What is the difference between unibody and body-on-frame repair?

A unibody has no separate frame. The body panels, floor pan and structural members are one welded structure, so a hit to a rocker or a pillar is structural damage rather than cosmetic. A body-on-frame truck has a ladder frame underneath and a body bolted to it, so the two can often be repaired independently. Sprinter, Transit and ProMaster vans are unibody. Cutaway chassis, box trucks and most commercial vehicles are body-on-frame.

Can a unibody van be straightened, or does it have to be replaced?

It can be straightened. Unibody structures are pulled on a rack the same way a frame is, anchored at factory reference points and measured against specification. What is different is that the tolerance is tighter and the structure is less forgiving of repeated pulls, so getting it right the first time matters more. Sectioning is also more constrained: manufacturers publish where you may cut and where you may not.

Is a repaired unibody as strong as the original?

When it is repaired to manufacturer procedure, yes. That means pulling to specification rather than to close enough, sectioning only at approved locations, using the specified weld type, and replacing rather than heating and straightening any high-strength steel component that the manufacturer designates as non-repairable. Cutting corners on any of those produces a vehicle that looks correct and behaves differently in the next impact.

My Sprinter conversion has a full camper build inside. Does that complicate the repair?

Considerably, and it is worth knowing before you file. Structural repair on a unibody needs access to the inside of the shell, which means the build comes out and goes back. Cabinetry, insulation, wiring, plumbing and solar all have to be removed, stored and reinstalled. That labor is real and it is frequently missing from an adjuster's initial estimate, so we document the build at teardown with photographs and submit it as a supplement.

How do I know if my van has hidden structural damage?

Doors that no longer close cleanly, a sliding door that binds or drops, uneven gaps between panels, a windshield that cracked without an impact, and water finding its way in at a seam that used to be dry. Any of those after even a modest impact is worth measuring. On a unibody the structure is the body, so a symptom that presents as a fit or leak problem is frequently a structural one.

Unibody and Chassis Repair for Vans and Trucks

Unibody and Chassis Repair

In short: Unibody vans and body-on-frame trucks fail in opposite ways, so a Sprinter with a crushed rocker and a box truck with a cracked rail need entirely different repair strategies even though both get called chassis work.

Typical range

$2,500 to $15,000+

Labor hours

12 to 70 hours

Updated

July 30, 2026

Chassis work covers two fundamentally different structures that get discussed as though they are the same thing. Getting the distinction right determines the whole repair strategy, and getting it wrong produces vehicles that pass a visual inspection and behave badly in the next impact.

Unibody: the body is the structure

Sprinter, Transit, ProMaster, Metris and most modern cargo and camper vans are unibody. There is no separate frame. The floor pan, rockers, pillars and roof rails are a single welded structure engineered to manage crash energy along designed paths.

This has three consequences.

There is no such thing as cosmetic damage to a structural member. A crushed rocker on a unibody van is structural, even when it looks like a dent. The rocker is a load path.

Repair is procedure-driven. Manufacturers publish where a section may be cut, what weld is required, and which components must be replaced rather than straightened. High-strength and ultra-high-strength steel loses its properties when heated, so a component made from it is frequently designated replace-only. Straightening it anyway produces a part that is the right shape and the wrong strength.

Tolerance is tighter. A quarter inch out on a truck frame is a problem. A quarter inch out on a unibody is a door that will not seal and a structure that will not fold correctly next time.

Body-on-frame: two structures that can be treated separately

Cutaway chassis, box trucks, semis, flatbeds, refuse and utility bodies and most commercial vehicles have a ladder frame with a body bolted to it. The frame carries the loads, the body carries the cargo.

The advantage is separability. A damaged body can often be repaired or replaced without touching the frame, and a bent frame can be pulled with the body lifted off. The failure mode is different too: body-on-frame chassis crack at mounting points and sag under sustained overload rather than crumpling.

Our frame straightening service covers the ladder-frame side of this in more depth.

What the work involves

Measurement against specification. Unibody or ladder frame, the first step is the same: anchor the vehicle and measure reference points in three planes against manufacturer data. We produce a before sheet and an after sheet.

Access. On a van conversion this is the expensive part nobody budgets for. Cabinetry, insulation, wall panels, wiring runs, plumbing, solar and battery banks all come out to reach the shell, get stored, and go back. On a commercial vehicle it may mean lifting a body off the frame.

Pulling. Hydraulic rams against anchored reference points, in increments, with re-measurement between pulls.

Sectioning and replacement. Where a member is beyond recovery, it is cut at a manufacturer-approved location and replaced. Weld type follows the procedure, not preference.

Corrosion protection. Every cut and weld gets sealed and coated. Bare steel inside a rocker is a rust problem on a two year fuse.

Reassembly, alignment and road test.

What it costs

Job	Typical range	Labor hours
Single-panel unibody repair with pull	$2,500 to $5,500	12 to 26
Multi-point unibody straightening	$5,500 to $11,000	26 to 50
Unibody sectioning with panel replacement	$8,000 to $15,000	40 to 70
Camper build removal and reinstall around the repair	$3,000 to $12,000 additional	15 to 55

Structural labor is $260 per hour, body labor $210. The build removal line matters: on a fully converted Sprinter it can approach the cost of the structural repair itself, and it is the line most frequently missing from a carrier's first estimate.

Vehicles we handle

Mercedes Sprinter across all generations including gas and diesel, RAM ProMaster, Ford Transit, Mercedes Metris, Nissan NV, Chevrolet Express and GMC Savana, electric delivery vans including Rivian EDV platforms, Class B camper vans built on any of the above, cutaway chassis under Class C motorhomes and shuttle buses, and body-on-frame commercial trucks across the range.

Converted vans are the most common and the most misestimated. A Sprinter with a professional camper build is three vehicles in one repair: a structural job, an interior job and a systems job. Treating it as a van with a dent is how a repair goes wrong.

The hidden damage problem

On a unibody the structure and the skin are the same object, so damage propagates in ways that are invisible from outside. The signs worth taking seriously are a sliding door that binds or has dropped, uneven panel gaps, a door that needs a shove, a windshield that cracked without being struck, and water at a seam that was dry.

Any of those after an impact justifies a measurement. Our hidden damage assessment is the process for finding out, and it exists because the alternative is discovering the answer two years later when the leak has already destroyed the floor.

Estimates are $150 and credited back against an authorized repair.

Bring us the job the other shop turned down

We work on all years, all makes and all classes, from Class A diesel pushers down to enclosed cargo trailers. Estimates are $150 and are credited back against an authorized repair, so the money goes toward the work rather than to a shop that never touches your vehicle.

23281 La Palma Ave, Yorba Linda, CA 92887 | (949) 799-3387