727 vibration

68dodge

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Had a bad vibration in park and in neutral on a rebuilt small block 727. Changed out the convertor to another new rebuilt stock one. Now the car has a vibration, not as bad, but when you drive it, I get a vibration like a consant come and go vibration. Is this transmission rebuild not right'
 

Murray

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Do you have the correct combination of components for balance? Neutral balance or weighted? Engine, flex plate, convertor?
 

67Dart273

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Need to run it up in neutral and see what it does, then drive it and carefully "feel" and note the difference. Could be converter/ engine balance, something in the drive belts, or out of true/ unbalanced drive shaft.

You could disconnect the drive belt(s) when engine is cool for a short time to eliminate them.

Also if the car is modified, could be a pinion angle problem

And of course don't forget tires/ wheels mount/ true/ balance problems
 

Last of the Fast

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Had a bad vibration in park and in neutral on a rebuilt small block 727. Changed out the convertor to another new rebuilt stock one. Now the car has a vibration, not as bad, but when you drive it, I get a vibration like a consant come and go vibration. Is this transmission rebuild not right'
When I bought my 340 Duster new, the alternator was out of balance and caused a vibration at around 2,000 rpm. It was so bad that it was breaking the alternator mounting bolts. Also, check the trans-cross member mounting hardware, including the rubber mount.
 

408 swinger

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I rebuilt my time machine, but, when I plug in the coordinates and accelerate to 88 mph, nothing happens. What is wrong???????
Maybe a little info on your combo might help. Everyone's crystal balls were broken, stolen, or confiscated.......
 

Last of the Fast

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If the vibration fades in and out as you are driving, then check the pinion angle and trans mount. If the vibration happens when you are sitting still, then it has to be engine related up to and including the torque convertor and flex plate.
 

68dodge

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Car ran very smooth, only has 82000 miles. it a 79 Chrysler 300 with 360. Transmission got a bad leak , whick ended up being the front pump cover. Transmission was taken to a trans shop for a inspection and seal replacement, trans shop replaced anything that was worn with a rebuilt torque convertor. Has a new trans mount. Car still has vibrations when you bring RPM's up. Even when you drive it. Nothing else was changed. Flex plate is still the same one. As said before, had original torque convertor rebuilt and replaced the one the was put in the first time and still have the vibrations.
 
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408 swinger

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Since you refuse to tell us engine and car model, there were three engines that would be EXTERNAL balance. If your trans shop put in a "rebuilt" convertor, but didn't put the correct weighted one back in, it's gonna shake like a ****. Did the shop get the prop shaft installed correctly? Loose bolts/straps? Any vacuum lines disconnected? If it's a small block, did they let the distributor rest on firewall during repairs? Thus, cracking the cap or even bending the shaft?
 

68dodge

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Since you refuse to tell us engine and car model, there were three engines that would be EXTERNAL balance. If your trans shop put in a "rebuilt" convertor, but didn't put the correct weighted one back in, it's gonna shake like a ****. Did the shop get the prop shaft installed correctly? Loose bolts/straps? Any vacuum lines disconnected? If it's a small block, did they let the distributor rest on firewall during repairs? Thus, cracking the cap or even bending the shaft?
If you read above its a 79 Chrysler 300, 360 motor all stock , with the original convertor with weight that was in the car since new, rebuilt after the first convertor that had a weight was vibrating also. I removed and installed the transmision twice now.. No vaccuum lines to transmission. Motor runs perfect.
 

67/6barracuda

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Output shaft bearing? probably not changed out during rebuild. Sounds like a typical symptom.
 

408 swinger

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If you read above its a 79 Chrysler 300, 360 motor all stock , with the original convertor with weight that was in the car since new, rebuilt after the first convertor that had a weight was vibrating also. I removed and installed the transmision twice now.. No vaccuum lines to transmission. Motor runs perfect.
I did read "The Above". You went back and edited your post after I called you out about lack of info. Cool. Since everything is as it should be, I'll bow out of this one. Good day sir.
 
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