93 T-Bird Tranny problem

I have a multiport fuel injected 4.6L V8 T-Bird. I love this car. The four wheel independent suspension is outstanding. I take the speed bumps my town is infested with at 30MPH. It just glides over them. But alas after about 2 years the transmission started the infamous shuddering. It got steadily worse until all forward motion ceased.. So! I read everything I could find. I talked to dealers etc. End result. I put in a NEW one from the factory. $2,100! Plus!! You are required to put in a new ECM(computer) $350!! I did all this. All service manuals, notices said you must use "ultra high" quality ATF. I used exactly what was recommended $4 bucks a quart.

Within six months it was up to its same old tricks, almost identical.

What happens is a light shudder occurs but ONLY when the vehicle has reached a steady state balance with road conditions and pedal position. It always occurs. It resembles running over a uniform road texture like a very, very, light cattle guard that's hundreds of yards long. No cattle guard noise though of course. Any, and I do mean ANY pedal adjustment stops it instantly. But inevitably the new pedal position will result in a new steady state balance and the shutter returns. For years now I have been driving this thing in a bizarre constant pedal movement mode. As I drive; the instant I feel the shudder come in I make a pedal adjustment to extinguish it. This gives maybe a minute of respite.

Obviously Ford has a problem here as you look at the used car ads you will see that virtually every 4-sale T-bird of this era has a "new transmission"!!! Gag. At any rate what I want to know is what causes this? I have no qualms about taking this tyranny down to it's molecular components, if need be, I have repaired several auto trannys starting in high school. My suspicion is that if I take this thing apart it will not be obvious what is causing it, only perhaps the wear results of the malady.

Since no dealerships appear to repair trannys, they just swap them, I can find no one to tap for info.

My guesses would be:
1) A sensor problem.
2) Software problems that start a shift sees a pressure drop which causes the software to abort the shift which changes the measured pressure which starts the shift... No hysteresis.

Guesses?

Flush your tranny and advance the TV cable about 1/2-1 inches. If it HAS a tv cable. Otherwise, check all connections to the transmission and the wires associated. If its an AOD, their notorious for that

Lack of servo pressure at cruising speed,,,maybee due to poor design,,,,try installing a Tow and Go Kit,,,,this may help.

Ford had problems with these trans--convertor shudder..Most common fix is to drain fluid from the trans--making sure you drain the convertor--new fluid and filter. Sometimes the EPC solenoid may create the same problem. Fixed this problem on many ot heses trans by simple fluid drain. Sometimes the rebuilder don't do all proper upgrades. Just make sure convertor gets drained.

reborn55,
But this tranny started the shudder a couple of months after being installed new/empty. You still think a drain/refill would help?

What's the EPC soleniod? Do you know why the EPC would cause the shudder?

drg84,
It is an Automatic Overdrive Transmission...interestingly if you hit the OverDrive OFF switch it makes no difference the shudder still happens. I will try the cable adjustment.

Thunderbucket,
That's a good idea too.. I'll look into it.

I must add,,,If you need to get your tranny serviced,,try get someone who works at a tranny shop,,but also works at home,,,you will find the quality of the work is superior and cheaper,( doesn't have the sales manager breathing down his neck) i've seen too many bad things go down with tranny shops,,,usualy because of the service/sales guy,,,,the mechanics are honest,,,but the sales guy will keep you away from them.
A good transmission mechanic can attach a guage to your transmission and he will determine which hydraulic circuit is giving you the problem.
As to "Tow and Go" kits,,,,they are a little harsher on shifting,,but a lot of guy's will swear by them,,for extending the life of the tranny.( lessens slippage )

Hi ThunderB,

Anyone tears this tranny apart it will be me... I'm just fishing for
info so I can modify-alter-correct the problem. Like I say, I doubt visual inspection will lead to any repair, only someone who knows why these suckas do this. I put no faith in a factory manual as two of these trannies have had the EXACT same problem which shows the factory doesn't seem to have a clue. As a kid I took out and tore entirely down, the tranny out of a Lincoln Continental five times in two weeks because ALL the factory gasket sets were defective! I finally traced the entire hydraulic logic system out with air. The gaskets were all lacking a hole which blocked a critical logic circuit. I have seen many factory designed mistakes... It's hot rodders that figure them out.

Ahhhh DennyW..

OUTSTANDING sleuthing man! I have spent hours looking for info... Whad u google for?

Thanks man I will be calling them tomorrow.

Sounds like you'll have it all covered Kcress,,,,man after my own heart,,,,if you've got a trans pressure guage you can hook up to it,,,then go for a drive and see what kind of main pressure your getting when cruising.
I'd be thinking the main servo is loosing pressure,,thereby letting the main band slip at cruising speed.

Looks like that link Denny put up will give ya what you need.

Thunder I have many gauges.. What pressure am I likely to run into? Whats max gauge pressure I need? 300psi? I want to see this cuz I bet the shutter screws with it.

EPC solenoid--Electronic Pressure Control solenoid--regulates TV pressure--controls line pressure.

DennyW : Sweet! Now if it would just stop raining.....

reborn55: Thanks for that info.

Just out of curiousity==isn't it covered under warranty? It should have at least a 12 month-12,000 mile warranty if not more. most of the one I put in my ambulances from Ford have at least a 24/24 warranty and some are as high as 36/36. Just a thought.

reborn55,
Good point but unfortunately it's been 2.5 years. I can't even find the paperwork. I could also replace a dozen of these and not "fix" the problem... And they are a real pain to pull as that tranny is sunk into the body like an Arizona tick. There is maybe one inch of clearance around 200 degrees of it. You have to pull the fuel tank just to drop the driveline!

Denny,

I spoke with the guys at the drivetrain place.. Turns out there is a circuit board you install in the tranny oil pan that goes between the power train computer and the torque converter lock up control valve. It intercepts the screwy modulated computer signal and stops the SHUDDER.

I ordered one.. I'll keep you posted.

Kinda makes you walk away scratching your head,,,wandering why they didn't build it proper in the first place,,,i mean,,,they do test them before releasing to the public,,,so they must know.

ahh Thunder,

I Suspect the auto tranny is by far the most complex item in any vehicle. Mix this with trying to make it cheap and you probably end up with shudder problems that are in a hard to troubleshoot package. I mean come on, hydraulic/spring based logic. Gads!

Then the service system would rather pull and replace because of the horrendous labor and the cut on the high priced material.

Now if I was designing a tranny.... It would have NO logic in it at all. It would be entirely computer controlled. I don't understand why this hasn't been done yet! Then it just becomes electric valves that run each of the three to five transmission states. No springs!! No orifices! No shift plates. No shift bodies.

I had a washing machine that blew its nightmare timer control. I bought a new control $70. It failed in 5 months. It had probably 20 different bent metal spring contacts. I tore that out isolated every control mechanism, about 6. I hooked them to a junk
PC thru isolation. I wrote a few basic programs for the different types of loads, diapers, towels, etc. That worked for years! Until the transmission dropped out. The same would work on these trannys.