Sinister_Z28

Ok so i got a 98 z28 M6 that i just put a Iron 408 in. So i was driving to work the other night and when i shifted from first to second around 3500 RPMs and floored it immediately after the shift i heard a loud pop from behind me. It sounded like i just snapped something. So i coasted over to a parking lot and looked under the car absolutely no fluid leaking and the car wasn't making any funny noises and nothing looked out of place. Well today i crawled under it and still no fluid was found and nothing is obviously broken. So what do u guys think would make that noise without any obvious damage to be found. Just so u guys know i haven't modded the suspension or rear since ive owned it and im on cheap street tires. I know im on borrowed time with a stock drive train and rear end but im currently saving for a Strange S60 and supporting drivetrin and suspension mods. So where/what should i be looking for that caused this sound.

99Bluz28

iTrader: (35)

How about the TA(torque arm) and drive shaft ?

AndersonsSS01

Did you put a polly tranny mount in it? Because that sounds like that could be something that could have went out by the way you explained what happened and wouldn't cause and fluid leaks, or possibly the torque arm mount. They get pretty week when you start throwing a bunch of power at them.

Sinister_Z28

I looked at the torque arm and it looked fine wasnt broke but it looked kinda bent. Also sometimes when u floor it the trans will move a little cause i can feel my shifter move. Is that a bad mount? Also what mount was it. I do know that i torqued every thing i took off suring the swap back to spec so it isnt a loose bolt. Also on my torque arm it looks like it has some thing sprayed on it like a ruber sealer ill load pics later. And it isnt grease and grime its hard and rough.

AndersonsSS01

It wouldn't necessarily be the torque arm it self that is bad, but the rubber mount where it mounts to the tail shaft of the tranny. I have seen them go out on several vehicles and they will knock under acceleration. You said that the shifter moves and yes that could be a sign of a bad tranny mount as well if there is alot of movement.

Sinister_Z28

So basically i need new trany mounts and a TA mount?

Sinister_Z28

So bassically i need a new TA mount and tranny mounts?

99Bluz28

iTrader: (35)

You'll have to get under you car and physically check to be sure. The TA mount could be broken or the bushing trashed, and the transmission rubber mount might also be trashed.

Sinister_Z28

When i was under it last night they didnt look broke but they deffinitely looked old and worn

TakeaShift

Lately I have been getting a clunk/knock noise on the underbody under hard acceleration that would otherwise cause wheelspin or wheelhop (on hard launch or fishtailing a corner). The car is fine between normal shifting.

At first thought it was related to the exhaust, at nearly the same time I had re-adjusted & raised it, thought it was hitting from engine roll.. but at the same time had visions of a cracked torque arm.

Haven't gone under to look at it closely yet, but based on this thread have just ordered a new TA mount bushing. Will swap it out either way once I do get under the car. Thanks for posting info

http://www.jegs.com/i/Energy+Suspens...1111G/10002/-1

Sinister_Z28

Yeah for me it happens when i grab second gear on a wot pull then its gone.

TakeaShift

it only occurs when shifting into 2nd ?
Not when pulling off hard from a stoplight in 1st

San Diego Car Guy

Geez, now I'm thinking it is tranny related. But it doesn't make the sound under normal (not WOT) driving, right.

Sinister_Z28

Basically it only made the pop when the power hits the rear heels and they hook. It makes no weird sounds under normal driving conditions. And the trans works flawlessly. Also when i pulled the trans during the engine swap when i drained the fluid the fluid looked like it was new. No burn smell or dirty trans fluid. I hadnt even touched the trans since i bought the car and i put 5000 miles on the car after i got it before the engine went.

Sinister_Z28

It has also done it in first when the tires hooked coming out of a burn out. I thought i broke my rear but that isn't the case.

RevGTO

iTrader: (12)

Sounds like a tranny mount to me. The rear of the tranny would smack the tunnel on a hard 1-2 shift on my M6 car. When I pulled the mount, it looked perfectly fine. Replaced it and problem solved.

Sinister_Z28

Which tranny mount are we talking about. Is it the one on the passenger side by the back of the tranny?

99Bluz28

iTrader: (35)

Bottom rear, between transmission x-member and trans tail shaft.

Sinister_Z28

Sorry to resurrect a old thread but i think i found my problem and im baffled at what i found. So ive just started installing my tsp true duals today and when i was under there i was just looking around and i noticed a little drop of trans fluid on the bottom of the tail shaft so i started looking for where it came from. I found that one of the stud/ bolt that holds the torque arm mount to the tail shaft was gone. Like it just vanished. I know for a fact it was put back on during the engine swap. It was the bolt closest to the front of the trans. Needless to say i can wiggle my torque arm a little with one hand. Maybe the two pops i heard coming from the rear was that bolt breaking/ cracking. What are ur guys thoughts?

SuperSport01

A UMI or BMR torque arm relocation trans crossmember is what I think. Get the torque arm off the side of the trans. If you broke the bolts that hold the torque arm mount onto the side of the trans without breaking the trans tailshaft you're lucky. GM is retarded for putting the torque arm mount on the trans anyway.