139],{},"Provide a stable, level platform regardless of frame twist",[134,141,142],{},"Mount to the truck chassis without compromising its structural integrity",[134,144,145],{},"Define a clean mechanical interface between the truck and the body system",[92,147,148,149,153],{},"The sub-frame is ",[150,151,152],"strong",{},"not",":",[131,155,156,159,162,165],{},[134,157,158],{},"A replacement for the truck frame",[134,160,161],{},"A body or enclosure",[134,163,164],{},"A camper tie-down system",[134,166,167],{},"A decorative or aesthetic component",[92,169,170],{},"The sub-frame must remain valid as camper models, body configurations, and truck variants change. Only the mounting interface and dimensional variables need to adapt.",[112,172],{},[123,174,176],{"id":175},"design-posture","Design Posture",[92,178,179,180,183],{},"The sub-frame is conceived as a ",[150,181,182],{},"three-point zero-torsion kinematic system",", where a single front lateral pivot and two rear fixed mounts form a statically determinate structure.",[92,185,186],{},"Key assumptions:",[131,188,189,192,195,198,201],{},[134,190,191],{},"Three-point mounting eliminates over-constraint",[134,193,194],{},"The front pivot allows rotation on the lateral axis only",[134,196,197],{},"The rear mounts are fixed — no rotation",[134,199,200],{},"Together, the three points define a plane that remains stable regardless of chassis twist",[134,202,203],{},"The body above sees no torsional input from the chassis below",[92,205,206],{},"The sub-frame does not fight the truck. It decouples from it.",[112,208],{},[123,210,212],{"id":211},"geometry","Geometry",[92,214,215],{},"The sub-frame geometry prioritizes:",[131,217,218,221,224,227],{},[134,219,220],{},"Minimum deck height above the frame rails",[134,222,223],{},"Maximum clearance from the tire swept volume at full suspension travel",[134,225,226],{},"Clean load paths from the body to the chassis mounting points",[134,228,229],{},"Compatibility with Ford factory body mounting provisions",[92,231,232],{},"Flat-top deck geometry is the default. The sub-frame presents a level platform to the body above regardless of chassis state.",[92,234,235],{},"Exact dimensions are intentionally parametric and adapt to the specific truck variant.",[112,237],{},[123,239,241],{"id":240},"structural-concept","Structural Concept",[92,243,244,245,248],{},"The sub-frame is designed as a ",[150,246,247],{},"welded steel structure"," carried by the truck chassis.",[92,250,251],{},"Structural behavior is achieved through:",[131,253,254,257,260,263],{},[134,255,256],{},"Rectangular hollow section main rails",[134,258,259],{},"Welded crossmembers at regular intervals",[134,261,262],{},"Full-penetration welds at all primary load-bearing joints",[134,264,265],{},"Outrigger provisions for body attachment extending beyond the main rails",[92,267,268],{},"The sub-frame:",[131,270,271,274,277],{},[134,272,273],{},"Carries the full body and camper load",[134,275,276],{},"Transfers loads to the truck chassis through three defined mounting points",[134,278,279],{},"Does not assume structural contribution from the body above it",[112,281],{},[123,283,285],{"id":284},"zero-torsion-pivot-system","Zero-Torsion Pivot System",[92,287,288],{},"The front pivot is the defining component of the system.",[92,290,291],{},"The pivot allows:",[131,293,294,297],{},[134,295,296],{},"Rotation on the lateral axis — left and right frame twist",[134,298,299],{},"No rotation on the longitudinal axis — handled by the rear mounts",[92,301,302],{},"The pivot is constructed from:",[131,304,305,308,311,314],{},[134,306,307],{},"A ground steel shaft (the pin)",[134,309,310],{},"An SAE 841 oil-impregnated bronze sleeve bushing",[134,312,313],{},"A machined threaded retaining ring",[134,315,316],{},"Steel laser-cut brackets welded to the sub-frame and the truck frame adapter plate",[92,318,319],{},"All pivot components are standard catalog parts. No proprietary hardware. No special tooling required for service or replacement.",[112,321],{},[123,323,325],{"id":324},"chassis-interface","Chassis Interface",[92,327,328],{},"The sub-frame mounts to the truck chassis exclusively through:",[131,330,331,334,337],{},[134,332,333],{},"Factory Ford body mounting holes — no new holes in the frame flanges",[134,335,336],{},"U-bolt and shear plate assemblies per Ford Body Builder Guidelines",[134,338,339],{},"Web drilling per LiquidSpring installation template where applicable — Ø21\u002F32\", web only",[92,341,342],{},"Drilling in the top or bottom frame flanges is explicitly prohibited.",[92,344,345],{},"The chassis interface is designed to be reversible. Removal of the sub-frame restores the truck to its original state.",[112,347],{},[123,349,351],{"id":350},"tire-clearance","Tire Clearance",[92,353,354],{},"The critical constraint in sub-frame geometry is the tire swept volume.",[92,356,357],{},"The swept volume is defined by:",[131,359,360,363,366],{},[134,361,362],{},"Tire outer diameter at minimum inflation pressure",[134,364,365],{},"Full suspension jounce travel",[134,367,368],{},"Any camber change through the travel arc",[92,370,371],{},"No sub-frame structure may enter the swept volume envelope. A minimum 25mm clearance margin is maintained beyond the calculated envelope at all points.",[92,373,374],{},"This constraint is modeled explicitly in CAD before any other geometry is committed.",[112,376],{},[123,378,380],{"id":379},"parametric-design","Parametric Design",[92,382,383],{},"The sub-frame is fully parametric.",[92,385,386],{},"Key variables include:",[131,388,389,392,395,398,401,404,406],{},[134,390,391],{},"Truck wheelbase",[134,393,394],{},"CA dimension (cab to rear axle)",[134,396,397],{},"Frame rail width",[134,399,400],{},"Frame rail height",[134,402,403],{},"Suspension jounce and rebound travel",[134,405,362],{},[134,407,408],{},"Body width at the base interface",[92,410,411],{},"Changing these variables adapts the sub-frame to a new truck variant or suspension configuration without redesigning the system architecture.",[112,413],{},[123,415,417],{"id":416},"interfaces","Interfaces",[92,419,420,421,423],{},"The sub-frame defines ",[150,422,416],{},", not implementations.",[92,425,426],{},"Interfaces include:",[131,428,429,435,441,447,453],{},[134,430,431,434],{},[150,432,433],{},"Chassis interface"," — the three mounting points to the truck frame",[134,436,437,440],{},[150,438,439],{},"Body interface"," — the outrigger bolt pattern that receives the aluminum body",[134,442,443,446],{},[150,444,445],{},"Deck interface"," — the top surface that receives deck boards or a flatbed platform",[134,448,449,452],{},[150,450,451],{},"Air line interface"," — routing provisions for onboard compressed air distribution",[134,454,455,458],{},[150,456,457],{},"Electrical interface"," — wiring conduit provisions for tail lights and body electronics",[92,460,461],{},"Interfaces are explicit, documented, and conservative.",[112,463],{},[123,465,467],{"id":466},"manufacturing-neutrality","Manufacturing Neutrality",[92,469,470],{},"The sub-frame geometry is designed to be built by any competent structural steel fabricator.",[92,472,473],{},"Compatible fabrication paths include:",[131,475,476,479,482],{},[134,477,478],{},"CNC plasma or waterjet cutting from DXF files",[134,480,481],{},"Manual cutting and fitting from dimensioned drawings",[134,483,484],{},"Any combination of the above",[92,486,487],{},"No specialized tooling, proprietary processes, or specific equipment is required. The design is intentionally accessible.",[112,489],{},[123,491,493],{"id":492},"coating","Coating",[92,495,496],{},"The sub-frame is designed for a two-stage corrosion protection system:",[131,498,499,502],{},[134,500,501],{},"Blast clean to bare metal — Sa 2.5 standard",[134,503,504],{},"Line-X polyurea applied directly to bare blasted steel — same day as blasting",[92,506,507],{},"No primer between steel and Line-X. Line-X bonds chemically and mechanically to the blast profile. Primers intermediate between steel and polyurea risk blistering under the exothermic application heat.",[92,509,510],{},"All bolt holes, threads, and mounting surfaces are masked before blasting and coating.",[112,512],{},[123,514,516],{"id":515},"open-source-intent","Open Source Intent",[92,518,519],{},"All sub-frame designs published under OpenOverland are released under an open license.",[92,521,522],{},"This includes:",[131,524,525,528,531,534],{},[134,526,527],{},"Complete engineering drawings in DXF and STEP format",[134,529,530],{},"Bill of materials with supplier part numbers",[134,532,533],{},"Fabrication notes and lessons learned",[134,535,536],{},"Real cost data from verified builds",[92,538,539],{},"The goal is not a product. It is a standard — an engineering baseline that any builder anywhere can take to any competent fabricator and get a correctly built sub-frame at a fair price.",[112,541],{},[123,543,545],{"id":544},"closing-notes","Closing Notes",[92,547,548],{},"The sub-frame is the foundation of the body system.",[92,550,551],{},"If the sub-frame is correct — level, isolated from torsion, properly mounted — everything above it can evolve.\nIf the sub-frame is compromised — too high, too wide, incorrectly mounted — no amount of body refinement will fix it.",[92,553,554],{},"This document exists to ensure the sub-frame is treated as an engineered system, not a welded shelf.",{"title":556,"searchDepth":557,"depth":557,"links":558},"",2,[559,560,561,562,563,564,565,566,567,568,569,570,571],{"id":125,"depth":557,"text":126},{"id":175,"depth":557,"text":176},{"id":211,"depth":557,"text":212},{"id":240,"depth":557,"text":241},{"id":284,"depth":557,"text":285},{"id":324,"depth":557,"text":325},{"id":350,"depth":557,"text":351},{"id":379,"depth":557,"text":380},{"id":416,"depth":557,"text":417},{"id":466,"depth":557,"text":467},{"id":492,"depth":557,"text":493},{"id":515,"depth":557,"text":516},{"id":544,"depth":557,"text":545},"md",null,{},{"title":44},{"title":46,"description":556},"bhkruxRkagNjZBJQvPYK-G2L42uim9AD0A8rEZuXaAs",[579,581],{"title":44,"path":40,"stem":41,"description":580,"children":-1},"F-550 Crew Cab 203\" Wheelbase — Zero-Torsion Subframe",{"title":52,"path":53,"stem":54,"description":582,"children":-1},"Step-by-step installation guide — Ford F-550 sub-frame and aluminum cabin floor.",1783042607491]