95 a4 trans am, a bang when downshifting

[Trans Am]

I can feel and hear a bang almost like a broken transmision mount when the car is downshifting. I m not sure what it is, could it be something wrong with the gearbox, or just the lower a arm bushings worn (from accelerating and braking hard often). Anyone else had this issue? it is most noticeable when letting off the accelerator and letting it downshift.

[Joe 1320]

Broken rear transmission mount. what youlikely hear is the the transmission rising off the mount and hitting the trans tunnel.

[Trans Am]

sorry I should have mentioned I got tired of breaking transmission mounts and installed a polyurethane one. I checked it and it isnt broken, but I still have to check if the bolts are ok once I get it on a lifter. What else should I check? play in the driveshaft u joints? engine mounts? I have the poly engine mounts that came in the kit with the transmission mount, should I replace those too?

[Joe 1320]

Yes, check all the engine mounts but also check the torque arm mount to the transmission and check the torque arm bolts to the differential.

[Trans Am]

I have checked the mount and crossmember and all related bolts and seems ok, the mount is an energy suspension poly mount, about 3000 miles on it and it has a slight crack on the driver side. its not torn, just looks like thats where it will lol. Rear lca s and relocation brackets are ok.
Torque arm bolts are ok, the mount is the stock one but looks ok, same with the enine mounts. I ll replace the engine mounts with the poly ones as I have noticed the engine moves a bit when I rev it up.

Also the a arm rear bushing on the drivers side looks shot, the rubber has come off the metal, the same bushing on the other side seems broken too. Can a worn rear bushing on the lower suspension arm cause this thump?
It it noticeable mostly when downshifting and coasting. Its weird as everything seems ok, transmisson shifts ok.

[Joe 1320]

I have checked the mount and crossmember and all related bolts and seems ok, the mount is an energy suspension poly mount, about 3000 miles on it and it has a slight crack on the driver side. its not torn, just looks like thats where it will lol. Rear lca s and relocation brackets are ok.
Torque arm bolts are ok, the mount is the stock one but looks ok, same with the enine mounts. I ll replace the engine mounts with the poly ones as I have noticed the engine moves a bit when I rev it up.

Also the a arm rear bushing on the drivers side looks shot, the rubber has come off the metal, the same bushing on the other side seems broken too. Can a worn rear bushing on the lower suspension arm cause this thump?
It it noticeable mostly when downshifting and coasting. Its weird as everything seems ok, transmisson shifts ok.

Yes. When a load is put on as in acceleration, the torque arm will attempt to rise and the lower control arm will attempt to move forward. On deceleration, the torque arm will want to dive and the control arms will pull against the mount as the differentail tries to rotate. Any bad bushing will become apparent during those conditions. At a steady state cruise, not much would be happening so everything should be quiet. It's the acceleration and deceleration that puts more force on the bushings.

[Trans Am]

I have replaced the transmission mount, it had cracks on both sides I think only cosmetic cause it didnt seem broken (energy suspension) and installed a new prothane one. only difference is I can feel the thump harder when it downshifts.
I also replaced one of the front lower a-arms as the rear bushing was broken, rubber came off the metal.
I added a liter of transmission fluid and that seemed to improve the downshifts but very little so I am not sure it made a difference. Is it possible it is slipping only on downshifts? A while ago I did a few time manual downshifts but was careful not to over rev the engine, I think it only went up to like 3000 3500 rpm, not sure if that can cause this.

I have checked all the suspension bolts and mounts and noticed the k member bolts on the drivers side were loose so I tightened them up. do the rear lca bolts have to be super tight?

[Injuneer]

The Energy Supsension trans mount has the upper and lower metal parts overlapped inside the polyurethane, so if the polyurethane tears, the trans is limited in how much it can move up and down. As a result, when they break, the break may be hard to find, and the trans won't lift much if you jack it to check the mount.

Hard to believe the ES mount broke. Mine is 14 years old, and has been under three different tranny setups (original T56, swapped TH400 and TH400+Gear Vendor O/D) and its never been a problem. That includes 6K clutch dumps with a McLeod Street Twin on sticky slicks, and transmitting 800HP and 800 lb-ft on nitrous.

[Trans Am]

Thanks!

seems like I overlooked checking the transmissin fluid level properly.
I m still testing , so far it seems to shift fine.

But I finally got round to change that front lower a-arm with the broken bushing and checked the subframe bolts . the only two bolts that I havent tightened myself when I did the drivetrain swap were loose

I have been looking for dexron 3 for a few days seems like they dont make it anymore and I didnt want to mix the old dexron 3 with new dexron 6 . I eventually found castrol atf import multi vehicle and it meets dexron 3 specificantions, probably has more additives than just regular dexron 3 but I thought it cant hurt the transmission. It also seems to have better viscosity at higher temperatures and viscosity index than dexron 3. nut sure thats good or bad. It was the ony type of atf that I could find that is close to the original dexron 3.

http://www.castrol.com/castrol/secti...tentId=7028224

What transmission fluid would you use ? I am going to change the filter and maybe flush the old fluid out. is this type of castrol atf ok to use? is it ok to mix with old dexron 3 if I only drop the pan and change the filter without a flush?

I have noticed all the transmission pan bolts were loose also the oil pan bolts on both the t/a and the 97 camaro! I guess the gaskets get soaked with oil over time and that makes them softer.

Also I need to get an alignment now because I have replaced the a-arm. The car has hotkis lowering springs and kyb adjustable shocks and lca relocation brackets. Do I keep the factory alignment specs?


The energy suspension mount seems to be a better design as it has a different shape than the oem one, and the overlapped metal parts inside. I am going to check it and reinstall it if its ok, i prefer it over the new one, its a little softer now than a new one.

[Trans Am]

seems like I overlooked checking the transmissin fluid level properly.
I m still testing , so far it seems to shift fine.

scrap that lol . I overfilled it big time, its way over full mark on the dipstick and coming out the vent tube. is this bad for the transmission?

Its te same as before, upshifts are fine, but downshifts especially 2-1 are harsh. it sorts itself out after driving for a while, I think when the fluid gets hot. it was really hot when I cheched the level after driving around town for 20 minutes or so, the dipstick was very hot too.

harsh downshifts when cold and ok after it warms up.

when I press performance button it shifts way up in the rpms, over the yellow almost hitting the limiter.

[ConElite]

Curious, Is there any reason why you are Downshifting an Automatic transmission? Are you doing this Manually?

[Wild Willy]

Good luck finding your issue- just jumped in to point out that my Z28 shifts pretty hard, both upshifts and downshifts. Almost feels like there was a shift kit installed, if you know what I mean. I read that the Firebirds came with a switch that affected the shifting, having a 'sport' mode and normal mode, where the Camaro was always in 'sport' mode.

I got tired of the shifter moving around under load transitions, on throttle/off throttle, and put a UMI torque arm that is "frame" mounted under there. I don't think it made good sense to put those torque loads on the transmission tail. Still clunks and shifts hard, though. I just figure it is the nature of the beast- not expecting luxury car shifts from a light, powerful car with a firm-shifting transmission.

[Ultra_Z]

I can feel and hear a bang almost like a broken transmision mount when the car is downshifting. I m not sure what it is, could it be something wrong with the gearbox, or just the lower a arm bushings worn (from accelerating and braking hard often). Anyone else had this issue? it is most noticeable when letting off the accelerator and letting it downshift.

Check your tq. arm bushing... and tranny mount while your under there

[Trash man]

Good luck finding your issue- just jumped in to point out that my Z28 shifts pretty hard, both upshifts and downshifts. Almost feels like there was a shift kit installed, if you know what I mean. I read that the Firebirds came with a switch that affected the shifting, having a 'sport' mode and normal mode, where the Camaro was always in 'sport' mode.

I got tired of the shifter moving around under load transitions, on throttle/off throttle, and put a UMI torque arm that is "frame" mounted under there. I don't think it made good sense to put those torque loads on the transmission tail. Still clunks and shifts hard, though. I just figure it is the nature of the beast- not expecting luxury car shifts from a light, powerful car with a firm-shifting transmission.

i know im late to the party, but that sounds like a tranny mount thats weak or torn...