The Fordson Tractor Pages Forum

Hi all,

Just curious if anybody has considered changing the rear differential fluid from 90 weight to hydraulic fluid. Reason for asking is, I would like the hydraulics to be a little quicker. Any drawbacks anybody can think of? obviously it doesnt get worked real hard anymore.

Have a search amongst the previous postings 6 -12 months back witty73 as I can't recall what the specified oil grade should be, but it is not anywhere as heavy as 90 grade and someone (Brian ? Robert?) explained why a straight hydraulic oil is not suitable.

A previous owner may have upped the thickness to stop it pouring from gearbox to back end through the seal and thence out of the axle seals and down the wheels.................

HTH

Rick - who has a special bit of hose hung on a nail which just fits between trailer pipe nipple and gearbox filler to shove oil back into the gearbox from time to time

The weight should be 30wt according to the update bulletins. I have 80-90 in my Power major and no problems. I have heard Brian say many times that only 30wt should be used in the Supers because of design. Common old time hydraulic oil was 10.wt. Modern Hydraulic/ Trans fluid is 20 wt. Perhaps not quite heavy, or thick enough for our old iron. Dandy Dave!

Ok, my original owners manual specified the 80 Weight, and I replaced it when I bought the tractor about a year ago. Having used it a little, It seems to me as far as hydraulic function is concerned, it is too heavy. I dont have the update bulletin. My tractor is a 53, making it a very early major. DD, are you saying a 30 wt gear oil is acceptable? because even if I have to special order, it will still work better then the 80 / 90 that is in there now.

hi i thought the 30 w was for the supers updated hydraulic system which played up with the heavy oil and then with the lighter oil they started eating bull gears ? the power wouldnt need it b

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Who are we to argue with Ford Motor Company? This was an upgrade. I used 80-90 in my tractor because that is what I found for info at the time. It works for me. However F.M.C. said that running 30WT in all E1A's will not be a problem. Even the first one built in 52 and up. Dandy Dave!

jeez, yeah. I wish I had found that before I filled everything with 15 gallons of 80-90. I to went with what the owners manual said. I dont mind the heavier oil at all, with the exception that anything I hook to the hydraulics is awfully slow. I think the lighter might help with that a bit. Biggest question now is, if I choose to drain the rear end and spend the money on 10 gallons of lighter oil for the rear end, how much will leak between that and the gear box? no way of knowing really.

point taken as for speed its only a 18lt 4 1/2 gal pump so its going to be slow the pumps on older tractors were kept small so as not to waist power pumps have got bigger as time went on and tractors needs have changed and moden pumps work to demand and back off when not being used. on a loader with say a ton 1/4 lift and a lot arnt any thing under 30lt 12 gal ish is not fun i bought a new tractor in 83 with 12g and after my cable loader the cycle times were very frustrating the next in 2000 with 25 gal will nearly throw over your head b

If you go for lighter oil in the rear end, it won't be tempted to move to the gearbox, as the gearbox level is higher. If the PTO housing seal is leaking, the oil will be coming the other way, even though it's thicker.
When I rebuilt my Super, I put Morris AG90 in the gearbox and rear end, as I had done with my previous Diesel Major. Then I read the oil spec! The fact is though, I have had absolutely no problem with slow hydraulics under pressure - the arms raise just as fast as they did on my Diesel Major. When exhausting, and cold, the oil does move more slowly - with no weight on the arms, you have to push them down if you don't want to wait. With a weight on, again you don't notice any difference. Lowering a trailer bed after tipping also takes time, but I'm talking about a wooden buck Pettit 3 ton trailer.
On the plus side, the AG90 is perfect for the other vital function it has to perform - keeping the gears well lubricated. Whip the hydraulic lid off and have a look at the diff & bevel pinion, the bull pinions and final reduction gears. When these mesh, there's some serious work going through the teeth. Work produces heat, which thins the oil. Just a run up the road puts a lot of energy through the oil. Go any further or put an implement on the back and the oil gets hot. That's when the thicker oil comes into its own. It's still providing a film between the meshing gears.
I'd live with the thicker oil for a while before making your decision to change it to something thinner. This may be a situation where solving one problem creates another. All in all, the thicker oil might end up being the best option.
Best, Adrian.

My Power Major hydraulics are plenty fast even with the 80-90WT. One of the reasons I left it that way. I have heard Brian say the heavier oil is a problem for the NP Supers upgraded Hydraulic system. Dandy Dave!