Transmission gear box

[GITRDUN]

So i have a '98 machine with the standard Haas 2 speed gear box that will not shift into high gear. I bought this machine used for virtually nothing as the previous owner did not want to rebuild the gear box. When i first powered it up it was in between gears and would not shift into high or low gear. I drilled out the little orifices in the air lines going to the gear box and it imediately shifted into low gear as soon as i hooked up the air. It will try to shift into high gear but the shifter shaft does not fully retract to get high gear fully engaged. It will shift back into low gear with no problem. I also checked that the Mac solenoid valve is working correctly and it is, the air pressure changes from one line to the other when you manually switch the solenoid. I can get it to run in high gear by switching to high gear and then unplugging the high gear micro switch so the control thinks it is fully engaged. But when the spindle runs this way it sounds like the gears are dragging on each other, the RPM is correct so i know its running in high gear. I wouldnt run it this way obviously but i just wanted to know if it was actually in gear or not.

So i guess my question is what is there inside of the gear box that could prevent the gear shifter from being able to fully engage the high gear? I have numerous Haas machines so fixing the gear change problem is nothing new, however i have never had one that will not switch into high gear its always low gear that wont engage.

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[airjet]

Did you try to use the air gun to blow the air directly into the copper tubing (high gear side) and make sure you turning the spindle while doing this. If it doesn't work - most likely that's your shifter inside the gear box .

[rbooth]

Ah i have had the happen to my 1996 vf 2 when we started it up and went to home the machine it would not shift from low to high, and alarm out.
On the very top of the spindle the is a air line that powers the actuator. not the flip top on the top of the spindle it is for adding gear oil for the gear box.
but a haas tech told me to disconnect the air line that goes to the actuator and put some high quality tool oil in it and start machine up and make it change gears repeatedly and hope it lossens up.

also check you gear box oil and make sure its not to dirty and full. it can only help.

if that dont fix it pm me and ill call one of my buddies that is a Haas tech

[JMFabrications]

I had the same issue on my '01 VF2. I pulled the gear box out and it turned out the bearing shaft that is connected to the shifting plunger which moves up and down was really gunked up. I pulled out the shaft and polished it to a mirror finish and its now shifting smooth. If the normal fixes like the solenoid and drilling the orifices dont work its def something internally. The gear box is very simple, its also pretty easy to get out.....just a bit time consuming.

[Precision MT]

The shift piston may be boogered up, the solenoid could be bad, but most of the time it is caused by the gears wearing into each other, preventing proper shifting. If this is the case you are usually in it for a new tranny, since no one sells just the gears. You could make the gears, but that may be cost/time prohibitive.

Thank you,

Precision MT