Front Transfer case

Voymom

Well-Known Member
Does anyone have a picture? And where is it located? I can do my rear diff fluid, but I don't want to touch the transfer case as I don't know ANYTHING about it, but I would still like to learn at least where it is located on the Voy, and exactly what it does. I plan on taking the truck to a trusted mechanic to do this part of our maintenance, unless of course it isn't that difficult and the hubby could do it, but I won't be going near it until I can learn more about it.

What is involved when servicing the transfer case? Drain old fluid and add more? Would I need any new gaskets(is there a gasket)? I will be pulling out my manual later on in the day, and reading up on it there as well.

Also, didn't see anything in the articles/how-to. Would anyone have a video? I guess I could check youtube too.
 

strat81

Well-Known Member
Voymom said:
Does anyone have a picture? And where is it located? I can do my rear diff fluid, but I don't want to touch the transfer case as I don't know ANYTHING about it, but I would still like to learn at least where it is located on the Voy, and exactly what it does. I plan on taking the truck to a trusted mechanic to do this part of our maintenance, unless of course it isn't that difficult and the hubby could do it, but I won't be going near it until I can learn more about it.

What is involved when servicing the transfer case? Drain old fluid and add more? Would I need any new gaskets(is there a gasket)? I will be pulling out my manual later on in the day, and reading up on it there as well.

Also, didn't see anything in the articles/how-to. Would anyone have a video? I guess I could check youtube too.
There is a front differential and a transfer case. They are two separate parts, both part of 4WD/AWD system.

The transfer case is what turns your normally RWD/2WD vehicle into 4WD. It sends power to the front wheels.

The differential distributes that power to the front wheels and allows for different wheel speeds, particularly in turns.

Replace the fluid in both of them is easy. Both have a drain plug and a fill plug with no gaskets or filters to worry about.

The front differental plugs can be accessed by removing the front driver's side wheel. They'll be "on the engine" near where the axle enters the "engine". I say "engine" because the front differential lives under/near the engine and it appears to be the same part. Loosen the fill plug (top plug) first, then remove the drain plug. Fill with synthetic 75W-90 gear lube such as Mobil 1. It should take 1-2 quarts. Fill until it overflows.

The transfer case is accessed from underneath the vehicle. It is about midway beneath the vehicle, close to the center, gray, maybe twice the size of a typical box of tissues with driveshafts coming in/out of it. There are two plugs which can be removed with a 3/8" hex bit (available at any auto parts store). Remove the fill plug first, then the drain plug. Fill with GM Auto Trak II fluid only! Available at any GM dealer, should cost about $9 a quart. You'll need two quarts. Add the two quarts until it overflows. If it doesn't overflow, it's OK, it's probably the angle of the vehicle. Stick a finger in there and make sure the level is high.

Getting the fluid in the transfer case can be tricky since you don't have the space to pour the bottle. I used a piece of vinyl hose, other people have used inexpensive pumps (also available at a parts store).

Both jobs are very easy. If you can change your oil, you can change your front differential fluid and transfer case fluid.
 

C-ya

Well-Known Member
I'll plug MAY03LT's vids on Youtube. He explains everything nicely. I will be doing front, rear and xfer case in the next month or so.

[video=youtube;qST91kDjTIE]https://www.youtube.com/watch?v=qST91kDjTIE[/video]

[video=youtube;qcjiWgNWD3Q]https://www.youtube.com/watch?v=qcjiWgNWD3Q[/video]
 
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Voymom

Voymom

Well-Known Member
Thank you so much! I can definitely change the oil, so I should be able to save a few bucks doing all 3 myself.
 
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Voymom

Voymom

Well-Known Member
the roadie said:
Just whipped this up. Should have done it years ago.

Thanks Roadie!!! This will help bunches!
 

WarGawd

Well-Known Member
C-ya said:
I'll plug MAY03LT's vids on Youtube. He explains everything nicely. I will be doing front, rear and xfer case in the next month or so
Scooped...I was gonna point OP in that direction as soon as I saw the thread title

the roadie said:
Just whipped this up. Should have done it years ago.
BEAUTY! Sometimes it's hard to know exactly where the reference points are in a video...this will help a lot as I do mine (following some more questions in my Series :biggrin:)
 

meerschm

Well-Known Member
I picked up two quarts of AutoTrak at the local chevy dealer on the way home, came to $18.80 (they said they charge like $30 a quart for the 75w90 diff fluid, so I will shop around.)

any other thing to look for in differential fluid? I have the limited slip differential, would the same fluid front and back work, or should I look for fluid with an additive or marked for the limited slip for the back and none for the front?

also related is: http://gmtnation.com/f79/drivetrain-fluids-specifications-197/
 

McGMT

Well-Known Member
meerschm said:
I picked up two quarts of AutoTrak at the local chevy dealer on the way home, came to $18.80 (they said they charge like $30 a quart for the 75w90 diff fluid, so I will shop around.)

any other thing to look for in differential fluid? I have the limited slip differential, would the same fluid front and back work, or should I look for fluid with an additive or marked for the limited slip for the back and none for the front?

also related is: http://gmtnation.com/f79/drivetrain-fluids-specifications-197/
If you do have the LS out back your gonna have to put a bottle of modifier in it with the 75w90... that is correct. But just straight 75w90 in the front...
 

strat81

Well-Known Member
McGMT said:
If you do have the LS out back your gonna have to put a bottle of modifier in it with the 75w90... that is correct. But just straight 75w90 in the front...
Not necessarily. Mobil 1 LS and Valvoline Synpower both have the additive that eliminates chatter in the rear end. The GM "grape juice" is not necessary, at least for those of us with the G80. Not sure about the SS guys.
 

Lima Tango

Well-Known Member
What size tube will fit in the fill hole? 3/8" outside diameter? 1/2"? My 18oz syringe tool for this purpose has a pretty big tube and I am not sure if it will fit into the fill hole. I will be getting under there this weekend but since I am 30 minutes away from the nearest parts store or lowe's I would prefer to have what I need on hand.
 

tblazerdude

Well-Known Member
For t-case : It matters more if it will fit on the bottle of auto-trak. Take the bottle with you. Find a bottle at the store like the one you bought. You have to squeeze the bottle to get all the fluid out. (Hint; the cap on my 75w90 fit on the bottle of autotrak and I used the same tube) You need a tight connection on the bottle end. The other end would then be irrelevant since the fill hole on the t-case is much larger (1/2'') then the tip of the oil bottle. Find the hose that will work with the bottle. I have used a pump for the t-case, and that wasted almost 1/2 quart of autotrak> (Buy three if you're prone to spills, the capacity is 2.0 qt)

I found the front diff easier, more room to move the bottle around, big fill hole to get the hose in, etc.

I suggest (if this is the first front diff change) to heat up the fill plug before removing. It has tight, thin, threads and many become seized to the housing.
 
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Voymom

Voymom

Well-Known Member
I'm getting slightly confused lol I have the G80, do I still use the Mobile 1 full syn 75w90? And Autotrak II for T-case? Now I can put the mobile 1 full syn 75w90 in the front diff too correct? I just read some where that the front diff fluid is completely different weight than the rear diff....wish I could find that damn link but I just cleared out history and cookies. BLAH!
 

tblazerdude

Well-Known Member
No front diff and rear diff are the same fluid. The popular Mobil 1 75w90LS goes in both differentials, G80 on our trucks makes no difference here. GM actually states that only limited-slip (you have a locker, not limited slip) requires the special additive.

TO RECAP:

you need 5 bottles of 75w90 to do front and rear differential fluid changes. You can use 4 if you don't spill any of the fluid.

you need 3 bottles of auto-trak II (GM only) if you use a pump. You can use 2 bottles if you don't spill/waste any of the fluid.
 

MAY03LT

Founding Member
Lifetime VIP Supporter
C-ya said:
I'll plug MAY03LT's vids on Youtube. He explains everything nicely. I will be doing front, rear and xfer case in the next month or so.
Thanks! I've got a vid coming up for the rear diffs that not only shows both versions (with and without drain plug) but also shows a much better transfer pump that is more commonly available then the one shown in the front/t-case vids. Stay tuned!

Voymom said:
I can definitely change the oil, so I should be able to save a few bucks doing all 3 myself.
As shown in the vid, the front diff check/fill plug can be a real beeotch even with a 2' ratchet. Be prepared for war!!!!!:wootwoot:
 
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Voymom

Voymom

Well-Known Member
tblazerdude said:
No front diff and rear diff are the same fluid. The popular Mobil 1 75w90LS goes in both differentials, G80 on our trucks makes no difference here. GM actually states that only limited-slip (you have a locker, not limited slip) requires the special additive.

TO RECAP:

you need 5 bottles of 75w90 to do front and rear differential fluid changes. You can use 4 if you don't spill any of the fluid.

you need 3 bottles of auto-trak II (GM only) if you use a pump. You can use 2 bottles if you don't spill/waste any of the fluid.
I knew I had the locker and not the limited slip. I think I was confused because the mobile 1 fluid was mentioned as mobile LS which either means Limited slip or Less stuff lol and since I don't have limited slip, and was told to use 75w90LS....it was just confusing lol

I will just stick to the Mobile 1 full syn 75w90 and Autotrak II. As far as not spilling any....I can't make any promises so I think I will just stick with the 8 bottles total. I'm going to try to find a pump to get the fluid in before I attempt it.

ETA-After reading the other posts here I remembered the article which stated I needed the additive, not a different fluid up front. I got confused trying to type and yell at kids lmao
 

strat81

Well-Known Member
Lima Tango said:
What size tube will fit in the fill hole? 3/8" outside diameter? 1/2"? My 18oz syringe tool for this purpose has a pretty big tube and I am not sure if it will fit into the fill hole. I will be getting under there this weekend but since I am 30 minutes away from the nearest parts store or lowe's I would prefer to have what I need on hand.
The tubing I use is 5/8"OD x 1/2"ID. Any decent hardware store should have it.
 
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Voymom

Voymom

Well-Known Member
MAY03LT said:
Thanks! I've got a vid coming up for the rear diffs that not only shows both versions (with and without drain plug) but also shows a much better transfer pump that is more commonly available then the one shown in the front/t-case vids. Stay tuned!



As shown in the vid, the front diff check/fill plug can be a real beeotch even with a 2' ratchet. Be prepared for war!!!!!:wootwoot:
May I seen that! I will give it hell until I bloody my knuckles, and then I will pass the torch over to the hubby....


That's if the hubby lets me even do it lol So far the only thing I have been "Allowed" to do on Phantom is a bath and the seafoam. But yet he(hubby) is the one who put the crappy fuel additive in which almost killed the truck :raspberry:
 

Phantom

Well-Known Member
Ok Ok. Now guys, at my work I have mobile one gear oil and we have it by the industrial 55 gal drums. We have all kinds of weight. I know we have the 75/90. Now when telling my lovely fiance that i could get it from work, we were looking at the bottles of the mobile one 75/90 at like 13.99. She told me that if it didnt come in that bottle she didnt want it.
So can somebody tell her it will be ok to get it from my work. I'm working tomorrow and I can take a pic of the label and post it for you guys to see. I just think that getting it from work and saving 90 bucks is a sweet thing to do.:thumbsup:
 
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Voymom

Voymom

Well-Known Member
Phantom said:
Ok Ok. Now guys, at my work I have mobile one gear oil and we have it by the industrial 55 gal drums. We have all kinds of weight. I know we have the 75/90. Now when telling my lovely fiance that i could get it from work, we were looking at the bottles of the mobile one 75/90 at like 13.99. She told me that if it didnt come in that bottle she didnt want it.
So can somebody tell her it will be ok to get it from my work. I'm working tomorrow and I can take a pic of the label and post it for you guys to see. I just think that getting it from work and saving 90 bucks is a sweet thing to do.:thumbsup:
Until we stick it in the truck, hear grinding, and smell french fries. You will go into work and ask so and so and find out it's freaking cooking oil from damn McDonalds! :no: :no:

On the other hand.....go for it. You kill Phantom, your getting me a PINK freaking SS that YOU will HAVE to drive to work in :biggrin: :raspberry:
 

tblazerdude

Well-Known Member
As far as I know, all Mobil 1 75w90 has the "LS" Some people refer to it as either/or since on the bottom of the front sticker has the little LS in black letters. This means limited-slip.

On their website they list no other kinds.

Mobil 1 Synthetic Gear Lube LS 75W-90

View attachment 22785

Side fact: All 75w90 oil is considered synthetic. The "dino" oil equivalent is 80w90. 75w90 was not a natural oil weight until synthetics came along. In order to be less viscous all 75w90 weight oil must have synthetic properties. I can not claim however, that all 75w90's are fully (100%) synthetic. Mobil 1 does claim to be, whereas, the walmart brand 75w90 is more of a synthetic blend. I have used both. Walmart is a lot cheaper. Mobil 1 75w90 here is $11.99/Qt. Walmart 75w90 is $8.00.

View attachment 22786
 

Attachments

meerschm

Well-Known Member
Phantom said:
Ok Ok. Now guys, at my work I have mobile one gear oil and we have it by the industrial 55 gal drums. We have all kinds of weight. I know we have the 75/90. Now when telling my lovely fiance that i could get it from work, we were looking at the bottles of the mobile one 75/90 at like 13.99. She told me that if it didnt come in that bottle she didnt want it.
So can somebody tell her it will be ok to get it from my work. I'm working tomorrow and I can take a pic of the label and post it for you guys to see. I just think that getting it from work and saving 90 bucks is a sweet thing to do.:thumbsup:
four times 14 is more like $56
 

meerschm

Well-Known Member
I checked my folder and my transfer case and f&r differential fluids were changed in early 10, at 124000 by a local GMC dealer. I'm not quite to 150k, so might wait, but then again, I think the earlier one was the first time it was done, so might just wait for the next oil change, probably in the spring. my indicated oil life is at 70%, and i used Wal Mart full synthetic, so no hurry
 

RedEnvoyDenali

Well-Known Member
tblazerdude said:
As far as I know, all Mobil 1 75w90 has the "LS" Some people refer to it as either/or since on the bottom of the front sticker has the little LS in black letters. This means limited-slip.

On their website they list no other kinds.

Mobil 1 Synthetic Gear Lube LS 75W-90

View attachment 9226

Side fact: All 75w90 oil is considered synthetic. The "dino" oil equivalent is 80w90. 75w90 was not a natural oil weight until synthetics came along. In order to be less viscous all 75w90 weight oil must have synthetic properties. I can not claim however, that all 75w90's are fully (100%) synthetic. Mobil 1 does claim to be, whereas, the walmart brand 75w90 is more of a synthetic blend. I have used both. Walmart is a lot cheaper. Mobil 1 75w90 here is $11.99/Qt. Walmart 75w90 is $8.00.

View attachment 9227
If you find a pump like this (Harbour Freight for a very few $) it will screw onto the bottles above and you can just pump the fluid in, no spills no mess. This pump is for putting oil in the lower end of an outboard engine, but you don't need the screw fitting on the end of the tube.

Amazon.com: Lumax LX-1348 White Marine Lower Unit Flush and Fill Pump: Everything Else

Sta-Lube Gear Fluid Oil Pump

This makes it easy and clean and save it when you need to do it again. :thumbsup:
 

MAY03LT

Founding Member
Lifetime VIP Supporter
Phantom said:
So can somebody tell her it will be ok to get it from my work. I'm working tomorrow and I can take a pic of the label and post it for you guys to see.
If it was legit I would use it:yes:
 

Wooluf1952

Well-Known Member
According to the 2003 owners manual:

Rear diff = 4 pints
Front diff = 2.6 pints
T-case = 2 quarts (The Auto-Trak II comes in one liter bottles.)

So, three (3) quarts of 75w-90 should be plenty. Buy an extra if you feel more comfortable. You can return it if you don't need it or save it for next time.
 

AbsoluteZero

Well-Known Member
If you are unfortunate and have the underbody shield package access to the transfer case drain plug is limited without removing a shield. On my 03 Envoy it's RPO ZM5.
It looked to be a PIA to remove the shield so I took out the front bolts and was able to pull it down a few inches. I made a V-trough from heavy duty cardboard, let the fluid drain into it and into a catch-can.
 

HARDTRAILZ

Moderator
Phantom said:
Ok Ok. Now guys, at my work I have mobile one gear oil and we have it by the industrial 55 gal drums. We have all kinds of weight. I know we have the 75/90. Now when telling my lovely fiance that i could get it from work, we were looking at the bottles of the mobile one 75/90 at like 13.99. She told me that if it didnt come in that bottle she didnt want it.
So can somebody tell her it will be ok to get it from my work. I'm working tomorrow and I can take a pic of the label and post it for you guys to see. I just think that getting it from work and saving 90 bucks is a sweet thing to do.:thumbsup:
It is fine. Send me some and I will run it. I need to change my rear diff fluid anyway.


AbsoluteZero said:
If you are unfortunate and have the underbody shield package access to the transfer case drain plug is limited without removing a shield.
I think you mean FORTUNATE to have one. Any protection underneath is good.
 

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