360 Engine Vibration

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Bob Nossal

Dodgefor72
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Dec 20, 2018
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Milford, MI
My brother had someone (not a professional shop but someone he was told knows his way around Mopar engines/transmissions) rebuild the A727 trans in his '76 Duster with the 360 option. It is important to note that he has not checked to see if the engine and trans are numbers matching (working to get that information).

Upon reinstalling the rebuilt trans with a new torque converter, the engine now vibrates at idle and when in gear. He thought it was a bad torque converter so he replaced it again including a new flex plate. The vibration is still there otherwise the engine runs strong and the trans shifts well. Any ideas about the vibration?
 
i bet he put a neutral converter in. 360's are externally balanced. Need a converter that's for the 360 or get a balanced flexplate. Means you already have the new converter, get a flex plate from B & M that's balanced for this swap. Or, a good machine shop can balance the flex plate you have
 
He put a neutral balanced converter where a weighted converter should be. Get the right converter. Problem solved. Then go back and tell your Mopar genius to stick to Chevys.
 
318willrun said:
i bet he put a neutral converter in. 360's are externally balanced. Need a converter that's for the 360 or get a balanced flexplate. Means you already have the new converter, get a flex plate from B & M that's balanced for this swap. Or, a good machine shop can balance the flex plate you have
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The B&M flexplate made for a 360 is the easiest and least cost solution, assuming the TC is neutral balanced.
 
This may seem silly.........are all the nuts and bolts TIGHT??
 
JBurch said:
This may seem silly.........are all the nuts and bolts TIGHT??
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LMAO, NOT a silly question but a possible problem. I have fudged this up myself. Very embarrassing when it was found out in front of all the mechanics!
nm9stheham said:
The B&M flexplate made for a 360 is the easiest and least cost solution, assuming the TC is neutral balanced.
Click to expand...
THIS! This is my favorite route. The B&M flexplate. A little pricey but it allows for any zero balance converter which is cheaper.
 
stixx said:
Well, they did it twice... Still could be.
Click to expand...

I had a co-worker who would say "we do it twice cuz we do it right......."

They did converter twice, still a negative out come, after reading that, loose nuts and bolts came to me as a possibility and not to be over looked, that's why I said silly, yet a real possibility
 
Maybe check that the exhaust/header hasn't been moved against the frame/body during the job, cuz that'll cause a vibration as well.
You didn't mention the vibe in reverse .
Good luck
 
Thanks again for all the advice. I'll make sure I'm there when my nephew removes the trans. My brother is not able to do this type of physical work anymore.
 
Will do. My brother put the puzzle pieces together and is positive that the issue is the flex plate. I will post once I confirm.
 
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