Exhaust flanges are one of these little unobtrusive parts which most people don’t pay much attention to until something goes wrong with them or they’re trying to tune their exhaust system. Then it appears that these parts suddenly become important, which can annoy and frustrate many DIY mechanics. The exhaust flange performs an important and simple function. It’s what attaches the exhaust to the port on the engine’s head.
Without it, the exhaust header won’t be able to stay in place and the engine would vent right onto the rider’s leg or into the air. This will result in a lot of noise as well as some burned legs. So like most engine parts, an exhaust flange has to fit the vehicle that it is attached to. If it doesn’t, it can cause exhaust leaks, with the associated hot legs and noise. Even so, they can still be customized. The trick is in knowing which customizations are usable on what types of cars. Exhaust flanges can be purchased at car parts shops and on the internet.
There are several types of flange designs on the market. The most common works with exhaust pipes which are flared at the end. This flared end butts against the flange with a collar on the pipe to hold it steadily. An alternate design is the ball design, which has the header pipes bulged out just before the end. The bulged-out portion of the header pipe meets with the flange on the engine. Ball type exhaust flanges don’t require a gasket as the engine side of the bulge mates directly with a tapered part on the flange, providing a seal. Standard flanges do require an exhaust flange gasket, as the flange itself makes the seal with the end of the header pipe.
This is a very high temperature application, and the gaskets are normally made of soft metals, at times mixed with gasket material. If paper is used as part of the manufacturing process, it’s treated to allow it to resist heat without igniting. The exhaust flange gasket can take multiple forms, including tapered rings, crush rings, steel rings an steel mesh rings.
The flange clamps are attached to the exhaust flanges on the engine with either two or three mounting nuts or bolts. The pattern of this mounting hardware, including its distance from the pipe, location and size of hardware are all particular to the design of the engine. Without the right flange collars and flanges, the exhaust can’t be sealed correctly to the engine.