exhaust rattle

[skippychad]

so I have heard a knocking rattle while at idle or when just barely giving the charger gas.  I thought it was the trans rattling but found it to be the exhaust pipes right under the driver and passenger floor boards...pipe comes in contact with undercarriage between the manifolds and the cross pipe of the exhaust...pretty much right where the trans mount bracket is.  the exhaust is only attached by the manifolds and the rear brackets.  Is there a easy fix for this?  Maybe manipulate the exhaust tubes with a hammer? Or do they make heat resistant bushings I can slide between the undercarriage and the exhaust pipes?  thanks

[XH29N0G]

I am not an expert on this, but I think the proper fix for this would not require some sort of spacer but depends on getting the proper geometry.

I do not thing there is a problem bending or having the exhaust pipes bent.  I have done that (bending pipes up using a jack, bending them in other directions using various pulley/come along apparatuses).  there are pipe benders, but I don't have any.  I would think a shop that does exhaust could also fix it.  You just don't want it hanging too low, and it might be that when installed, that was the aim, but got it too close.  It is at idle, so not something where the engine is moving because of faulty mounts. 

I have a few general questions. 

• Did this just start happening?  Or has it been there for as long as you can remember?
• By any chance do you have an RB (440) and could you have drop pipes for a B (383 or 400)?

[skippychad]

383 motor.  new mounts for the motor but was happening prior to motor remove and reinstall.  in park or neutral...no issues.  set brake and put in gear and theres the rattle/knock.  rattle tends to go away once you get going, but initially when gassing it in gear you hear it pretty good.

[XH29N0G]

So my guess is just that the exhaust was fabricated in such a way that it ended up close to the bottom of the car.  I also have a 383 and put headers for a 440 and the exhaust was way too low (that is why I know about bending it).  The new motor mounts (and the way it behaves) suggests to me that it is simply the exhaust.  There are materials you can use to shield, but I think the easiest (and right) way will be to have it bent a little where the tube drops down from the manifolds and bends to the rest of the exhaust under the car. 

[ODZKing]

Naturally it depends on where the rattle is coming from. I looked all over for mine and couldn't quite pin it down. Until I took it to a shop and he put it up in the air running.
Short answer was it was something that had loosened in the machine-gun exhaust tip. since they are welded together it will prolly never be fixed but at least now I know what it is.

[green69rt]

so I have heard a knocking rattle while at idle or when just barely giving the charger gas.  I thought it was the trans rattling but found it to be the exhaust pipes right under the driver and passenger floor boards...pipe comes in contact with undercarriage between the manifolds and the cross pipe of the exhaust...pretty much right where the trans mount bracket is.  the exhaust is only attached by the manifolds and the rear brackets.  Is there a easy fix for this?  Maybe manipulate the exhaust tubes with a hammer? Or do they make heat resistant bushings I can slide between the undercarriage and the exhaust pipes?  thanks

Any type of bushing that you put between the body and pipes would probably transmit the exhaust noise directly to the pass compartment so not a good choice.  If it happens when you put in gear with brake set, then it's probably the driver side pipe because the engine is torquing over a little causing the left pipe to rise.  My guess is that any solution other than having the pipe bent, to clear, isn't going to work well. 

You might do a little test.  Get some welding blanket and stuff between pipe and the body and see if the noise goes away.  That will confirm the problem.

Just thought while I was typing, you might try this motor mount fix to keep the engine (and the exhaust pipes) from moving so much.
http://www.dodgecharger.com/forum/index.php/topic,13216.0.html

[skippychad]

it is definitely more prominent on the drivers side....and the exhaust hits is the frame where the trans mount link is..