Front Differntial failure L3940

[5030]

Could you elaborate on the gear oil instead of the sudt. The stuff is stupid expensive. And from what i am hearing they are pretty straight forward to fix. And if they are failing for shock load issues, don't see where the expensive fluid is getting me anywhere. Chances are I am going to break something long before using sudt makes any sense.

GL 4-5 gear oil has much better shock loading capability than SUDT or UDT, at least in my application it does. Is it cheaper? I don't believe so but it stinks a lot more...lol I use Shell 85 140 GL5 myself and if your seals are marginal, it won't leak out as much either.

 

[rScotty]

Could you elaborate on the gear oil instead of the sudt. The stuff is stupid expensive. And from what i am hearing they are pretty straight forward to fix. And if they are failing for shock load issues, don't see where the expensive fluid is getting me anywhere. Chances are I am going to break something long before using sudt makes any sense.

Gear oil/gear lube is considered better for shock loading and also clings better than other types of oil.
I think that makes it a better choice for the front axle than UDT/SUDT or any of the trans/hydraulic oils.

The company that invented that bevel gear type of front axle used on most 4wd tractors now originally recommended 90 wt gear oil. Today we have more options on oils as well as more types of seal materials. But the differential and bevel gears and bearings on the inside are still the same.

So my preference is to use a multiweight gear oil in the front axle. We've done that since they first came out, some 30 years ago. 4 tractors; no problems. Use either 80w-90 or 75w-90. Those gear oils have an SAE viscosity similar to Rotella 20w-50 engine oil.

The way I rate them is syntetic over conventional, 75W-90 preferred over 80w-90, and I prefer that the oil NOT have any of the limited slip additive. Most of the premium oils make one like that for a reasonable price. I think the last one I got was Valvoline. Mobil, Shell, Amsoil & Chevron have similar.

rScotty

 

[big bubba]

agree with your selection of GL5 over UDT as stated above for tractor ft axle. & personally go with 75/90 over 85/140 (esp for someone in colder climate) on the tractor. note i have no empirical experience or other data to support the decision other that what i've read.

would be curious why you tend to shy away from limited slip additive in gear oils.
although my own tractor ft axle is limited slip, i don't pay attention to the LS additive in gear oil selection since the rpm is so low on a tractor

would be interested why you shy away from LS additives in gear oils, & data to support. just a lube question, i know a deviation from the OP's question. your posts seem to be well reasoned & factual
best regards,

 

[rScotty]

agree with your selection of GL5 over UDT as stated above for tractor ft axle. & personally go with 75/90 over 85/140 (esp for someone in colder climate) on the tractor. note i have no empirical experience or other data to support the decision other that what i've read.

would be curious why you tend to shy away from limited slip additive in gear oils.
although my own tractor ft axle is limited slip, i don't pay attention to the LS additive in gear oil selection since the rpm is so low on a tractor

would be interested why you shy away from LS additives in gear oils, & data to support. just a lube question, i know a deviation from the OP's question. your posts seem to be well reasoned & factual
best regards,

Oh. Yes, glad you asked. There are some big tractors with limited slip but ours doesn't have it.
I've no particular reason to shy away from limited slip additives. It's just that I don't have much knowledge about how or which limited slip additives work in tractors, and didn't want to recommend something I don't know about or have used.

When I was writing that post I figured that most of the size tractor that TBNers use don't have limited slip, and our big tractor doesn't either. Now as for big tractors like your big Kubota with limited slip, I'd be curious to hear if you notice anything different with the additive.

Since it's not needed in a standard diff, then I'd avoid the additive for a couple of reasons: one is I don't see how an additive made to reduce lubricity could be an advantage in there.... and it does add to the cost.

But I'm willing to believe that the additive might do nothing at all harmful in a regular diff. I've not ever heard of it causing a problem - in which case it makes no difference and no harm; no foul.
No harm; no foul.
rScotty

 

[big bubba]

excellent response, cut to the chase. my choice of GL gear oils is for tractor & older pick up. i've stayed w/conventional GL5 80/90 hypoid since factory on tractor.

for my '92 pickup, after using full syn GL5 75/90, have had numerous seal leaks, & now use conventional valvoline 75/90 that has LS additive that i haven't paid attn to.
Anyway, back to OP: in your case i'd recommend either syn or conventional 75/90 GL5. valvoline is my personal choice, best regards

 

[5030]

Limited slip additive is nothing more than a friction modifier to eliminate clutch pack chatter. Nothing more.

 

[rScotty]

excellent response, cut to the chase. my choice of GL gear oils is for tractor & older pick up. i've stayed w/conventional GL5 80/90 hypoid since factory on tractor.

for my '92 pickup, after using full syn GL5 75/90, have had numerous seal leaks, & now use conventional valvoline 75/90 that has LS additive that i haven't paid attn to.
Anyway, back to OP: in your case i'd recommend either syn or conventional 75/90 GL5. valvoline is my personal choice, best regards

That's what I run in ours, too.

 

[loggin]

I typically stick with conventional 80/90 weight GL5 on my equipment since most of my gear boxes and axles are older and I'm not sure how the synthetic oils might react with those old seals.

Just my 2 cents.

 

[GarthH]

In a past life I tried to sell Pnz up here in Canada. We were involved with a quote from a small city, from my reading of the specs it did not seem that Pnz met the cold temperature specs. I arranged an oil engineer from Houston to have a call with the city. I was quite surprise to find out that they were not even close to qualifying for the cold temperature specs, in fact the engineer suggested that is not likely an oil that would. The city indicated that Petro Can (was a Cdn oil company now owned by Suncor) certainly met the spec. I guess I learned that not all oils are the same. I buy Petro Can exclusively, hard to find and a bit more expensive.
Oddly I thought the front diff was connected to the main UDT system.
I am from the city originally and Kubota is the first tractor ever, so it is a learning curve. I wish the dealers would go through exactly what is needed to be maintained. I always say if I know about it, I can do it.

 

[GarthH]

We are getting back into the snow season. I loaded the front mount blower a couple weeks ago and of course I'm checking everything very carefully, front dif, tires, etc. I do not want another problem that cost the $10K.

The tractor was home from the dealer repair last May. The front diff is dry, no leaks that I can see.

I did the winter oil change in mid October. Checked the front diff, no gear lube coming out of the test port, so I topped it up ... I think it took close to 2 qts.

I've been out a couple times with the blower now, checking the front diff each time, I think I've added another qt.

I called the dealer who did the repair, he thought maybe the oil was finally getting down to some of the areas in the diff that is hard to fill. He was alarmed about the 3 qts, advised it takes about 7 qts in total.

I have the tractor in my shop now, concrete floor and I'm putting cardboard under the front diff. I'm not seeing any drips.

I don't know where the oil is going! He suggested the rear seal but said they are very reliable. The front blower has a subframe so I can't see the pto attaching to the front diff at all. I wonder if the oil might be dripping onto the subframe and moving around although I do not see much on the floor.

I've been adding a 75w90 synthetic gear oil, the dealer did not comment on the gear oil so I'm guessing its OK.

It is so strange, the wheels are both dry, bottom of the axle is dry, any thoughts?

Should I change the oil out?

Thank you again.

Garth