i drove my friend's 91 s13 and for some odd reason at exactly 2700rpm in every gear it makes a rattling noise not sure if its tranny or motor, but mechanic said it's something thats bent in the motor, im confused here any ideas or help, and o yea i heard something about a backing plate?
i dunno im lost here thanx for any help

 

It will help if you know where it was kinda coming from.

 

hard to tell but im guessin its the tranny since it does it at exactly 2700rpm in every gear

 

Does it rattle or clunk? If it is a rattle, check the heat sheild on the cat and the manifold. At certain rpms, the motor will vibrate more or less, and at 2700 it might cause the sheilds to vibrate. Just a guess, though.

 

thats exactly what mine does. mines the manafold shield its gota crack in it. in the last few days its doing it worse cuz the cat shield just started doing it too

 

old age + frequencies?

meaning: old cars naturally develop loose things, and maybe at exactly 2700 the engine is vibrating at the right frquency to make those loose things scream it up.

Does he feel the vibration in the shifter if he puts his hand on it?