Cat 931b lost forward and reverse trans fluid is filling into bevel gear any thoughts

1. #1pittsburgh cat man2026-03-30 17:41

   Bevel gear or clutch compartment Pretty hard to get in bevel gear thru a drive shaft

2. #2Tyler d4c2026-03-30 19:53

   If it had a wet clutch conversion and the clutch accuators leaking do it? Should still have seals between the clutches and bevel tho.

3. #3pittsburgh cat man2026-03-30 20:05

   conversion did nothing with bevel gear seals if it's going in clutch compartment the only place is the slave cylinder

4. #4shopguy2026-03-30 20:19

   then if the clutch compartment is over full and pressure it can push past the one way seal to the bevel compartment ?

5. #5pittsburgh cat man2026-03-30 20:29

   It's like anything else it's possible If It did have a conversion there should be plugs on rear of the clutch compartment towards the sprocket I remember you had to have grouser in the right place so you could drill the hole The other plus is each clutch has it's own compartment could give you a big hint witch slave cylinder is leaking

6. #6Welder Dave2026-03-30 20:54

   Or both slave cylinders are leaking. Maybe the line to the slave cylinder(s) is split or fittings are leaking. Need to see if you do have wet brakes. If not it must be leaking really bad. Did it have trouble steering when the trans. did work? Not sure if I'd put the leaked oil back in the trans. It could be contaminated.

7. #7yardbird442026-03-31 08:17

   It didn't seem to have trouble steering

8. #8pittsburgh cat man2026-03-31 08:57

   I believe it could be possible for the slave cylinder to leak and still steer as long as it has enough flow to make up for the leak

9. #9Welder Dave2026-03-31 23:17

   Seems like it would need to leak a lot to fill the clutch compartment enough to get into to the bevel gear case.

10. #10OzDozer2026-04-01 09:28

    29Y01311 serial number tells me the tractor is early 1983 year of build, and it's fitted with the 3F/3R transmission. The earlier 931B's only had a 3F/1R transmission, but the 3F/3R came in as an option around the late 1970's. Virtually all 931B's had dry steering clutches up until about 1986, but a conversion to wet steering clutches could be purchased from the early 1980's. I'm not sure how many 931B's would have been converted to wet clutches, but I'd hazard a guess that it wasn't many. If the steering clutches have been converted to oil, they will have a fill point and oil level dipstick. There is no way that transmission oil could get into the bevel gear compartment. It is a sealed compartment (apart from the breather on top), and no transmission lines run into it, or through it. However, the transmission oil is used to actuate the steering clutches via hydraulic pistons inside the steering clutch compartments. The oil lines run from the top rear of the transmission to the valves behind the foot pedals, and thence to the steering clutch pistons. The transmission should not use the same viscosity oil as the bevel gear compartment. The transmission should be filled with a Cat transmission oil (TDTO or TO-4) rated at 30 weight, and the bevel gear compartment should be filled with TDTO or TO-4, 50 wt oil. You can also use a regular 80-90 wt gear oil in the bevel gear compartment, as used in most automotive rear axles. I'd like to see a photo of the underside of the rear main housing (where the bevel gear and steeering clutches are located), and the plug identified, that you are draining the "excess" oil from. If the transmission is only working for a few minutes, then it is running out of oil pressure, and is likely running out of oil, which causing the loss of oil pressure. The transmission needs oil pressure to keep the clutch packs engaged.

11. #11yardbird442026-04-15 21:59

    Here's some pictures 1st ones are under the seat and last plug under the rear

12. #12yardbird442026-04-15 22:02

    I got to look at it a little more this weekend it appeared as right final drive had excessive fluid about 4 gallons in right side and about 2 gallons in left spec looks to be 2.5 gallons

13. #13Welder Dave2026-04-15 23:35

    It looks like, I think the right, steering clutch could be leaking. I discovered I had one leaking while investigating a hydraulic leak. The top of case below the steering valve was soaked but more than yours. The stem needed to be rechromed and matched to the bore. Interesting location for a battery disconnect. That could fool a thief. I'd expect the slave cylinder for the right steering clutch or the line connecting it is leaking into the case. That's the only way for transmission fluid to get in the case. If it was real bad could leak a lot when the right brake pedal was pushed. I'd expect it wouldn't turn right very easily.

14. #14yardbird442026-04-16 07:51

    Is there a good way to verify this im new to this world of machinery

15. #15HATCHEQUIP2026-04-16 09:04

    How long has the machine been sitting

16. #16yardbird442026-04-16 10:25

    Not sure on that I've owned for few months now bought knowing it had a problem but my guess would be a few years

17. #17yardbird442026-05-20 14:15

    UPDATE on machine Found hard line inside of steering clutch housing to have a hole in it the line that goes to slave cylinder and was filling cavity up and over into bevel gear,got new lines and all seems good so far thanks for help

18. #18Welder Dave2026-05-21 14:48

    Glad you found the leak.