1. A38E86D32

    A38E86D32 Active Member

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    I'm at a bit of a dilemma here fellas. I have a fully rebuilt engine and transmission. Car of subject is my '71 Fury 4 dr sedan. Engine dyno'd at 410 horsepower, trans has 22-2400 stall converter, shift kit, rear is 3.23s. I purchased an ATP flexplate with the correct 6 bolt crank, 10" spaced 5/16 converter bolt patern. It looks like an oem replacement. It mates perfectly to the converter and crank. My question is, WILL it hold up? It is stamped "made in Mexico ". I originally was going to use a solid round flexplate, but heard there could be misalignment issues with the trans pump bushing.
    Thanks in advance
    -Marc

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  2. Davea Lux

    Davea Lux Old Man with a Hat FCBO Gold Member

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    B&M 10230 is probably the best flex plate (SFI approved) for high performance applications. Available thru multiple vendors, the correct round pattern and they are drilled for either large, 11.25",or small pattern, 10", torque convertors. ATP makes a good unit for stock applications.

    Dave
     
    Last edited: Dec 30, 2019
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  3. Turboomni

    Turboomni Old Man with a Hat

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    It has always amazed me that even on a stock engine these thin metal flexplates can transfer all this power without turning to a wad of wadded up metal.
     
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  4. A38E86D32

    A38E86D32 Active Member

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    Originally i was going to buy one of those, but have read that to run one you need to check that the trans input and engine crankshaft are centered with each other within a certain tolerance. If not it would prematurely wear trans pump bushing. Have you ever heard this?
     
  5. 413

    413 Well-Known Member

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    The part I don’t like is made in Mexico. The originals from Chrysler will take a beating and live on.

    I don’t see why that B&M piece won’t work. I saw a lot of them out there when I ran at the drags for years.
     
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  6. Davea Lux

    Davea Lux Old Man with a Hat FCBO Gold Member

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    If anything, I would think the round style flex plate should be more stable. It is all about how torque is transmitted. To avoid distortion of the flex plate which causes the bushing to wear out, it needs to run true with a minimum of stress related distortion and the full metal plate is ideal for this as the torque is evenly distributed across the surface of the circular pattern.. The 4 way flex plate can accomplish this as well as long as the four flex arms are sufficiently robust. If you are more comfortable with a 4 way plate, find one that is SFI approved and it should also preform well. Any SFI plate is supposedly pre-checked for alignment and run out. for At 410 horsepower, you will not be pushing the limits of either style plate. Most of the racers still run the circular plates on the track, but that is probably overkill for a street machine. I am not aware of any SFI circular flex plate issues causing front bushing burnouts. Most front bushing failures result from poorly balanced components or distortion of the transmission case due to missing bolts, improperly torqued bolts, mismatched components or an application with limit pushing horsepower/torque ratings. Usually in excess of 600 horses and 600 lbs torque at high rpms. At those numbers, the block is likely also flexing unless a lot of work has been done to the lower end.

    Finally, when procuring a flex plate, be sure to order one for either the cast steel crank which is internally balanced or for the forged steel crank which is externally balanced. There is a world of difference between these two flex plates. (There is also a nodular iron crank starting mostly with '74 and later 440 engines, but these are not usually retained for high performance builds.)

    Dave
     
    Last edited: Dec 31, 2019
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  7. 413

    413 Well-Known Member

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    Dave What In the wide world of sports is SMI?



    Try “SFI” here
    The SFI Foundation, Inc. (SFI) is a non-profit organization established to issue and administer standards for the quality assurance of specialty performance and racing equipment.
     
  8. Lefty71

    Lefty71 Active Member

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    I think the OP is referring to the fact that he could possibly have a dowel misalignment issue (which he didnt check for). Now he'd like to button it up, but he can't find an OEM style flex plate, and the solids like B&M's that are SFI rated will not flex as effectively as an OEM. There are SFI flex plates, that are not the solid, round style. But, I will say I had trouble finding one to fit a small bolt pattern 5/16" torque converter like BossHog makes. If he's running large bolt pattern, or 7/16" converter bolts, then there should be no issue, as they are available from multiple vendors.
     
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  9. Davea Lux

    Davea Lux Old Man with a Hat FCBO Gold Member

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  10. 65sporty

    65sporty Old Man with a Hat

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    I know guy's check dowel alignment when running manual transmissions, but I have never heard of anyone trying to check it with a automatic
     
  11. Davea Lux

    Davea Lux Old Man with a Hat FCBO Gold Member

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    If the OP rebuilt the transmission and engine that were in the car, it should already be a good mate assuming the front bushing had not failed. If there is a suspicion that the transmission has a dowel alignment problem, that should be addressed as that is not something that the flex plate is going to fix. Lefty is correct that the circular style flex plated have less give to them than the 4 way type, but on a properly aligned engine and transmission that is a big advantage. If there is a significant alignment problem, something will usually break regardless of which plate is used.

    Dave
     
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  12. Lefty71

    Lefty71 Active Member

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    You and Davea are spot-on. Most of the time you won't see problems with automatics, and the OP will likely be fine with a standard flex plate (or a heavy duty round SFI approved one). If I were him I would probably seek out a good OEM one before I would choose a $20.00 knockoff. Questions arise if there are known problems that existed as the unit is pulled down, such as damage like a heavy wear ring in the converter snout, or a pump bushing worn on one side, repeated seal or pump failures, and of course damage to the old flexplate for reasons unknown, which can all also just be a bad converter. But since he does'nt mention any of things to be known facts with these existing parts, I assume he just wants to be sure he's good ahead of time. Good chance he's fine, IMO.
     
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