i'm having a wicked vibration problem that i need to have resolved, car is a 305/ 5 speed, when i drive on the highway at speeds of 70mph i get a horrible vibration, it's not the front end as i ran it on a lift at this speed and still had the vibe, but the funny thing is sitting still with the clutch disengaged i get the vibes at 2300 rpms release the clutch same rpms vibes still there no change, it's a new clutch new pilot bearing, new flywheel, rebuilt tranny, what could this possibly be? i also changed to a different motor and the vibes are the same with the new one, is it something to do with the clutch pressure plate? i really appreciate any help guys, i just rebuilt the motor and the rear and i dont want to screw up the bearings.

 

could possably be your driveshaft is bent a little or maybe your tranny mount is busted. just a few thoughts

 

tranny mount is new poly urethane, tried 2 different driveshafts, vibration is there without the car moving

 

well, was it like this before you switched the tranny and clutch assembly?

 

How are the motor mounts & are they tight?

You using the correct dampner?

just a few thoughts for ya.

 

Try re-indexing the driveshaft. What I mean by this is to unbolt it and turn it 180 degrees and bolt it back in. Most of the time this cures those vibration problems.

 

i did that already with the driveshaft, tried 2 of them, car vibrates without moving but is worse at speeds of 70+ motor mounts have not been changed, the car didnt vibrate like this till i rebuilt the tranny installed a new clutch / flywheel, could the motor mounts have gone bad from the motor tilting backwards while dropping the tranny?

 

Did you install an Energy Suspension tranny mount?
The universal E/S mount is a little taller than a stock mount.....

 

Twice you have said the car vibrates without moving... I dont understand that but if its vibrating sitting still then you have some sort of tuning problem.

 

Make sure the flywheel bolts are TIGHT.

~M~

 

I have the same problem with my car. One thing that improved it was when I boxed the panhard bar by welding in a piece of flat steel. when I had my drive shaft balanced it was bent. So I put a drive shaft from a '96 chevy short bed Z71 in it. The truck drive shaft is only a 1/4" shorter then the camaro's. The viberation was still there after the new drive shaft. My transmission has never been apart but I have replaced my clutch and the vibration was still there. So now I just deal with it. After 75 MPH my car seems beter but I wish I know what problem was???

 

no it's not a tuning problem my car runs like a bear, if i'm STOPPED and the clutch is DISENGAGED and i brint the rpms's up to 2300 i get that vibration coming from the flywheel area, this also happens while the car is moving at speeds of 70mph + but is much worse then when the car isnt moving and the rpms are at 2300

yes i have a polyurethane tranny mount, but i had the stock one before no difference there

 

86Z,

I understand that the vibration is present @ 2,300 RPM without the driveshaft/transmission moving. I'd suspect a poorly balanced flywheel, or a clutch/pressure plate that is not mounted concentrically with thw flywheel (flywheel was either machined or drilled incorrectly. It's also possible that the pressure plate is out of balance. In any case, I'd repair the problem before the rear main bearing gets worn from the imbalance.

You DIDN'T get one of those Chinese clutch kits from AutoZone, did you?

 

Another thing it could be, when you installed the flywheel there may have been something stuck on the crankshaft or flywheel mating surface thats not letting it tighten down evenly.I would put it back on the lift and pull the flywheel dust cover and run the motor to see if the flywheel and clutch are running true.Also, are you sure its the correct flywheel? 305s and 350s are internally balanced and use flywheels with no balancing weights.454s & small block 400s are externally balanced and have big balancing weights on them.I bought a used 454 once and installed it in a 66 Impala.It vibrated so bad, every 100 miles or so I had to retighten and replace bolts under the hood so things wouldn't fall off while driving.I found out the guy had put the wrong flexplate on it.They will bolt on but will cause vibrations.

 

Vader thank you very much! and yes it's the correct flywheel i replaced it because of the worn starter teeth, to answer your question vader yes i did put an autozone clutch in it, why?

 

Why? I'd be very suspicious of the pressure plate balance and alignment. I'd remove the inspection cover and start checking/measuring closely. TXTurbo had a good idea about watching the clutch at idle for out-of-round and true running.

When the clutch is disengaged, only the flywheel and pressure plate are turning, not the clutch disc or trans input shaft. What's that tell you?

Good thing AutoZone has a liberal return policy...

 

Transmission parts from the flywheel to the pressure plat are indexed. Need to make sure they are installed as they were before dismantling. I have also seen a bad clutch disc do this on an Audi.

 

But the clutch disc isn't moving (nor is the input shaft) when the clutch is disengaged. Unless it is grabbing, it wouldn't make any difference. And if that were the case, it wouldn't vibrate with the clutch engaged.

 

yes vader is correct, i just rebuilt the motor and i put the same damn clutch back in, for some reason i knew i should have changed the clutch and the motor mounts, but i did check the input shaft on the tranny and it was fine, i rebuilt the tranny about 200 miles before i had to rebuild the motor, so vader you think it could be the pressure plate eh? when i put in the new flywheel i didnt have it turned down neither, i wonder if it was bad

 

i see you said new flywheel,did it also come from autozone,i've found the hard way that is not the ideal place for parts,i got a pressure plate clutch set from there,and $$$and time later found the components werenot balance at all,vibrated real bad,clutch in or out,got a borg warner set from NAPA,and bingo,now problems since,except did have to replace the ring gear on the flywheels due to starter not aligned properly,and same time resurfaced,it had a cone look before,and now smooth!!!too bad a lady driver took it out!!

 

nope genuine gm flywheel straight from GM

 

It's possible that is was still machined incorrectly, but less likely. Either way, the clutch will still have to come out. I'm still thinking pressure plate assembly.

 

i think the pressure plate too vader, i'm gonna replace the clutch and see if there is a place around here that can check the balance on the flywheel and have it turned down, was looking at the hays clutch assembly in the jegs catalog, what do you think vader?