A904 Woes.. not working right..

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MonkeyMadness

MonkeyMadness

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I have a 72 A904 behind a 318 in my daily driver.
It was recently rebuilt and has been driving well with nothing out of the ordinary. Until yesterday my son and I were curzing and running errands and left a bit harder at a light than normal, and instead of a burn out we got slippage so I let off and took it easy home. Once home I ran through the gears and then test the tran a bit, then holding the brake I gave it the gas and the tire chirped a bit. But now it slips and shudders bad in first under any throttle. Still runs and drives but make odd noises under load once up to speed.. At a loss and looking for help.
Thanks
 
First order of business would be dropping the pan, if it's full of clutch material and metal glitter it'll need to come out.

When you first pulled away from the light and it was slipping, was that in manual Low ("1") or in Drive? Does it still slip badly in first if you have it in manual Low?

When it was rebuilt, were any upgrades done to the hard parts or valve body or was it just rebuilt with stock parts? 904s won't hold up very long to spirited driving without at least a shift kit to increase hydraulic pressures and make the shifts quicker.
 
MopaR&D said:
First order of business would be dropping the pan, if it's full of clutch material and metal glitter it'll need to come out.

When you first pulled away from the light and it was slipping, was that in manual Low ("1") or in Drive? Does it still slip badly in first if you have it in manual Low?

When it was rebuilt, were any upgrades done to the hard parts or valve body or was it just rebuilt with stock parts? 904s won't hold up very long to spirited driving without at least a shift kit to increase hydraulic pressures and make the shifts quicker.
Click to expand...
Dropping the pan today...
When we pulled from the light it was in "D"
Yes it slips in D and in 1 but not as bad..
No it was a stock rebuild, clutches and steels, gaskets ect.

RustyRatRod said:
Time to pull it.
Click to expand...
Ugh... I have that feeling too....
 
How is reverse?
In reverse the VB sends full pump pressure to all the involved circuits, which are the L/R band and the Hi-drum. There is zero pressure regulation.
In all forward gears, the forward Clutch is engaged and one of; either the Second gear band for Second, or for Third gear, the Hi drum. In Drive, to get First gear, the rear one-way (sprague) clutch gets the job done. But in manual Low, the L/R band is applied.
Thus, with a little detective work, it's fairly easy to diagnose what went wrong.
BTW for future reference, to do a first-gear blast-off, with a stock A904, it is customary to shift the trans into manual low, because the sprague is not designed for that.
To make matters worse, the sprague does not come in a rebuild kit, and must be ordered separately.

As for my guess, I'll chose the Forward clutch, which is a bit unusual.
 
Dana67Dart said:
Have you checked the fluid level
Click to expand...
Yes it's perfect...

AJ/FormS said:
How is reverse?
In reverse the VB sends full pump pressure to all the involved circuits, which are the L/R band and the Hi-drum. There is zero pressure regulation.
In all forward gears, the forward Clutch is engaged and one of; either the Second gear band for Second, or for Third gear, the Hi drum. In Drive, to get First gear, the rear one-way (sprague) clutch gets the job done. But in manual Low, the L/R band is applied.
Thus, with a little detective work, it's fairly easy to diagnose what went wrong.
BTW for future reference, to do a first-gear blast-off, with a stock A904, it is customary to shift the trans into manual low, because the sprague is not designed for that.
To make matters worse, the sprague does not come in a rebuild kit, and must be ordered separately.

As for my guess, I'll chose the Forward clutch, which is a bit unusual.
Click to expand...
Yes reverse was fine now you have me worried about the Sprague.
-Duly noted on the on the blast off advice!

RustyRatRod said:
Time to pull it.
Click to expand...
You're not my friend... jk

Pulled the pan and found clutch and glitter...

20231028_173219.jpg
 
......................................The work begins...............................
 
MonkeyMadness said:
Yes it's perfect...


Yes reverse was fine now you have me worried about the Sprague.
-Duly noted on the on the blast off advice!


You're not my friend... jk

Pulled the pan and found clutch and glitter...

View attachment 1716159381
Click to expand...
I'm sorry. I have a bad habit of cuttin to the chase. Makin noise and slippin. It's gotta come out. Just no other way. Look at it this way. At least it's not a modern somethin er other with AWD.
 
Are you planning on rebuilding it yourself? If you can pull it, you can rebuild it. If you rebuild it, you'll know it is correct.
 
66fyssh said:
Are you planning on rebuilding it yourself? If you can pull it, you can rebuild it. If you rebuild it, you'll know it is correct.
Click to expand...
Yep, that's my plan.. Just ordered a DLX 2 kit with all new bands and shift kit and alto friction plates. Also ordered a new sprague kit as well.. pulling the trans now. I will postup pic's as I go..
:thumbsup:
 
Transmission is out and on the bench. Pulled it part and did not find the carnage I was expecting. Both planetary gears and bands look fine aswell as the sprague gear, the first clutch pack looks good aswell. Looks like the other clutch pack and steels didn't fair so well, they were smoked bad..
Also I found the the rear case housing plate between the governor and the sprague gear shows some wear due to running dry? I'm guessing???

I haven't pulled the valve body apart yet. I'll do it later..

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The first clutch out is called the front clutch, go figure but everybody I know calls it the High Drum, cuz that's the clutch that makes high gear.
The second one out, the one you found all burned up, Mopar calls the rear clutch, but again, everybody I know calls it the Forward clutch, because it causes the car to go forward, lol. Obviously yours is toasted.
That aluminum piece you unbolted from the back, that you found all messed up; I think it's called the governor support, but really, it supports the L/R drum, which supports the sprague inner race. Look inside the drum and it'll look similar. Since it's aluminum welded to steel, if the part is otherwise reuseable, you can remove it with weak hydrochloric acid, sold in hardware stores as muriatic acid. Unfortunately, that stuff is only 5%, so it's pretty slow.
 
MonkeyMadness said:
Transmission is out and on the bench. Pulled it part and did not find the carnage I was expecting. Both planetary gears and bands look fine aswell as the sprague gear, the first clutch pack looks good aswell. Looks like the other clutch pack and steels didn't fair so well, they were smoked bad..
Also I found the the rear case housing plate between the governor and the sprague gear shows some wear due to running dry? I'm guessing???

I haven't pulled the valve body apart yet. I'll do it later..

View attachment 1716159772

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View attachment 1716159776
Click to expand...

Would you mind posting a pic of the big spring for the low/reverse band servo? I'm working on my 904 right now and it looks like it's been rebuilt before, I'm trying to figure out which parts might have been upgraded.

I circled the location in red...

20231029_142403.jpg
 
MopaR&D said:
Would you mind posting a pic of the big spring for the low/reverse band servo? I'm working on my 904 right now and it looks like it's been rebuilt before, I'm trying to figure out which parts might have been upgraded.

I circled the location in red...

View attachment 1716160028
Click to expand...

I could be wrong, but I don’t think anyone upgraded the spring for the reverse band servo.
The servo itself sure, as there are billet upgrades for those.
 
Get Tom Hand's torqueflite book. Looks like you found the issue. Now I'd try to find the cause. You don't want to duplicate this.
 
TrailBeast said:
I could be wrong, but I don’t think anyone upgraded the spring for the reverse band servo.
The servo itself sure, as there are billet upgrades for those.
Click to expand...

Ope sorry, I meant on my transmission. I was wondering if I needed to install the spring that came with my TF-2 kit but I decided not to and it seems fine. I got it all back together today and just came back from a test drive, no issues with it going into 1st or Reverse (or any gear for that matter) harshly.
 
RustyRatRod said:
Get Tom Hand's torqueflite book. Looks like you found the issue. Now I'd try to find the cause. You don't want to duplicate this.
Click to expand...
I’ll put a second on Tom‘s book. Just finished rebuilding mine a few weeks ago it’s back in the car And working appropriately. Went with the TCI kit and will probably put the manual valve conversion in over the winter.
 
MonkeyMadness said:
Yep, that's my plan.. Just ordered a DLX 2 kit with all new bands and shift kit and alto friction plates. Also ordered a new sprague kit as well.. pulling the trans now. I will postup pic's as I go..
:thumbsup:
Click to expand...
Here is a good book if you don't already have one.

IMG_3557.JPG
 
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