My D8H clutch gets very stiff to pull into engagement after about an hour and a half of work. When cold it is good. From hour and half on gets very hard to pull back. Not on every engagement though. I have changed oil and use cat oil 50 grade transmission oil. The clutch plates don't need adjusting. The old girl will stall every time in low cog if you want to. After about 3 hours working I've had enough of a workout in the D8 Gym Club and shut down and find something easier to do. I' wondering if it has something to do with the hydraulic assist mechanism. Anyone have any ideas? markw
I've always used 30 Wt. oil in the transmission? Does your machine have the compound levers where the short pull disengages the couch and the rest of the way applies the brake?
Yair . . . I think there may be some confusion John C. . . . I assumed markw was referring to the master clutch on a stick shift? Cheers.
If it's a direct drive the master clutch has a pump on the back, it lubes the clutch and provides pressure for the booster. It may be worn and when the oil warms up does not provide enough pressure to the hydraulic assist.
On the top of the hydraulic clutch booster there is a 1/8" pipe plug, connect a 500lb pressure gauge to this port. You should have 375-400 psi at that port. If not, you have a pump issue or bad seal rings in the booster.
I was thinking I should have asked the serial number. All I've worked on in that model were 46A units with a power shift. I have to go back to 14 A models for direct drives in my history.
If you have it open make sure and check the idler gear that runs the pump, it has a brass bushing and a small circular clip to hold it on the shaft, just grab it and wiggle to check play. You can get it off thru the top cover and replace the bushing if needed. If it comes off the shaft during operation it can raise hell. We always ran 30w in the clutch
Oh boy, does it make mess if that gear comes off. Worked on an old D9D last summer that had that issue. Built in 1956 and the owner didn't understand why parts are obsolete. Strangely enough the serial of the machine was a 19A series originally built with the diesel fuel torque convertor. Apparently those weren't a big success?
Yair . . . RZucker They were doughy bastards. Twelve hundred revs going into diesel converter just didn't work. I never ran a converter D9 but the D8's of the era were just as bad. Similar converters behind the Allis Chalmers engine at twenty one hundred were really pretty good. Cheers.
When's the last time you checked the pump suction screen?
I have run the early/mid 60s AC HD21s and they are a pushing beast. the 21000 engine was an awesome piece to behold. Considering they only had 2 speeds forward or reverse, the torque convertor they used was pretty successful.
Thanks for the replies. The old girl is a stick shift. Her serial no is 68A149. Now that will confuse you all as 68A is a power shift machine. This machine was converted to direct drive in 1979. Reason being a lot of work was available in developing and farming irrigation country and the power shift models would over heat in our climate under constant pulling of equipment such as cutter baring, deep ripping, 80 to 100 foot land plane. We have always been under the impression the clutch and gearbox were out of a 22A. I used 50 grade oil as thought the heavier grade would be better in a hot environment as both 30 or 50 are recommended. Looks like I should try and find the clutch pump and have it checked. Can a pressure gauge be put on the pump anywhere to check it out? In the meantime I can use it for gym workout, as I did today.
Yair . . . . Spot on there RZucker That was tha Allis Chalmers heyday. We found the later models with the oil clutch and converter and wet arse end was actually a pretty reliable tractor, the Timken Tapers in the rollers were always an issue though . . . it was all downhill from there when they bought out the power shift. Cheers.
There are test ports on the pump and on the booster. Booster relief valve is set at 340-360 psi.