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1994 GT AODE transmission mystery

3K views 2 replies 1 participant last post by  sniemisto 
#1 · (Edited)
Hello,

Problems with this transmission started with 1-2 accumulator spring break. Firstly fitted new spring and carefully sanded marks from accumulator bore. It was ok for a while, then started slipping in 3rd gear.

I stripped down transmission and found out 3rd clutch (Direct clutch) where burned.
I inspected oil pump, washed everything with brake cleaner and installed "AODE 4R70W SUPER REBUILD KIT WITH ACCUMULATORS 1992-95" from ctpowertrain.

I also installed "TransGo SKAODE AODE 4R70W 4R75W Shift Kit For Ford Lincoln Mercury 1991-on New". Carefully readed instructions and drilled every hole to easiest setup, no Police or Taxi.

After rebuilt it seemed to work quite fine, noticeable problem was that first shift was really late, 2500-3000 rpm. I firstly tough that it was some chance with shift kit and that it was supposed to act like that or some problem with 1-2 accumulator

I bought 1-2 accumulator sleeve kit: 1-2 Accumulator Sleeve Kit - 76890-01K - Sonnax

Didn't notice any big difference with it, maybe it was shifting bit earlier but not sure. Tried accumulator also with shift kit springs and with stock, no noticeable difference.
SS-1 and SS-2 shift solenoids also replaced with no difference. No fault codes from transmission.

After 30 mile test drive I decided to drive it to my Dad's place 200 mile away. After 130 mile I noticed shutter at 1st gear in traffic lights. 10 mile after that it started to brake with transmission when speed was going over 70 mph. I slowed down and it stopped braking. Repeated later this 70 mph and braking again. I drove it rest way 60 mph with no problem.

Next morning car was going only with reverse. In D you could get car moving only with 4000 rpm. Car on trailer and 200 mile back to my garage.

Replaced filter and oil and checked 1-2 accumulator, it was ok.
Valve body bolts were a bit loose, not finger turning, but could be turned 1/8 turn with torque setting.
With new oil it needed again bit revving to start on D but then started working like before trip.

Started measuring pressures. At that point I realise that it wasn't late 2nd engagement, it was 3rd that was going in!

Line pressure ok / bit over.

1st clutch (Forward clutch) ok / bit over.
When coming from 4th to third by pressing gas pedal it will firstly only give 20 psi to Forward clutch. Normally pressure would be 50 psi. If you go with O/D cancel button then it will be 50 straight by change.
When starting from could you might need 1 minute or some revving to get pressure for Forward clutch. Firstly could give only 20 psi, with 50 psi it start to move normally. Car will go in reverse with no problem.

2nd clutch (Intermediate clutch) ok / bit over.
Pressure comes when 2nd should engage, still no shifting happens.

3rd clutch (Direct clutch) pressure ok / over.

After 4th gear engages Forward clutch disengages as it should.
When measuring Direct clutch pressure on 4th gear, you will see big pressure rise when going to 70 mph and transmission brake starts.
Pressure should be 50-75 psi but it will go up to 200 psi. Braking starts from 100 psi and increase with pressure.

I wanted to test if problem is with shift kit. I ordered used valve body and changed it. At same time I checked accumulator under valve body, ok. There was some hole differences with valve body's but I made couple new holes to gasket to mach these.

After valve body swap transmission braking problem where gone!

I still got some pressure rise at Direct clutch when going over 70 mph but it won't brake anymore! Pressure may go even to 150 psi and it may bounce between 75-120 psi. Before it wasn't bouncing that much.
It also engages 1st immediately even on could.

But still no 2nd. It will go with 1st until it change to 3rd. When down shifting it will neutral at 2nd until it gets 1st or 3rd.

Any ideas? I don't want to take transmission apart and find out Intermediate clutch is ok..

Really hoping that somebody have ideas / knowledge!

With best regards,
Sami Niemistö from Finland.
 
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#2 ·
AODE operation

Here is how power transfer should go in AODE:


First Gear in Drive

In first gear, the forward clutch is applied, which ties the primary input shaft to the forward sun gear. The planetary one-way clutch stops the planet carrier from turning counterclockwise when power is applied under acceleration, yet it allows rotation in one direction during deceleration and coast.


Second Gear in Drive

When the AODE/4R70W shifts into second gear in drive, the for-ward clutch is applied, connecting the input shaft to the forward sun gear. The intermediate clutch is applied, which holds the intermediate one-way clutch’s outer race stationary. The intermediate one-way clutch keeps the reverse clutch drum, shell, and reverse sun gear from rotating counterclockwise when power is being applied (acceleration). The planetary one-way clutch overruns.


Third Gear in Drive

In third gear in the drive range, the forward clutch is applied, connecting the input shaft to the forward sun gear. The direct clutch is applied, tying the input shaft to the planet carrier to the smaller inside input shaft (stub shaft). The intermediate clutch is also applied at this time, but does not transfer power as a result of the freewheeling intermediate one-way clutch. The planet’s one-way clutch overruns.


Fourth Gear in Drive (Overdrive)

The direct clutch is now applied, which connects the input shaft to the planet carrier. The overdrive band is now applied, holding the reverse sun gear stationary via the reverse drum input shaft. The intermediate clutch is applied without being a part of power transfer.

(Copied from: Ford AODE/4R70W Guide: Calibration, Building, Troubleshooting )



When going with this, 2nd gear needs:
-Forward clutch. This must be ok because there won't be 1st gear without this
-Intermediate clutch. 1st, 3rd and 4th won't need this though it's applied in 3rd and 4th?
-Reverse clutch drum, shell, and reverse sun gear keeped from rotating counterclockwise. How about this? Can there be problem when Reverse is working?


Regards Sami
 
#3 ·
Hi,

One guy I talk to was saying that this might be intermediate clutch one-way bearing.

One-way bearing seemed to be ok when transmission was apart. Is there possibility to but this bearing in wrong direction? Manual I have doesn't say anything about that.

Can I check this some how while transmission in car? Would there be any other affects on one-way clutch failure?

Shift kit description says that it is also to prevent 2nd roller breakage. Is this the same thing? If it is then this might be common?

With best regards,
Sami Niemistö
 
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