I've had it with this 904, about to give up!

-
I went through something very similar to this. I tried different valve body's swam in trans fluid many times, smoked the band etc. I ended up putting a different dipstick in it and found out I was low on fluid the whole time. Some A hole threw a dipstick from who knows what in it before I got the car I got the transmission out of. May seem far fetched but weak 2 & 3 shifts to me is low pressure or low fluid.
 
I totally agree with Trailbeast and his suggestions.

Nothing in the accumulator circuit will cause your problem because the only time it's even pressurized is when the trans. is in 2nd gear. And the throttle pressure linkage adjustment won't cause it to not go in gear, it can cause the shift flare issue but it'll always go in gear no matter where it's adjusted.

For some reason the front drum isn't being pressurized or it'd go into gear. Like TB said it could be a front drum seal (your air test should have revealed a problem there but maybe it let go on fire up??), worn stator support where the sealing rings ride, etc.

Do some pressure tests like recommended above and see where it's at. That'll tell you a lot.

BTW: I assume when you rebuilt it you checked and adjusted clutch plate clearances as needed?
 
plypete said:
I went through something very similar to this. I tried different valve body's swam in trans fluid many times, smoked the band etc. I ended up putting a different dipstick in it and found out I was low on fluid the whole time. Some A hole threw a dipstick from who knows what in it before I got the car I got the transmission out of. May seem far fetched but weak 2 & 3 shifts to me is low pressure or low fluid.
Click to expand...

That's another possibility. I believe a 727 dipstick is longer so if it has a 727 stick in it it'd read full when it's low.
 
Thanks for checking in :)

I was out of town and now need to finish up my other car and get it's 6 speed back in before I can go back to this one. More than likely I have some boyfriend chores to take care of before I'll have time to tear back in to this one ... from what you guys are saying, the transmission is coming back out, again...I just can't wait!
 
Wow, the time flies. I need to get this thing running tip top ASAP. Ready to drive it again. Pulled the drivetrain again. Filmed my air check. Seems ok, front clutch seems quiet but it may be ok?

csq1tth6cs4
[ame]http://youtu.be/csq1tth6cs4[/ame]

csq1tth6cs4
 
Air pressure test sounds fine to me. That being the case and you say you tried a different valve body also I'd take the converter to a converter shop and have it opened up and checked. You really should have done a hydraulic pressure test before you tore it down. That would have told you the hydraulic circuits are working ok. Now your just flying by the seat of your pants
 
fishy68 said:
Air pressure test sounds fine to me. That being the case and you say you tried a different valve body also I'd take the converter to a converter shop and have it opened up and checked. You really should have done a hydraulic pressure test before you tore it down. That would have told you the hydraulic circuits are working ok. Now your just flying by the seat of your pants
Click to expand...


Well, crap. Stupid me. The converter was rebuilt by a reputable converter shop (and stall upped at much as possible) so hopefully it's not that.

Will the air test reveal sealing issues with the pump/stator etc, or is it only good for the clutch packs themselves?
 
Ok, and if the 1-2 AND 2-3 shifts flare, as I seem to recall that they did, and it randomly loses gear while driving or just won't go in to gear (rev included) from park...from what little I know so far it seems like the issue would definitely be somewhere that supplies pressure to the entire trans right...not just a single clutch pack etc? I'll try to look at the pump seals and all that when I get home. Was tired after all the other work yesterday and didn't try to fight the convertor that didn't want to come off.
 
Think I figured this out ... and I really can't even believe I'm going to tell the world about it, but it's a good lesson in paying attention to what you're doing. The front of the pump came out and left the back section intact. I was like...that's strange, don't they bolt together? Yeah, I didn't bolt them together. Don't ask me how that happened, it's been like a year and a half since I built the trans. I'm going to dig around and see where they are. I had acquired a spare 904 and quickly confirmed the one I built was missing the bolts that secure the two halves of the pump together. Pretty sure it's damaged now..see that stray ball?

photo2_zps694b362c.jpg


photo1_zps33311ac1.jpg
 
If the surface in the circle on the right is flat (can't tell in the pic) and you put that ball back in the hole circled on the left and stake it in like the other two are, I run that puppy.

You dont even have to worry about the surface around the balls much.
That ball is just there to plug the hole where the factory drill bit went in to make an oil port.

The ball is just a plug.
 

Attachments

  • ball.jpg
    66.9 KB · Views: 119
Always good to find the problem. Fustrating but rewarding at the same time. Crap like that has kept me up many a nite.
 
Really...very interesting. The ball is a little malformed now. Maybe I should try to find one that's the same size to replace it? Surface looks good, now that you point it out it looks gouged in the pic but I just checked and it must have been the light or something. I can't for the life of me find the bolts in any of my transmission parts bins, I guess the ones from my spare trans are going to get snagged.

Story of my life, 80fbody - I pulled a similar deal with my old chevy truck. Several months ago I swapped cams and heads on it (350) and after I got the timing cover installed and the oil pan re-fitted, I realized I forgot to torque the timing sprocket bolts. Thank goodness I remembered, and the only bad thing was making a mess removing fresh black RTV to pull it back apart.
 
mplex2000 said:
Really...very interesting. The ball is a little malformed now. Maybe I should try to find one that's the same size to replace it? Surface looks good, now that you point it out it looks gouged in the pic but I just checked and it must have been the light or something. I can't for the life of me find the bolts in any of my transmission parts bins, I guess the ones from my spare trans are going to get snagged.
Click to expand...

Yea, I have a drawer of them here from another life.
Ace hardware is a good place to get another one, and be sure to stake it in.

If you can put a straight edge on that pump face where that mark is and it's flat it'll be fine.
Just for kicks pull those pump gears out (Keep them facing the same way they are now) and if the other side of the pump gear area looks as good, I wouldn't have a worry in the world about it.

Re grease it with trans lube or vaseline on both sides and in between the gears and go.
Hint: A fair amount of lube around and inside the gears will insure the fastest possible pump prime when the car fires off.
 
Glad you found it Mplex. When you assemble the pump it needs to be aligned good. I went to NAPA and bought 2 of the biggest hose clamps they had and put them together to make one huge clamp that wraps completely around the pump to hold it in alignment while tightening down the bolts.

BTW: to answer your question in post # 33 "does the air pressure test tell you anything about the pump stator seals", yes it does. When everything is assembled and you inject air into the case for each clutch port it travels through the stator to the clutch packs so if the stator sealing rings aren't sealing you should be able to hear it. I think it was mentioned earlier but in case it wasn't you will hear some air leaking out cause air doesn't seal up real good. As long as it's just a little air leakage your ok. In your test video everything sounded normal to me.
 
Thank you guys, you've been so helpful. I really appreciate it. Too often I have these self imposed problems that are hard to diagnose because they're not normal problems :p

Thanks for the additional info also. Feel like I'm getting a little better grasp on the operation of these things. Getting a little excited to drive this thing again!
 
Alright, looks like a little more damage than I had thought. If you look in the pic, the ears on the inner pump gear are pretty much gone. Looks like it did machine itself in to the outer pump face also, so I guess it's new pump time. All the listings I see are for 68 and newer. I inspected this one and compared it to the spare 904 I have which I think is a 73. I can't tell any difference but don't want to use that spare one if it's wrong. I shouldn't have used that 67 trans but it's what was in the car and I had already started on it when I figured out 67 and earlier are oddballs.
 
I personally don't remember what years interchange and Fishy68 does mostly 727's
If you do a google search you just might find it somewhere.

Just for safety you should flush your cooler lines and take a good look at the converter, and have it flushed also.
If the pump drive lugs are gone the metal went into the converter, and I wouldn't be surprised if the valve body and governor stuck from it either.

That sucks.
It might be best to find a later trans put your good parts in it.
 
I just called up A&A, they're sending me out a new pump support and pump gears, plus the gasket, rings etc and the damn pump bolts that I lost. Expensive lesson, but still less than having the trans built by someone and a definite good learning experience. I would have used a later trans, but I'd already started work on this one and had the converter rebuilt so I wanted to stick with it. If I ever put a meaner engine in this car, I'd like to swap the engine and trans in to another car to flip. I'll then use my spare 73 trans for the new engine.

I'll see if I can get the convertor flushed and I'll go back through the original valve body just to make sure everything is clean. I put a magnet in the pan and it looks to have caught a bit of stuff, so hopefully the trans will pull through.
 
Just thought of something. What year is the engine this trans is behind? I ask because 67 and earlier engines had a small crank register and 68 and later have the large register. You can use a 67 or older trans behind a 68 or newer engine but you need an adapter to properly center the torque converter in the back of the crankshaft. If you don't use the adapter it can possibly break the input shaft on the trans. and/or damage the pump and converter. If the engine is 67 or older you can't use a 68 or newer trans. behind it without a specially built converter.
 
fishy68 said:
Just thought of something. What year is the engine this trans is behind? I ask because 67 and earlier engines had a small crank register and 68 and later have the large register. You can use a 67 or older trans behind a 68 or newer engine but you need an adapter to properly center the torque converter in the back of the crankshaft. If you don't use the adapter it can possibly break the input shaft on the trans. and/or damage the pump and converter. If the engine is 67 or older you can't use a 68 or newer trans. behind it without a specially built converter.
Click to expand...

Thank you, I did get the Torqueflite Patty adapter when I first assembled the combo. That part I've confirmed WAS installed, unlike the pump housing bolts.
 
You must log in or register to reply here.
-

Back
Top