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broken flex plate.

Started by mopar jack, July 16, 2022, 09:00:38 PM

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mopar jack

This is the first flex plate I have broken in the 50 years that I have been driving mopars. I have a 71 barracuda with a mild 440 and 727 auto that I put together in 1996 and raced in the street class about 8 years with an Art Carr high stall converter and no problems. In 2011 I flattened the cam and decided to go with a stock type converter with  lower stall. Looking for suggestions on replacing the flex plate and should I have the converter and transmission checked.

Chryco Psycho

The B&M full plate flex plates are stronger , possibly the trans is misaligned on the dowels causing extra stress .

73chalngr

I broke the flex plate on my small block many years ago . A piece of metal went through my oil filter. I just replaced it with a Mopar performance solid flex plate. So far so good.


mopar jack

Quote from: 73chalngr on July 17, 2022, 04:11:33 AM
I broke the flex plate on my small block many years ago . A piece of metal went through my oil filter. I just replaced it with a Mopar performance solid flex plate. So far so good.

This is a solid flex plate  from mopar performance I installed back in 96. The transmission never showed any vibration until recently it would shake a little at idle. I suspect the converter could be the cause as there is less than an 1/8 inch between mounting tabs on converter and flex plate when bolts are removed. I recall my other converters having a lot more gap when separated.

73chalngr

Ouch .  Do you have the motor and trans separated ? Did the bolt heads strike the block somehow?

mopar jack

Quote from: 73chalngr on July 17, 2022, 10:42:52 AM
Ouch .  Do you have the motor and trans separated ? Did the bolt heads strike the block somehow?

Just pulled the transmission and removed the flex plate from the crank. The bolts never came loose and I actually  struggled breaking them loose, Lock Tite did it's job. The converter was also hard to remove off the input shaft which I've never experienced before and I had to pry hard on the flex plate to remove from the crank hub.
No part numbers on plate so probably not mopar performance and there is a crack on a third tab. I don't know how it stayed together.

torredcuda

Obviously aftermarket as it has an SFI sticker but the only ones I remember seeing are the full circle B&M ones.  :dunno:
Jeff   `72 Barracuda 340/4spd
https://www.facebook.com/jeffrey.hunt.750

Northeast Mighty Mopar Club
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Locomotion

B&M flexplates are the strongest and offer the optional bolt hole sizes and spacing. Nothing wrong with the solid ear version like yours, but anything will break over time & hard use, like yours. I've broken a couple like this one over the decades, but it was race-only applications. I assume your current "stock type converter has the race converter bolt size & spacing? Considering the converter was difficult to remove, checking it and the trans would be a good idea. Lots of time on the trans!

mopar jack

Quote from: Locomotion on July 18, 2022, 09:32:49 AM
B&M flexplates are the strongest and offer the optional bolt hole sizes and spacing. Nothing wrong with the solid ear version like yours, but anything will break over time & hard use, like yours. I've broken a couple like this one over the decades, but it was race-only applications. I assume your current "stock type converter has the race converter bolt size & spacing? Considering the converter was difficult to remove, checking it and the trans would be a good idea. Lots of time on the trans!

Thanks for confirming the B&M plate, ordered it this morning. The round shape had me worried as I have only dealt with the stock looking plates. My current converter was built by Spec Rite in Redding Ca. it's a 9 inch with 2400 stall and the small bolt (10 Inch) pattern and 7/16 inch torque converter bolts for 6 bolt crank. The trans was working well  up until I pulled it so I'm going to take a chance on it for now, just no more time to spend  on the car.

Strawdawg

Before you install it, compare the depth of the offset on the new flexplate to the prior plate and make sure they are basically the same so it does not screw up the desired clearance between the plate and the torque converter.

Steve