Transfer case question: Manual vs Automatic

[fryer1979]

Hey guys. So I've been out looking at 1999-2002 Chevy pickups, and have a question for you existing owners. Does the maunal shift transfer case allow the driver to shift into 4 wheel drive while in motion? I didn't know the manual gearbox was still an option, so I'm just curious if you still have to stop before placing the truck into 4 wheel drive. Didn't want to try it with a truck that wasn't mine yet. Thanks guys.

[DirtyLarry]

Yes, with the manual shift transfercase you can still shift into 4hi while in motion. I shifted in to 4hi at highway speeds with no issues. Actually, you can still buy new trucks with manual shift 4x4 but they are hard to find and they are only in the base model work trucks (unfortunately). I hate the electric shift stuff with a passion.

[MAC67]

As Dirty Larry stated . Go with Manual shift if you can find it " as evident from my thread below this one" every push button gm vehicle my wife has ever owned has shot craps on several different occasions and its always something stupid somewhere to cause it and its never cheap .

If you can find a manual shift go for it , save yourself loads and loads and loads of headaches.

[fryer1979]

Sounds good fellas, thank you. I'm normally a bigger fan of manual accessories when they are an option, but just wanted to make sure this manual gearbox would allow an at-speed shift into 4 high.

[northerngmc]

IN GM terms the electronic shift is still considered a manual shift. I ran into this when I was buying new fluid to change my transfer case. You have to manually shift the transfer case, either with a shifter or a button.

They refer to automatic transfer case as one with an auto function that the vehicle will sense spinning and automatically shift it into 4WD.

[MrDude_1]

3 types:
manual shifted, electronically actuated (push the button)
manual shifted, manual shifter (levers on the floor)

automatic shift, PCM decides when to engage 4wd automatically... still auto even if theres a push button override.

[spudz]

Originally Posted by northerngmc

IN GM terms the electronic shift is still considered a manual shift. I ran into this when I was buying new fluid to change my transfer case. You have to manually shift the transfer case, either with a shifter or a button.

They refer to automatic transfer case as one with an auto function that the vehicle will sense spinning and automatically shift it into 4WD.

yep

[fryer1979]

Originally Posted by MrDude_1

automatic shift, PCM decides when to engage 4wd automatically... still auto even if theres a push button override.

Was something like this even available in the 1999-2002 Chevy trucks? I have yet to come across it.

[northerngmc]

NV-246 Auto T-case used in Chevrolet full size pick-ups and SUV's
from 1998 to present

[fryer1979]

Ok. To a guy used to driving 80's and older vehicles, any gearbox that shifts itself weather you have to push an electronic button or not is automatic enough (you still have to put your vehicle in "drive" or "park", yet that is considered automatic....not much different if you ask me). The point of my post was only to find out if the manual lever T-cases could be shifted from 2 wheel drive to 4 wheel drive while the vehicle was in motion, and even at speeds allowable in the usage of 4 wheel drive. However, thank you for adding one more feature to my "do not buy" list, it's bad enough having a vehicle think it knows when to shift better than I do. Fully automatic 4 wheel drive activation just sounds like a totalled truck waiting to happen. It sure is difficult to find a 5.3L, 5 speed, 4x4....I'm beginning to think they weren't made. Think it might be too much to ask for that truck to also have the Z-71 package as well?

[DirtyLarry]

Originally Posted by fryer1979

It sure is difficult to find a 5.3L, 5 speed, 4x4....I'm beginning to think they weren't made.

There weren’t any made

5 speed manuals only came behind 4.8L and 6.0L engines. All 5.3L trucks have been automatics.

[fryer1979]

Originally Posted by DirtyLarry

There weren’t any made

5 speed manuals only came behind 4.8L and 6.0L engines. All 5.3L trucks have been automatics.

Figures... The 5.3L auto's I've driven so far seem to hold their own alright, so I guess I may be stuck with an auto for this pickup.

[northerngmc]

I agree it is confusing. I did not post to create problems.

I ran into this when I went to purchase transfer case fluid to change it. I assumed because I press a button to put it in 4WD that I had an automatic T Case. Boy was I wrong. I needed oil for a manual shift T Case.


Best of luck finding a new to you truck....... GM does make it complicated.......

[jocko]

Originally Posted by northerngmc

I agree it is confusing. I did not post to create problems.

I ran into this when I went to purchase transfer case fluid to change it. I assumed because I press a button to put it in 4WD that I had an automatic T Case. Boy was I wrong. I needed oil for a manual shift T Case.


Best of luck finding a new to you truck....... GM does make it complicated.......

Bringing this back to the 'ol top for a quick cross check and reminder in case it helps anyone...

I just re-discovered what northerngmc apparently discovered back in 2010... ha. It confirmed what I think I just stumbled across working on a new-to-me 01 2500HD.

Part of my confusion stemmed from the fact that I have been driving an 01 K1500 since new that has an "Automatic" transfer case (btw, has nothing to do with trans type it's connected to) - for which I had been using GM Auto Trak II fluid.

The Owner's Manual describes 3 transfer case types in 2001:
Automatic, Manual, and Electronic
All except the "Manual" have dash push buttons for shifting the T-Case - the "Manual" is the floor-shifted type.

What it doesn't do a very good job of telling you is that the "Electronic" is also indeed a "Manual" variant of the T-Case, as northerngmc mentions above. It also has dash push buttons, but one less than the "Auto" T-Case. In fact, it doesn't tell you this at all (except in the tables if you look back and forth between them enough), you kinda have to figure it out.

This becomes readily apparent when one checks which fluid is recommended for the T-Case, as that section only lists 2 types - Manual or Automatic (which I'd imaging many confuse with the transmission type it's connected to) - and leaves the "Electronic" T-Case dude high and dry as far as fluids.

Anyway, once one deduces that the Electronic T-Case is really better described as an "Electronic Manual" T-Case and that the only "Automatic" T-Case is the one for which there is an additional push button on the dash labeled "Auto 4WD", well, then it all begins to make sense.

So, speaking of fluids, ONLY the AUTO T-Case uses the GM Auto Trak II fluid. All others (i.e. all Manual T-Cases) use Dexron III.

Aside from the presence of an "Auto 4WD" button on the 4WD push button panel, one can also confirm an "Auto" T-Case by checking your RPOs on the SPID. NP8 indicates the Auto T-Case - so, RPO NP8 is the one for which to use the GM Auto Trak II, all others get the Dexron III. The GM VIK refers to an NP8 as an "Active" T-Case, just to add a little more to the confusion

Hope that helps. Probably old news to most, but some was new to me as I've always driven an Auto T-Case, and probably didn't even know it. I've never used the Auto 4WD feature once in 18 years. Guess I won't miss it in the 2500...

[hatzie]

Yup... 2007 GMT800 and earlier Autotrac cases used Smurf blood the rest used Dexron III.

For Dexron III Transfer case oil See TSB 04-07-30-037E
Dexron III is no longer being tested. The AC Delco 10-4033 GM 88861800 replacement is less than $7/qt from Summit. Mobil Valvoline etc Dexron III compatibles usually cost more.

[truckdude239]

Valoline makes a tcase fuild that covers the auto track and all the regular fcase fuilds

[hatzie]

Originally Posted by truckdude239

Valoline makes a tcase fuild that covers the auto track and all the regular xfer case fluids

One size fits all is usually less than optimal for either.

At $6.99/qt for the GM recommended 88861800 AC Delco 10-4033 Dexron III replacement transfer case juice why bother with experimenting with "They say it works" for more or the same or almost the same money. My NP263HD (RPO NP1) transfer case fills with just under 2qts so it cost me just under $14 to change it with the GM fluid...

If you have the NP246 Autotrac (RPO NP8) that uses GM Smurf blood. The blue Autotrac fluid is AC Delco 10-4017 or GM 88900402... It costs $9.65/qt at NAPA.

[jocko]

Originally Posted by hatzie

Yup... 2007 GMT800 and earlier Autotrac cases used Smurf blood the rest used Dexron III.

For Dexron III Transfer case oil See TSB 04-07-30-037E
Dexron III is no longer being tested. The AC Delco 10-4033 GM 88861800 replacement is less than $7/qt from Summit. Mobil Valvoline etc Dexron III compatibles usually cost more.

Hatzie, interesting. TSB does direct use of Manual Trans Fluid in place of DEX III (in the t-case) - I never ever would have known that... But it also says to use Dexron IV in the trans if the trans was spec'ed to use Dexron III.
So, for a 2001 with NP1 (manual t-case) and Allison, i.e. yours truly, sounds like Manual Trans fluid in the t-case and Dex IV in the trans... (?) Since Dex III is still available at auto parts stores, I wonder how many folks are totally unaware. Or do you use Mobil or Valvoline Dexron III in the trans..? Hmmm.... VERY interesting! Btw, 88861800 also shows up as Manual Trans Fluid 75W90 (but at 8.99/qt - at Summit). Wonder how they could have the same PN.

[hatzie]

I think you mean Dex VI... No such thing as Dex IV or Dex V.
Strange that it's listed as 75W90. 88861900 is not 75W90 AFAIK.

This is a link to the in-stock $6.99 AC Delco 10-4033 GM 88861900 at Summit.
https://www.summitracing.com/parts/a...xoC13sQAvD_BwE

[jocko]

Thanks Hatzie, yep, meant VI. Dang Romans... anyhoo. Here’s the other one https://www.summitracing.com/parts/ado-779338
The 6.99 is the correct one for the t-case though, as you mentioned (the name matches the tsb exactly) - i just thought it odd they would have the same pn. I’m glad you posted this - I was planning to buy fluids today. So now will be ACDelco DEX VI for the ol trans and the 6.99 MTF & TC for the t-case. Thanks again!

[hatzie]

I just did a new-to-me fluid swap on my 2005. The transfer case oil ran out pretty dark. The axle fluids didn't look much better.

The transmission and engine oil looked pretty good but the oil pressure runs around 35psi and rises with RPMs with the new WIX filter and 5W30 Synthetic I poured in the 6.0... It didn't on the old oil and filter. The 4L80E is unchanged on the fresh pan full of Dexron VI with a brand new strainer even tho the oil wasn't clear like red glass.
GM released TSB 08-07-30-040C about pan magnets that were not up to the task on the 4T65E & 4L60E. I replaced the pan magnet on my 4L80E with the one from the TSB. The donut magnet in the TSB is supposedly the same part as the magnet that's supposed to be present on top of your M74 Allison 1000 spin on filter and usually isn't. The Dirtymax diesel guys don't like to use anything but the Allison filters because of the significant differences in the way the aftermarket filters are constructed.

I changed all of the fluids at 83,000 miles on the clock so it might've been the original juice from 2005 in that xfer case or it might've been some unknown pedigree fluid put in by the previous owner.
I ran it for 2,000 miles and changed em again. It ran out of the transfer case and axles just a little darker than the new stuff so I'm pretty much good to go.

If you have the Eaton G80 Locker in your rear axle DO NOT use limited slip additive. Some Gear lubes have Limited Slip Additive already in the witches brew so I'd look carefully at the bottle.
See TSB 91-4-109

I'll use Delco fluids where they make monetary sense but I'm not a fool... The Delco 10-4016 Gear oil I just used in my 2005 has gone up in price drastically. I only paid $11/qt... about on-par with Mobil 1. It's almost $18/qt from Summit now and I cringe at the thought of what a GM dealer would charge for it. At those prices I could buy designer oil from Amsoil or the like.
Honestly any decent quality 75W90 Synthetic GL5 gear oil will work in both axles as long as it doesn't have Limited Slip additive. $18 is too high for the pretty Delco label when I can get Mobil 1 or Valvoline or Castrol or Pennzoil 75W90 GL5 Synthetic for a much more reasonable price. I don't bother with store and other off brands but the big names in oil are all pretty good.

[jocko]

Yeah i had already purchased Mobil1 75W90 synthetic for my rear and Valvoline 80W90 for the front. Will take a look to confirm they don’t have lim slip additives, but pretty sure they are good to go. Thanks for the TSB #s. My fluids aren’t high mileage but are 18 years old, so even though it might not be necessary, wanted to start with fresh fluids for the truck’s new lease on life. It’s been sitting for most of its life.

[jocko]

Originally Posted by hatzie

If you have the Eaton G80 Locker in your rear axle DO NOT use limited slip additive. Some Gear lubes have Limited Slip Additive already in the witches brew so I'd look carefully at the bottle.
See TSB 91-4-109

Honestly any decent quality 75W90 Synthetic GL5 gear oil will work in both axles as long as it doesn't have Limited Slip additive. $18 is too high for the pretty Delco label when I can get Mobil 1 or Valvoline or Castrol or Pennzoil 75W90 GL5 Synthetic for a much more reasonable price.

Another timely note Hatzie - The Mobil1 Synthetic 75W90 Diff lub I bought indeed does have some tiny print that states "Limited Slip Friction Modifier Included" (and also states safer for conventional and limited slip differentials)

I do have a G80 locker, so it it appears I'll be heading back to visit the ol pep boys yet again (for a refund) and ordering the ACDelco stuff from Summit, regardless of price. I haven't yet found anything other than ACDelco that doesn't have the LS additive blurb in small print. I think there's often confusion between diff oil "for LS axles" and diff oil "to which one adds an LS additive" - but if I'm reading the TSB correctly, G80 is a unique animal and should have no LS additive in it (to include not being an LS blend at purchase). As far as I can tell so far, only ACDelco, and maybe Lucas, are the only ones that aren't for LS rears or with LS additives. Pretty confusing. I'm tempted to wait a few more days to change my oil in case any more TSBs show up that tell me I'm missing the boat yet again... Ha. Thanks again for posting this info.

[hatzie]

Originally Posted by jocko

Another timely note Hatzie - The Mobil1 Synthetic 75W90 Diff lub I bought indeed does have some tiny print that states "Limited Slip Friction Modifier Included" (and also states safer for conventional and limited slip differentials)

I do have a G80 locker, so it it appears I'll be heading back to visit the ol pep boys yet again (for a refund) and ordering the ACDelco stuff from Summit, regardless of price. I haven't yet found anything other than ACDelco that doesn't have the LS additive blurb in small print. I think there's often confusion between diff oil "for LS axles" and diff oil "to which one adds an LS additive" - but if I'm reading the TSB correctly, G80 is a unique animal and should have no LS additive in it (to include not being an LS blend at purchase). As far as I can tell so far, only ACDelco, and maybe Lucas, are the only ones that aren't for LS rears or with LS additives. Pretty confusing. I'm tempted to wait a few more days to change my oil in case any more TSBs show up that tell me I'm missing the boat yet again... Ha. Thanks again for posting this info.

There are a bunch of different Mobil 1 synthetic 75W90 gear oils. I believe at least one of em doesn't have Limited Slip additive.

Supposedly I'm supposed to run 80W90 dinosaur squeezins in my front diff but I just used the Synthetic 75W90 front and rear. I doubt it's a big deal. It might be one of the reasons why I seem to be getting slightly better fuel mileage than when I drove it home from the shipper... Naah. I doubt it...

[GASoline71]

jocko and hatzie. There has been a lot of good info you two have shared. Thank you!

I am getting ready to do a full fluid drain and fill up on my '06 Silverado K2500 with a 6.0L, 4L80E, (unsure of what T-case I have) and both front and rear diffs. I had topped of the rear diff last year after i replaced the rear outer axle seals. But want to pull the cover and inspect the internals as I am now over 200,000 miles.

Gary