TF904 w/ lockup shift issue

[66durgederp]

Im at a loss, and am after suggestions. got an 87 vintage 904 with lockup, and the second gear shift is sloppy at mid to full throttle but ONLY when the gear shift is in second or drive, and it will be sloppy jaloppy when I start from a dead stop, or a slow roll. If i manually hold first, and shift to second (bypassing governor pressure) it shifts nice, hard, and crisp. the shift to drive is always nice and firm whether I go into it manually or automatically, lockup is great as well, no shuddering or anything wierd.
second gear shift is very stiff when im cruising around town, but the second i romp on it, it takes at least a full 2 seconds to hook 2nd.
now heres what ive done:
1. the kickdown adjustment slot is tight to the carb stud, and throttle wide open I have the trans arm all the way BACK to the rear of the trans.
2. I did turn the line pressure screw IN 1 full turn. (im thinking this was possibly too much)
3. the bands are properly adjusted
4. The fluid originally and still is nice and pink, no schrapnel in the pan of any sort.
5. This unit does have a pro-king 1800 stall converter, factory was 1200.
6. Ive checked all the springs and valves in the valve body, and cleaned it very thoroughly twice now, everythings checked out great, and I torqued the valve body to case bolts to 58 inch lbs.

do these lockup transmissions have issues when any sort of stall is thown at them? Also, the only thing to me that would make halfass sense is that im having governor pressure issues, thus making the second gear shift sloppy, maybe when I cranked line pressure governor pressure is having a hard time overriding it? Im not entirely sure, hence this thread....any suggestions are greatly appreciated. Muchos gracias.

 

[fishy68]

The front band is solely responsible for 2nd gear application so the issue is with it or it's apply servo or the accumulator. Here's my list of possibilities.

1. The valve body to case torque is 100 inch lbs. Not 58. It may not be sealing good allowing leakage to the accumulator or front band servo.

2. The sealing rings on the front band servo may be leaking.

3. One other possibility is the front band is glazed so it doesn't hold good. It would be really rare but a possibility.

4. If it has a real soft spring under the accumulator that'll make the 1-2 shift slow/soft.

Why it seems to shift good when you manual shift it is because when you do that the rear band stays engaged longer giving the front band more time to apply. Normally on a stock torqueflite if you manually shift it they'll experience shift overlap.

BTW: 1 turn on the pressure regulator isn't much in terms of a pressure increase. I highly doubt it's a problem.

 

[TrailBeast]

The front band is solely responsible for 2nd gear application so the issue is with it or it's apply servo or the accumulator. Here's my list of possibilities.

1. The valve body to case torque is 100 inch lbs. Not 58. It may not be sealing good allowing leakage to the accumulator or front band servo.

2. The sealing rings on the front band servo may be leaking.

3. One other possibility is the front band is glazed so it doesn't hold good. It would be really rare but a possibility.

4. If it has a real soft spring under the accumulator that'll make the 1-2 shift slow/soft.

Why it seems to shift good when you manual shift it is because when you do that the rear band stays engaged longer giving the front band more time to apply. Normally on a stock torqueflite if you manually shift it they'll experience shift overlap.

BTW: 1 turn on the pressure regulator isn't much in terms of a pressure increase. I highly doubt it's a problem.

Yep, front band, servo, or a leak somewhere sounds about right Tracy.
Possibly even a shattered accumulator if it's new enough to be plastic.
The mainline pressure valve is 1 turn per 3. something pounds increase so that wouldn't do it.

Seems to me that second would never be better if was a servo seal though.

 

[oldkimmer]

..................don't forget if u turned the adjuster in 1 turn that u actually lowered the line pressure..............put a blocker rod between the accumulator and the case.........what shift kit is installed in it...........block the shuttle valve also.............kim.........

 

[fishy68]

..................don't forget if u turned the adjuster in 1 turn that u actually lowered the line pressure.QUOTE]

That's right. The adjuster works backwards. Good catch Kim... I looked right past that

 

[66durgederp]

oh crap kim....thanks for the good call....the servo rings are cast iron i do remember that. Also the bore wasnt scarred or rough at all, however that doesnt mean they couldnt be leaking. 100 in. lbs, thanks fishy ill jot that down too. I recently acquired a "shift correction kit" from the mid 80s sold through napa, now discontinued, that has detailed instructions to tweak the valve body. New check balls for some spots, a couple holes drilled here and there, new springs, line pressure adjustment specs and whatnots, and new 2nd gear servo seals. in the destructions they said to take 400-600 grit sandpaper and rough up the bore when installing the new rings, and if the bore is marred up, use a ford AXOD input bushing as a "speedi-sleeve" of sorts. im thinking this will be the next plan of attack and hopefully make things more kosher. Any reason this wouldnt be beneficial?