Hello , I am new to this forum so forgive me if I brake a few rules . I just purchased a 1985 D7G at auction with a bad transmission. Before I just rip the cab off and swap the transmission are there a few things I can do to verify it needs to be replaced and not just a simple fix. A few things I have checked..... 1 linkage from thr shifter was undone so I replaced the hardware . Both the magnet /screen and filter were clean and free of debris, and there is sufficient pressure coming from the transmission pump. Started to pull the drives but the grease packed in there is to thick to mess with this time of year . Any help would be greatly appreciated.
how much is sufficient pressure did you test main pressure and P1 and P2 pressure. does the drive shaft spin and does it stop when you put it in gear
I did not put a gauge . What would be the proper way to get P1 & P2 . The drive shaft does not move at all when put in gear
The shaft between the torque converter/divider and transmission should spin when not in gear, and not spin when in gear but the machine not moving. But if you pull both steering levers back it should spin again.
Make sure the parking brakes are released. Bob
See attachment. It also gives the setup/adjustment procedure for the transmission shift linkage. When you engage any gear and try to increase engine RPM does the drive shaft try to turn or does the engine RPM bog down.?
Get a 600 psi gauge p1 p2 is under the top cover on trans you can check main pressure on top of trans filter
The shaft does not spin in gear or by hand in neutral . When testing P1 and P2 the guage bounces back and forth from around 320-360. Except when shifting between gears is when it drops low .
It won’t spin at all
Do you mean the shaft won’t turn even if you put a bar through the u-joint with the engine stopped.? If that’s the case I suggest to remove the u-joint and try turning the converter output yoke and transmission input yoke separately. Report back which one turns.
Did you know this dozer had a transmission problem when you bought it?
It would appear so.
So you can not turn the drive shaft by hand with the machine off like Nige said pull drive shaft and see what side is locked up then get back with us. pressure looks OK
I was just wondering if this was one of those "SURPRISE!!! " after the purchase.
I think the G's run around 400 psi + on pressure with a Sequence Valve on the right side of Torque case, the outer most pipe on the valve has a pump pressure test port at its mounting, this is the good spot to test the pump pressure for a novice, so you need a 0 to 600 psi gauge to test this correctly, the turning by hand the shafts with the drive spider removed is the next step but do not start the engine unless the drive is complete. tctractors
Note this. Do NOT start the engine with the u-joint removed.