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Discussion Starter #1

I Took my '71 Ranchero 351C 4V C4 Trans. to a Performance Transmission Shop to have a Higher Stall (2500 RPM) Converter installed and now there is a severe vibration at all RPM's. What happened?
They sent the converter back had it rebalanced but it still vibrates.

The original Converter was smooth, no vibration. I just wanted a higher stall, about 2500 RPM. The shop wants to put my old converter back in and give my money back.

I would rather have the problem fixed.
What can be done??????
Should I have the converter balanced with the Flex Plate? Or would that change the balance of the Crank?
HELP!!!!!!
 

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Lenny, if they want to put your old convertor back and refund your $$$ then I say do it. Then if it's still vibrating you can really pin down that THEY broke something.

If the vibration is gone, you can take it to someone else for the convertor work. Hopefully someone who can build a balanced convertor without doing it twice.

Good luck!

Greg
 

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I'm assuming this stuff has been looked at but I'll mention it anyway...

Could it be an engine miss? Something simple like they cracked the distributor cap... plug wire off etc..

Did they replace any transmission mounts? Maybe they put something in wrong...

When you say any RPM, is this driving or in park?
 

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Discussion Starter #5
It vibrates in Park. This is no little Vibration you could call it shaking. At 1500 RPM'S the rear view mirror is a blur.
 

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Discussion Starter #7
They are going to start the Engine today without the Converter. That should indicate whether its the Flex Plate or the Converter.
All I know is no vibration before they worked on the car.
 

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Start the engine without the convertor? You mean NO convertor attached to the flexplate?

BAD IDEA! Don't let them do this. Sounds like this is a shop full of crackheads. Get your car put back like it was before they messed it up, and take it somewhere else!

Greg
 

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The convertor is a big flywheel. The only flywheel the engine has.

Most likely the engine will kick back and damage the flexplate and the starter without the inertia of the convertor.

Plus it is a stupid idea for a trans shop to isolate THEIR faulty part with YOUR expensive lesson. Are they paying you for this educational session on your car?

Sorry to rant, but transmission shops really get me chapped when they pull this stuff. Plain old good parts plus good troubleshooting would get this problem fixed ASAP.

Greg
 

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Discussion Starter #12
They started the engine without the Converter and ther was Zero Vibration.
They are going to get a different Converter from a different manufacturer.
I had originally purchased a TCI Breakaway from JEG's but the shop said it was the wrong one. It fit the C4 26 spline trans but was too small for the flex plate. I thought I ordered the right one. I ordered the 1970 and up C4 26 spline with the dipstick in the case. But it was the small converter. Which one should I have got?
 
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