Why Parts Don’t Fit!

Why Don’t My Parts Fit?

Restoring a classic car can be a very rewarding experience, and a frustrating one too. Seeing your vision come together is a great feeling, but sometimes installing replacement parts on can be frustrating. More often than not it seems like the parts are close, but just don’t fit that well. These manufactures do know what they are building parts for right? So why don’t the parts fit?

Recently we were working on a ’55 Bel Air. We were installing a rear bumper from Classic Industries. At the end of the installation we realized how great the bumper fit. The gaps were equal, we didn’t have to fight it, and it went together smoothly. That got us talking about all the parts we’ve installed that do not fit. More often than not, we’d have to modify a brand new part before we could get them to fit even though they are new.

What we did was call up Classic Industries and asked them simply, why don’t some parts fit? Gabe Flores chimed in and gave us some perspective as to why parts might not fit – it’s not from a lack of trying. “Obviously our goal is to carry and sell the best parts out there that are the highest quality and have the best fit and finish. There’s a ton of variables that go into making parts that most people don’t realize,” stated Flores. 

Limited Choices

For starters, Gabe told us sometimes there just aren’t many options. There might be only one manufacturer making a part and that’s all that there is. This means that maybe the part doesn’t fit the best, but it’s better than having no part at all. In some instances there might be three or four different manufacturers and they are able to choose the best one. It really depends on the part itself. 

Second, these classics are old. They’ve been driven thousands of miles, been in fender benders, and who knows what else. “You’d be surprised at how different two identical cars can be after so many years. Things wear out differently and one might have been repaired in its life. If we have a part developed off one car, it might not fit the next car very well. We try to test fit numerous vehicles each time,” Gabe told us. 

We’ve seen this ourselves. These cars are 50 years old in most cases and have a long history. On our Project No-Name Chevelle, the previous owner told us it had been in some sort of accident in the rear but everything looked great. Stripping it down we found 1″ thick bondo on both rear quarters and some terrible welding. That meant two new quarter panels were in order and who knows how well they would fit on a crashed car. 


Another consideration is modifications. When you upgrade one part, the components that surround the new part might not fit, Gabe explained. For example, when we ditch the factory manifolds and install headers – now the factory exhaust doesn’t fit. Or maybe we upgrade to a modern overdrive transmission which requires modification to the transmission tunnel and cross member. We have the best of intentions for upgrading and modifying these cars, but that doesn’t always mean everything is going to work together properly. 

“Remember too that these cars weren’t perfect even when new. They didn’t have perfect 1/4-inch gaps on all the body panels. Nobody expected that back then, and to expect it now after you install new parts– you’re setting yourself up for disappointment. You often have to put in some extra effort to get professional-grade results,” stated Gabe. 

At the end of the day there are a number of reasons why parts might not fit perfectly. That isn’t from a lack of trying on the manufacturers part and it doesn’t mean companies like Classic Industries want to sell you subpar parts. Their goal is to stock the best parts they can, so you can keep your project moving along.