87 Dakota LoadFlite A998 automatic transmission band adjustment puzzler, with slippage

Maintenance/Repairs
1

This is a puzzler for those conversant with vintage Dodge/Chrysler ATs. This transmission has 170,000 miles and was serviced at regular intervals, never flushed, but filter and oil changed and band adjustments. Here’s what happened.

Four days ago, I started the truck at 8:00am in Fresno, CA, as I usually do, temperature above 75 degrees Fahrenheit. I put it in drive and the transmission is slipping. The truck lurches forward as the transmission engages and disengages at about a one second interval. When I increased rpms the transmission engaged more solidly. I would have to increase rpms even more to get it to upshift. Not knowing exactly what was going on, and being in the middle of traffic, I continued to drive it as I quickly learned what was needed to keep up with the other road warriors. After about 1 1/2 to 2 miles, the truck began driving normally. I drove it another 1 to 1 1/2 miles to where I was going, parked and after three hours got back in and drove around the parking lot before getting back into traffic for the trip home. It drove fine. Came to realize that this problem only occurred when the engine and transmission was fully cooled down, and after a couple of miles of driving it drove normally. AT fluid is less than 1 year old and looks and smells normal.

[Rod_Knox took the mystery out of why the band adjustment described below caused the reverse to lock up. That will be corrected as soon as I get over the shame and embarrassment of not reading the manual thoroughly.]

I put the front end up and crawled under to check the “kickdown band” adjustment which is accessible with out dropping the pan. To get to the “low-reverse” band, the pan has to be dropped. I come to find out that the kickdown band adjusting screw is loose. I tightened it to spec, 72 inch/pounds, and torqued the lockdown nut to 30 inch/pounds. After making this adjustment the transmission locked up when I put it in reverse. It drove forward without a problem. We are talking feet. The truck is inside the garage at this point. The truck, with engine running would not move in reverse, except if I increased rpm sunstantially. It was as if the brakes were applied. I then put it in neutral and tried to push the truck back, which is normally easy to do, but could not budge it. I then put all four wheels off the ground, put the transmission in neutral, wedged one back tire so it would not turn and tried to turn the other back wheel in reverse. It would not budge. Forward, OK, backward, nay. I then loosened the kickdown band adjusting screw a bit, and then tried to rotate the same back tire in reverse by hand. It turned with effort and the driveshaft turned with it. I loosened the kickdown band adjusting screw a bit more, and the tire and driveshaft turned with ease. That when I came in to write this puzzler.

I have next to zero knowledge of the inner workings of an AT. The only other thing that I can do other than replacing the transmission with a rebuilt or junkyard pull, or take it to a shop, is to drop the pan, and adjust the low-reverse band. I do not know if these two adjustments affect each other. Perhaps they both need to be adjusted together.

I don’t understand why the transmission slips after a cold start, but then runs normally after a complete warmup. The ATF is not old, not discolored and is up to the top of the mark on the dipstick when fully warmed up, run through all the gears, and in neutral with engine running, which is to say, checked correctly.

I especially do not understand why the reverse locks up when the kickdown band is adjusted to factory specs, albeit with the low-reverse band adjustment unknown.

I hope you enjoy this puzzler more than I have!

Jack

2

After torquing a band the instruction should specify how far to back off the band.

3

“After torquing a band the instruction should specify how far to back off the band.”

GOD, I am so stupid! Thanks. It certainly does say that!

4

No experience w/that particular AT, but I had a kick-down problem w/my Ford truck’s C4 one time, and I just disconnected the kick-down linkage. Now if I want it to shift from 3 to 2 for more power to pass another car, I just shift it manually to “2” using the lever. Not much of a burden. Your trans may not use a mechanical linkage for that function though.

5

This is the kind of post and answer I love to see where someone explains clearly and completely their problem and what they have done to try and solve it and someone (in this case a pro) is able to jump in and help them.

We have been getting too few questions like this.

1 Like
6

Hi George, I use the shift lever for that function also, like a semi-stick shift. Yeah, the linkage is totally mechanical. There are two cables going to the trans, but not sure what the function. Never had a problem before this so no need to know of their existence, let alone function. I got the the situation back to where it was originally, thanks to Rod_Knox, just the original slippage problem. I dropped the pan and drained the ATF and that is where it sits tonight. I will get a new filter and gasket tomorrow, adjust the band , reassemble, add new ATF. It that does not fix I will go shopping for a new vehicle. Even if it does fix I will go shopping for a new vehicle. In the meantime I have a nice old Trek bicycle and two good legs to get get around on.:stuck_out_tongue_winking_eye:

7

Disconnecting the kick-down linkage will cause the transmission to up-shift prematurely, that won’t help at all. The second gear/kick-down band must be properly adjusted or it will burn up and fail.

8

Thanks for the appreciation of my post, OT. I guess I had you in mind when I wrote it.:smiley:

9

Thanks to Rod_Knox I was able to get the kickdown band adjusted properly and I am now faced only with the original problem of slippage, which I will describe again here.

  1. The problem came on suddenly, not gradually. When I started the truck at 8am a few days again, the transmission slipped badly. Very little of the engine’s torque made its way to the back wheels, and the power that was applied came in spurts, like a pulsation of power. The outdoor temperature was above 70F degrees.

  2. The transmission had trouble upshifting. It upshifted at much higher engine rpms than normal.

  3. After driving for a couple of miles the truck operated completely normally. This gives me hope that the problem may not required a rebuild.

  4. Whenever the truck cools down completely it then acts in the same manner as described above, transmission slips when first started, but operates normally after a couple of miles.

  5. I pulled the oil pan last night and that is where it stands. There appears to be some metal shavings on the filter, not much, but some. This is obviously a cause for concern. I will take a photo later and upload, some time after 12 noon PDT. I plan to install new filter and gasket and fill with ATF+4.

10

If you want to squeeze out every possible mile from the transmission for the least money out of your pockets I suggest you replace the filter and pan and refill with the proper ATF + a bottle of STP added after the transmission is fully warmed up. My best guess is that your transmission is suffering from weak pressure compounded by worn clutches.

1 Like
11

Thank you, Rod. Any particular flavor of STP, or just the original? Can you shed any light on what might be behind the sudden onset of the slippage? This was not gradual. Also, why might it drive normally after a couple of miles?

Anyhoo, I am about ready to put on the greasy jeans and adjust the band that hides inside pan and install a new filter and gasket with some gasket sealant that worked very well the last time I dropped the pan. We will see what we shall see.

12

The original STP molasses is what often brings the life back to old Mopar transmissions for a while.

Once the pressure drops to the point that the already worn clutch discs are unable to lock up the discs begin to wear quickly. If you have already run it too long while slipping it’s a lost cause requiring a total rebuild.

The black slime in the bottom of your pan was the worn friction plates and the silver metal from the steel discs…

13

Not saying this applies to the OP’s transmission, but the following link applies to the Ford C4.

“Unlike later overdrive transmissions that burn up when their throttle valve cables are disconnected or out of adjustment, missing or maladjusted kickdown linkage won’t damage an old three speed Ford C4 automatic. The C4’s vacuum modulator will shift the transmission ok during normal driving. Without a properly installed and adjusted kickdown however, the transmission will not drop from third to second gear under hard acceleration, and during normal driving the two-three upshift comes very quickly. You can still manually downshift for a passing gear, or for a spirited run down a country lane, but engine vacuum alone doesn’t give the transmission enough information to operate at its best.”

https://partsandprojects.com/projects-and-features/auto-projects/how-to-install-and-adjust-kickdown-linkage-on-a-classic-mustang/

It makes common sense of course to configure the transmission as designed, but if the only thing preventing the use of the vehicle is the kick-down function, on a C4, just disconnect it.

14

That has nothing to do with the second gear band adjustment, if the second gear band is dragging it will burn up.

15

No disagreement there. I’ll add that whenever my car knowledgeable hot rod high-school buddies would start adjusting their transmission bands, their car was soon in the shop for a trans rebuild. I don’t think the bands have much adjustment leeway.

16

When the symptoms have indicated a possible band problem I have adjusted a few and never found one that was out of adjustment enough to cause a problem but I have found that even following the instructions closely a band can be overtightened and drag requiring going back to loosen it another 1/2 turn.

Late model transmissions seem to never need more attention than fluid and filter change until they totally fail. It’s been a long time since I did anything beyond pressure testing and cycling an automatic to confirm it was over the hill. And the only transmission I ever rebuilt was a C4. I took it down 3 times to get it right and decided to farm out that job in the future. I seem to recall a bent spring washer that ate my lunch on that job.

17

This link isn’t for the C4, but for those car-curious folks interested in what’s inside an automatic transmission, I found this article interesting and informative. Good photos of the innards. Easy to see how even a single defective washer could foul the entire job.

https://www.hotrod.com/articles/rebuild-junkyard-transmission-hold-nearly-1000-hp/

If the photos appear blank, no worries, just click on the first one and you can then move from one to the next using the arrow on the right.

18

UPDATE: I dropped the pan, adjusted the band, changed the filter, re-installed the pan and refilled with ATF+4 and 24 ounces of thick and gooey Lucas Transmission Fix. First time I started it up, the transmission slipped as it had been, and after driving slowly for a couple of miles it drove fine. The next day, same story. Today I learned about torque converter drain-back and thought that might be the problem. However, no way to really know without professional help. So I tried the following:

Seeing as how after the truck was driven for a couple of miles it drove fine with no slipping I decided to stick a hot plate about 12 inches under the tranny pan and heat up the oil. After allowing the oil and tranny to heat up for about one hour I cranked it up and off it drove with absolutely no slipping. Tomorrow morning I will attempt to drive off without heating the tranny/oil first to see what happens.

19

Take a good look at the color of the ATF on your dipstick and smell it also. Transmission fluid can’t stand much heat. If the color or smell indicate it’s been too hot you should drop the pan and repeat the clean up and fluid change.

1 Like
20

Given the update above, I second RK’s idea, repeat the pan drop & refill. Unless you drain & refill the torque converter also, you are only replacing about 1/4 - 1/3 of the fluid w/just a pan drop. OP, you are thoroughly cleaning the bottom of the pan, right? And sieving the old fluid to see what’s coming out, specifically looking for metal debris? That can provide a clue. I wouldn’t experiment w/ the Lucas product until it was proved just using fresh correctly spec’d transmission fluid only can’t do the job by itself. With a little luck and trial and error experiments you may well be able to squeeze quite a few more miles out of this transmission.