D7F sn 94N8313 Transmission Problem

[Ladell]

After tractor warms up it doesn't want to engage in reverse. Replaced pressure control valve, seems to have helped some but still erratic. Able to get it to engage with lots of shifter movement back and forth from 3rd range to 1st. Direction pressure on PCV goes to zero when this happens, once engaged goes to about 310psi hot. Once engaged pulls good. Transmission has been in and out 3 times, clutches like new.

 

[Bob/Ont]

Get a look at a manual and adjust the shift spool ends.
Later Bob

 

[Mobiltech]

I just had a D7g do the same thing. I tried adjusting the direction spool. I then tried changing the valves which didn't fix it. I finally pulled the trans and tore it down. Very little clutch wear and reverse would apply with air pressure but not as quick as forward. I replaced the piston and steel seal rings which only improved the air application a bit. Put trans back in and problem was solved.
You can check the clutches with air with trans in machine if you remove the valve stack. See how reverse compares to forward .

 

[Nige]

Just out of curiosity what brand and grade of oil are you using in it..?

 

[Ladell]

Mystic W30

 

[Ladell]

Does anyone have a copy of this part of the manual they can post?

 

[Nige]

Mystic W30

There doesn't appear to be much information on the net regarding this oil. Does the label on the pail say anything about it meeting TO-4 specification..?

 

[d9gdon]

Mystik 30W?

http://www.oreillyauto.com/site/c/d...-1_687&mn=Mystik(R)&mc=MYS&pt=N0436&ppt=C0162

Made by Citgo I think.

 

[Ladell]

Yes the correct spelling is Mystik, their web site is www.mystiklubes.com it does not show to be meeting TO-2 or TO-4, http://docs.mystiklubes.com/msds_pi/M20003.pdf

 

[Nige]

I'm not for a moment suggesting it is definitely the root cause of your problem, but the use of an oil not designed for powershift transmissions might just be contributing to it.