okay so the clutch went out in my 88 crx si so i bought a clutch for an 88 and used the pressure plate and flywheel off of a 91si. now when i start my car up there is a terrible rattling noise but it stops when i press on the clutch. I now know there is a difference in the flywheels and i was wondering if this could be the reason why or maybe something else is wrong?

 

are all the parts new? why didnt you just buy a clutch kit? its not the 80s anymore

 

Take it all apart and check the condition/installation of the throw out bearing. Most likely will need to be replaced.