By John Blais
I think equal opportunity legislation requires car companies to hire a certain quota of monkeys for their design teams.
I have two Japanese vehicles, a Nissan Maxima and a Honda Odyssey both of which experienced the same design related problem: unnecessary difficulty in repairing a gasket failure between the catalytic converter and exhaust pipe connection. I suspect it’s a common problem with many makes. The catalytic converters have integral connecting studs made of corrosion prone steel. These studs are on a mounting flange that mates with a mounting flange on the pipes at both ends of the converter.
Hex nuts go over the studs. After a few years, the studs/nuts become unrecognizable lumps of rust, probably due to the high temperatures in this area of the exhaust. To repair a gasket failure between the converter and the pipe flanges on either side of it requires grinding off the studs/nuts. Assuming the converter still meets spec, the studs then have to be drilled out of the converter so that hex bolts can be fitted to reassemble the exhaust system. This is difficult and time consuming but less expensive than replacing the converter. Why in the world would they not use bolts instead of studs in the first place. I suspect studs save about three seconds of assembly time per vehicle in the factory, but it makes repairs much more difficult. While they’re at it, why not use stainless nuts and bolts?