is my transmission mount done?

**Z28pwrHecz** · 03-13-2009, 01:03 PM

I haven't had my car check because I haven't had anytime, but I was wondering if my transmission mount is out. when I'm at mid rpm on any gear, and I accelerate hard, I can feel and hear a thump coming from under the car. It also happens when I'm taking off on first gear and the car boaghs down. Have any of you guys gone through this?

**Rhinohuey** · 03-13-2009, 01:50 PM

thats what it sounds like. Mine did the same thing. I just replaced it with a poly mount....my rubber one was torn completely in half

**Justin23454** · 03-14-2009, 09:29 AM

Originally Posted by Z28pwrHecz

I haven't had my car check because I haven't had anytime, but I was wondering if my transmission mount is out. when I'm at mid rpm on any gear, and I accelerate hard, I can feel and hear a thump coming from under the car. It also happens when I'm taking off on first gear and the car boaghs down. Have any of you guys gone through this?

Mine does the same thing! Is it easy to replace the transmission mount if this is the case?

**silversho89** · 03-14-2009, 11:56 AM

Its easy to replace. Support the tranny with a jack, unbolt the mount from the tranny crossmember, remove the crossmember. Then unbolt the mount from the transmission. Next reverse. I used a mount from an lt1 car becuase the only place to buy one for a ls1 is the dealer, at least thats all i ran across. And they wanted 95 bucks.

Might want to think against doing a poly mount if you have rubber motor mounts. I read up that if you only have a poly trans mount that with the motor twisting it can crack the trans case. I dunno, i didn't do it. Ill replace a $20 part 100 times before i replace a transmission.

Rob

**Z28pwrHecz** · 03-14-2009, 04:30 PM

i found a poly mount on jegs for $22.00. where are the motor mounts to know if mine are rubber. i havent changed them since ive had the car so i think they are the stock motor mounts.

**Quik** · 03-14-2009, 04:41 PM

could also be the TA bushing

**Z28pwrHecz** · 03-15-2009, 09:41 AM

What are the brushings. Where are they located

**Spikito** · 03-15-2009, 10:08 AM

my car kinda does the same thing, i thought it was just slack in the rear end. when i accelerate the pinion catches up with the ring, when i let off hard, the ring catches up with the pinion, making a clunking sound...could i be wrong?

**Quik** · 03-15-2009, 05:08 PM

Originally Posted by Z28pwrHecz

What are the brushings. Where are they located

on hte TA mount on side of trans tail

**IanR** · 04-13-2009, 04:05 AM

Originally Posted by silversho89

Its easy to replace. Support the tranny with a jack, unbolt the mount from the tranny crossmember, remove the crossmember. Then unbolt the mount from the transmission. Next reverse. I used a mount from an lt1 car becuase the only place to buy one for a ls1 is the dealer, at least thats all i ran across. And they wanted 95 bucks.

Might want to think against doing a poly mount if you have rubber motor mounts. I read up that if you only have a poly trans mount that with the motor twisting it can crack the trans case. I dunno, i didn't do it. Ill replace a $20 part 100 times before i replace a transmission.

Rob

Is there any difference between the LT1 mount and the LS1 mount? Did you have mod it to make it work?
I have the same banging problem and I think that my mount is shot as well.

**01ws6er** · 04-13-2009, 04:23 AM

Mount is easy to replace but I'm not sure about just replacing the trans mount and not the motor mounts and having issues (if you go with poly mounts). Only other thing I could think of would be your u-joints...

**IanR** · 04-13-2009, 04:26 AM

Good point about the motor mounts. I will probably replace them as well. The Ujoints are a possibility, but I am thinking that it is the mount. I noticed that the tranny is leaking and dousing the mount with tranny fluid so, I am sure that the rubber is shot. I'll get a better look when I sevice the tranny.

**Hi-Po** · 04-13-2009, 03:24 PM

Have you checked to make sure the bolts that hold the transmission cross member are tight?Mine is after market but should have 4 bolts... 13mm maybe?) Mine backed out and caused the same noise when I would push clutch pedal. Tightened them up and put some blue loctite on them. I re-check them every 5-6000 miles.

I have a Energy Suspension Poly mount Brand new if you need one.

The question about mixing Poly mounts with stock rubber engine mounts. I have a Poly Transmission mount and stock rubber engine mounts. When the car wasnt cammed, it never made a difference at all. I never, not once noticed any vibration's at any speed. Now that the new cam is in, my engine is flopping all over the place. I DO NOT want to replace those engine mounts.

**01ws6er** · 04-13-2009, 04:26 PM

Originally Posted by Hi-Po

Have you checked to make sure the bolts that hold the transmission cross member are tight?Mine is after market but should have 4 bolts... 13mm maybe?) Mine backed out and caused the same noise when I would push clutch pedal. Tightened them up and put some blue loctite on them. I re-check them every 5-6000 miles.

I have a Energy Suspension Poly mount Brand new if you need one.

The question about mixing Poly mounts with stock rubber engine mounts. I have a Poly Transmission mount and stock rubber engine mounts. When the car wasnt cammed, it never made a difference at all. I never, not once noticed any vibration's at any speed. Now that the new cam is in, my engine is flopping all over the place. I DO NOT want to replace those engine mounts.

Have fun

**Hi-Po** · 04-13-2009, 05:59 PM

Originally Posted by 01ws6er

Have fun

I am seriously thinking about paying for it. You did!!!

**Z28pwrHecz** · 04-14-2009, 08:05 PM

i switched out the mount with the energy poly mount and the noise stopped. car is running good once again.

**konigandy6** · 04-15-2009, 03:25 AM

I would recommend motor mounts as well... Sometimes what causes that thumping sound on aggressive acceleration is your exhaust pipes hitting the floor board from all the engine twist. They make bump stops you can install too to help it out but you should swap out motor mounts as well. Hope this helps.