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aod: lockup or non lockup stall converter?

24319 Views 5 Replies 5 Participants Last post by  dodgestang
hi i have a 89 mustang lx 5.0. ive decided to keep the aod for now. ive been looking at stall covertors on ebay.whats the difference between non lockup or a lockup convertor.i have already put 3.73 gears in the car.and bought a cobra intake and a b303 cam.that iplan on installing next. any suggestion or answers would be helpful thanks.
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Lock up convertors are made for improving mileage. A convertor locks up when you are at a steady cruise about 45 mph or higher. When a convertor locks up yor RPM will drop about 300. Thats the benefit. I personally dont like lock up[ convertors.The mileage benefit is so minor. They can also start to have problems like clutch chatter when they get old.
For the AOD a non-lock up converter is a siginificnat upgrade in performance. You can not install one without also buying a one peice input shaft which will let you get rid of the 2 peice input shaft which is a break point in power applications using the AOD
But, on the flip side:

The whole purpose of using an AOD is for mileage concerns. The OD drops rpm quite a bit. Use of a higher stall converter combined with running (normally) 1500 RPM on the freeway would create a lot of heat and converter "slippage" with a non lockup converter. Lets say your AOD normally runs 1500 at 60 mph. Add that 3500 converter without the lock up feature, you're going to increase that RPM to probably 1800-2000 RPM...and creating some more heat that needs to be dealt with. With the lockup feature, you can still keep your 1500 cruise speed, but also have your great launch.

But, the AOD's design doesn't really work that well with lots of torque and a lockup converter. That's where Lentech and a few other companies have redesigned an AOD valvebody that (in some cases) will allow you to use a electric solenoid to lock the converter at highway speed, yet still have a reasonably strong transmission. I recently took a ride with a buddy that had a '92 LX coupe with a 393 that I built for him. It also uses an AOD...with a Lentech VB. The first 3 gears are exactly like a c4/c6...then with a flip of a switch he locks the converter and puts 'er in OD with the shifter.....makes a GREAT cruiser, and a decent strip car.

"it is better to appear ignorant than to open your mouth and remove all doubt"--Mark Twain

<font size=-1>[ This Message was edited by: mavman on 2/20/06 12:13am ]</font>
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The AOD has a mechanical locking converter. Third gear is 70% locked, fourth is 100%. The trans. is more like a standard trans. in third and fourth gear, the converter isn't slipping, and it tends to lug the motor down a bit when shifting into third. A non lock converter can be purchased for use with a two piece or one piece input shaft. For strip use a one piece shaft and non lock converter is the way to go. A stronger center shaft can be put in the trans. without disassembly of the trans. (the trans has to be removed of course), and a lock up or non lock converter can be used on the street.
On 2006-02-19 09:12, mavman wrote:
Too much to repeat
Do not confuse lock-up with OD. They are seperate. OD works just fine with or without a lock up converter. The total RPMs in the system are slightly higher with a non-lockup converter but you are still recieveing a large benefit of over drive.

I run 400 RWHP through an AOD with a non-lockup converter. When I do the speedlimit I get 15-18 MPH...not bad for a 408c.

The AODE tranny uses an electonic control entering OD so if you want to run an AODE tranny you get a little switch that you hit to put it in OD as opposed to the throttle positions and vehicle velocity helping the tranny to determine when it was appropriate to shift into OD.
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