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Technical 351w balance issues

Discussion in 'The Hokey Ass Message Board' started by 31Vicky with a hemi, Aug 26, 2016.

  1. Well it's my baby to rock now.
    My research leads to that ford only mated the 351w to the AOD Trans in some crown Vic platform and most were police cars. It's a rare flexplate.

    Supposedly the 164 tooth for C4 Trans with 28 imbalance will work. I ordered this one, we will see.

  2. You do know that the '28 oz damper' is now suspect also? (He got one part wrong, did he buy a 'set'?). I don't recall seeing a 28 oz damper with that 'balance lump' on it, but I have seen a 50 oz unit that had that feature...

    As to the flexplate, there appears to be some confusion there; some claim that some OEM SBF 164 tooth count 28 oz C4/FMX flexplates will work with a AOD (if they have the right bolt pattern for the torque convertor, which is one issue), some claim that 'flexplate offset' is off enough on these to cause issues with convertor engagement into the trans. Ford did make a special dedicated 'conversion' flexplate for this application at one time (now discontinued), and both Summit and Jegs show these as 'special' parts for this specific application (with corresponding higher prices).

    As to why Ford changed the balance, the 50 oz crankshafts are considerably lighter compared to the 28 oz versions and that helped with both throttle response and fuel mileage (which is why this was first used on the HO motors). But they aren't as strong, which is why the 351 retained the early design and balance.
  3. If someone has a part number for the correct flexplate that would be awesome. If it happens this would be the only thread on the entire internet that had a part number for this issue and the right flexplate for 351w with AOD.

    The balancer is a early 3 bolt with a smaller bob weight on it.
  4. Summit lists that for c6 applications and the rest of the Internet says a c6 plate and AOD eats the Transmission
  5. There's apparently different torque convertor size/bolt pattern differences which seems to be the hang-up. I think you'll need to know what convertor you have before you order one...
  6. Johnboy34
    Joined: Jul 12, 2011
    Posts: 1,381

    from Seattle,Wa

    Last edited: Sep 1, 2016
  7. OK, My bad, the vans and trucks used a E40D, not an AOD and that number was for the C6/E4OD which use the same flexplate. I'm going to delete my posts to delete some confusion.
    The correct one for the 351W AOD is Ford part # E0AZ-6375-A according to a guy who did the swap. ATP crosses that the Z-105
    This quote is from a guy who had researched and done the swap - The C4 164 teeth flexplates and the AOD 164 teeth flexplates will physically interchange, but there are two balance weights to be concerned with. Part# OEM E0AZ-6375-A (164 teeth flexplate, 28.2 oz-in balance factor, 351W with AOD applications).
    ATI Performance Products says the C4 and AOD are the same.
    Performance Automatic says they are the same also.
  8. town sedan
    Joined: Aug 18, 2011
    Posts: 1,290

    town sedan

    Did some looking and I've seen a PERFORMANCE AUTOMATIC part# 26467 come up a couple places. Summit has it for almost $185. Description from CJ Pony Parts reads "1965 to 1980 28 oz balance 289/302/351w mustang with an AOD transmission." But they sell it for a few bucks more. It sounds right, but I have no personal knowledge of this company, or part.
    Last edited: Sep 1, 2016
  9. It might just be where the timing marks are.
  10. If you go to Summit Racing and do a search for Ford flexplates, when you use the various 'filters' i.e. select Ford/Windsor/351/28 oz/AOD trans, four flexplates come up. These ARE NOT the same as the 'generic' C4/C6 flexplates (and cost more) so there is obviously something different about them. And even these have some 'notes' on them about torque convertors, so you really need to know what convertor you have specifically...
  11. C4 and C6 are NOT the same - the C6 sits a 1/4" deeper. But there a number of Auto Tranny specialist company's that say the C-4 and AOD 164T DO interchange.
  12. tom in nh
    Joined: Oct 16, 2011
    Posts: 72

    tom in nh

    Has the torque converter been checked for balance?
  13. Engine man
    Joined: Jan 30, 2011
    Posts: 3,476

    Engine man
    from Wisconsin

    I bought a low mileage 74 Monte Carlo in 76 very cheap because it supposedly had a bad 350 engine. The owner drove it over a curb in a parking lot and bent the flex plate. It was replaced but the engine shook. He took it to a tranny shop and they replaced the torque converter still shook. He took it to another shop that replaced the damper and it shook worse. They pulled the transmission and ran the motor. It shook and the flex plate wobbled. They decided it had a bent crankshaft. The guy traded it in on a new jeep and the dealer never test drove it. A quick check of the VIN told me it was a 400. I replaced the flex plate and damper and drove it for 16 years.
  14. I have no idea
  15. 57Custom300
    Joined: Aug 21, 2009
    Posts: 1,347

    from Arizona

    I have a 79 Ranchero w/a 351m c4 that vibrated the same as yours. Drove it for more than a few years that way. Knew it had the wrong flexplate but I worked on cars everyday and didn't want to mess with it. One day on the Hamb I saw a thread that was related to this. Guy said he added two flat washers on each of the 2 convertor studs that was opposite the weight. Fixed 98% of the vibration. Drove it that way until last year when I went thru the engine and had everything balanced while it was out. Might be worth a try for a quick fix.
  16. Ordered this one too.
    Soon I'll have them both in my hands and compare.
    Thanks guys


  17. Here's the update and closing.
    The performance automatic 26467 is the correct flex plate if you need a AOD Trans to a 351w.
    Yep it's 185.00
    It matched up in every way and when installed solved the problem.

    When compared to the other one (prw) I ordered from Amazon,,,,
    it's 164 tooth 28 ounce for C4

    First off, the plate is stamped from thicker material, almost 2 times so it was considerably heavier.

    The offset of the two, the Prw was almost 1/8 less- so that would move the converter closer to the crank, but the thickness difference would move the converter bacteria towards the Trans. Finishes out that the converter is very slightly more towards the crank.

    All of The bolt holes in the PRW would need to be opened up a few thousandths so the crank bolts and converter studs would go thru.

    The oval holes were not present, you'd only need to cut one hole for the converter drain plug clearance but you'd need 3 more holes to maintain the balance equilibrium.

    So I'd say that particular version of a C4 plate was not the same as a AOD.
  18. That's the right one,
    Thank you

    Thanks to everyone who chimed in
  19. town sedan
    Joined: Aug 18, 2011
    Posts: 1,290

    town sedan

    No problem

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