June 14, 2006
Unfortunately for you, the passenger side is more involved in replacing a seal than the driver side is. However, it is nothing to be scared of. Since I am in a tutorial kind of mood, I will try to spell it out as best as I can for you.
The GM 8.25 IFS Diff utilizes an axle disconnect that allows the ring gear to not have to turn unless 4wd is engaged. It does this by separating the left from right axle shafts inside the differential housing. It accomplishes this with the acutuator, engagement gear and stub shaft.
Look at the following pictures to try and get a better idea:
This is the engagement gear with the support it sits inside (on the left) and the axle stub shaft on the right. The stub shaft splines into the side gear on the passenger side.
FYI, on the driver side, the output shaft is splined into the side gear on one end of the shaft, and the flange on the other. Thats why it is so much easier to swap the seal on the driver side, because you just pull tthe shaft out, replace the seal and push the shaft back in.
Contrary to popular belief, there are NO c-clips inside this diff.
Anyway, back to the topic at hand. So the stub shaft is splined into the side gear on the passenger side of the carrier, right? This is the section where the axle disconnect comes into play.
This is the passenger side housing. Notice the gear on the end of the axle shaft (the protrusion is the end of the axle shaft. The other end is the passenger side flange). Also, notice the open hole to the left of the picture. This is where the actuator motor sits, and the piston inside the motor comes out the bottom (top in the pic) of that hole.
So this is how it works,
When you select 4wd from your switch panel, a signal is sent to the Transfer Case Module inside the cab. This signal is then deciphered into what gear (2 hi, 4 hi or 4 lo) selection you are wishing to make and is then sent to the Transfer Case Encoder Motor on the transfer case housing itself. This motor is what shifts the tc case gears. A sensor inside the Tcase sends a signal to the front differntial housing, more specifically to the actuator motor . The signal either extends or collapses the piston inside the motor.
The engagement gear ( refer to picture above)sits inside of the support which rests on a spring inside the case (notice the round shaft coming out of the bottom of the support? The spring slides over that) . When in 2wd ( the actuator piston collapsed) the spring forces the engagment gear away/ off from the stub shaft (refer to picture above). This means that the engagment gear is splined all the way into the gear on the end of the passenger side housing (refer to 2nd picture).
When the pistion extends, it pushes down (to the left when the diff is in the truck though) on the engagement gear, compresses the spring, and allows for the engagement gear to touch both the stub shaft and the passenger side gear. Make sense so far?? Hopefully so.
Now with the Transfer Case turning the front shaft, the pinion gear is turned, which turns the ring gear, which turns the side gears - thus turning the axle shafts.
It just occured to me, I have yet to cover your topic
, so I apologize.
I told you all of that, to tell you how to replace the seal.
The passenger side housing that attaches the the main housing, keeps that engagement gear spring from coming flying out. This is what makes the passenger side more involved, you have to put it back together and make sure the spring is in the right place- not hard at all, just wont work if you dont.
So, here we go:
1) Remove the cv flange from the passenger output flange via the 6 bolts or so. Slide the two flanges apart. Remove the actuator wiring from the main harness.
2) There are around 5 ( I think ) bolts holding the passenger side housing onto the main housing. Simply trace the housing back ( the one in the second picture) to where it bolts up, and remove the bolts.
3) You are going to have to remove the housing from its mount to the frame. This is done with the 2 bolts on the far right side of the housing. Remove those.
4) Now simply pull the passenger side housing away from the main housing, making note of how the pieces sit inside. If you screw up, I can easily tell you where they go- no big deal.
Note: Odds are the engagement gear will fall out, bringing the support with it. The spring will shoot out, just keep an eye on it. The stub shaft will stay in place though.
5) Now take the pass housing ( will look exactly like the one in the 2nd picture) and take it to your work area. Notice the dimple in the end of the shaft? Take a punch and a hammer, and push the shaft out of that gear.
6) Flip the housing over, remove the seal with a screwdriver, clean the area with brake parts cleaner , and replace the seal.
7) Put some gear oil on the ribs of the seal to prevent a dry contact. Push the axle shaft back in, and align the splines with the gear you just pushed it out of. You will kinda have to hammer them back together - dont worry bout the amount of play you find.
Ok, now here is where a 2nd pair of hands come in handy. Take the spring and put it back into its hole ( youll see it when your there). Place the engagement gear along with the support back in its place ( the support can only go 1 place too- and thats over the spring). Now while holding those things together, place the housing back over and tighten the bolts down.
9) Reconnect the actuator wiring, and bolt the two flanges up together again.
Sorry for the novel, but I have nothing to do tonight.
Hope this helps, let me know if you need anything clarified etc as I have not yet read back through this to check for typos/ weird wording.