Vibration from trans?

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jwicker

jwicker

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Hey all,

I have a vibration that sort of comes on and gets really bad at particular RPMs. It happens in neutral as well. Without a tach, I can't say quite what RPM, but it's easy to reproduce at 50MPH in 3rd gear. More gas makes it go away, less gas makes it go away.

I believe my motor mounts are totally shot, so I was planning on replacing those soon, and maybe even the trans rear mount.

Any thoughts on what to check?
 
jwicker said:
Hey all,

I have a vibration that sort of comes on and gets really bad at particular RPMs. It happens in neutral as well. Without a tach, I can't say quite what RPM, but it's easy to reproduce at 50MPH in 3rd gear. More gas makes it go away, less gas makes it go away.

I believe my motor mounts are totally shot, so I was planning on replacing those soon, and maybe even the trans rear mount.

Any thoughts on what to check?
Click to expand...


Purple...
 
jwicker said:
Hey all,

I have a vibration that sort of comes on and gets really bad at particular RPMs. It happens in neutral as well. Without a tach, I can't say quite what RPM, but it's easy to reproduce at 50MPH in 3rd gear. More gas makes it go away, less gas makes it go away.

I believe my motor mounts are totally shot, so I was planning on replacing those soon, and maybe even the trans rear mount.

Any thoughts on what to check?
Click to expand...


We need more info on engine, trans, body style combo...

However with it vibrating in neutral, I would start looking into the flex plate, torque converter, or vibration damper... This could be a 360 with the wrong flex plate or torque converter combo....
 
Sorry - Slant 6, 225cc, torqueflite automatic push button. 64 Dart GT. Rear end is original, don't know what size though.
 
My suggestion is put it in park. lol!

Need more info to help you make model and year and any mods that you know of.
That helps us help you.
A video is good too!
Syleng1
 
Was the engine ever replaced with a newer slant 6 engine or crankshaft ? If so the torque converter registry could be to small for the hole in the crankshaft. Seen this many times. You may need to have a bushing made and installed on the converter if the car has a newer slant 6 installed with the original cable shift trans.
 
jwicker said:
Hey all,

I have a vibration that sort of comes on and gets really bad at particular RPMs. It happens in neutral as well. Without a tach, I can't say quite what RPM, but it's easy to reproduce at 50MPH in 3rd gear. More gas makes it go away, less gas makes it go away.

I believe my motor mounts are totally shot, so I was planning on replacing those soon, and maybe even the trans rear mount.

Any thoughts on what to check?
Click to expand...

when you say it happens in neutral do you mean stopped in neutral and revving it or coasting in neutral and revving it?

have you gotten under it to check anything out besides the mounts? which you should do as a matter of course.

i'd take a WAG and say either something trans related or the harmonic dampener is coming apart.

years ago i had car in with a /6 that would shake like crazy at specific RPM and especially under load. it seemed perfectly fine at idle and wasn't bad driving per-se, just a little less than desirable in the smoothness department. turns out it had a bent rod.
 
I doubt it's in the trans or axle if it vibrates in neutral...

It's most likely in the rotating assembly...

The flex plate, torque converter, crankshaft, vibration damper...

The outer ring on the vibration damper may have slipped and is mis-clocked... The way to check/verify is to get a dead stop TDC tool and verify TDC by putting the engine at TDC and make sure the timing marks are correct...
 
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