5.0 question for yas

[flyboy]

My '92 5.0 automatic is completely stock. I bought it so that I can transfer its guts into my '69 coupe. My question is this: When I punch the pedal down at highway speeds, it slowly goes down to a lower gear. At 45mph and below, it kicks down fast and hard, just how I want it to. Why doesn't it kick down hard from 4th to 3rd at highway speeds? Is it some sort of control module, or is it something in the transmission that needs to be changed?

[RBatson]

4th gear is overdrive. All you need to do is downshift it yourself, pull it down one and it will be in 3rd. The other shift you feel when accelerating at lower speeds is the 3rd to 2nd shift, once its in od it tends to stay there. You can get a shift kit for it or you can even get a valve body that will let you shift it manually with a toggle switch for od. I have one in my car, I got it from Lentech. It sounds like all you need to do is pull it down one to get the results you are looking for though.

[rwhite65]

I have a shift kit in my AOD, along with some other mods. Mine does not do that, it has good firm hard shifts almost instantly. With that said, a word of advice. Hard throttle shifts between 3rd and 4th is usually what will burn an AOD up (stock AOD).

If u are driving it hard, u need to lock 4th out. If u want to be able to drive it hard in and out of 4th gear, there are a few fairly simple modifications you are gonna need to do.
Ryan

[Capri306]

I think he's just reporting the fact that the downshift is slushy feeling at lower speeds, and yes, partially due to OD & lockup.

However, it's a direct function of throttle valve (TV) pressure. You don't have as much TV pressure at lower speeds because, typically, the engine is spinning slower and the throttle valve isn't open as far. The throttle DIRECTLY augments the position of the TV cable running from the throttle body to the transmission linkage. The TV cable is the only input the transmission has regarding the load upon the engine; there is no vacuum modulator or kickdown rod as on older, less sophisticated automatic transmissions. As such, it monitors throttle position directly, and is constantly augmenting TV pressure (the pressure which is responsible for the firmness AND timing of each upshift and downshift).

I believe this is where the root of the problem lies with most AOD-equipped vehicles: the plastic grommet that the TV cable end snaps into (at the throttle body) wears out, and the shifting characteristics of the transmission are gravely changed. So much so that it can be one of the chief reasons that the transmission fails. Most owners will just have the transmission rebuilt or replaced, but they never actually fix the cause of the problem. All that is necessary is a short trip to the local Ford dealer for a new TV cable grommet, and <5 minutes to complete the repair.

In addition, the proper adjustment of the cable is CRITICAL to proper operation of the AOD!!! Even moving the sliding adjuster at the end of the cable ONE TOOTH (~1/32") can cause a big difference in performance. Pick up a small flat-blade screwdriver and a Haynes manual to learn how to adjust it properly, and you'll almost be guaranteed a difference in overall "feel". Personally, I like to crank mine up just one micro-smidgeon (yeah, I just invented that unit of measure ) so it holds the gears out a little longer on takeoff (that shift to 3rd is a b!tch IMHO).

One final note: there's a good possibility that your valve body is plugged with goo from years of useage. The fix? Easy as cake. Arm yourself with a 10mm socket and socket wrench after you've dropped the pan (you're gonna be changing the filter and gasket here too, so get the stuff to do it FIRST). Following a transmission repair manual -- again, Haynes makes a great one -- drop the valve body. Spray it out thoroughly with BRAKE PARTS CLEANER ONLY!!! This is the only aerosol cleaner that's going to do three things vital to success: 1) it leaves no residue, 2) it will not harm rubber seals in the transmission, and 3) it cleans like a mother. After spraying it out and letting it dry by air, do it again. While that's drying, spray out the pan.

The best point to install a shift kit is here. Your valve body is out and clean, and a shift kit is going to virtually eliminate any sloppy shifting by stopping the overlap of engagements. Not only does the trans shift faster and respond more quickly, but it'll last much longer. I basically "roll my own" because I've had the (mis)fortune of having a few AODs fail and repairs were left in my hands. It's amazing what you can learn from careful inspection of failed or fatigued parts...and it's even more amazing when they all fail in the same way! *sigh* I digress...

If you're not in business after this, a new transmission may be in due order. Cranking TV pressure a ludicrous amout skyward isn't going to help for long, and will completely destroy what's left of the clutches and bands eventually. Spend the clams and get a good AOD, and never worry again. I highly recommend Art Carr and Lentech; I'm getting the latter once I graduate college.

Having said all that, I'm moving this to the Windsor Power Forum. It's where this type of question belongs, and you'll get more responses in there. In the future, ya might wanna try a more descriptive topic. Not a flame, just good advice.

[flyboy]

Thanks for the replies! I'll check the cable grommet. I'll also look into shift kits. The stang is a strong, fun car. I'm looking forward to the day that my '69 is finished; however, that day is still far into the future.

[grey88gt]

I agree with Capri306. When I got my car it was the same way. I adjusted the TV cable and wow what a diffrence. I then moved it just a bit more. My car is all stock, 88 GT with 2.73 gears and itll bark the tires hard going into 2nd. It stays in gear longer during normal driving.