shanebang76

Anyone else having trouble with thier longtubes "thumping" the floorboard?? Mine will do it when I first take off in first...thats about the only time...when I initially get on it, not the whole pull. Checked the trans mount..its fine, its a new energy susp. one. Dont think its the Y-pipe cause it feels further up, like under my feet..

Cstick

I have a banging problem, but its my y-pipe. I am going to install poly motor mounts which I have heard from many people fixes the problem.

shanebang76

The ones on the frame or the ones on the motor?? My motor does seem to move alot when I rev it up with the hood open...

shanebang76

The ones on the frame was one of the hardest jobs Ive done on my old Camaro. Royal PIA!!

DanBUCF

I have this problem from time to time as well.

ShaneS

Common problem on some longtube brands (usually FLP though). I've heard that the poly tranny mounts can actually make it worse though (by moving the tranny - and engine - slightly closer to the floorboard.

Some people have had luck using a BF hammer to add some clearance in the contact spot. Others (myself included) have used a band clamp and some heater hose (or heat-resistant rubber exhaust mounts) to insulate & deaden the contact. And, still others have upgraded the engine mounts as mentioned above...
good luck

Cstick

$50 gets you poly mounts for both sides. You have to take your mounts off, drill the rivets out so you can split the mount in two, take out the factory rubber, put in the new poly, and bolt it back together, and slap it back on the car. Now I do not think it is that easy but I will find out. I have read it can be done by removing the altenator, and A/C with headers still on the car. Replacing the driver's side is the most beneficial.

TA_LS1

i had the exact same problem as u but i fixed it by pounding up the floor board where it banged like 1/2 inch or so

teke184

the poly motor mounts will make all the difference in the world.

my engine moves less than 1/4" when reved up compared to well over 3/4" previously, and the mounts only had 55k miles on them.

my ypipe doesn't even move when reved now and is less than 1/2" from floor and has never hit.

NOW THE BAD NEWS

with the manifolds on it took me over 10hrs to swap the mounts. most of that time was spent trying to get the mounts out of the car. i tried every possible combination of raised motor, raised tranny, raised one side then the other....it was HELL.

when i installed my headers a month later and had the manifolds out, it would have been a 1hr job to do
now with my LTs i've looked up in there, and i think there is LESS room than with manifolds! so i think it would be many times worse with headers compared to manifolds.
probably better off removing the headers, at least unbolting them and sliding em out of the way a bit.

i have some pics of my mounts about 2/3rds of the way down the page

CollectorTA

BFH Method will be the easiest just look and see where it is hitting and it should only need a little reshaping if it is hitting your floor board. If it is hitting your K-Member then that will be another issue and you will have to notch it out not too hard but sometimes these things are harder to find than fix look for marks from the headers and Y-pipe on your car first.

Droopy

had the same problem when i installed my quicktime LT's. it being so tight and snug for good ground clearance it banged for a little while. just give it time and let it settle in...soon u wont notice as much and then it ceases all together.

i wouldnt give up any ground clearance...see if it adjusts itself before you start pounding on it with a hammer!


dave

shanebang76

Found where it the y-pipe was hitting the frame. Got the muffler shop to pry down on the y-pipe with a pry bar and when they welded in my new muffler, it was just right. Hasnt banged once since......Also... Just got my new chambered "powerstick" muffler installed and it is a world of difference from the LM resonator. Got the 18 inch 3" muffler and it took away just about all of the raspiness and popping from the LM away! Still almost as loud on WOT, but MUCH mellower when off the throttle! Just my 2 cents!!