Vibrations!!

[markmine]

Hello everyone!

I think I’m cursed!! My 73 Roadrunner 340, 4 sp has persistent vibrations and I’m hoping someone might have some ideas.

I bought the car about 6 years ago and it had a nasty driveline vibration, I mean it would rattle your teeth! I found the transmission only had 2 of the 4 bolts holding it to the bell housing and one of the transmission mounting bolt holes was gone – broken off the case! When I removed the transmission, the bell housing was trashed. The transmission was installed on the wrong bell housing! So I replace the bell housing, clutch, flywheel, mount and transmission and most of the vibration was gone, but I could still feel it through the shifter.

I recently picked up a rebuilt ’72 340 engine. I installed the new 340 but now I have a vibration when the engine is running! It's not too bad but it gets worse as the rpm’s increase. I know these engines can be either internally or externally balanced and when I originally replaced the flywheel on the old engine, I purchased a McCloud neutral balance flywheel and a balance kit for a cast crank 340. My new engine has a forged crank and requires a neutral balance flywheel, so I removed the balance kit from the flywheel and installed the flywheel on the new 340. When I installed the new engine I replaced the pilot bushing and motor mounts and installed the bell housing, clutch and transmission that I bought a couple years earlier that only have about 300 miles on them. I appreciate any suggestions, Thanks!

 

[68383GTS]

Driveshaft maybe..

 

[rumblefish360]

Whew! I know this bear well. My '73 - 4spd Cuda has the same issues for a long time and I'm down to the driveshaft of it's the previous accident it was in.

The first issue was a 318 was swapped inplace the 340 and used the 340 balancer and flywheel, which the '73 - 340 is externally balanced. Same crap with the bolts holding the tranny on the bell as well.

Are you sure the engine was balanced and internally so?
If so and the new balancer and flywheel are correct, it still could be out a bit due to the whoile assembly not being done as one unit on the machine to balance it.

Also, check wheel alignment at the rear end. Measure with a tape the distances from center wheel to centerwheel on each side and then accross.

Vibration with engine running in gear but gone when in neutral is an engine issue.
Vibration with engine running in neutral not so present in gear is a body/suspention issue.

Double check driveshaft for dents/crease's and/or missing weights.

 

[D Dodge]

I had a vibration in a '70 Coronet that turned out to be a loose torsion bar.