My 83 z28 has a t5 and vibrates badly above 60mph at all times. It's at its worst in neutral. It is slightly better under a hard load but still bad. I can feel it in the shifter not in the wheel. I need some help.

 

Ujoints...

 

Maybe check the driveshaft for dents or pull the driveshaft and check the yoke to see if there is any wear on the splines. It could also be the pilot bearing/bushing wore out. If it has a pilot bushing and not a bearing, it is sometimes hard to "eyeball"if it's bad because a lot of times the bushing will wear evenly. Also, if the pilot bearing/bushing is too far in the crank, it won't support the input shaft properly, creating a vibration and eventually causing transmission damage. Just some things to look at. Good Luck.

 

Borrow the driveshaft from your other third gen. If it fixes it, you've narrowed it down.

Same for wheel/tire assemblies. " " " " " " " "

Then the T5. etc.

 

Do you have a polyurethane transmission mount? I have a T5 and had a very bad vibration and had my driveshaft balanced twice. Vibration didn't go away. I bought a Spohn Top Gun driveshaft and vibration was still there. I swapped the polyurethane trans mount for a factory one and vibration disappeared. Apparently the poly mount was transferring the vibrations from the T5 to the body of the car.

 

^same as above poster. I had an energy suspension poly mount and had a terrible vibration. Replaced it with a stocker and vibration went away. I've really heard nothing good about them and vibration.

 

[QUOTE=91formula5speed;5193863..... It's at its worst in neutral.QUOTE]

Here's the solution to my vibration problem. Your comment about the vibration being worse in neutral eliminates the driveshaft and tire balancing issues (unless you meant neutral at 60 mph).
https://www.thirdgen.org/forums/tran...vibration.html

 

yes I mean neutral at highway speed. The faster you go the worse it gets.

 

I changed the mount and it got better. But still there it almost seems as if it only does it in 5th gear. if ibrun 60 in fourth I don't feel it.

 

It could be the transmission. But I'd still do the driveshaft and wheels before going to the trouble of the trans. swap. So... you've got some work ahead of you. See post #4 and if it needs the rebuild, maybe consider a T56.

 

Very disappointing just got it and its a nice car. It had a poly mount but even with the factory it vibrates.

 

Did you swap driveshafts yet?

 

can you let me know the tracking number on the ecm and memcal I bought from you on the 8th? It should not take this long to come from indiana to colorado ?

https://www.thirdgen.org/forums/engi...-complete.html

 

Kennedy, are you going to reply or just rip me off ?

 

It turned out to be the rear end. The now has an Ls2 and a 6speed and on the first test drive the vibration was still there. Man I was pissed. 4th gen rear and its finally gone.

 

In most circles, that could be described as kharma.

 

I just swapped a T56 into my 87 Trans Am, and i'm getting a bad vibration as well. I've got a factory style rubber trans mount. Only thing is, the vibration is even present at idle. Idk if the flywheel is out of balance or what? The guy I got the trans from said that the flywheel had been resurfaced, and it had some drill marks on the back, like they balanced it, or at least tried to. I'm stumped.

 

Lsx hater I see.

 

@ pwd by Chevy your car is bad a**.