I dont know what it is. When I accelerate quickly something bangs on the floor pan or something in the mid rear. I cant really point it out. I thought it may have been my y pipe but i cant find any shiny areas to see where it bangs.


This dosnt happen when im going cruising speed and then i punch it. only during accelerations.

 

This just started happening to me after I reinstalled my y-pipe. Looked under there and couldn't see anywhere where it would be hitting so I just pulled the y-pipe down a bit from the floor pan and the banging/vibrating noise under quick acceleration stopped. Just gotta pull the y-pipe away like a 1/4 of an inch.

 

Still have stock motor mounts? If so my first guess would be Y pipe.

 

yes stock motor mounts. at this point im not going to pull the mounts and replace until i get my new engine. when i first installed my system it wouldnt bang. but after a year it started. everytime during hard acceleration it bangs like a ****. ill try to reinstall the y pipe.

 

Poly engine mounts will fix it. This is the most common problem associated with puting LT headers on a car. You won't even notice poly engine mounts so dont worry about vibrations. Just dont pair them with a poly trans mount. Most people experience extremely bad vibrations when the put a poly trans mount in.

 

Its your Y pipe hitting the floor board. Get some poly mounts and it will fix your problem

 

So for the trans mount, just replace it with stock rubber mount? Or some higher durometer one? Any advice on which?

 

Stock rubber. There's plenty of bracket racing cars that still run the rubber mount.

 

I'm having a shop install my headers and told the guy I wanted to a poly motor mount and stock trans mount. He immediately told me not to do it that the ride will be nasty even with JUST poly motor mounts.

 

That's because he's never actually ridden in one with poly engine mounts... or he's like that fairy tale princess that could feel the pea under ninety mattresses. Ask him, just for curiosities sake, how many cubic inches he thinks your car is, and whether or not having full 3" exhaust pipes on your car would be a good thing. If he gives you the typical exhaust shop answers "350, and it needs back pressure" then just nod your head and explain to him that you want him to do what your paying him to do and that's it.

Adding a poly trans mount will most likely be horrible. Some get lucky and don't have any vibrations, but most do. I could watch coins walk across the carpet at 55 mph. If you've got any sort of imperfection then the poly trans mount with exaggerate it. Start with poly engine mounts only. If you really want to firm it up then start upgrading your other suspension stuff.

 

some guys have been know to stick a spacer in thier between the y-pipe and the floor pan, i didnt do it. Eventually it will stop from beating on the car so much. I was going to do the poly motor mounts when i did my headers but it took us so long cause we were on our backs i said **** it, that was quite i few years ago now. Anyway, polly mounts should fix u right up sorry for the rant.