Still cant figure out vibration

[youngmanvr4]

Well my transmission went out so I replaced it hoping it would fix my vibration problem but it didn't.

I did some more testing and my vibration seems to be comming from more towards the front of the can...but everyone and a while it seems like its comming from the rear. It only does it when I'm coasting (foot off gas) and in any gear from 2400 rpm to 2100 rpm. Only during that time, foot off gas, coasting from starting at 2400 rpm down to 2100 rom in any gear will it make the vibration noise. It almost sounds like a exhuast pipe is hitting/vibration against something but the whole exhuast system seems good. When I had the transmission off the clutch seems ok and the driveshaft seemed ok too. The carrier bearing is a little beat up but since its only during that rpm it sorta cancels out a transmission back problem I think. Before the new transmission it made the noise...still makes it after it, I've taken out the open diff. and put Kaaz 2 way lsd in...that didn't fix it, I doubt its suspension related since it is only at that rpm range. So what could it be? I took off the radio trim and shift boot to try to hear it better and it sounded like to was coming from engine/transmission area. I'm pretty stomped. Have any idea? I'll be happy to test anything out or try to explain any questions. Just would like to get this taken care of. I've been trying to figure this out for the past 9 months.

Car is 90 with a DOHC...see sig for more.
Modified by youngmanvr4 at 6:27 PM 9/12/2006

[youngmanvr4]

A bump for help.

[180fan]

metal clanging kinda sound eh? You need to give me a ball park idea of where it's coming from. It could be alot of different things like subframes, ball joints, upper mounts and heat shields as examples.

[youngmanvr4]

At times it sounds like its coming from the exhuast, so you could say metal clanging type of sound. Then sometimes it sound like transmission/engine or even the diff. So drivetrain somewhere, but you cant pin point where its at. But it really sounds like where the engine bolts to the transmission...that area. But remember its only seems to do it at 2,400 rpm down to 2,100 rpm during deaccleration (coasting) in all 5 gears. If I step on the gas, its goes away. If I press in the clutch, it goes away.

[youngmanvr4]

Well I think I just made the most progress today. I took all the shift boots off (leather and rubber) so that way I could see the transmission from the inside and drove around and tried to locate the problem. Though it doesn't totally explain everything I think its the driveshaft. I'm 97% sure of it. So I'm going to get a new driveshaft and see if that fixes it

[mr2lickit]

Does your transmission and engine move alot? WHen your in neutral and at a stop if you rev your engine does it seem like it moves up/ or side ways some? IF so you might wanna replace your engine and transmission mounts. Mine was moving to much and it snapped the welds on my exhuast.

[l80_240]

ive got the same problem after swapping clutches in my 92, makes a wahwah kinda sound when off throttle at certain rpms, let us know if swapping driveshafts does it, cause ive got nismo motor mounts on the way and ive already replaced the transmission bushing

[youngmanvr4]

Yea I wont rule out that its not a engine or transmission mount. My passenger side engine mount looks a little beat up and almost thought that was the problem but then with todays testing I think its the driveshaft. I'll do the driveshaft and if it doesn't fix it I'll do the engine mounts.

I haven't really tested to see if the engine and/or transmission moves much but I'll try that too. I know it moves some...just dont know if it moves more than normal.

Let me know if the engine mounts fix your problem l80_240.