I just had my engine rebuilt and I added a aluminum flywheel and SPEC Stage 2 clutch. I need to rev the engine high (2-3K RPM) to get it to start in 1st gear smoothly, and even that is iffy. Shifting is very rough (chatter) if I am not pushing hard on the throttle and shifting at high RPM (at least 2.5K) Downshifting can be really rough - sometimes ALOT of chatter. On the highway, at 70 MPH, if I put it in 6th gear an try to accelerate or decelerate, the transmission sounds like it is going to buck out of the car. I have not been able to use 6th gear.
Thanks in advance.

 

Mine is chattery as well. It grabs like no tomorrow, but it chatters even after 5K miles unless I rev it high when first starting out. As for 6'th gear, I have 3.73 gears so I don't have any issues; you may want ot consider a gear change if you have anything less.

 

Does it chatter on downshifts? Does it chatter if the RPM goes below 2000 and you accelerate in any gear?

Aside - I notice you mention LT1 edit - what do you think?

 

what exactly is chattering and whats it sound like?

 

Mine will make a bit of chatter on a downshift if I mess up the shift, but not regularly. Any RPM below 2000 and the car lurches a bunch, and yes it does feel like the tranny is bucking. This I attribute to cam surge. The engine likes to be loaded, then everything feels smooth. I used LT1 Edit to run a bit more timing from 800 to 3000 and this helped smooth things out a bit. I also set the idle speed up a bit. All in all the car definitely feels like a bit of a wild animal, but that is what sports cars are about, so I'm OK with it. I sure wouldn't want it a whole lot rougher though.