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AOD 1988 in LTC funny behavior in OD

mannebk

Member
38
13
8
Germany
Hi Folks,

yes I am aware of the dreaded bushing of the TV cable, and mine is fine. It's still the original in good shape.

However, I had a shop do an oil and filter change for the gearbox as good measure after 32 years.

Now before I had that done, I was test-driving the car and noticed no slipping OD but I was not doing long Autobahn runs, as I had a stuck brake, boiling dot3 on the front right tire and no insurance.

Then on my long run back home I found that the OD kind of slips if I drive in OD and gently apply throttle.

If I do a sudden almost WOT but no kick down it does not slip.

If I go kickdown it shifts down and when it goes back up to OD at 70 to 80 there is no slipping. If I go faster, I tested up to 165kmh/103mph, no slipping regardless of throttle position.

Now I did read there is this toe-in torque boost thing that make it slip out of direct drive OD if you open the throttle gently while cruising. According to what I did understand the AOD then using the alternate power path trough the torque converter instead of the direct input shaft so you would have still the low rpms from 4th gear but higher due to the involved torque converter, but still not like 3rd gear kick down fuel consumption. Good for passing on interstate.

Would that explain my AOD behavior?

How are yours doing?

Regards Manne
 

Brian J. Patterson

Active member
137
68
28
Northern Illinois
Hi, mannebk.

The 1988 FoMoCo AOD (first generation) is a good transmission. Unlike its newer cousins the AOD-E, 4R70W and newer, this is still an "old school" transmission without computer controls, though it will have some electric solenoids "here and there."

The behavior you described may in fact be normal. There is a point under mild acceleration where the car will want some torque multiplication (unlocking the converter) but not not a downshift. This is particularly true in overdrive at highway cruising speed.

However, I'm roughly 900-1100 miles away from you, and have never ridden in your car. You also had a very trying and expensive journey bringing your new (to you) car up to your temporary home in Canada, to instantly welcome your new son or daughter (congrats again) into the world. So, you will be hypersensitive to any mechanical imperfections with the car. I know I would be. Or, the locking clutch pack may be slipping when it shouldn't instead of unlocking when it should.

The process I describe below will either reassure you that the transmission is in good condition, or confirm the onset of the lockup clutch pack in the torque converter going bad. If there is a "problem" caused by something other than the torque converter lockup clutch pack itself going bad, these steps will remove the underlying cause.

If the torque converter is starting to go, you will need to replace it, since the lockup clutch pack is not a field-replaceable assembly.

First, replace as many of the linkage bushings as you have access to, both for the shifter linkage and for the TV cable. These bushings are all as old as the car itself, and are likely not in the best of condition. Now would be a great time to install the metal bushing on the throttle end of the TV cable.

Second, adjust the shift linkage and TV cable as specified in the appropriate shop manual. These first two steps eliminate the shifter linkage and TV cable as possible causes of any trouble.

Third, if you are absolutely certain that the "other shop" changed the fluid correctly and replaced it with the correct new fluid, change it again. Be sure to use the correct fluid, and use the Motorcraft brand from the Ford dealer just to make sure. Also make sure the valve body bolts are at the correct torque. If the filter is replaceable, replace it. If it is a cleanable metal screen, clean it. Yes, you did read that correctly. Since the torque converter doesn't have a drain plug, a "single" fluid change only gets about half the fluid. Doing a second "single" change will still leave some "old" fluid in the mix, but it will be less than what it was.

Fourth, if you have any doubts at all about the other shop's fluid change, real or imagined, drive the car just enough to get the old fluid out of the torque converter, and change it again. When changing transmission fluid "in the field," without a specialized flush cart with the correct fluid in it, the "double-change" is what you actually do to get a fresh change of the correct fluid into the transmission, since you can't easily get the old fluid out of the torque converter.

Fifth, during the "last" transmission fluid change in this cycle, replace the valve body to transmission gasket and verify using the correct torque on the valve body mounting bolts. These steps remove contamination in the transmission fluid and the transmission fluid itself as a possible cause of any transmission misbehavior, and also eliminate any valve body leakage as a potential cause of trouble.

Finally, with the misfiring issue described in one of your other posts solved, test drive the car. The power loss caused by the misfire can present itself as transmission problems even with a good transmission If there is actual slippage of the torque converter clutch pack, and not a "clean and smooth" unlocking and relocking under the described circumstances, you will need to replace the torque converter.

While I'm pretty sure you won't have this problem, the car is thirty-two years old and has sat marinading in its own juices for years. "Bad" things can happen to a car when you do this. Hopefully, you have already fixed those "bad" things.

Good luck.
 

Brian J. Patterson

Active member
137
68
28
Northern Illinois
Hi, mannebk.

While not a show-stopper if you can't, fitting a tachometer temporarily (if you can't read the engine rpms in real time via an obd2 wireless adapter to your smartphone) may make it easier for you to see the difference between a slip and a "designer-intended" release of the lock-up clutch pack.

Good luck.
______________________________
 

mannebk

Member
38
13
8
Germany
It turned out the bushing on the throttle body is wasted now. I slowly really hate that shop in Atlantic City who told me everything is fine. This will bite them in their arse. They almost made me waste my tranny. They are so lucky I heard it revving. And did those 1000 miles in 3rd or above 80 miles in OD where the line pressure was high enough to keep the OD clutch engaged.

So we justput a bigger cable tie on the cable to tighten it and it's already better behaving. All ad a small one on top and I'll be where the line pressure should be.

And I need to get that bushing.

I'll report back. Thanks guys. IMG_20200323_100942525.jpg
 

mannebk

Member
38
13
8
Germany

Brian J. Patterson

Active member
137
68
28
Northern Illinois
Hi, mannebk.

This should be the correct bushing, since it is for the TV cable to throttle linkage on a 1988 FoMoCo 302 V-8 to AOD transmission.

Don't forget to replace the other bushings in the TV Cable and shifter linkage. Using bronze bushings should not be necessary for the other bushings. However, all the bushings are 32 years old, and haven't improved with age.

You will also need to periodically lubricate the bronze bushing on the TV Cable once installed. The "rubber" bushings are formulated to not need periodic lubrication, as well as to block vibration transfer from the power plant to the controls in the passenger compartment of the car. While the "infamous" TV Cable bushing sees enough stress to justify replacing the "original-type" bushing with a bronze one, the other ones don't see the same degree of stress, so the "rubber" ones are quite adequate for anything short of a "Cannonball Racer."

Good luck.
 

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