The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - 47-55.1 Exhaust Flex Joint Required?

1project2many · 08-07-2019, 05:01 PM

So...

1) Engine flexes, chassis flexes, exhaust must allow for flexing.
2) Steel changes size approximately 0.000016" per degree, up to an inch for a 9' exhaust system with catalytic converters.

You must allow for engine flex and thermal expansion. Stock systems use a "doughnut" or cone and cup type of seal that allows engine rotation. I have found that installing a cup/cone coupling into a vehicle with headers improves header gasket and exhaust system life considerably. When it comes to exhaust pipe hangers they must be installed so that the exhaust can move fore and aft. "Universal" hangers with a single pivot point are not as good a choice imo as the "dual pivot" hangers in the links provided by dsraven. In most cases with RWD vehicles the flexible mesh pipe is not needed. It is used in front drive vehicles to account for high degree of engine rotation which results in both fore and aft and vertical motion at the exhaust coupling.

08-07-2019, 05:01 PM	#8
1project2many Registered User Join Date: Mar 2012 Location: Lakes Region NH Posts: 3,158	Re: Exhaust Flex Joint Required? So... 1) Engine flexes, chassis flexes, exhaust must allow for flexing. 2) Steel changes size approximately 0.000016" per degree, up to an inch for a 9' exhaust system with catalytic converters. You must allow for engine flex and thermal expansion. Stock systems use a "doughnut" or cone and cup type of seal that allows engine rotation. I have found that installing a cup/cone coupling into a vehicle with headers improves header gasket and exhaust system life considerably. When it comes to exhaust pipe hangers they must be installed so that the exhaust can move fore and aft. "Universal" hangers with a single pivot point are not as good a choice imo as the "dual pivot" hangers in the links provided by dsraven. In most cases with RWD vehicles the flexible mesh pipe is not needed. It is used in front drive vehicles to account for high degree of engine rotation which results in both fore and aft and vertical motion at the exhaust coupling.