My 93 Prelude Si VTEC has had a vibration in 3rd gear ever since I've got it. Since then I've driven 18,000 miles and it has not gotten worse. In a couple of weeks I'm having the tranny pulled to replace the clutch and rear main seal so I figure now would be a good time to get it fixed. It shifts smoothly into 3rd gear at any rpm, even at redline. Once its in gear I can place my hand on top of the shifter and feel vibration. If I apply a minimal amount of pressure to the top of the shifter and push it forward just a little bit the vibration goes away. It doesn't vibrate all the time either, it's the worst when the tranny is loaded, for example, accelerating up a hill from 2500rpm in 3rd. Any ideas?

 

check your axle..

My driverside axle boot is gone for a 2 weeks now, i start to feel vibration on 3 gear sometimes.. might be worth to check your axle..