94NDTA

It's hard to see a witness mark where I think it is unless I remove the header. I think I am going to change my tranny mount (which I suspected of being bad anyways) and try to the header up just a little bit. If that doesn't work, I have some heat wrap I will slide in between to try and lessen the sound of metal on metal contact.

94NDTA

Working on it today. I'm going to replace the tranny mount. I can't find a pic of a transmission mount, but this looks like it's shot too me. Maybe this will help a little.

cookseyb

I had A 99 Z-28 that I chased false knock on for 7 years.. I racked my brain and spent thousands of dollars trying to figure it out. Thinking back it all started when my son bought me a SLP under drive harmonic balancer for Christmas. I took it off and replaced it with a stock one and the problem was solved! It had a faulty bond on the rubber to steel, it would pull timing out at about 4200 rpm and smooth back out at 4600 rpm, sounded like it was bumping the rev limiter. This was only at WOT. I guess a stock balancer could be bad as well. Worth checking... Bill

94NDTA

My transmission mount was broken. Header that was basically sitting on k member. A little massaging too. Haven't had a chance to scan, but looks like this will work a lot better.

smitty2919

Thanks a lot. Someone else in here mentioned the balancer too. I marked the outer portion and the inner portion as they suggested to make sure that it was not spinning/twisting out of place when running. Not to say it isn't bad, but it did not twist.

A friend of mine has a LT1 that he is rebuilding. Maybe I'll try his to see if there is a difference. Worth a shot since it's only removing the belt and 3 bolts.

94NDTA

I'm getting to the point where I might turn off my knock sensors if I can't fix it. The car is really low on power, I took it to the track, its highest trap was 106mph with a 13 flat. When I went to the track (wasn't planning on going, last minute schedule change) my y-pipe started banging on the tranny mount crossmember, worse than the header hitting the k -member. I know right where I need to fix it, but was already at the track. I also forgot my computer (it was last minute) but I know it's still pulling timing.

Yourboy87

I moved the knock sensors from under intake to bottom of the block guessing in same areas as an ls3. Dont put them next to headers/manifolds if i need to say more you shouldn't be under a hood of a vehicle lol. I was having similar issues solved everything. Oriellys had on the shelf male and female pigtail ends for the knock to extend the wires but I made my own set up with butt connectors and shrink tube over that to seal the hole and won't be exposed, it will be if you use regular harness and used that liquid tape around it where it's pinch together just to be safe cause it doesn't look that water tight to me. I have done it a few times it has always been the knock sensor at back of motor (sensor b) and you could just do the one witch worked the same as both and the rear I run on bottom of the block on the driver side you will need male and female pigtail ends to run it back to the front one an extended wire to bottom one. Number of ways to go about it but any knock sensor in the valley pan is going to be a problem once you start adding bolt ons intake, headers, exhaust, bigger throttle body, cold air intake will mess with the sink of things. The c5 Corvettes are the worst for that crap. Need those things right on the block.