Ok, not sure what the problem is here but I know I'll ruin things if I try and drive it like this!

1983 Firebird with the V6 with nearly 200k on it.

Horrible vibration at certain RPMs (rather it be driving or stationary).

Sometimes the engine will hit a sweet spot and just run normally.

Pulley is NOT bent as it smooths out depending on RPM.

Pulley is NOT loose as I checked that!

Could it be a bad balancer? Hope it isn't bad crank bearings or something! haha

Took a video of it though it's not as obvious in the recording: http://www.youtube.com/watch?v=8PrxP...ature=youtu.be

Ideas?

 

I'm just curious , Exactly what are you seeing wobbling ?

Thing is , the pulley is bolted to the center section of the harmonic dampener which is then in turn bolted to the crankshaft . The harmonic dampener's outer ring , the heavy outer chunk of metal , is held on to the center section by rubber . If that rubber deteriorates , it can cause the outer ring to slip out of proper alignment with the center section and yes throw the balance off badly at certain RPMs , which is just what you described . Now if the outer ring HAS slipped , it should be that , the outer ring ONLY , that you see wobbling . If the pulley is wobbling , well then it's either bent , loose , or the entire dampener/pulley assembly is loose from the crankshaft (which is highly unlikely)

Best guess , the rubber has allowed the ring to slip , and ya need a new dampener .....

 

Yeah it's hard to catch on video.

It's the whole pulley that wobbles; actually wiggles the belts and everything. It's the ONLY pulley that wobbles too.

I checked the center bolt and it was tight.

The pulley definitely isn't bent as I can play with the throttle while under the hood and rev to a spot where it doesn't wobble at all. Nice and smooth.

So... sounds like the dampener might be loose? Isn't that held on by the central bolt though?

I don't post much but I'm really confused on this one!

 

The balancer has a outer ring that is seperated from the inner ring by rubber. I believe its called a inertia ring. The inner ring is fixed to the crank the outer is not and can move if it really wants to.

 

Hi , Ok , so it is the pulley itself your seeing wobble as you say it's also wobbling the belts . Also , you say you checked the big center bolt and found it tight . Now , did you also check the 4 little bolts that actually hold the pulley to the dampener ? You see , the big bolt does in fact hold the dampener to the crankshaft , but it's the little bolts that hold the pulley to the dampener . There may be enough road crud in there for you to not be able to see em all that well , but if you look around the area where the big bolt is , look about an inch or so from it , and you should see the smaller bolts .

Good luck , and let me know what ya find with them .....

 

Here is a picture of the bolts im talking about ..... If those are missing or loose , the pulley will wobble but not fall offf since the washer of the big bolt will have the pulley entrapped behind it

 

Yes , but , this would not cause the pulley itself to wobble since the pulley is mounted to the inner , and not outer , portion of the dampener . For rubber failure to affect the pulley , the pulley would have to be mounted to the outer ring , which it isn't ....

 

Wow, guess I've been working on imports too long

I'll check that after work as well as see if I can check the outer ring on the balancer to see if it's loose!

 

I didnt mean that would be his issue if the pully was wobbling I just thought that he may want to be aware that the balancer is really divided into more pieces.... and not just one solid piece of metal.

 

Cool ... Oh , and , here's another pic where ya can see the bolts I'm mentioning . If they are hopefully just loose on yours , a tightening may be all that's needed . I now don't think rubber failure of the outer ring is gonna be found here , for the already mentioned reason of what the pully is actually mounted to .

Good Luck ...

 

Sounds great to me ...

 

Dang that is one big pile of parts on that pic. Nice. Thats what my garage looks like on a regular basis....

 

Yea , got into the firebird a few years back for some new gaskets and such , Fun project , that's for sure . it's my daily driver on non snowy days ...

 

Turns out it was my transmission... which locked up on the highway not long after.

Clutch was missing material on both sides... but that wasn't from this. Looks like it happened a long while back. Bet that wasn't helping the vibrations!

The pilot bearing was also wasted. Luckily the crank was ok.

And the hot spots on the clutch and flywheel... ouch! Apparently the poor car had a very inexperienced previous owner. We'll fix all of that

Replacement transmission is now installed with a new Luk clutch & bearings. Had the flywheel machined as well. Went with Energy suspension torque arm & tranny mounts for all that 2.8 power! XD