when i accelerate hard i hear a knocking underneath the floor of my car sounds like something is banging around, could it be a loose trans or engine mount? ANY SUGGESTIONS??? Thanks

 

Yep, could be both. Replace the trans mount and see if it goes away.

 

could it just be loose? why do i have to replace it

 

It's doubtful that it's just loose. The stock tranny mounts are nothing but weak rubber that break all the time. They're very easy to replace though, if you're worried about that.

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89 iroc-z 305 tbi
k&n filtercharger, open element air filter. nuffin' else

 

The nut to the tranny mount is 15mm and the 4 bolts holding the cross member on are 15mm.... one wrench does the job. Actually there's two bolts holding the tranny mount on but I'm not sure the size off the top of my head... probably 15mm too. Once you get the cross member off you'll know for sure if the mount it broken or not. I know when mine busted I could see it before I even started taking things apart. Guess someone failed to tell me that revving the engine to 3k and dropping the shifter into gear was bad. I found out one night when I did that and heard a big BANG right underneath me. No more neutral drops for me.

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1986 Trans AM
355 TPI
4 Wheel Disc Brakes
9 bolt Borg Warner Rear (2.77's....oh joy) :P
6" rods, approx. 9.7:1 Compression, Stock TPI (soon to be ported), 24#/hr LTI injectors (cleaned and flowmatched by Cruizin Performance), Hedman Shorty Headers, 3" exhaust with 80 series flowmaster, SBC 993 heads completely redone and modified for 1.6 RR, 1.52 RR (for now), Comp Cams XE262-14 TPI Cam, Holley AFPR, TPIS airfoil, MSD wires, MSD 6-AL Ignition, Hypertech 53,000 volt coil.

Track times to come.

 

Ouch. Drops like that are incredibly harsh on your tranny anyways. heh

 

yeah i have been quite hard on the trans, ive blown the trans on my last 2 cars

 

Have we learned anything yet???
If you put the car up on stands and get a jack positioned under the tranny you can verify that the mount is bad. Try to jack up the tailshaft of the transmission (gently and not too far). If it moves a lot the mount is busted. I could tell mine was gone just by looking at it. It was split right in half.
bsa