550 - Diff fluid change and final drive?

[mcraigchr]

Howdy y'all,

I have the service manual, but it leaves me with questions.

1)  It is time to change the diff fluid.  The service manual says 80w-90 for the rear and Dextron 3 ATF for the front!  Is that correct?  That seems odd to me.

2) The service manual also speaks of the need to change the transmission fluid but gives no detail about it.  What needs to happen here?

3). The service manual also discusses changing the final drive fluid with 80-90 Hypoid.  Is the final drive actually the tranny?

Any details about the changing of the fluid or what fluid to use ... or even other things that need to be changed that the manual does not mention would be appreciated.

Thanks,

Craig C.  

[cliffyk]

The latest SM for my HS400 (Coleman UT400) also states using Dexron 3 ATF (Dexron, no "t", the "t" is a common misspelling) in the front differential.

from the latest Hisun HS400UTV-5 Service Manual:

I have confirmed with Hisun that this is correct--ATF is used in many gearboxes, not just automatic transmissions. It is VERY heat and wear resistant (it has to be to survive the clutches and planetary gears in an auto-tranny) --the Tremec TKO-500 transmission in my 2003 500 HP Mustang cobra used Dexron 3. I suspect in the Hisun front-end it may help the 4WD/Differential Lock mechanism work more smoothly (on my 400 the shift in and out of 4WD and "lock" sometimes requires a quick "jerk" of the accelerator.

I changed my front diff to 85W-90 SAE GL-5 at 20 hours use as I had not yet received the latest service manual, but at the next change it gets Dexron 3...

 

The "final drive" is the rear axle gearbox. The transmission is in the crankcase lubricated by engine oil (that's why it's IMPORTANT to keep the engine oil clean).

BTW, the rear axle gearbox is not a differential--it is a "spooler", equal power to both wheels , the narrow track makes that possible (at the expense of tire wear)--but it is also why traction is so good in 2WD...

 

[mcraigchr]

Great information.  Thanks so much.

Craig C.

[mcraigchr]

Ok, got the front diff done (Valvoline Dexron III / Mercon (Blue Bottle)).  Rear diff Mobil 1 75w-90 synthetic GL-5.  Nobody in 100 mile radius sells hypoid anything.  Hoping this will work ok?

Most concerning ... 66 hours.  I went ahead and changed the oil for the 2nd time.  I changed it at 39 hours the first time.  Mobil 1 10w-40 4T.  With only 27 hours, that sh*t was nasty.  I could not believe how blackish gray it was and gritty.

Is this what y'all are seeing?  Not sure this is the mark of a good running engine?

I sent a sample to the lab (Blackstone Labs).  Not sure I want to know the results.

Coleman 550.

Craig C.

[tsheh4]

Let us know how the lab report comes out. Just did my first change at 22 hours and it wasnt bad, a little dark but still fairly clean oil. 

My front diff wound up with tractor trans - hydraulic oil because thats what I had a huge pail of laying around. As far as I understand it is very similar to atf, maybe a hair thicker, but still thinner than gear oil (the hypoid oil you refered to is just gl3 4 or 5 rated gear oil as far as I know) or 30 wt motor oil.

[cliffyk]

GL-5 is a "hypoid" rated oil (hypoid refers to the gear tooth profile --that's what most axle reduction gears are--those who toss out flap such as "hypoid oil" are Fast & Furious magazine mechanics who don't really know what they are talking about). I changed my engine oil out with STP 20W-50 Pro conventional at 17.7 hours, still clean on the dipstick at 55 hours.--good oil, ran it in my 2003 Mustang Cobra for almost 200k miles...

[cliffyk]

52 minutes ago, tsheh4 said:

Let us know how the lab report comes out. Just did my first change at 22 hours and it wasnt bad, a little dark but still fairly clean oil. 

My front diff wound up with tractor trans - hydraulic oil because thats what I had a huge pail of laying around. As far as I understand it is very similar to atf, maybe a hair thicker, but still thinner than gear oil (the hypoid oil you refered to is just gl3 4 or 5 rated gear oil as far as I know) or 30 wt motor oil.

Don't know about the tractor trannny stuff in the diffedrential? That's made for hydro-static transmissions--a whole different beast...

While the viscosity of 80 weight gear oil  is similar to 20-30 weight engine oil--that's about the only similarity, among other differences, gear oils have EP (extreme pressure) and other anti-wear additives not found in engine oils. Viscosity is actually just a small part of the story--engine oil works OK with spur gears, but is not good with the higher sliding loads produced by  spiral cut bevel ("hypoid") gears with offset axes

[tsheh4]

Only reason I went with the tractor fluid other then it was what I had was the fact that it is universal trans hydraulic oil. Plain hydraulic oil does not have the additives it has as far as I know. Modern tractor uses it for the hydraulic pump, uses it for lubrication of the gear case, uses it for the brakes and diff locks (a wet clutch setup if memory serves in by Kubota,) and uses it for lubrication of the hypoid gears for the rear diff in the tractor. Similar demands of ATF. Ill report back if it gives me any issues.

[mcraigchr]

On 4/27/2021 at 10:09 PM, tsheh4 said:

Let us know how the lab report comes out. Just did my first change at 22 hours and it wasnt bad, a little dark but still fairly clean oil. 

Got the oil report back.  Not good.  27 hours on the oil.

 

[tsheh4]

Ouch. That is pretty rough news. I will be keeping my eyes out mine....

[mcraigchr]

14 hours ago, tsheh4 said:

Ouch. That is pretty rough news. I will be keeping my eyes out mine....

I think I am going to buy a new Kubota UTV.  Special financing right now (0% / 48 mo).  They'll take the Coleman in trade.  I have a Kubota MX5800 tractor that I have worked hard and never had an issue.  And ... it is easy to work on.  So, perhaps sticking with a brand that I know works will be of benefit?  Idk.  Just know that I am not happy with this POS.

I am monitoring the Kubota sub-forum to see what issues they have.