pyr0b0y

So I've been trying to chase a problem where my shifter will vibrate violently when I am at 4k rpms and above (KA24DE motor). I recently had the transmissions completely rebuilt, as well as a new transmount installed. I inspected the motor mounts and they look just fine, no wear or cracks like that. I also have the driveshaft replaced (with new u-joints). I believe the person installed a Mwgan Racing v2 short shifter before me.

I also found out that the bolts on the heat shield are broken off inside. The shop I took my car to was not able to replace them, so I could see that causing a bit of vibration, although I can't imagine to the extent I'm feeling. I also checked timing and am at 20 BTDC.

Reading other posts, it sounds like the v2 shifter I have is not a shitty one and I shouldn't be getting a rattle. While some posts people complain about a similar issue to mine.

Is there any way to isolate the short shifter is actually causing the issue before I sink more money into this? If the shifter is the culprit, what are my options?