I did some searching and nothing seems to match my situation. I have a pretty good engine vibration right around 2000-2300 RPM's. It's not a straight vibration but it has a definite lope to it. It does it regardless of the gear. I put it neutral sitting in the driveway and on the road once and even then I got the same vibrations right through that RPM range. I thought I might have screwed up when I did my timing chain and put the harmonic balancer on wrong. I had a couple people tell me it was weighted. It wasn't until after I replaced it with a pricey Fluidampr that I learned, on here, it actually wasn't. I had the vibrations with both the stock unit and the Fluidampr. I had it at the dealership a while back and they told me it could be my mounts because they looked worn and they said they could be "bottoming out." They also told me that it could just be like that because the LT1 isn't "balanced like a race car engine." Anyways, that didn't sound right to me, but nevertheless I changed them to some Energy Suspension mounts...and that did nothing...
So boys...what do I check next? I'm thinking maybe I should pop the belt off and see if one of my accessories is out of whack? Could that be a cause? What else should I be checking?

 

The stock damper does have weights in it. There are holes drilled in the outside ring. I have a couple of weights in those holes.

 

You are correct, sort of. Supposedly some are weighted and some are not (says several sources including my local Chevy parts guy), mine did not have any of the holes filled, so (unless something fell out) mine was not weighted. Either way the vibration did not start until quite some time after I did the timing chain so, in hindsight, I don't think that was ever an issue. Also I did not notice a positive or negative effect of swapping balancers, maybe it is a little better after the swap. I would think I would have seen more of a change if that was the main cause of the problem.

 

You may have a slight misfire. When my opti started going out, it didn't throw a code but there was definitely a slight lope at idle and lower RPMs.

 

Another thing to consider is if you have an M6 then this vibration could be attributed to a bad or going out pilot bearing. Just my 2 cents.

 

There is no heavy side to a damper for the LT1. What you see is the result of zero balancing the damper itself.

deliryumtrigger- do you have a flashing SES light by chance? This could also be from a possible misfire or dead cylinder.

 

No SES light. I was thinking misfire myself, but I have no lights...unless it is just not setting a code for some reason.

Also it's an automatic.

 

AHHHH, nevermind then. Could be a misfire caused by a bad or going ICM, Coil or Opti and it won't necc throw a code all the time. Take the IMC and Coil off and have them tested at your local autoparts store.

 

check your exhaust pipes for rubbing against the frame or body.

 

have you taken the engine apart from the tranny or replaced the tourqe converter?

 

You could check the converter.... I have the same exact issue in mine and it is just a SBC. felt odd for about 500 miles, then the trans started to tick.

 

I haven't touched the tranny/converter. I to looking and there is a 1/4 cut in the insulation of one of my plug wires, looks like its from rubbing on the belt. It doesn't look like there is anything close enough for it to arc to, but I'm used to household and 12v wiring and have heard stories about plug wires arcing through the insulation and across 6 inch gaps so I supposed this is a possibility. I'm thinking that my converter/tranny may also be the problem...or is a separate problem all on its own. When its cold it feels like it goes into gear, but its obvious that the car is only getting a fraction of the power to the wheels. Once its warm there is no problem. I'm not sure if that's a converter or tranny problem. Also when I come to a stop lately I've been getting a completely different vibration. It seems if I take my foot off the gas and roll forward and brake again I can make it stop. Could a bad converter cause some kind of problem based on where it's stopped? Sorry but I don't have much transmission experience.

 

Maybe I misunderstand what you are telling me, but I think you are wrong on this......

This is straight from the factory manual.....


If these weights were for the zero balance of the damper, itself, then the weights would be in it from the manufacture of the damper. They would also not need to be installed in the exact same spots as the old one. I think these weights have got to be for crankshaft balancing. Also, read the warning at the upper right of the picture....it cautions about engine imbalance due to not installing the hub/damper in the same orientation that it came off.

It's the same thing as with the weights in the flywheel.

I think they zero balanced the flywheel with the drilled out spots in the back of the flywheel(this is straight from GM...no other shop touched it)...and the weights in the flywheel are for the external balancing of the crankshaft.

Edit:I am wrong in the above paragraph....The flywheel is not zero balanced....there is a massive weight cast in on the back side of the flywheel(along with press in weights in holes around the outside of the flywheel)