if it needs a carrier bearing just find a one piece driveshaft from a 4th gen and put er in. torque converter is what first comes to mind when i hear that noise. thats not to say thats what it is cuase its a recording and like gorn sayin recordings are most times off. a miss will make things jump around its the noise that got me.

 

3 grand as in 3000 rpms at 70-80mph

 

Thats was my first thought as well. And the one piece fixes a lot of problems. I did it in my old camaro and will be doing it in this one as well.

Listen to this guy, I have yet to see craby be off about something. haha

 

3000 rpm for an automatic....crap that's not good. It goes up to maybe 2300. Now that's going into something else eeerrrr. I don't think it's the torque converter because its not really giving symptoms, no clicking noises just shaking.

 

Ok vibrations needs energy to occur, when your car is sitting at idle in park the only thing turning is the motor, torque converter the transmission front pump and input shaft. So we know the vibration must be coming from that area. For now forget about the drive shaft there is NO way it can cause a vibration in park at idle because it has no energy. Lets look at the transmission. As you said the torque converter is not making noise and the car drives. This would be a very rare failure. Add in the fact is gets better when you drive the concept it could be convert/transmission fall into almost impossible. With 7 years as a mechanic and 2 as a transmission specialist I have never seen that. Converters and front plumps are very delicate. They may make some nasty noises but to shake the whole car and still function more than a few minutes would be amazing in my mind. As a general rule as the converter and front pump fail the transmission will have all kinds of issues because both of these items will push metal shavings into the clutch packs plugging ports and cutting seals.

There is very little chance your tach/speedo issue has anything to do with your vibration. I am not even sure you have an issue. When I am going 70 MPH my motor is at 2300 RPMs at 75 I am going 2500 RPMs. But that is with 3.23 Rear. You most likely have 2.73s which means your RPMs should be lower than mine. Also I have a five speed so the gearing is a little different. All that is moot because there is NO failure mode that can make a car go faster on lower RPMS. You can go slower on higher RPMs but Not Faster on lower RPMS without breaking a few law of physic. IF your RPMs are reading low then they used to it is simply a tach/speedometer system issue.

 

His rpm's are right. The 94 V6 model came with 3.23 gears, whether it was an automatic or manual trans. And you're gonna have to re-write your hypothesis Gorn, his shaking isn't happening while in park or neutral.

 

yeah Gorn, when in park or neutral its fine but once i change gears to drive the vibration appears. Of course that goes away once i push the gas and move the car.

ok so it maybe a tachometer issue ok thats no biggie.

Gorn so your leaning towards a torque converter issue...

 

I still don't think converter. They are normally noisy long before you feel anything. I wish I could just lay my hand on the valve cover. How much do the RPMs drop when you put the car in gear? Is the RPM needle erractic when it is shaking? Do you have a vacuum gage? That would tell if it is a idle issue for sure.

 

well since the car elecrtically system has been a little...off, it does get a little jumpy but i think that has something to do with the IAC valve. when i turn on the car it does high rev and then goes down to 1000 rpms. once i change to drive it goes to 900 rpms.

Now ive been doing this for years and what i forgot to mention and maybe not the best course of action but ill explain. now this problem has been happening for 6 years now and since i was inexperienced whenever i was at a full stop i than swtiched gears to netural. ive been doing that since and perhaps it wasnt the best options but i learned to deal with it. so since the car is aging id figured id finally fix that problem once and for all.

when the car is in drive and the shaking is happening the rpm needle (as of late) doesnt shake, pretty still.

no vacuum gauge but i dont think theres a leak. ill check again this week but im pretty sure theres no leak.

 

If it is a idle issue you would see the vacuum needle shake. If it was a idle issue i would expect it to drop off a little more than that. Can you have someone power brake the engine a little while you watch the motor mounts?

It does sound like you have a vacuum leak or the throttle is hanging up.