Confusing imbalance issue

Discussion in 'Technical' started by SERE Guy, Sep 27, 2009.

  1. SERE Guy

    SERE Guy Member

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    I recently swapped my transmission for a T-5. In the process I found that I had to switch to a 164 tooth flywheel. The larger flywheel however is a 50oz imbalance. To counter this, I thought I could swap out the harmonic balance for a 50oz imbalance. It has since come to my attention through some research that the imbalance used is specific to the crank, and my crank, being in a 302 that allegedly came out of a '69 Ranchero should be a 28oz imbalance (I say allegedly because I didn't build the engine). Here's where it gets weird. With a 28oz imbalance crank, and 50oz flywheel and harmonic balancer, I should have severe vibration (according to common sense/everything I've read). For some reason though, there is no detectable vibration, even when I rev the engine. It's difficult to really hear whats going on, due to the fact that the car has open headers. I'm not driving it that way, I just haven't gotten to the point of putting exhaust on yet. From what feel and see though, there is no vibration. What gives? This Frankenstein'd project is about to drive me out of my mind.
     
  2. Mavman72

    Mavman72 Gone backwards but lookin' forward

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    If you have a 28OZ crank...The 50OZ stuff will eat it alive.As for vibration.You are probably experiencing alot of harmonics due to the open headers.They could be masking other vibes from other things.You cant mix different imbalance components.They all have to be the same.
     
  3. SERE Guy

    SERE Guy Member

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    I'm gonna go find a wall to smash my head on for a bit. I guess it's not too big of a deal, I'll just have to swap balancers back out and have the flywheel milled down to a 28oz imbalance, but that means pulling the trans AGAIN. I might have to take a break from this project for awhile. It's making my head hurt.
     
  4. maverick maniac

    maverick maniac Banned

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    I have 3 164 tooth 28 oz. flywheels it would be better to change to correct one .
    Don't think they can fix your nobody here does
     
  5. baddad457

    baddad457 Member

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    I want to know how you fit a 164 tooth wheel in a T-5 bell. It don't fit and the starter doesn't line up as T-5 bells were all 157 tooth. As for the imbalance difference, you're not going to start to notice that untill you rev it above where you can in the driveway. It'll hit a point where it'll gradually get worse and worse. At idle, it's just going to add a bit of vibes to make it seem that the cam is bigger than it is.
     
    Last edited: Sep 27, 2009
  6. SERE Guy

    SERE Guy Member

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    Maybe I'm remembering wrong, but my 157 tooth Maverick flywheel wasn't large enough for the starter to engage. I swapped out for a flywheel pulled from a 3.8L V6 Mustang (T5 also came from a 3.8L Mustang), that I'm pretty sure I remember being a 164 tooth. It was definitely slightly larger than the Maverick one, and now the starter engages.

    Either way I have learned a very valuable lesson from all of this. Do the entire build on paper first, to make sure everything will work. I've been doing it as I go and I've wound up chasing my tail getting this thing swapped.
     
  7. Mavman72

    Mavman72 Gone backwards but lookin' forward

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    Gotta do your homework before re-engineering a car of any kind.Devils in the details my friend...At least you figured it out before you did any damage...Lesson learned.
     
  8. baddad457

    baddad457 Member

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    Hmm, first time I've heard of a 164 tooth T-5 bell.
     
  9. SERE Guy

    SERE Guy Member

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    I could be wrong, just going off of what I remember from assembly, but it was definitely the larger of the two flywheels I had.
     
  10. mavdog71

    mavdog71 Member

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    You nave your mav flywheel or flex plate ??????? If so take it to a engine balance shop with your 3.8 flywheel they should be able to tell you what the balance is on both unit and be able to rebalance the one you need to use..



    JUST my 5ct. worth
     
  11. justin has a 74

    justin has a 74 Maverick bandit official

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    someone may have changed things over the years??? i had a truck trans with 164 bellhousing and flexplate... it was an automatic though
     
  12. cdeal28078

    cdeal28078 Member

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    I would think the vibrations would be bad enough to notice sitting in the driveway. I had a flywheel milled once and they got a bur under it so that it milled one side more than the other. It was not much but I thought that engine would jump out of the truck just as soon as it started up.
    I know we arn't talking about the exact same thing but still is kind of close.
    A 69 302 is a bit old and may of been rebuilt sometime in it's past. Do you still have the orginal flywheel?
    Clint
     
  13. maverickdragger

    maverickdragger GearHead

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    i have a c4 in my car. i couldnt get my headers in with the 164 tooth bellsousing. i got the 157 bellhousing and flywheel and it works great. my only problem now is that my pistons arent balanced to my crank and its got a lil vibration. bad news.
     
  14. baddad457

    baddad457 Member

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    What changed about the pistons ? Those had nothing to do with changing the flexplate.
     
  15. maverickdragger

    maverickdragger GearHead

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    yeah everything was fine but i stock rod bolts on a motor that turns 8000 when i shift and i stretched them and the bottom came apart. i got another crank and a set of rods out of a 85 gt that were balanced together. and when i put my pistons on i didnt thinm it would hurt to not balkance them. well i was wrong. got a vibration idling
     

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