Custom Fabrication and Welding in Brea, CA
RV custom fabrication in Brea, CA is metalwork made to fit a specific vehicle: rear bumpers and receiver mounts, ladder and cargo racks, generator and battery trays, storage boxes, bike and spare tire carriers, step and rail assemblies, skid plates, and one off structural brackets for anything that does not exist as a catalog part. We work steel and aluminum in house with MIG, TIG, and stick processes, we design the load path before we cut anything, and we build to the vehicle rather than adapting a universal part until it almost lines up.
This page is fabrication, meaning new metal designed and built to purpose. Repairing a bent factory bumper or a damaged frame member after an impact is collision and structural work and belongs to those pages. The two overlap constantly, since a rear end impact often needs both a straightened structure and a new bumper built to replace one that is no longer available, and we quote those as separate lines on the same job.
- California BAR licensed ARD00288521
- 35,000 square feet facility
- All work performed in shop at our Yorba Linda facility
- Direct billing with 16 carriers on covered claims
Ready to get this looked at?
We inspect on the lift, document the damage, and give you a written scope. The estimate fee is credited against the repair when you authorize the work.
What this repair covers
Fabrication starts with a load question, not a drawing. How much weight, applied how far from the mounting point, in which directions, through how many cycles. A cargo rack that carries 200 pounds statically may see 600 pounds of dynamic load over a bad expansion joint, and the difference between a bracket that lasts and one that cracks is whether that number was considered before the steel was cut.
We build in mild steel, in 5052 and 6061 aluminum, and in stainless where corrosion demands it, and the choice is driven by the mounting structure and the weight budget rather than by preference.
Scope for this page:
- In scope: rear and front bumper fabrication, receiver hitch mounts, and tow point reinforcement.
- In scope: roof racks, ladder racks, cargo baskets, awning mounts, and solar panel mounting structures.
- In scope: storage boxes, generator trays, battery trays, propane tank mounts, and toolbox mounting.
- In scope: bike carriers, spare tire carriers, and swing away arms with latching hardware.
- In scope: steps, grab rails, handrails, running boards, and access platforms.
- In scope: skid plates, rock guards, mud flap brackets, and underbody protection.
- In scope: one off structural brackets, subframes, and repair sections for interior and exterior mounting.
- In scope: aluminum and steel welding, plus finishing in powder coat, primer and topcoat, or bare stainless.
- Out of scope: straightening a damaged factory frame or bumper after an impact.
- Out of scope: fiberglass and composite panel work.
Damage and failure modes we see
Most of what comes to us for fabrication is a replacement for something that failed, and the failures repeat. Understanding why they cracked is what keeps the replacement from doing the same thing.
Galvanic corrosion at mixed metal joints
Bolt an aluminum rack to a steel roof rail with plain steel hardware, add rain and road salt, and you have built a battery. The aluminum is anodic to the steel and gives up material at the contact face. The symptom is a white powdery bloom at the joint and bolt holes that grow oval.
Owners see corrosion and add more torque, which crushes the weakened aluminum. The correct build isolates the metals with a nylon or fiber shoulder washer and an isolating gasket, uses stainless hardware with the right insulation, and seals the joint face. This is the single most common defect in aftermarket racks we are asked to replace.
Heat affected zone softening in 6061-T6
6061-T6 aluminum gets its strength from heat treatment, and welding destroys that heat treatment in a band roughly an inch either side of the bead. In that zone the material drops from T6 strength toward annealed strength, sometimes losing half its yield. A part designed on the published T6 numbers and then welded at the highest stress point is designed to fail at the weld.
The failure looks like a crack running parallel to the bead rather than through it, which confuses people into blaming the weld. The weld is usually fine. The design put the joint in the wrong place. We locate welds away from peak stress, use 5052 where forming and welding matter more than peak strength, and add gussets that move load into the base material.
Cantilever cracking at bumper and carrier mounts
A spare tire or bike carrier hung off a rear bumper puts a long lever arm on a structure that was never designed for a moment load. Every bump applies a bending moment at the bumper to frame joint, and the crack starts at the weld toe on the top surface of that joint where tension is highest.
The early symptom is paint cracking in a line at the weld, which owners read as cosmetic. It is not. It is the coating telling you the metal underneath has begun to yield. Continuing to drive on it takes the crack through the section, and the failure mode when it lets go is the carrier and its load departing the vehicle at speed. This is the failure we treat as urgent regardless of how it looks.
Weld porosity from contaminated aluminum
Aluminum grows an oxide layer that melts at roughly three times the temperature of the base metal, and it holds moisture. Welding through it without mechanical cleaning and solvent degreasing traps gas in the bead, producing porosity that looks fine on the surface and has a fraction of the intended strength.
The result is a joint that passes a visual inspection and cracks at a third of its design life. Prevention is process, not skill: dedicated stainless brushes used on aluminum only, acetone degreasing immediately before welding, welding within a short window of cleaning, and correct shielding gas coverage. Anyone who welds aluminum with the same wire brush they use on steel is building porosity into the part.
Hard mounting to a frame that flexes
RV frames flex, and they are supposed to. A rigid rack, box, or bracket bolted hard across two points that move relative to each other becomes the thing that resists that movement, and it either cracks itself or cracks the frame at its mounting points.
The tell is a crack that appears at the mounting bracket rather than in the rack, or elongated bolt holes in a frame rail. The right answer is a mount that accommodates movement: a single fixed point with a slotted or floating second point, rubber isolation where vibration matters, and load spread over a plate rather than concentrated at a bolt. Bolting a stiff assembly rigidly to a flexible chassis is the most common design mistake in this whole category.
Receiver hitch capacity mismatch
A receiver welded to the back of a motorhome is limited by whatever it is welded to, not by the receiver tube rating. Owners see a two inch receiver and assume a two inch receiver rating, then load 500 pounds of tongue weight onto a bumper mount rated for a fraction of that.
Symptom is a sagging rear, a bumper that has visibly rotated downward, or a crack at the frame extension weld. The consequence is a detached tow connection. When we build a hitch mount we tie it into frame rails with a designed load path, not to the bumper skin, and we state the intended tongue and gross trailer weight capacity in writing so nobody guesses later.
| Aluminum (5052, 6061) | Mild steel | |
|---|---|---|
| Weight for equal strength | Roughly one third the density, but needs more section | Heavier, smaller section for the same load |
| Fatigue behavior | No true fatigue limit. Cycles eventually crack it | Has a fatigue limit below which it runs indefinitely |
| Corrosion | Self passivating oxide. Excellent on its own | Rusts. Requires coating and edge sealing |
| Welding | TIG or spool gun MIG. Heat affected zone softens 6061 | Forgiving MIG or stick. Minimal strength loss |
| Repair on the road | Few shops can weld it properly | Almost any welder can repair it |
| Best use here | Roof racks, trays, boxes, anything carried high | Bumpers, hitch mounts, anything taking impact |
| Galvanic risk | Corrodes rapidly where bolted to bare steel | Sacrifices to stainless at fasteners |
| Cost | Higher material and higher labor | Lower on both |
How we perform this repair
Fabrication is a design job with a welding step in the middle. The welding is the easy part.
How a custom fabrication job runs:
- Define the load case in writing. Static weight, where it acts, the dynamic multiplier we design against, and the directions it applies. A rack carrying 150 pounds gets designed against several times that to survive road inputs, and that number goes on the drawing.
- Survey the mounting structure. We find real frame members, identify what is structural and what is skin, and check for wiring, plumbing, and tank locations behind every intended mounting point before a hole is drilled.
- Template and mock up. Cardboard or steel rod mockups confirm clearance for slides, awnings, doors, compartment lids, tire travel, and departure angle before material is cut. Nothing gets built to a measurement taken once.
- Select material by duty. Mild steel tube and plate for impact and tow structures, 5052 aluminum sheet for boxes and trays that need forming, 6061 for extruded structural sections, and stainless where a fastener or a rail lives in constant weather.
- Cut, form, and fit. Shear, bandsaw, and press brake work in house, with joints designed to be fitted tight rather than gap filled, since a weld that fills a gap is a weld carrying the wrong kind of load.
- Weld to process. MIG with the appropriate wire on steel, TIG or spool gun with 4043 or 5356 filler on aluminum chosen for the base alloy and the service condition, full penetration at structural joints, and gussets at every corner that carries a moment.
- Isolate every mixed metal joint. Nylon shoulder washers, isolating gaskets, stainless hardware, and sealed contact faces wherever aluminum meets steel, without exception.
- Finish and load test. Steel gets blasted and powder coated or primed and topcoated with sealed weld edges, aluminum is left bare or coated to taste, and the assembly is loaded to its rated capacity and inspected at the welds before the vehicle leaves.
What this costs and how we quote it
Fabrication is quoted as design hours, material, fabrication hours, and finish, listed separately. The design portion surprises people, but it is where the value is. Taking measurements, checking clearances, verifying what is behind the mounting surface, and working out the load path is often a third of the job on a one off part.
Simple repeatable items like a battery tray or a straight bumper replacement are quoted flat once we have seen the vehicle. Complex assemblies with articulating arms, latches, or integration into an existing structure are quoted in stages, with design and mockup authorized first so you can approve the concept before committing to material and fabrication hours. Powder coating is quoted as a sublet line. Our pricing page has the current rate structure.
Vehicles we perform this on
The mounting structure changes completely by platform. A diesel pusher has heavy steel frame rails that will take almost anything with a properly designed plate. A travel trailer has a light A frame and thin wall tube where load has to be spread carefully. A Sprinter or Transit van has factory mounting points with published ratings that should be used rather than bypassed, and a box truck has a body subframe separate from the chassis frame that must not be tied rigidly to both.
What this page does not cover
- bent frame rails and structural straightening Repairing damaged original structure is a different discipline.
- repairable factory bumpers and body dents Repair before fabrication whenever the original can be saved.
- fiberglass and composite panel repair Non metallic structure, repaired by a different method.
Get a written scope before the damage spreads
We inspect on the lift, document the damage, and give you a written scope. The estimate fee is credited against the repair when you authorize the work.
If this damage is on an insurance claim
Custom fabrication reaches a claim in two ways. First, a collision destroyed a bumper, rack, or carrier that no longer exists as a replacement part, so the only repair path is fabricating a replacement. Carriers accept that when it is documented with parts unavailability, and it is a normal outcome on older coaches.
Second, the custom equipment itself was damaged. This is where owners get hurt, because aftermarket and custom equipment is frequently not covered under a base policy unless it was declared and scheduled. If you have several thousand dollars of custom racks, carriers, and boxes on your coach, read our page on custom and aftermarket coverage before you need it rather than after.
Why Brea owners bring this work to us
Very few shops will do genuine one off structural fabrication on an RV. General welding shops will weld what you bring them but will not take responsibility for how it mounts to a vehicle, and RV dealers install catalog parts. Brea owners come to our La Palma Ave facility in Yorba Linda because we do both halves: the design and welding, and the vehicle side of how it attaches and what it does to the structure.
Because we run a collision and structural repair operation in the same 35,000 square foot building, we know what a frame rail is actually made of before we bolt to it, and we see what happens to badly mounted equipment when it comes back on a claim. We have been here since 2015 under California Bureau of Automotive Repair license ARD00288521 and EPA identification CAL000367879. In shop only, with no mobile welding and no roadside calls.
Frequently asked questions
Should a custom RV rack be built in aluminum or steel?
Aluminum for anything carried high or where weight is critical, steel for anything that takes impact or tow loads. Aluminum is roughly a third the density but has no true fatigue limit, so it eventually cracks under enough cycles and needs generous sections and welds located away from peak stress. Steel is heavier, forgiving to weld, repairable anywhere, and the right choice for bumpers and hitch mounts.
Why did my aluminum rack crack next to the weld rather than through it?
Because welding 6061-T6 destroys the heat treatment for about an inch on either side of the bead, dropping the material from T6 strength toward annealed strength. If the joint sits at the highest stress point in the part, the softened band becomes the weakest section and cracks parallel to the weld. The weld itself is usually sound. The design put it in the wrong place.
Can you add a receiver hitch to a motorhome that does not have one?
Usually yes, but the capacity comes from what the receiver is tied into, not from the tube size. We locate structural frame rails, design a load path with plates and gussets rather than mounting to bumper skin, weld and bolt into that structure, and state the intended tongue weight and gross trailer weight capacity in writing. A receiver hung off a bumper is the most common unsafe installation we replace.
What is galvanic corrosion and why does it matter on my rack?
When aluminum and steel touch in the presence of moisture, they form a galvanic cell and the aluminum corrodes preferentially at the contact face. You see white powdery bloom at the joints and bolt holes that go oval. Every mixed metal joint needs nylon or fiber isolating washers, an isolating gasket at the contact face, stainless hardware, and a sealed joint. It is easy to build correctly and expensive to ignore.
Can you fabricate a part that is no longer available from the manufacturer?
That is a large share of what we do, particularly on coaches over fifteen years old where bumpers, brackets, step assemblies, and trays have been discontinued. We reverse engineer from the damaged original, from the mounting points if the original is gone, or from photographs and measurements of an identical coach. The replacement is usually stronger than the original because we are not building to a production cost target.
How do you keep a rigid rack from cracking a flexible RV frame?
By not tying it rigidly across two points that move relative to each other. We use one fixed mounting point and a slotted or floating second point, spread load over plates rather than concentrating it at a bolt, and add rubber isolation where vibration is the dominant input. Bolting a stiff assembly hard to a flexing chassis makes the assembly resist the flex, and one of the two loses.
Do you powder coat what you build?
Steel work gets blasted and powder coated or primed and topcoated, with weld edges sealed since that is where coating fails first and rust starts. Powder coating is sublet to a coater we work with regularly and shows as its own line on the estimate. Aluminum can be left bare, since it passivates naturally, or coated to match the coach. Stainless is typically finished mechanically rather than coated.
How long does a custom fabrication job take?
A simple tray or bracket is typically a few days. A bumper with an integrated receiver and a swing away carrier runs one to two weeks including design, mockup, fabrication, and coating. The coating turnaround is often the longest single item. We give you a schedule when the design is approved and hold the vehicle only for the portions that require it to be here.
Written and reviewed by the OCRV Center Technical Team. Last updated .
Book your paid estimate
We inspect on the lift, document the damage, and give you a written scope. The estimate fee is credited against the repair when you authorize the work.
Related repairs and pages
- frame and structural repair after impactStraightening existing structure, as opposed to building new.
- bumper and dent repairWhere a factory bumper is repairable rather than replaced.
- collision repairThe impact event that often precedes a fabrication job.
- solar panel and battery installationThe mounting structures we build for them start here.
- steps and lift gate mechanismsAccess equipment with its own mechanical scope.
- toy hauler racks and carriers
- diesel pusher frame mounting
- Sprinter van fabrication
- flatbed truck bodies and racks
- mobile workshop van builds
- coverage for custom and aftermarket equipmentCustom fabrication needs to be declared before it is damaged.
- how design and fabrication hours are quoted
- our fabrication and welding capability
- discuss a fabrication project