This is the shifter: http://www.samsteffansson.se/products/images/competition/95084330.jpg
Does anyone else have it?
It's not loose or anything. It is the spring and reverse lever that vibrate when drivetrain is under load. If I put my hand around them the sound stops. I thought about increasing the spring's tension but I don't know how to remove the knob. I removed the screw but it still sits tight.
First of all, it's a racing part and not even remotely designed to be quiet. But putting that aside, there is very little than be done other than adding softer parts to absorb vibration. I had the same problem when I was using the Craving Boost shifter, which was similar. I was able to dampen *some* vibration by wrapping some stretched silicone vacuum hose around the bottom pivot. It provided tension while not restricting free movement.
I have that shifter in my car. It is not excessively noisy. My knob comes off easily. Mine has some vibration on overrun but my transmission is very noisy so I may not be hearing everything you hear with a normal transmission.