Technical Exhaust question

Can I mount my exhaust system solid to the chassis as long as I install a braided flex joint between the headers and the first mounting point of the exhaust system?

 

Don’t see why not

 

I believe that is what the flex joints, actually called Bellows were designed for. However there is also a reason for rubber hangers mounting the rest of the exhaust system. It's called resonating sound transfer. Depending on the rest of the Vehicle you may or may not be able to live with it.

 

Is there some specific reason that you would need to do that? I mean, sure, you could do that but why would you want to. You would need to consider the thermal expansion of the tubing. It's going to grow lengthwise a wee bit when it gets hot. You could rigid mount one end and rubber mount the other. Is this for street use?

 

Only if you want noise transferred to the chassis. A lot of noise, me thinks.

Ben

 

To find the parts your talking about go to S.P.D. Exhaust sight, click on accessories then on Bellows.

 

Thanks guys....gives me something to ponder

 

I did it but put rubber isolators on each hanger.

 

The first one behind the expansion bellows is going to get hot. Others going back progressively cooler. Otherwise you did isolate them for vibration and sound. They should have a type of locking nut so they can be snug but not tight. Not nylon..

 

Looks to me like the hanger will pass the vibration through the bolt to the frame ,I don't believe thee rubber washer is going to do much ..Nice & clean though ..

 

Absolutely.
Done it several times.
I hate those rubber or belt exhaust hangers
I do use a cushion to insulate the mount.
As far as a reason why folks do this, I do it on lowered vehicles. Tucks the exhaust up.

 

Here are a few online pics.
I usually build something like this last one

 

Passes my basic sniff test. I would and often do use a piece of 3/8" tube and sleeve the tube for the bolt to pass through. Now you have a flat surface for washers on both sides. Just a different way to skin the cat.

 

The bushings are stepped and go through the hanger so the hanger never touches the bolt. I’m hoping that will take care of vibration transfer.

 

never had a vibration issue, especially in loud, big cam stuff we built
or just was never able to notice one

 

I have not had good luck with these types of isolators. They wear through the polymer and pretty soon, you have metal to metal. I had to replace them all on my Plymouth. YMMV.

 

You did good!

Ben

 

I also have used an aluminum spacer between the hanger and body.
I kinda like this better than the rubber bushing.

 

As long as there is a rubber or other means of isolation go for it. In the title it kind of represents that you would attach it solid to the frame with bolts or welding. That would not be recommended due to the chassis flex and heat expanding and contracting the tubing. You will definitely want more than one flexible joint between the exhaust system and the engine.

 

Every situation is different.
I have severely dropped unibody cars, you don’t have much room for exhaust. I have tucked exhaust in the trans tunnel. Those were directly bolted to the body. Of course a flex was used between the headers and exhaust. No issues.
On my bus, 3 out of 4 standard parts store flexible hangers broke. The section bolted to the chassis didn’t. That’s with 30k+ hard miles on it.