Got a dyno run scheduled for Tuesday, my first one and the car's first too I imagine. Anyway after reading it on coolcats I started running my AOD in Drive rather than Overdrive unless I'm gonna be on the highway for a while. In Drive I've found the car feels much stronger, I don't know if that's by design or if my overdrive band is just screwed. My first instinct is to make this run in Drive but I've never really pushed the car to the limit in Drive before, should I have any reservations about it?
yes, OD would give the tranny a 1:1 ratio, for the numbers to be accurate.
I'm not 100% positive, but OD would actually give you <1:1 ratio since it is OVERdrive, where Drive is 1:1.
One more thing that I'm less sure of since I've never been on a dyno before, but I'm not sure it would matter if you had it in OD anyway since I doubt it would ever shift up to OD, especially since you would be pushing it at WOT.
Hopefully someone else will chip in and tell me I am correct (or completley refute me :)
I believe final drive for OD gear in the AOD tranny is a .75:1 ratio not 1:1
Seems it’s 1:1 in drive and .75:1 in OD… I’ll see if I can find the info someplace
From" http://www.thepontiactransampage.com/transgears.html
"
Ford AOD 4-spd automatic
2.40, 1.47, 1.00, 0.67
"
From: http://realbig.com/detomaso/1998-02/266.html
"If better acceleration is the goal, a ring and pinion swap may be in order.
The beauty of this swap is that the AOD's 0.67:1 overdrive ratio can make
a
"
And finally from: http://lists.twistedpair.ca/pipermail/classic-mustangs/1996-December/000644.html
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Ford Transmission Ratios
------------------------
Stock Stock WR Stock WR E4OD
C4 C6 C6 AOD AOD
1st 2.46 2.46 2.72 2.40 2.84 2.72
2nd 1.46 1.46 1.54 1.47 1.55 1.53
3rd 1.00 1.00 1.00 1.00 1.00 1.00
4th ---- ---- ---- 0.67 0.70 0.71
"
I was off... .67 not .75 but still not 1:1
correct, i was wrong. trans needs to be in 3rd gear. OD is a 0.67:1 ratio.
http://www3.telus.net/cbradley/Drivetrain_Ratios.html
Great info, thanks guys.
NO O/D on the dyno!!! EVER!!!
Most older design trannys are very weak in O/D, usually the owners manual even says not to tow using O/D... Now you know why...
Not to hijack,but should I have the tranny in Drive instead if oerdrive most of the time,like "in town" driving?
It's mentioned on Coolcats that experienced tranny guys recommend keeping it in Drive unless you're going to be driving it at high speed for a length of time. It's actually better for the transmission and fuel economy. I started doing it a while ago and I find the car more responsive. Try it.
Too hi jack even further.. I do that.. if I'm in town I always put the car in drive instead of overdrive. Especially on the older non electronic AOD's. I turn off the O/D on my Mountaineer too in town.
Basically if youre in town chances are youre gonna be cruising at around the speed it shifts into OD, and if youre hovering around there its probably gonna be constantly shifting between 3rd and 4th, so you might as well save the trans a lot of work and keep it in 3rd. Also allows the engine to stay at an rpm where its happy speeding up and slowing down.
I agree. My Titan has a five speed auto in it and I keep it out of overdrive unless I am on the freeway. Or a road that doesn't have many stops. Trans coolers extend the life of a transmission as well.
Brian
My '88 won't shift into O/D till about 50mph... With 3.73 gears, thats perfect(good thing, I have no way to lock it out, D is 1st & 2nd only)... That ed '95 thinks it has to be in O/D at 35mph, with the 3.08 gear that sucks, so yup It's generally off in town...
My 83 and 88 (when auto) would shift into O/D at about 35mph.. The speed limit in town is 35mph so I would be in and out of O/D constantly so I saved the transmissions and kept them in D.
If all AOD's were like the later 4R70W's, then yes, we could safely keep the car in OD all the time without much worry. But the whole AOD design and its notoriously weak OD band is the reason that I advocate keeping the car in D all the time, unless you are going to be on the freeway or are going over 45mph for at least 5 minutes. This is a tried-and-true method that will save your overdrive band (at least, delay the inevitable rebuild).
I drive in what you can consider "city" traffic to work. It's 3.4 miles one way. The longest stretch of open road without turning or a stop sign is 1 mile. My top speed is usually 35-40mph. Then there's the steep hill (down, going to work and up, coming home). So there is absolutely no reason why I need overdrive on the daily commute. I'm with Claude...OD is locked out in the Mountaineer also. It's a habit that carried over from the Cougars to the truck, and I feel safer running the truck that way also. And it even has the towing package, with the external oil and trans coolers.
The OD lockout just makes good sense. Use OD gear only when you need it, and you'll be okay.
or get a 4R70W
Easier said than done. Electronic controllers for those things are pricey.
4r70w's seem to be very long lasting...the one in my 94' tbird has 204,000 on it and it still shifts strong. of course the trans cooler i installed is helping. It does chatter in reverse though.