904 torqueflite won't move in low

[cueball446]

Ok, so I looked through the forums and I have searched the web and I have not found anyone with my issue. So here we go, when you put the transmission in low the car wont move. It feels like the brakes are on or it is engaging low and reverse at the same time. The transmission was built by a local shop about 5 years ago and has roughly 10,000 miles on it. Leading up to this I was driving when I pulled away from a stop, not getting on it, and the car shifted "funny". At the next light I noticed if felt very sluggish so I shifted into low and the rear tires locked up and the car would not move. I shifted back to drive and I was able to limp the car home (about 4 miles). I pulled the pan it had some definite build up on the filter and pan. I had a shift kit on the shelf so I cleaned the valve body and installed it. When I pulled it out of the garage it did the same thing. So, any ideas? The car has a mildly built 360 and 323 sure grip.

 

[Photon440]

Check the band adjustments first, especially the easy to get at front band.

 

[Hemi Rebel]

Sounds like the overrunning clutch is no longer holding

 

[cueball446]

I appreciate your time to respond. I have checked and adjusted the bands per the manual. If it is the overrunning clutch is there anything that can be done?

 

[Photon440]

I don't think it's the over-running sprag clutch. Even if it totally broke, putting the selector in '1' to engage the rear band would get you moving. Both the overrun clutch and the rear band will stop the planetary housing when accellerating, so same result.

 

[Hemi Rebel]

Do you have reverse? You said you changed valve bodies. Did you check the bands when you had it out? the reason I mention overruning clutch is the low reverse band is off when the shifter is in drive and starting in first gear and the overrunning clutch is holding. Not sure how confident you are in your skills. You did the valve body yourself so going onto the rest of it really isn't that hard. Pulling it on the ground is probably the biggest pain. And if you can't figure it out then that woukd be the perfect excuse to get a 727.

 

[cueball446]

I do have reverse, I adjusted the bands per spec and they looked ok. I do have a 727 from a 1976 dodge truck and it appears to be in decent shape. The filter didn't look to bad and there wasn't too much in the pan

 

[cueball446]

Do you have any ideas what is going on in the transmission? Even if I swap out the transmission I would want to try to fix the 904. Thanks for all your help.

 

[dvw]

The rear clutch is applied in all forward gears. The front clutch is applied in 3rd and reverse only. The front band is applied in 2nd only. The rear band is applied in manual low and reverse only. The low roller functions as the same as the rear band but holds in forward rotation only. I would bet the forward clutch is jammed up or you have some type of hard parts failure. The clutch being jammed on would cause it to start in 3rd gear, it would bind in 1st and 2nd, reverse would work nornal.
Doug

 

[cueball446]

Now that sounds like what I am dealing with. What would cause the clutch to jam? Is there a way to check it and unjam it? What hard parts failure might cause this? Thanks, I really appreciate your time and input.

 

[heinz13]

There's definitely a front clutch problem....it's not releasing, the clutches might be welded from excessive slippage. At any rate it's an internal problem and the unit will have to be removed and dismantled for inspection.

 

[dvw]

Now that sounds like what I am dealing with. What would cause the clutch to jam? Is there a way to check it and unjam it? What hard parts failure might cause this? Thanks, I really appreciate your time and input.

If you have a ring or seal failure the clutch will slip and overheat. It will warp the steels so bad that the frictions can weld themselves together. Time for a rebuild. Parts are cheap.
Doug

 

[cueball446]

Thank you too all who helped I really appreciate your time. I will pull the transmission and put in the 727 and then rebuild the 904 as a "nice" learning experience.