TF A904 reverse issue - band adjustment

[dave225]

I have done some reading and it appears I can adjust my reverse band. The car is a 74 Dart Swinger with a slant 6.

The transmission in the morning (cold) has reverse but it is weak and noisy. Shifting back and forth from reverse to drive a couple of times get reverse working just fine. After driving it the trans works fine all day and then starts over with the problem again in the morning.

Will adjusting the reverse band remedy the problem? Fluid level is good and it shifts fine once warm.

Thanks for the help!

 

[AJ/FormS]

how is the shift into third gear(Drive) when cold? The hi-drum is used for both third and reverse. So if hi works fine, then
Yes I would do a band adjustment first. But since is is noisy, chances are that the lining is possibly gone, and you will see it as soon as the pan is off.
The Reverse servo gets full pump-pressure, usually about 250 psi, so if the band doesn't apply properly, it is usually because the servo is out of travel, or the band is toast.
So time to take the pan off and look.
But if the rpm flares on the 2-3 shift, then the hi-drum is toast, and the trans has to come down.A flare is when the rpm goes up instead of down during the shift, and when it gets real bad, you have to lift off the gas to finish the shift.

 

[dave225]

how is the shift into third gear(Drive) when cold? The hi-drum is used for both third and reverse. So if hi works fine, then
Yes I would do a band adjustment first. But since is is noisy, chances are that the lining is possibly gone, and you will see it as soon as the pan is off.
The Reverse servo gets full pump-pressure, usually about 250 psi, so if the band doesn't apply properly, it is usually because the servo is out of travel, or the band is toast.
So time to take the pan off and look.
But if the rpm flares on the 2-3 shift, then the hi-drum is toast, and the trans has to come down

The shifting throughout the gears is fine. With that said I do wait until reverse works well until I pull out of the driveway. It is possible that third has an issue. I think I will back in tonight and just pull out tomorrow to see how it goes through the gears cold. Thanks for your insight!

 

[Murray]

I think you have a common problem on Mopar automatics with cold starts. At rest, your torque convertor is draining back to the pan, so on cold starts your convertor is basically low on fluid. Most of us have learned to live with this little problem. On cold starts we shift from P, to N, to D, to N, to R, to P. This gives the trans the pathway and the time to fill the convertor. Then the rest of day it will be good.

 

[tonysrt]

Isn't this more of a problem with the 727's? I know my 71 340 was always a little hesitant in reverse when it was cold or I hadn't used the car for a week.

 

[dave225]

I think you have a common problem on Mopar automatics with cold starts. At rest, your torque convertor is draining back to the pan, so on cold starts your convertor is basically low on fluid. Most of us have learned to live with this little problem. On cold starts we shift from P, to N, to D, to N, to R, to P. This gives the trans the pathway and the time to fill the convertor. Then the rest of day it will be good.

Thats exactly what I have to do. Are you saying this is normal?

 

[Murray]

I'm not really a tranny guy (others here are) but I have been told that a check ball in the front pump is the problem, allowing the fluid to drain out of the convertor when sitting. While not a "serious" problem, the cure is to replace the front pump and the check ball. Most of us live with it. Hopefully a real tranny guy will respond and clarify things.

 

[fishy68]

Isn't this more of a problem with the 727's? I know my 71 340 was always a little hesitant in reverse when it was cold or I hadn't used the car for a week.

It may be more pronounced in 727's but can happen with 904's too. It's usually because the stator and/or rings or the front drum are worn and lets the pump drain back. The 904 is the same design as the 727, just smaller

In the case with the OP I agree with AJ/FormulaS that the issue may be related to the stator and/or front drum

 

[Bakerlite]

Could be hardened seals as well, since it works fine when hot.

 

[RedFish]

Condition in my 67 904 is a little different. No reverse for a couple seconds then it engages hard. I think that hard engage is because the accumulator spring was removed. So I just let it idle in neutral a couple minutes. Problem disappears.

 

[Oldmanmopar]

Wrong fluid to thick or its dirty with a bad filter. adjust the low and reverse band while in there. That noise you hear is the flat prop from the adjuster that holds the band because its loose. You may get some more mileage if you do this but when it falls out it usually takes out the case when the band starts spinning. Have the trans rebuilt soon.

 

[dave225]

OK, I drove the car to dinner last night and then first thing this morning. Reverse engaged about 90% so I backed out of the driveway and proceeded down the street. It shifts fine through the gears with no flare between 1 and 2 or 2 and 3.

I have never experienced the converter draining back in to the trans and causing this type of problem on any other car I've owned. I guess dropping the pan and adjusting the rear band is then next step. We'll see what happens.

Thank you for your replies, I was hoping for someone having this same issue and the band adjustment was the remedy.

 

[Oldmanmopar]

i just had this issue with a 904 in this brown Duster . The motor and trans had 30+ K from a 73 Charger. I installed it to get this car running and painted everything and added a 4bbl so all the 340 parts could be used.

I dropped the pan drained the fluid ,Installed a new filter and it works perfect. I used a Auto zone kit with the rubber gasket and it kept dripping fluid. I thought it was the front seal installed wrong because it was dripping from the bell. I put it on the lift and dried it and with it on the lift and not leaning forward you could see it was the pan. Put a cork gasket in and no more leak. This 904 73 trans has a stall converter from the factory and works perfect for performance.

 

[toolmanmike]

ALways nice stuff OMM

I would drop the pan, adjust the bands according to the manual and make sure the linkage and kickdown are properly adjusted as well. You may have a converter drain back issue. I have 2 96 Dakotas, both with the A500 transmissions. (904 overdrive) One has issues in the morning and the other one doesn't. I just start it in neutral and it's ok. The 904 in my 70 swinger has the drain back issue as well.

 

[CudaFactHackJob]

Start it in park. Put it in neutral for 10 seconds. Then try reverse. If that works, then I wouldn't drop the pan at all.

 

[AJ/FormS]

OK, I drove the car to dinner last night and then first thing this morning. Reverse engaged about 90% so I backed out of the driveway and proceeded down the street. It shifts fine through the gears with no flare between 1 and 2 or 2 and 3.

I have never experienced the converter draining back in to the trans and causing this type of problem on any other car I've owned. I guess dropping the pan and adjusting the rear band is then next step. We'll see what happens.

Thank you for your replies, I was hoping for someone having this same issue and the band adjustment was the remedy.

Most hi-mileage TFs of that era have this problem. But no one can say a band adjustment is THE remedy; it is only the first go-to, of the diagnostic procedure.
You could put a pressure gauge on the L/R servo port, and if you get 250 psi there at 1600rpm, instantly, then the servo will be at full travel, and then the the only known cure is to check/adjust the band. But if you drop the pan and see band chunks in there, or you see the band adjuster flopping around in there, or you manually apply the servo lever and it goes to the bottom of the bore, then you also know what you gotta do, and you didn't have to buy a gauge. By contrast, the gasket is super cheap, and if you buy a filter kit, the gasket is sorta free.