986 reverse only

[poortruckfarmer]

My 986 has been slipping in high torque for a while and has got progressively worse. Got to the point where it will not pull at all with a load. Have been having problems and no time to check it out so we have been using low torque instead for a while. Now it made a slight "clunk" today in the transmission or clutch and we have no low or high gear at all, had to drive in reverse to get it home. Plenty of hydraulic fluid, new Hyd. filter couple of weeks ago. Is it clutch or a TA problem? Or is this new development a new problem with the transmission?

 

[Janicholson]

If the progressively worsening slippage is in both high and low in all faster gears, it is likely the master engine clutch. If the low TA position would pull a moldboard plow. Then it is likely the front TA clutch, or MCV pressure. I think the no forward gears is a different issue with linkage. Jim

 

[the tractor vet]

well like Jim said son ya got a Heep of problems . Lets start with main clutch first as i am pretty sure it is TOAST and the flywheel will need refaced . Now as for the transmission HUMMMMMM that is the last transmission in the drive line , so what could it be ???? IF it ain't linkage related then you have BIG problems . . If ya got a cab then pull up the floor mate and the plate and see if ya have linkage movement , If ya do then the top cover needs to come off . To do this first ya need to block up the park loc and this can be done by placing a 1/2 inch nut under the park lock lever on top of the range transmission cover , next ya need to remove the side cover on the left side of the rear end under the cab or platform behind the steps the one with the clipped corner . This cove can be removed with out draining the oil from the rear end if the fluid level is at the full mark on the dip stick with only about a gallon loss . I like to remove this cover to watch as the top cover comes up and the rev shift rod pulls out of the rev. shifting fork. and it is also helpful when replacing the top cover.

 

[BarnyardEngineering]

There is nothing hydraulic about the high-low-reverse transmission. It's all purely mechanical. High-low is on one shifter and reverse is on another.

Floor panel will expose some of it but the real action happens under the seat. The whole seat plate comes up with 6 bolts and 2 hydraulic lines if it's a hydraulic seat. Well worth the effort in my experience. Exposes the whole shift mechanism and top cover so you can see what's going on.

The high-low problem might be an easy fix but it may not. Even if it is you're not doing the tractor any favors by continuing to try and use it in its current condition.

When you say you were using it in "low torque" do you mean the TA lever in low? Or low range?

 

[Mrfred54]

The cover that tractor vet is talking about with the clipped corner is behind the
lower fuel tank if you have one. Have to drain the fuel to remove the tank and easier
to remove tank with the wheel slid out on the axle

 

[poortruckfarmer]

(quoted from post at 23:35:55 09/11/23) If the progressively worsening slippage is in both high and low in all faster gears, it is likely the master engine clutch. If the low TA position would pull a moldboard plow. Then it is likely the front TA clutch, or MCV pressure. I think the no forward gears is a different issue with linkage. Jim

Thanks for responding, linkage is working as it should. Yes it pulls a moldboard plow in low torque but not in high torque.

 

[poortruckfarmer]

TA lever in low.

 

[Janicholson]

I suspect MCV pressure. if the pressures are low, or the front Direct clutch is slipping from wear, the sprag clutch in the rear of the TA will still hold the unit correctly. ans allow low TA to work, as it is mechanical, not hydraulic. Jim

 

[BarnyardEngineering]

(quoted from post at 13:04:01 09/16/23) I suspect MCV pressure. if the pressures are low, or the front Direct clutch is slipping from wear, the sprag clutch in the rear of the TA will still hold the unit correctly. ans allow low TA to work, as it is mechanical, not hydraulic. Jim

That is true, BUT the tractor will still move with the TA lever in direct, because the sprag will still be pulling. Normally in direct the sprag simply "overruns" like spinning the socket on a ratchet wrench by hand.

If the tractor stops dead in its tracks in direct, that sprag is not working.