D6C Tranny Lube Pressure

I am not sure the D6C SERIE 74A should have 20 or 30 oil in transmission and stering cluch not 80/90w

I spaced out on that one, it's new 30w oil not 80/90w.

Did you removed the strainer housing cover and clean the magnet just before the oil pump.

If that's the strainer that has about 5 or 6 round magnets that slide over the frame then yes, if that doesn't sound correct then I haven't.

Are you sure your reading transmission pressure? I have a 74A ,D-6c ,and it only has a Engine oil pressure gauge on the dash ! Unless you have an extra gauge someone has added ,and taped into the transmission pump on the right side at the bell housing,should only be a plug on top of pump

Upon re-checking, it is 80/90 oil in the tranny. It was recommended to us to run the same oil it there as we had in the finals. Is this too stiff and causing a problem?

Yeah it's on the left side of the dash and it has lube pressure on it and someone wrote transmission underneath the gauge. It looks like maybe it's plumbed to the left side of the machine just behind the dash and right inside the side rail. Didn't have a camera or I should have took a picture.

Yes the 80/90 oil in tranny and stering cluch is too heavy and causing probleme ,I had a guy who had 80/90 oil in master cluch and scrapped complet the cluch and pump.

80/90 is too thick for the tranny because the same oil applies,and releases the steering cluch pistons .The Desiel engine ,master clutch and tramsmission ,called for series 3 ,30wt oil when tractor was new. Cat also at the time was using 30 wt in the finals ,but later changed it to 80/90 then 140 for a time and than back to 80 /90 as I remember it at the time

Hi Team,
as I recall these gauges were removed later on due to confusion over their use on a Direct Drive machine, and, indeed the Powershift units too.
The gauge reads Steering Clutch release pressure at the steer pressure relief valve on the inlet to the steer control valve, and the trans is supplied lube oil from the same pump thru a seperate line from the steering valve under the tank, if I recall correctly. The pump should be on the upper front left side of the flywheel housing.
The trans filter should be on the left side of the engine just to the rear of the engine oil filters. The suction screen should be under the floor plate just behind the left steer brake pedal. Although I think they were moved on later S/No machines.
The individual steer clutch pressures can be checked at tapping plugs on each respective supply elbow coming out of the steer control valve under the fuel tank.
You may also need to check for correct steer linkage adjustment. Sorry do not have a OMI for this machine to help.
Some notes I have say that the steer pump pressure should be 265-300 psi at the pump tapping and 250-300at the elbows with the steer clutches "Dis-engaged at low idle"
Low readings indicate leakage past the cluch release piston seals, rotating hub seals on the bevel shaft or maybe O rings blown on the pipes taking the release oil from the elbows to the hubs in the steer compartments, first easy place to check after doing the linkages. Then mabe pump condition, & relief valve.
If the bevel shaft bearings get loose then the rotating sealing components taking oil to the clutch release pistons fail and oil pressure loss results.
Below are poor quality scans of photo-copies of an article from my Cat school notes, 1965. Have tried to locate an original in my other lit, but no luck so far.
Hope this helps.
Cheers,
Eddie B.