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Thread: AOD - Slipping OD Band Thoughts

  1. #1

    Default AOD - Slipping OD Band Thoughts

    Hi guys,

    hitting the road tomorrow with my trailer to pick up my second box wagon. I'm hoping this will be a long term build but hoping to get it mechanically sound for the time being. I'm told overdrive is slipping. My newbie research has indicated this is common on the AOD due to the undersized band. I'm hoping to use this to negotiate the price down a bit.

    Assuming it's the OD band, what're the thoughts on a remedy? I'd eventually like to make more power with the car, likely an HO conversion and (possibly) a roots style low psi blower set up to suit the torque needs of a heavy car. This isn't going to happen in the next six months to a year I'm guessing. I'm wondering if I should just get the band replaced and enjoy the car in the meantime or does it make sense to build the transmission for my future plans while it's out? I'm a newbie with this transmission so I'm trying to educate myself in a hurry and advice would be appreciated. I'm up in Canada but I'm seeing street-built AOD's for $23-2500usd. I'm guessing a local shop would do a factory rebuild for $1500ish. If it's possible to replace just the band for under $1000, I'd consider doing that to keep it on the road for now and then build it up once the motor is making more power.

    Thoughts?

  2. #2
    GMN Regular
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    If you can afford it you might as well have it built now so you donít have to throw money at it twice.

  3. #3
    Carthago delenda est Lutrova's Avatar
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    I have to imagine that for the amount of labor required to pull the trans and disassemble it far enough to get to the overdrive band, you're probably pretty close to the price of a full rebuild anyway.

    But if you're building it up for more power, perhaps that pushes the total cost closer to what a pre-built one would go for.

  4. #4
    Wagon Addicted Tiggie's Avatar
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    If yours is like mine, the TV bushing is broken. Throw one on and drive it for another 100,000km. You might have caught it early enough.

    If OD is slipping still, just run it in D. The drum the OD band goes on is probably glazed over as well.
    1990 Country Squire - weekend cruiser, next project
    1988 Crown Vic LTD Wagon - waiting in the wings

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  5. #5
    I'm an air-conditioned gypsy gadget73's Avatar
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    I really don't know that they are so much undersized for the stock engine as the pressure tends to be on the low side from age, bushing failure, wear, etc. I can tell you it is possible to get a lot of miles out of an AOD. The one in my Mark VII is at 235k and the overdrive band is fine so far as I can tell. It was also very regularly serviced, had the bushing changed long before it failed, and was never used to tow or do anything unusually stressful besides what it takes to move close to 2 tons down the road with an HO engine.

    You can get more clamping pressure by using the larger servo but you're pretty much stuck with the stock width because of the transmission design. There is a kevlar band but my understanding is thats really not a good choice. Kevlar is tough but slippery so it needs way more clamping force to actually grip and hold the drum correctly.

    Not sure what year we're talking about, but the early AOD used the "C" overdrive servo, which changed to the "B" I think in 1986. There is also an "A" servo but I think that was trucks? Aftermarket there is an A+. The higher on the list, the more surface area there is, so more clamping force. The hole that thing sits in is only so big though, and the drum the band runs on only allows the stock width so ultimately there is only so much that can be done. If the trans is tuned properly it will downshift quickly and that takes a lot of stress off the band. Stock they tend to be pretty lazy about downshifts.

    86 Lincoln Town Car (Galactica).
    5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

    91 Lincoln Mark VII LSC SE, triple black (Timewarp) - poly front bushings, KYB struts and shocks, Holley SystemMax1 lower intake, SilverFox AOD valve body,

    1984 Lincoln Continental TurboDiesel - rolls coal

    Quote Originally Posted by phayzer5 View Post
    I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

  6. #6
    Still Wrenchin'! friskyfrankie's Avatar
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    I'd try the brass bushing (check to see if the old bushing has failed). If it is gone you probably can't go over 25-30 mph or so. Problem is probably elsewhere if you are getting to normal speeds and only the OD fails.
    What I Own: 1993 Mercury Grand Marquis GS
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  7. #7

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    Turns out the transmission was one of many problems including a failed waterpump so I couldnít take it for a test drive but got it for less than a third of the asking price. Iíll check the bushing first when I can get it on the road!

  8. #8
    I'm an air-conditioned gypsy gadget73's Avatar
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    If you're doing the pump, at least rock the crank and check for timing chain slop. 88 should be the good double roller chain that last just about forever, but may as well confirm. With the pump off you're most of the way to pulling the timing cover so may as well know now while you're in the neighborhood. Change the fan clutch if it needs it, its already going to be off.

    86 Lincoln Town Car (Galactica).
    5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

    91 Lincoln Mark VII LSC SE, triple black (Timewarp) - poly front bushings, KYB struts and shocks, Holley SystemMax1 lower intake, SilverFox AOD valve body,

    1984 Lincoln Continental TurboDiesel - rolls coal

    Quote Originally Posted by phayzer5 View Post
    I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

  9. #9

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    Quote Originally Posted by gadget73 View Post
    If you're doing the pump, at least rock the crank and check for timing chain slop. 88 should be the good double roller chain that last just about forever, but may as well confirm. With the pump off you're most of the way to pulling the timing cover so may as well know now while you're in the neighborhood. Change the fan clutch if it needs it, its already going to be off.
    Appreciate the insight!

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