i have a 2000z28 and for some reason when im driving and the selector is in third gear it vibrates brutal around 2000-2500 rpm and about 75-90 mph or close to that, but then when its in 4 gear it wont vibrate at all in those ranges any suggestions or opinions???? Any help is appreciated, thanks.

 

no it doesnt vibrate at that rpm in any other gear just third.... thats why im confused

 

bump for help

 

I had a similar problem about a year ago before I rebuilt my tranny. It was in 3rd gear when it happened and always in the same RPM band. The only thing that I noticed was the drum on the input shaft had some damage to the OD. I didn't replace it, just sort of cleaned it up and reused it when I rebuilt it. It hasn't done it since. I'm not sure if that was the issue or not, but it seemed to be the only thing with any wear on it (other than the clutches). Bottom line, when I freshened it up that problem went away.

 

Thanks for the help buddy!