Alright well i have an 86 iroc with a 87 l98 383 stroker with the 700r4 trans. When I roll at slow speeds (40 and under) I hear a clunking noise coming from the tranmission. Also when i am in neutral reving 3000 and up or put a load on the trans while in gear it makes a grinding noise and a vibration. I've searched a lot of the forums and haven't seemed to find anything with the same problem as i have. I know its not the rear end or driveshaft because i just replaced the driveshaft and pinion bearings. Also after i looked under the car i noticed the flywheel has a big counter weight on it. It just seemed odd to me that the engine should already be balanced so why would the flywheel need to. Thank you for your time and help.

 

It's normal to have a weight on the flexplate.

 

My speedo gear broke a few weeks back and the check engine light was on for the vss sensor. My buddy went for a ride with me and said that my converter lockup wasn't unlocking and that could do damage. Do you think that could be the problem?

 

Over time it could, but its unlikely that it's done anything that quicly.

 

Take the inspection cover off and check the flexplate (not flywheel - those are for manual trans) for cracks. You may have a cracked flexplate... they can cause the vibration and grinding noise you are hearing.

 

That weight is called a batwing weight. It's used on cranks with a one piece rear main seal.

I had a cracked flexplate once and it made a lot of noise under a load. It sounded like a rod knocking!

 

alright thanks guys i'll take a look at it and get back to you