Tree farmer tranny lock up issue

[quilbilly]

97 tree farmer C7F transmission 4F 2R power shift 

Having problems getting into reverse. All forward gears work, I can hear the tranny pop into reverse and draw down the motor but it’s acting like the neutral lock-up won’t release. Checked for blown fuses and shorts but couldn’t find any. Doesn’t mean they don’t exist of course. Any other thoughts?

Fluid levels are normal also. 

[Southside]

How does the shifter work on that model? My 92 PGS has a series of neutral safety switches on a circular, dimpled plate so basically on or off, which controls the valves for the transmission. Had one go bad and all kinds of strange things were happening.

[quilbilly]

I think it works the same way. We were also thinking the same thing. 

[Southside]

With a multi meter it was easy to depress each switch and figure out which one had gone bad.

[kiko]

I hope you that your issue is the forward switch in the shifter sticking.  The forward clutch and the reverse clutch are one the top shaft where the driveline comes from torque convertor.   Directly opposite on the rear of the transmission is a cap, you can take that off and get to the seals that seperates the two oil flows to the f and r clutches. Those seals could be blown allowing it to lock both clutches at the same time causing the lock down.  Unfortunately the most likely senerio is the forward clutch has failed and stacked on top of itself keeping it mechanically locked in all the time regardless of gear selection.  So it will pull in for and lock in Rev.  The transmission can be drained and suction hose removed to check the strainer for debris.  The transmission will come out the door.

[quilbilly]

Kiko so it will still shift to all different forward gears in that scenario?

Also we had it rebuilt about 4 years ago. I have never thought it was quite right though. Don’t have tons of hours on the rebuild. Maybe 500. 

Could the pressure be the issue?

[kiko]

Low pressure could have caused the failure, letting the clutches slip and heat. This was the most common transmission failure on the P4-376 transmission when there was a population around here.

[quilbilly]

Kiko would I have noticed it slipping? One thing that was happening is that I had to wait for it to warm up for about a half hour before it would go into reverse and move. But if I drove it in forward for ten or so minutes it would then kick into reverse. I never noticed the clutch “slip” like you might with a car

[kiko]

The slip could have happen on one drag. I was just finish the troubleshooting steps the others started.  You should verify that none of the swifter switches are sticking first.  If no problem  is found there then I would recommend  draining the oil and checking for clutch debris in the suction strainer. And forget that you can check the shaft seals without removing the transmission. 

[quilbilly]

So we swapped power between the two plunger/solonoids on the front of the tranny, underneath floor pan and for some reason it works now. Any ideas? Is there somewhere I can get a schematic of the tranny? 

[quilbilly]

Finally got it tracked down. Had a bad ground on a solenoid. Very annoying. 

[kiko]

Annoying and good news at the same time it seems.  I can provide that schematic. 

[quilbilly]

Is it the same one you’ve posted on here before? If not I’d love to have it. 

[kiko]

It is the same .