Coastie Kyle
Full Access Member
Whats up, my name is Kyle. Im writing this "how to" guide for a couple of friends who wanted to know how I did my Diffs. Also for the guys who dont have a lot of "technical skills" (like my-self) when it comes to sevicing and adding mods to your vehicle. I only recently (a year or so) started seviceing and working on my own truck (a Ford Explorer), so its not that difficult.
To start, you should know the manual says to change your diff fluid every 60,000 miles or two years. The front diff holds about 1.5 qts of fluid (mine), book says use 80W-90. And the rear is a little more than 3 (also mine), book says use 75W-90 synthetic. The time frame for this project should be no more than two (2) beers, even for a newb.
Things you will need....
1. Drain pan
2. Gear oil, I used Moble1 synthetic in the rear, and Valvoline synthetic blend in the front.
3. 3/8 ratchet
4. 13mm and 15mm sockets (front diff)
5. A pump of some type (front diff) Autozone has a good one 10$
6. Some shop rags
7. Two beers of your choice
8. Posi-trac gear additive (limited slip diffs)
To make things easy, I also used:
1. Drive up ramps
2. A 5X3 drip pan (no mess)
3. Latex gloves (gear oil is not good for you)
4. floor creeper
Procedure:
1. Locate your drain and fill bolts. They are on the same side of the diff.
2. Remove the fill bolt (top obviously) useing the 15mm socket for the front, or just the 3/8 ratchet drive for the rear.
3. Next your going to move your drain pan in position, Id say a little to the side because the fluid is gonna have some momentum. Remove the drain bolt with the 13mm socket for the front diff, and again just the 3/8 drive for the rear diff. Let the fluid drip for a little while after it done and clean the bolt. The bolt (at least mine) had a magnet on it so if there is metal flakes, clean them off.
4. Re-install drain bolt, and start filling the diff up. For the front, this is where you will need a pump of some kind. There isnt enough room to get the bottle of gear oil high enough to squirt in. For the rear, you might need to add a tube of posi-trac gear oil additive, its about a 7oz tube for 5$. I dont know about all the Tahoes and Yukons, but a GMC tech told me mine needed it. You can call and ask if in doubt.
5. The book says to fill the pumpkin (differential gear houseing) up to 5/8 to 1 and 5/8 below the hole. Since it is really hard to measure this gap, I was told by my mechanic friend to fill it up till you feel fluid under the rim with your pinky.
6. Re-install fill bolt, and your set!
Since your down there, you mine as well do both, and maybe even the transfer case. I hope this helps all you guys if you had questions or what ever the case. There was NO squeeling or grinding noises when I was done, everything was fine. This forum seems to be lacking helpful "how to's", so I guess Ill start some. You expereienced guys have anything helpful to add, feel free!
To start, you should know the manual says to change your diff fluid every 60,000 miles or two years. The front diff holds about 1.5 qts of fluid (mine), book says use 80W-90. And the rear is a little more than 3 (also mine), book says use 75W-90 synthetic. The time frame for this project should be no more than two (2) beers, even for a newb.
Things you will need....
1. Drain pan
2. Gear oil, I used Moble1 synthetic in the rear, and Valvoline synthetic blend in the front.
3. 3/8 ratchet
4. 13mm and 15mm sockets (front diff)
5. A pump of some type (front diff) Autozone has a good one 10$
6. Some shop rags
7. Two beers of your choice
8. Posi-trac gear additive (limited slip diffs)
To make things easy, I also used:
1. Drive up ramps
2. A 5X3 drip pan (no mess)
3. Latex gloves (gear oil is not good for you)
4. floor creeper
Procedure:
1. Locate your drain and fill bolts. They are on the same side of the diff.
2. Remove the fill bolt (top obviously) useing the 15mm socket for the front, or just the 3/8 ratchet drive for the rear.
3. Next your going to move your drain pan in position, Id say a little to the side because the fluid is gonna have some momentum. Remove the drain bolt with the 13mm socket for the front diff, and again just the 3/8 drive for the rear diff. Let the fluid drip for a little while after it done and clean the bolt. The bolt (at least mine) had a magnet on it so if there is metal flakes, clean them off.
4. Re-install drain bolt, and start filling the diff up. For the front, this is where you will need a pump of some kind. There isnt enough room to get the bottle of gear oil high enough to squirt in. For the rear, you might need to add a tube of posi-trac gear oil additive, its about a 7oz tube for 5$. I dont know about all the Tahoes and Yukons, but a GMC tech told me mine needed it. You can call and ask if in doubt.
5. The book says to fill the pumpkin (differential gear houseing) up to 5/8 to 1 and 5/8 below the hole. Since it is really hard to measure this gap, I was told by my mechanic friend to fill it up till you feel fluid under the rim with your pinky.
6. Re-install fill bolt, and your set!
Since your down there, you mine as well do both, and maybe even the transfer case. I hope this helps all you guys if you had questions or what ever the case. There was NO squeeling or grinding noises when I was done, everything was fine. This forum seems to be lacking helpful "how to's", so I guess Ill start some. You expereienced guys have anything helpful to add, feel free!
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