I shift at 5.8k and the vibe definitely comes in around 4-4.5k and goes away by 5k.

It isn't bad and I'll admit I am hypersensitive to sounds and vibrations with this car, but there is something there.

It is externally balanced.

Anyone ever experienced something like this where the vibration was localized to only a ~2k rpm band?

TIA

Is the car stock? I am guessing not, considering that the engine is spinning to 5800.

Automatic or manual? If it's externally balanced, is it balanced both front and rear externally? Has it always done this or has some maintenance just been done?

I wonder if the harmonic balancer is coming undone? Is it OEM stock or aftermarket?

Where is the shaking feeling/vibration coming from?

Could be u-joints, exhaust loose and hitting something, HB as discussed, problem with wheels/tires, etc.

Can you localize the problem or give a more clear description?

Matthew

another question - is it always engine speed related or vehicle speed?

Sorry for the delayed reply, got very busy at work for a bit there.

The vibration is engine speed related and occurs in neutral as well as in gear.

It is most noticeable slowly climbing through 2nd gear (when I romp on it, well there is a lot going on and fast) and 3rd gear I hardly do slowly just due to the speeds. However, like I said, it happens in neutral as well.

383 w/ a 400 external balance crank, I don't recall this happening in the beginning. I doubt I wouldn't notice it but it is hard to say the motor has about 2500 miles in 4 years or so because I rarely get a chance to play with it.

I was thinking it was the balancer however, would checking the timing show that?

It could be one of the exhaust heat shields I suppose...

I'll try and take a video next time I have a chance to screw around with it. Here is a clip of trying out 5200rpm as the shift point, and forgive me, it is my wife's camera duct taped to my sweatshirt (haha) however as expected it made for a crappy mount and mostly you see my crotch. A little embarrassing and stupid, I need to get a roll bar mount set up but oh well, if it helps... http://www.youtube.com/watch?v=Iht1fw9TqYM

The car runs well and you can't really see or hear the vibration here, like I said I am hypersensitive. But there is definitely something going on in that 2000rpm or so window. If it is a balancer starting to wear out, I'd rather catch it sooner than later.

Thanks for all the help so far guys!

Ohh, recent maitenance. The only thing I can think of is I went from a bronze oil-impregnated pilot bearing to a roller bushing, started to hear some whining, swapped back. (Turns out it is the throwout bearing... of course, I decided not to swap it, it was practically brand new ~1500miles.)

So the throwout still makes a little tiny squeak when the clutch is not depressed otherwise nothing changed at all.

Hard to tell from the video.

Since the vibration happens in gear and neutral you can eliminate u joints, driveline, IMHO.

I'd check balancer and anything that might be rattling/touching. As far as checking the timing, it might be an indication. When I went to set mine, the timing mark had slipped about 4 inches. I couldn't see any change in the HB ring forward or back due to the pulley, but when I removed it noticed the HB ring had shifted about 1/4 inch towards the front.

Good luck.

Matthew

I agree, also the u-joints were replaced 2k miles or so ago.

I'll check to see if I have forward/aft movement.

Thanks!

(Did you have vibration throughout the RPM band or just at a certain range?)

When my HB slipped I didn't really have a noticeable vibration. I guess a minor amount, but I just attributed it to being a V8

Now that I got the new one on, it's much smoother and also resetting the timing made it run smoother. Previous rattle I had was caused by the exhaust.

You can also check to make sure you don't have any rocks or junk stuck by the trans or in the motor area. Sounds dumb, but I've had that happen and thought the car was gonna blow up....lol.

Matthew