980H Transmissions issues

Hey guys I'm working on my 980h JMS03132
so far I haver had hydraulic, steering, and braking issues since I bought it last winter.

Now I'm on to the transmission issues haha. the machine ran great all day saturday no problem all day. monday warm it up and grease it and go to dig into some piles and first gear has no power.
after a little playing around and getting it warm i learned that 2,3,4 all work properly with full power in both auto shift and manual. when you drop it into first to dig into a hard pile of dirt it drives fine with no load but once you get about a half bucket and start to really push the tranny starts to slip. the tires you can see start to chatter, its not violent just a slight chatter and no power to the wheels, the hydrualics have plenty of power though. after some more test of really ramming the bucket down to backblade the ground i realize first gear reverse has the same problem.

all the dashboard indicators match where ever i have the shift lever.

no codes at all

changed the tranny fluid and cleaned the screen and magnetics and installed a fresh filter on monday morning. oil and filter looked clean, the screen had a few plastic looking flakes but no metal or clutch material , magnets where clean also very clean,
i refilled the tranny with oil and warmed it up, it didn't help at all
i figured the first gear shift solenoid was acting up so i changed the number 6 shift solenoid because i was told by cat that one does first gear.
new shift soleniod made no difference either.
i ran the machine all day today in just second gear, the machine has plenty of power in 2nd but first is still no good.

I'm waiting on my gauges to come in to test some ports on the tranny, does anyone have any advice what to try next and what i should be looking for when i test the pressures?

thanks you in advance,
Jake Harrington

Hi Jake, I would swap the complete modulating valve group not just the solenoid. Interchange #6 station with #3,#4 or#5 and see how you go

Im not sure if u mean swap the solenoid valve part number 244-3114(which is what i did with number six. I swapped the whole piece that is bolted on with 2 bolts) or you mean swap the entire assembly which i assume is the entire piece that all 6 of the valves bolt into.

also i cut open my old tranny filter this morning. I looks really clean i think

Cut a piece of that filter media out and squeeze it in a vice. A YouTuber by the name of Adept Ape has a good “how to” video of cutting filters. Check that out before you start cutting. Unless you get rid of all the oil it will be difficult to see any particles that may be lodged in the bottom of the pleats in the filter media.

In your first post you said you changed the solenoid only
so I assumed you just changed the solenoid.
changing the 2 bolt modulating valve is the preferred option
did you replace with new or from another clutch station?

Ya bought a brand new one and put it in the number 6 spot according to the guy at cat. Apparently the 6 spot controls first gear?

#6 is the clutch that controls 1st speed (along with #2 which is the forward clutch). It’s marked “A” on the drawing below.

Ok thats good I definitely switched out the correct valve.
I throw a guage on the test port on tranny filter today. Im only getting about 250psi it looks like and thats through out the entire rpm range. I believe tht number is pretty low. Im planning on doing more pressure test once i get some of my remote fittings fixed and the right pressure gauges. Right now mine are all too high pressure scales

Did you cut that filter using the process in the video I mentioned yet..?

No i havent had time yet but i have saved the filter to try hopefully later today

Pressure specs on #1 & #2 are 330psi +/-25. On #3-#6 i's 370psi +/-25

My pressure at the filter housing is too low. It is at about 250 psi. Is there a relief valve i can adjust to raise it up? Or are my pumps shot? Pressuse remains constant throughout the rpm range?


I also took out the 10w oil i had in the tranny and put in the 30w this morning it made the problem less noticeable

Before condemning the pump, is it possible that the transmission pressure relief valve spool #7 is sticking (or the check ball inside it) or the spring #5 has broken..?

Where is that located?

Underneath the control valve that has the solenoids on top. You'll probably have to unbolt the complete valve and lift it up to get access to the relief valve.

I can find the plug in that picture so you must have to take off that control assembly and its on the bottom side. does that just unbolt and op right out or is it a whole project?

There is a small cover to remove and you can adjust (or try)the main relief in place. Also #17 Tc inlet relief in the picture likes to fall out as if it has not had the update the oring is the only thing that holds it in (and oil pressure when running).
Check your Main pump pressure in gears/forward/reverse etc to see if you have certain clutches leaking.

#1 is what you will be turning in. And don’t drop your wrench while doing it lol

From machine JMS03451 the converter inlet relief valve was secured with a pin instead of just relying on the O-Ring to hold it in place.
I was going to suggest that as another place to look once it was established that the transmission PRV was OK.