whenever i am in 3rd gear at around 2500 t0 3200 and i floor it to pass a car or something there is sometimes a loud clunk that seems to come from behind the drivers seat. Is it possibly the transmission mount or is something just loose? It is really annoying and also very loud, so any help would be appreciated.

 

Sounds about right - ripping your tranny mount. The one GM made for the T5 is really gay. Since the T5 sits about a half-inch higher than the T56 or 4L60-E, its not so easy to swap over to a standard GM mount from Energy Suspension, or Prothane etc. I've tried it. You have to cut up your tranmission crossmember just to make the bolt hole elongated enough to match up. There there is still the heighth differance. It ends up making the car vibrate really bad because of the driveshaft angle is now off.

I heard someone say that they did what I did, and that the vibration goes away after a couple days. However, that doesn't ignore the fact that your driveshaft angle is off. And if I really wanted to I could fix that problem with stack plates, but I ended up putting a new tranny mount in somewhere after 100,000 miles. And it's holding up okay, although I've already seen another tear start to form. It shouldn't be too much longer that I'll be swapping over to a transmission that I can use a standard GM mount. But the T-5 equipped 4th Gen. We are stuck with stock for now.

Before you buy one of those mounts. I'd go ahead and get under the car and remove the trans-mount and inspect it. It only takes about 5 minutes to remove including the cover plate. I believe the stock mount (dealer only item) runs around 90 bucks. Might want to check with a salvage dealer to see if you can get one from him.

 

The ES Poly tranny mount worked fine in my V6 with the M5 tranny. There was some vibration at first, but it is gone now and the car is fine. I would recommend going this route so that you won't have to continue to change mounts.

 

I too have the energy suspension mount, and I tried it, yes the vibration may go away but without a driveshaft angle measurement, you might be causing damage and lead to premature failure. It vibrates because the driveshaft angle is off by almost a half inch, that much I know from my installation, and subsequent removal. I've tried contacting ES about the problem and they haven't replied back yet. I doubt they will make a new mount just for us, but I do believe that the use of stack plates could be safely implemented.

 

I completely understand where you are coming from on the DS angle issue. I do not believe, however, that it is as big of an issue as you are making it to be. There are quite a few people here that have had the mount in for quite a long time with no problems. I personally have had the mount for 4 years now and have not had any problems.

 

Good point. I though about prefacing myself by saying that it may not be a problem. Truth is I don't know if a half inch is something to worry about or not? It might be - it might not be. But having had it in that long, I think it's safe to say it won't harm you. I might get around to putting it back in. It only takes about 5 to 10 minutes to swap.

The one thing I do know about driveshaft and engine/transmission angles is that the tranny must lean back by 4 degrees - so the motor too is at a slight angle. Then again, when you get down to the driveshaft. That's what the U-Joints are for to allow for varying pitch.

heck with it, I'm swappin'. If it blows the drive shaft, well I've got the stocker sittin' in the garage.