Replacing School Bus Side Body Panels: Patch, Stock Panel, or Custom Fab?
Custom Bus and Truck Panels · 2026-07-02
The lower side panels are the biggest patch of rust-prone steel on the bus. Here's how they're built, how to choose between a patch and a full panel, and how to get one that matches the contour.
The lower side panels run from the bottom of the windows down to the floor line, and they're the biggest single stretch of body steel on the bus. They also take the most abuse: salt spray, gravel, and standing water all live down there. When fleet shops and converters call us, side body is one of the most common things they're replacing, which is why we carry it for Thomas, IC and International, Blue Bird, and Collins.
How the panels are built
Factory side panels are thin steel, usually around 18 to 20 gauge, formed with a return lip top and bottom and attached to the bus posts with screws and structural adhesive, often hidden behind the rub rail. Contour matters here. Most of these panels aren't flat. They carry a slight crown or a body line that has to line up with the panels above and below, or the repair reads as a patch from across the lot.
Patch or replace
Same rule we use everywhere. If rust covers more than about three feet of one panel, replace it. Patching that much takes longer than swapping it, and you're welding fresh steel into corroded metal, so it comes out weaker. Patch when it's one isolated spot smaller than a softball and the steel around it is solid. Replace when you've got a long run of bubbling, several soft spots, or a creased panel with rust worked down into the fold.
Pull the rub rail first
The rub rail hides the top edge of the lower panel and a lot of the rust. Take it off before you decide anything. The panel almost always looks worse with the rail gone, and you may switch from patch to replace once you see how far it really goes.
Getting one that matches
For the common buses we stock side panels in standard sizes. If yours still has a readable part number, look it up and order the match. If it doesn't, and on a rusty bus it usually doesn't, measure the panel, note where any body line falls, and send photos from three angles. We'll match it to a stock panel or bend one to your contour. Custom side body is some of the most common work that comes through our shop.
Putting it on
- Pull the rub rail and any trim over the panel
- Cut the old panel back to solid steel at the posts, marking two inches past the visible rust
- Wire-wheel the posts and treat any surface rust you're leaving
- Dry-fit the new panel and check the body line against the panels above and below before you commit
- Attach it the factory way, screws and adhesive or weld, and put the rub rail back
- Coat the back. The original failed because nothing protected it from behind
Find your side panels
We stock side body panels for Thomas, IC and International, Blue Bird, and Collins, and bend to contour when the catalog doesn't have it.