I have an odd symptom.
I have a "zing" like metal rattling on metal noise when the throttle is pressed to about 3000rpms. You can hear it if you hold the throttle at 3k rpms, and you can hear the noise for a second once you let the throttle off at around this rpms as the rpm drops...The noise goes away after 3k rpms..

I no this because, I had my car on a lift the other day. In the air in first gear. When I revved the car in neutral there was no noise. But when I put the car into gear and started to press the throttle to 3k rpms the noise was evident. The noise is evident in all gears while driving on the road.

Any ideas of where I should focus my attention when trying to trouble shoot the noise?

My car is boosted so there are a few extra accessories in addition to your average honda civic. The noise sounds like it is coming from the engine bay passenger side..

The noise has only sprung up recently. It was not there at first but within a few minutes of driving the noise became evident.

I think the best description of the rattling noise is a metallic rattle..

Also, I have a hunch that when the mechanics were installing the transmission they may have been looking around under my car and possibly moved my 'downpipe' around which just "sits" in the catalytic converter..(see pic for details)

http://img829.imageshack.us/i/exhaust01.jpg/

yes its a five speed
the noise only became noticeable after the shift linkage was changed to one that had a stiffer bushing..

 

Why the heat wrap on the manifold? That can hurt you more than it helps you depending on certain criteria.

I would suspect the tranny. Could a bearing or something in the tranny itself

 

Hopefully not, its a low km jdm one..shifts smooth..

 

Take it back to the shop who did your tranny work and explain the noise. Warranties are great

 

no doubt, could be throw out bearing? they make noise when theyre goin out

 

found out its the shift linkage vibrating slightly off of the exhaust... Which makes sense, because when the shifter is in gear, the shift linkage moves closer to the exhaust. and since the shift linkage bushing is very stiff there is less play..

 

probably not throw out bearing cause it RPM noise not clutch noise.

Good to hear you found the problem though

 

Would there be any noise difference between going from a hollowed cat to just a test pipe? Does a hollowed out cat drown out sound?

 

maybe your exhaust line "touch" your lower arm when you drive.
I got the same noise

 

A mechanic mentioned to me that one of my drive shafts were a little bent and when the car was up on a hoist you could see a slight wobble... (indicating when the driveshaft was turning it wasnt perfectly straight.

Now i do not have any vibrations in the cabin or feel or hear any in the front of the car.

My question is this, if the drive shaft is only bent a tiny bit, will this still damage bearings and other drive parts quick? should I have this part replaced asap?

 

might also want to replace the rubber mount for the linkage sometimes they get warn out and cause noises with the linkage and even engagement problems if severe.

 

are the drive shafts for a d series the same LEFT and RIGHT? I am going to pick one up within a few weeks..

 

Input shaft bearing.. it's going bad, noise comes about in a variety of ways.. Though since your driveshafts are ****ed, might want to replace those first since they're easier to replace and already look ****ed up according to mechanic.

 

Its not the input shaft bearing, I replaced my old transmission that had input shaft bearing failure along with differential bearing failure.

Input shaft bearing sounds are quite different than what I am experiencing. ISB is present with the clutch out in neutral, its a metal on metal grinding, rather than the noise I am hearing which is a zing rattle type noise.. Trust me I drove on a transmission with bad ISB for 1 year...

 

can a "slightly" bent drive shaft cause immediate major damage ?

I am planning on having the drive shaft replaced within the next 5 days...If i drive lets say another 200kms on the slightly bent drive shaft, will this hurt anything inside my transmission?

 

I'm having the exact same issue rattling noise only at 3k rpms coming from the engine bay have u found out anything?