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

dsraven · 08-07-2019, 10:39 AM

like said, exhaust needs to flex some but the flexie pipe is more or less for the cradled engines in front wheel drive vehicles where the engine sits sideways and torques up differently than a rear wheel drive vehicle. these styles rotate the rear of the engine upwards under normal torque and if the engine mounts are worn out the flexie pipe is the first to let you know when it tears apart.
springs and donuts on the pipe to stock manifold and insulated rubber hangers down the line should be able to accept the flex in the system from engine torque. if you run headers then they will not have the flex at the engine end because they have a different header to pipe mount than a stock manifold with a donut so these would require a little more flexibility downstream in order to stop gasket leaks at the collectors and header to engine bolt up flanges. use a hanger with a longer rubber part if you can because this will allow more flex than some other more rigid rubber mounts. the newer style of rubber ring hangers work pretty good at absorbing vibration and also allowing quite a bit of flex. if using the flexie pipe on headers install where it will be able to deal with the engine movement from torque under load and also deceleration. also make both pipes, on a true dual exhaust, mount roughly in the same area on both sides so the whole exhaust system flexes at the same place and rate. this will give you the least amount of trouble from broken mounts, cracked pipes and leaky flanges. nothing worse than a nice looking truck that sounds like a fish wagon.
personally I like the rubber mounts like these because they are fairly easy to install by yourself and can be taken apart later easily without a worry of a seized u bolt etc. they also allow a bit more system movement than some of the more solid hangers. sometimes you want/need a good stout solid hanger though, so your system doesn't bump other stuff under the vehicle.

https://www.amazon.ca/Dynomax-36317-...56539090&psc=1

https://www.amazon.ca/Walker-Exhaust...92041793&psc=1

https://www.amazon.ca/Pypes-Exhaust-...66408854&psc=1

these styles ensures the pipes or mufflers hang straight and don't want to droop on one side from an offset hanger.

https://www.amazon.ca/Walker-36369-H...91380851&psc=1

https://www.amazon.ca/MBRP-HG6100-Fr...15102846&psc=1

08-07-2019, 10:39 AM	#5
dsraven Registered User Join Date: Nov 2010 Location: calgary alberta Posts: 7,866	Re: Exhaust Flex Joint Required? like said, exhaust needs to flex some but the flexie pipe is more or less for the cradled engines in front wheel drive vehicles where the engine sits sideways and torques up differently than a rear wheel drive vehicle. these styles rotate the rear of the engine upwards under normal torque and if the engine mounts are worn out the flexie pipe is the first to let you know when it tears apart. springs and donuts on the pipe to stock manifold and insulated rubber hangers down the line should be able to accept the flex in the system from engine torque. if you run headers then they will not have the flex at the engine end because they have a different header to pipe mount than a stock manifold with a donut so these would require a little more flexibility downstream in order to stop gasket leaks at the collectors and header to engine bolt up flanges. use a hanger with a longer rubber part if you can because this will allow more flex than some other more rigid rubber mounts. the newer style of rubber ring hangers work pretty good at absorbing vibration and also allowing quite a bit of flex. if using the flexie pipe on headers install where it will be able to deal with the engine movement from torque under load and also deceleration. also make both pipes, on a true dual exhaust, mount roughly in the same area on both sides so the whole exhaust system flexes at the same place and rate. this will give you the least amount of trouble from broken mounts, cracked pipes and leaky flanges. nothing worse than a nice looking truck that sounds like a fish wagon. personally I like the rubber mounts like these because they are fairly easy to install by yourself and can be taken apart later easily without a worry of a seized u bolt etc. they also allow a bit more system movement than some of the more solid hangers. sometimes you want/need a good stout solid hanger though, so your system doesn't bump other stuff under the vehicle. https://www.amazon.ca/Dynomax-36317-...56539090&psc=1 https://www.amazon.ca/Walker-Exhaust...92041793&psc=1 https://www.amazon.ca/Pypes-Exhaust-...66408854&psc=1 these styles ensures the pipes or mufflers hang straight and don't want to droop on one side from an offset hanger. https://www.amazon.ca/Walker-36369-H...91380851&psc=1 https://www.amazon.ca/MBRP-HG6100-Fr...15102846&psc=1