Banging under car when accelerating, NOT TRANNY MOUNT

**sezo** · 07-04-2014, 03:13 PM

Hey guys, so I've posted before about this but never came to a conclusion, and would like to ask for more help. So, when i accelerate from stop steadily, but quickly, I get a banging under the car. People have suggested the tranny mount, but I've had that checked, but the tranny mount is fine. A mechanic also suggested the motor mounts, but i took it to another mechanic and he said theyre fine. So, my last conclusion is the exhaust pipe. The whole exhaust is custom: long tube headers, into a Y pipe, high flow cats, and SLP loudmouth tips. After having a mechanic bring up the car, we can see that the whole end back side of the y pip (near the tips) is touching the body underneath the car. So, this gives me the conclusion that when i accelerate, the exhaust moves ofc, and slams the body. The mechanic said there was nothing he could do about it. I believe some of you might have experienced the same, so any suggestions on what i may do to stop this banging, or stop the y pipe from slamming the body underneath? If not the pipe, what else might it be? ALso, good thing to note, i once was on neutral at a red light, then when it turned green, i put it on drive, and stepped on the gas, and the bang was A LOT louder and stronger than usual. If this gives anymore information to what it might be, please throw me suggestions.. thanks fellas

**pajeff02** · 07-04-2014, 04:16 PM

Front torque arm mount - located on the side of the transmission. The stock piece is a rubber bushing that is clamped over the nose of the torque arm to a bracket with only a tab and a single bolt securing it.

**2002ssslp** · 07-04-2014, 07:36 PM

^^^^ What Jeff said.

***SMWS6TA*** · 07-05-2014, 06:06 AM

yep...most ppl forget that needs to be tighten or even install the bolt back. Has happen to me. The bolt came loose & backed out. Made one hell of a racket, scared the shit out of me.

**NoQuarter** · 07-21-2014, 09:01 AM

I just got my 99 SS Saturday, and when it downshifts from 60 mph, I had a bang against the floor (I guess). I'm getting her on the lift this afternoon at work and gonna check the mounts and torque arm.

***SMWS6TA*** · 07-21-2014, 10:19 AM

So Op find anything?

**sezo** · 07-21-2014, 06:28 PM

I haven't checked the torq arm bushings yet, not time between work. But i doubt it. When i had the tranny mount checked, they pretty much checked everything else and they said it was fine.I was told about a part by mufflex that make a clamp for the y pipe that keeps it from banging...i'm thinking it may solve my issue but i'm not sure how it's supposed to be installed, or where. Here's the link, let me know what you guys think:
Y-Pipe Support Bracket - Mufflex Performance Store

**sezo** · 07-21-2014, 06:29 PM

I do have long tube headers if that adds any idea

**raynor139** · 07-21-2014, 06:41 PM

I had a Texas speed y-pipe and it would bang constantly when taking off hard. Switched to true duals and I haven't heard a noise since.

**sezo** · 07-21-2014, 06:42 PM

Originally Posted by raynor139

I had a Texas speed y-pipe and it would bang constantly when taking off hard. Switched to true duals and I haven't heard a noise since.

Yeaa man it's a texas speed y pipe.. i guess i found the issue then

**pajeff02** · 07-22-2014, 02:08 AM

There isn't a whole lot of clearance between the driver side floor pan brace and Y-pipe. If that is the issue, you should be able to see where it is impacting the brace. Either adjusting the exhaust for better clearance or installing the bracket you found should fix the issue. On some cars, worn out engine mounts compound the problem as they allow the engine to sag in the front and push the exhaust closer to the underbody. A set of poly engine mounts may also remedy the problem.

**sezo** · 07-22-2014, 08:51 AM

Originally Posted by pajeff02

There isn't a whole lot of clearance between the driver side floor pan brace and Y-pipe. If that is the issue, you should be able to see where it is impacting the brace. Either adjusting the exhaust for better clearance or installing the bracket you found should fix the issue. On some cars, worn out engine mounts compound the problem as they allow the engine to sag in the front and push the exhaust closer to the underbody. A set of poly engine mounts may also remedy the problem.

Yeah i was told about the poly mounts but i took it to another guy and he said it wasnt needed, and since its a big job i didnt want to sped the 300+ dolllars. The y pipe actually has a lot of clearence under the driver side but the problem is in the back where the pipe splits into two, under the passenger seats and trunk. That's where the exhaust is directly on the body.

***SMWS6TA*** · 07-22-2014, 10:45 AM

big job??

It's $90 for the mounts and a couple of hours of time and patience to install.

**sezo** · 07-22-2014, 10:55 AM

Originally Posted by SMWS6TA

big job??

It's $90 for the mounts and a couple of hours of time and patience to install.

yeah the mounts are no problem, but don't you have to pull out the whole engine? the dude was gonna charge me $300~400

**pajeff02** · 07-22-2014, 11:03 AM

You can change the mounts with the car on ramps and a floor jack under the oil pan. It is even easier on a lift using a transmission jack to support the engine. As for the exhaust, everything from the Y-pipe back should be adjustable. Clearance is tight where the exhaust goes up over the rear axle, but by adjusting the insertion and rotation of the pipes it should all fit without banging.

**sezo** · 06-10-2015, 10:28 AM

i've been going crazy trying to get this fixed...i've purchased prothane mounts on ebay, went to the mechanic and he suggested i go to a muffler shop because it's most likely a problem with the pipes, where they can play with it. however, i went to one by the junkyard at citi field (i live in nyc), and these guys were goina charge me 20 just to check it out, i agreed. then, i told them be careful of the quarter panel tab thingy where if you lift it and touch it, it pushes out the quarter panel, also can crack the tab. he lifted, and sure enough the panel popped out a bit. i yelled to put it back down, i told him to BE CAREFUL, and he said it was already like that (yeah okay, i was staring at it as it popped out), then he took out the lift arms, and said "sorry i cant do anything, bye". so he wasted my time and cracked my tab thingy...cool. So, i went back to a muffler shop that i am familiar with (the last one was suggested to me by the mechanic) and he lifted it no problem (no charge) and basically said theres nothing at all he can do. he tried to move it as much as he can, he stuck a crobar in between the exhaust and yanked it to try to bend and try to lower it, and did what he could, and said try to drive and see what happens. he didnt charge me anything, but i gave him a 5 for the effort. this is the second time going to that shop (for a different reason) and every time he plays with it, the exhaust vibrates/slaps the floor board in different patterns. as of now, it vibrates/slaps in a quick session for like 2 seconds, then goes away. doesnt slap the floor board for as long as it used to, but the problem still is there. also, as he raised the car, i went under and checked it out with him, and the pipe is hitting the floor board in a couple places, it's not the entire pipe touching the floor, it is actually a little off from the floor board...but as i accelerate, it basically raises and slaps/vibrates violently on the floor board (you can see some of the marks where it scratches underneath). he's saying because it's such a fat pipe, it moves a lot...
i am a little iffy about getting the mounts replaced because im not sure that it will fix it, plus i dont wanna pay like 300, plus the 95 i paid for the mounts...im actually going to return the mounts today.