I need some help! I recently took my car for dealer service because I heard a clunk in the steering. While they found some loose bolts, they also tell me they found a weak transmission mount. I tell them go ahead and replace the mount.

Now, I accelerate hard for the first time since having this done, and while accelerating in first, I hear rapid popping sounds (sounds like it is coming from the rear). This is the FIRST time I had this issue EVER. What could be wrong? Please help. Thanks!

--EDIT-- It acts normal when I drive normal.

did they show you your old tranny mount? if they define weak by cracked or uneven structure then yes. if it's stock the hard plastic might have cracked. what type did they install? plastic or polyurethrane...most here will say a poly one is better because of the shock absorbing material. they might have not installed it right. if it's plastic then put on a poly one, it's not that much expensive..can get at autozone or checkers.
Rule Always get your used parts after taking your bird to any shop. Mark them if possible before removing them if possible in case you have to leave

Well, I didn't get a chance to look at the old mount (I dropped it off before going to work). Therefore I was not with the car when it was being worked on.

The new mount looks black, and seems to be rubber or something. I didn't think it was necessary to get used parts back since I expect a dealer to use OEM replacement parts, not some off-brand piece.

Sounds to me like they did not recenter the tranny before they tightened the bolts. I did this and that is what I heard. It was the binding of the U-joints. Sounds simple, but a lot of techs here forget that.





The poly mount is not recommended because of the shock absorbing. It is because it does not break after every hard launch and is made to not let completely go to allow the tranny to flop at will. Truth is, it will make more vibrations apparent.


Matt

I was thinking of poly mounts from Energy Suspension, but since you don't recommend them I'll skip that plan. I'll just try to explain the best I can to the dealer tomorrow morning.

I hope I didn't damage the car (transmission tunnel, or the transmission itself). I just can't believe that after spending money to have a new mount they recommend, this is what I get in return.

I am not saying NOT to get it. I have it installed on both of my cars and love it. I was clarifying that is not because of being a better shock absorber. Sorry for the confusion. It is about $35 and will last. I broke the mount in both cars almost immediately. In my 90 I replaced 3 before I found out about the poly mount. First mod I did on my 95.

Matt

Ahh, ok!

I think I would much rather have vibrations than what I am experiencing right now.

I just had the car out again (didn't floor it). Still seems normal with normal driving (even at 3/4 throttle it still seems normal). Should I be worried about possible damage to the transmission tunnel or the transmission itself?

EDIT -- What is the part number for the poly (or the Energy Suspension transmission mounts)?

I have a non poly on mine and I have no vibrations or thunks, but every car is diff especially if you have mods. with the way things are these days don't throw your trust around unless you know these guys at the dealer shop. I was trying to say get the used parts back, inspect them and then dispose of them however you want. I know what you mean now, I was under the impression you took your bird to some shop on the corner where they show up to work on sat all hungover and crap. get that checked out and make sure they don't charge you more. for now keep your foot off the gas

I just took it back to the dealer and demonstrated the issue to the mechanic who worked on my car (took a few tries then it finally did it). I asked if the tranny mount was OEM. He admitted it isn't, but said it's supposed to be a good "aftermarket" version, and yes it is made out of rubber. They are going to order an exact OEM for this car and will schedule an install when it comes in.

Or am I making a mistake getting an OEM instead of a poly? I never had this issue with the original mount, even when it was worn. What else could it possibly be? Could it be the rear gears? I notice it most when the rear wheels are breaking loose (even then it doesn't always do it).

No way, I would NEVER take the bird to some 'mom and pop' shop, no matter how cheap it is. I take too much pride in the bird for that!


If I do that, I won't be able to go anywhere! j/k, I know you mean 'don't floor it'.

Also, they say the only other possibility they can think of is maybe a u-joint (I assume driveshaft). Then again, it doesn't clunk unless I floor it (sometimes it will sometimes it won't). Also, the car still feels very smooth at highway speeds.

ha ha I saw that coming.
Could you do the complete tuneup on your bird by yourself if you had the time? What about memorized the oil amounts in the various parts in the car as well as viscosities? Just a question.
You see goes back to what I was saying, always get back your used parts for you to inspect and drive away safe and comfortable. Who knows someone might be willing to purchases them pending their use. Assume that whenver you take you car to a shop that everyone there is completely ignorant hence taking all safety precautions such as the one I mentioned above. I'm surprised how many people are clueless when I ask for a part for "my 95 trans am" and they look at me all confused because their little computer databases do not tell them "Trans Am" then I have to tell them "1995 Pontiac Firebird Trans Am, not a V6 but a LT1 V8 350" then they get it. Very rare these birds. Heck no those U-joints are very durable but you know how many times you have replaced it and how hard you have driven your car. They aren't that expensive, to me sounds like it's your tranny mount. You can even tell them they caused some U-joint damage by not putting OEM parts and threaten to report them to the BBB and who knows they might get you hooked up with that. It continues to work for me, they dropped the ball they deserve it.
Stay with the OEM if that's what you have used, from what I have read on these forums poly ones are more often better than OEM it's just that they need frequent replacement hence more money spent and effort/tiime to install, not to mention mechanical damage.

Since the dealer seems willing to work with me on this, I don't want to push the BBB on them just yet. Hopefully things will be all better once I get the OEM mount installed.

I just had a chance to look at the new OEM part they ordered, and it looks exactly the same as the "aftermarket" tranny mount on my car. GM part number is 15788795.

Since the part looks exactly the same, I am having some doubts that this will correct the issue. I did notice the tranny does sit up a little higher than it did before the new mount was installed. Is there a way to adjust the pinion angle on the stock rear w/stock torque arm?

Or is it possible the new tranny mount is already broken???

Can anyone with a 1993-1997 model take a pic of their tranny mount installed? I am beginning to think the dealer installed it backwards.

I don't think you can do that. What makes you think they did something wrong?

Matt

Cause I can't think of any other reason I would have this popping/clunk noise when accelerating hard AFTER they replaced my tranny mount, and never had this problem before the new mount installed.

I am really starting to get worried. The new OEM tranny mount is in but it looks exactly like the one they installed, so I am having doubts that it will fix the problem. I really hope they have enough knowledge to correct this issue when I bring it in this week (BTW, the dealer has an "A" rating with the BBB).

Oh, I thought they had already replaced the mount. Wait and see what happens after they replace it with the new one. If the trouble continues, then I would start asking a lot of questions. For now, I still think they did not recenter the tranny when they put the mount in.

Matt

Oops, sorry for the confusion.

What I meant to say is the new OEM mount arrived at the dealer, and it is scheduled to be installed later this week (weather permitting).

How do you re-center the tranny? It seems that there are only 3 bolts on the mount, and 4 bolts on the crossmember (with very little adjustment if any).

I used a prybar to pull it back to the passenger side of the car. Then you tighten the bolts on the mount to the cross member.

Matt

Well, I just tried unloosening the two crossmember bolts on the passenger side, along with the single mount bolt on the crossmember. I can't seem to get the crossmember to move 2mm so that it is in the exact same position as it was from the factory. Not sure if that is really the reason for the issue I am having.

I also checked the torque arm mount (I assume it's in the same general area), and was able to slightly shake it (with some effort, there wasn't any loose play in it).

I used the pretty useless scissor jack that comes stock with our cars o move my tranny upwards a tad (but to mostly support it so it didnt move) when I replaced mine...just used a floor jack to lift the car..did it in the driveway...


I wish I would have caught this earlier today I would have taken a pic of my tranny mount for you when I was at the garage today...sorry...I dont think you can put it in backwards tho...

Which one did you install? OEM? Anchor? Westar (this one was installed on mine)? Or did you go with a poly?

originally when it broke, I put a poly in...but I hated it...I think there was something wrong with the mount...possibly the wrong part even...whatever the case was, it didn't feel right, so I went back and got an OEM replacement...Im on my 3rd oem now...but they have lifetime waranties on them

I've had the one i have in there now for about 6 months now...fingers crossed she's holdin together!

Stock OEM mount is now installed, but it did not correct the issue.

hmmmm

Id take it back to them and have them figure it out...sounds like sumthin they did...something must be off center...?

That is exactly what I did (I called the dealer and told them I'm bringing it back because it's still clunking).

**EDIT**
I am starting to think of other things like engine knock or misfire. If it was engine knock, from what direction would the sound come from? And what would it sound like? Currently no SES light.

Turns out they were able to figure out what was going on. They said the exhaust was colliding with the driveshaft loop (which I am having a tough time removing). Hopefully this will really fix the issue I am having.

They were right!!! I removed the loop and no more clunking!!!!!!

Thanks everyone for trying to help, this board is great!

Well good thing that's fixed. Why the heck did you even have a loop? Based on your mods on your sig. line, you are not running that much power to require one. But then again why not, just in case? But now you see the trouble it causes. Ever thinking of putting it back later down the road?

I decided to install one after hearing some horror stories of breaking driveshafts and the damage they can cause. I also thought that since I have the Hypertech increasing the firmness of shifts, that it would put more stress on the driveshaft.

However, after this experience, I will definitely not put this back in my car. Much more trouble than it is worth.

If I remeber right, there's a croos plate that'd support the driveshaft if it did break....maybe I'm wrong.

Well while backing up I hear a thunk around the center console. I checked the tranny mount (non-polyurethrane) and it's still good. Bolts are tight. The car will shake kinda rough back and forth as I'm backing up then ease off when I shift to Drive. Got the car back in Feb. and it started doing this about half a month ago. Tripped out

That's gotta be the rear trans mount. The stock ones tear and unless they are removed (an easy job) it is almost impossible to see the tear. Everyone uses the aftermarket poly mount==they seem to be the best.

What and I'm usually aware of parts in our car. I had no idea that there was a rear tranny mount. I'll get that replaced soon then.

It is located on the rear of the tranny. This is connected to the cross member there. It is the weakest point and I have broken many until I put in the poly mount. It is an easy fix and will cause the thump on the floor pan when the tranny hits it.

Matt