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2022 Limited Blue Stone
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Discussion Starter · #1 · (Edited)
In the next couple of weeks, my SC's projected to complete the 1500 mile period, and I'd like to swap out the transfer case and rear diff fluids because I messed up and went over 110 mph in the first 200 miles while the gears were still getting broken in, and that must have generated quite some heat and possibly burned the fluids especially in the rear diff (or not if no power was sent to the rear drive assembly at high speeds, I wasn't paying attention to the power distribution infogram).

1992


interestingly both use the same fluid.
If I remember correctly, the HTRAC SC has open rear diff, so no friction modifier required there (and no harm done if the fluid already contains)

The question is the transfer case, it seems like we have a lockable center diff, and if that diff is clutch-type, does it need additional friction modifier when changing the fluid with synthetic gear oil that contains some form of friction modifier already?
One example of such gear oil is

1993
 

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it seems like we have a lockable center diff,
IDK, from reviews on the Tucson HTRAC folks seem to say the "locking center diff" isn't actually a diff but a "request" to the HTRAC software to split the power front/back. Some testing done by some youtubers showed the Tucson HTRAC still sending power to the front wheels only (before sending to the rear) with the "center diff" locked. With that said I have no clue how it really works and if the "locking center diff" is actually a locking center diff 馃し鈥嶁檪锔
 

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motorcycle nut here...friction modifiers (i.e. motor oil designed to improve gas mileage) is a big no-no in MC engines...the wet clutches get coated with friction reducing "stuff" and start to slip....I use M/C specific oil or diesel engine oil in my 2 wheel toys....I've used Redline two stroke oil in my vintage bikes...the brand is well known and makes good stuff...it's GL-5 rated and the book calls for that spec. ...so I wouldn't worry if you use it in both "cases" the clutches must be designed to work with that spec.

Amsoil makes some good stuff and has a full line of Differential oils...I believe they all meet GL-5 ( check the spec sheet)

the only chemical that I add to ENGINE oil in new engines is a Zinc additive ...they ( OIl formulators) don't use it anymore as it affects the catalytic converter...usually for the first 1000 miles then I don't add it after that ...here's some info on Zinc:

here's the stuff I buy:

hth
 

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2022 Limited Blue Stone
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Discussion Starter · #5 ·
IDK, from reviews on the Tucson HTRAC folks seem to say the "locking center diff" isn't actually a diff but a "request" to the HTRAC software to split the power front/back. Some testing done by some youtubers showed the Tucson HTRAC still sending power to the front wheels only (before sending to the rear) with the "center diff" locked. With that said I have no clue how it really works and if the "locking center diff" is actually a locking center diff 馃し鈥嶁檪锔
yeah, without actually finding out the exact transfer case supplier and model, it's hard to tell what mechanism used.
It seems that Hyundai uses the term HTRAC loosely because they have Genesis using some sealed non-serviceable transfer case and call it HTRAC, and the SC has serviceable transfer case so they must be of different transfer cases and quite possibly different suppliers
 

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2022 Limited Blue Stone
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Discussion Starter · #6 ·
motorcycle nut here...friction modifiers (i.e. motor oil designed to improve gas mileage) is a big no-no in MC engines...the wet clutches get coated with friction reducing "stuff" and start to slip....I use M/C specific oil or diesel engine oil in my 2 wheel toys....I've used Redline two stroke oil in my vintage bikes...the brand is well known and makes good stuff...it's GL-5 rated and the book calls for that spec. ...so I wouldn't worry if you use it in both "cases" the clutches must be designed to work with that spec.

Amsoil makes some good stuff and has a full line of Differential oils...I believe they all meet GL-5 ( check the spec sheet)

the only chemical that I add to ENGINE oil in new engines is a Zinc additive ...they ( OIl formulators) don't use it anymore as it affects the catalytic converter...usually for the first 1000 miles then I don't add it after that ...here's some info on Zinc:

here's the stuff I buy:

hth
interesting read after researching on AMSOIL, I think 75w90 actually would work slightly better in hot climate

 

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While under warranty I would use the exact fluid spec Hyundai recommends. I've read before (somewhere) that you don't want to mix GL-4 and GL-5 gear oils, that is about my limit of knowledge on the subject.

With that said 75W-90 wouldn't be a bad idea if you are really loading up the rear diff. I guess it depends how much power gets transferred to the rear, so this might be more important for those off roading since above 37 MPH the SC switches to auto or part time AWD.
 

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Discussion Starter · #8 · (Edited by Moderator)
With that said 75W-90 wouldn't be a bad idea if you are really loading up the rear diff. I guess it depends how much power gets transferred to the rear, so this might be more important for those off roading since above 37 MPH the SC switches to auto or part time AWD.
You're right, power is not being sent to the rear at all at high speeds.
So what exactly does it mean then? the propeller shaft just won't spin? but the rear wheels are still being dragged along by the road force and do they still spin the the gears in the rear diff in pure FWD situation?

Also, you can all see piano black screen shows dusts very well
 

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You're right, power is not being sent to the rear at all at high speeds.
So what exactly does it mean then? the propeller shaft just won't spin? but the rear wheels are still being dragged along by the road force and do they still spin the the gears in the rear diff in pure FWD situation?
Excellent question. I assume the propeller (drive) shaft isn't spinning and the rear diff is open so the rear wheels can rotate at different speeds while cornering. With no load on them in this (assumed) free spin condition the temps shouldn't build up. I'd love to see some animation showing how HTRAC actually works. Its clearly a FWD system that shifts power to the rear under certain situations, that is totally different then your standard 4X4 system that is RWD but engages a transfer case to route power to the front when engaged. Never owned a 4X4 or AWD so this is all new to me :unsure:
 

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Discussion Starter · #12 ·
Excellent question. I assume the propeller (drive) shaft isn't spinning and the rear diff is open so the rear wheels can rotate at different speeds while cornering. With no load on them in this (assumed) free spin condition the temps shouldn't build up. I'd love to see some animation showing how HTRAC actually works. Its clearly a FWD system that shifts power to the rear under certain situations, that is totally different then your standard 4X4 system that is RWD but engages a transfer case to route power to the front when engaged. Never owned a 4X4 or AWD so this is all new to me :unsure:
In the fall when it's not that hot anymore, I'll spend sometime get a gopro camera underneath and see if i can get some footage of propeller shaft, drives shafts in action and hopefully can reveal some mystery
 
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