My Long Tube header build

[malibuguy]

Originally Posted by xnamerxx

The stock motor doesn't have a flex joint, it uses a ball and socket joint. The reason the joint is located where it is stock is because that's the easiest and cheapest place to put it. There does have to be some flex in the exhaust and ideally it should be as close to the motor as possible but you work with the space you're given.
The exhaust itself is hung which allows some movement there so the only reason you even need flex in the exhaust itself is to reduce the wagging motion of the main pipe and reduce load from the header. If you look at the header there is a support beam the bolts to the block and the header and that's what's carrying most of the fore and aft load from the header which is another reason why the ball and socket is located where it is. I've done some analysis on this I have an idea of where the load is sitting. If the side bracket isn't in place all of the load will sit on the flange and the failure will be located on the flange, if the side bracket is in place the pipes are thick enough to handle most of the load but the secondary flange will still be taking some load under movement but its substantially less with the flex joint in place. So to get some flex I chose a flex joint over a ball and socket because its easier for me to incorporate it the multiple center section exhausts that I have.

the motor mounts in our cars are incredibly soft & these motors go all over the place. a flex joint at the end of a 3-4foot long 'lever' would not be adequate.

to get an idea of how much front scratchers (FWDs) boucne about. go to your local test-n-tune with all the kids beating the fuck out their cars...its quite alarming.

the flex joint NEEDS to be located as close as possible to the motor to reduce the leverage on the rest of the exhaust, period. the further away it is, the less its able to absorb.