EightBall

Right after the 1-2 shift, when I dump the clutch on max acceleration, it feels like something is jumping up and hitting the floorpan. It doesnt happen all the time, but most of the time. a dsm friend of mine mentioned that it could be a broken tranny mount, but he said he doesnt know much about f-bods. any ideas? I havent actually gotten under there to look yet...thanks

Fulton 1

iTrader: (9)

In my experience wheel hop feels something like driving over a washboard road surface. It'll cause the rear axle to shake or vibrate up and down when you're trying to get traction and will shake the **** out of the car's interior. This is usually pronounced on launch though, moreso than a shift.
If what you're describing is just one or two thuds/clunks on the floorpan then I would suspect the Y-pipe hitting the floorpan. Do you have an aftermarket Y-pipe? If so, then your clearance may be too tight. If not, then it could very well be due to a tranny mount or motor mount problem.

Just speculation of course...

EightBall

All I have done to the car is a lid, filter, and loudmouth cat back. when this hard thunk occurs, the tires dont really break loose on the 1-2 shift, which they did when the car was new...

EightBall

also, this doesnt happen when I do a burnout in first gear at all...that is totally smooth...only on the 1-2 shift under maximum acceleration...although it feels as though it is coming from directly underneath the front cupholder which is why my DSM friend suggested the tranny mount...would that be a warranty item?

Fulton 1

iTrader: (9)

Based on your description it really sounds like Y-pipe (or maybe tranny) banging the floorpan to me. I doubt the LM exhaust would be causing the problem, so it does sound like a warranty issue to me. The tranny mount is a cheap and relatively easy thing to replace, so if you're nervous about coverage or have a shitty dealer you might consider checking that yourself first.

Fulton 1

iTrader: (9)

Here's a good link if you're so inclined: http://www.installuniversity.com/ins...y_mount_m6.htm

Zero_FactiX

What about the I pipe hitting the Drive shaft I had that problem when i put My Hooker Catback on. Just had to bend the pipe a little.

EightBall

this is a good possibility, my LM catback keeps loosening up right at the y pipe/resonator connection which runs alongside the driveshaft...could be loose enough to come up and bang the driveshaft under hard acceleration. Ill check the driveshaft for marks I suppose

frey51

my LM comes loose there too, but I have a stock Y. Soon to be fixed in July with flps.

EightBall

yeah isnt it a bitch...makes an annoying *** rattling noise until it heats up to where the metal expands and causes the rattle to stop...makes the car sound like a POS

WS6FirebirdTA00

iTrader: (33)

i vote for wheel hop. my friends t/a did it and whatever was in the cup holder shot up. i dont think it coudl be the tranny mount if u can do a burnout adn not hear it. when u get heat in the tires it cleans the **** off lettin them spin smoother. what tires u have? its not lowered at all is it? if it was the tranny mount it would do it all the time. mine had nasty wheel hop all stock

EightBall

stock eagle F1's, stock suspension...but it never did this last summer and its only from an aggressive 1-2 shift, just to reiterate.

WS6FirebirdTA00

iTrader: (33)

yeah my friends car did this once his tires got older. its still weird it does it only goin to 2nd like that. might wanna just check out all the suspension. its easy to tell if somethin broke, just grab and shake it if it moves a lot thats the prob lol

TheSloth

sounds like a tranny mount to me... same thing was happening to me on the 1-2 shift until i put in one of those poly mounts

EightBall

whered you get it, how much did it cost etc?

WS6FirebirdTA00

iTrader: (33)

get it from any sponsor doesnt cost much just look for it

boondiggys

iTrader: (165)

well the torque arm on a burnout would push the trans down on the mount and then when you shift its letting up on it causing it to hit the floor..i would agree its a tranny mt. problem..i know i know you dont wanna get ur clothes dirty but you might have had it figured out by now...

EightBall

haha, oh I have no problem getting dirty...in fact I enjoy it, but Im livin in my apt right now and dont have any of my tools or jacks or jack stands etc and its kinda hard to get under the car without them thanks for all the advice, what you said really sounds like whats happening...I'll def check it out...

JLMoses

iTrader: (3)

a friend of mines Fbody did that and it was the Traction control doin something funky if i remember correctly

EightBall

nope, I turn that **** off as soon as I start the car every time...