Let's start with the ring gear. The only difficult part about getting the ring gear on is making sure that the 10 bolt holes are aligned as you press the ring onto its perch. I would suggest using some sort of long bolt, maybe two of them and line them up so that when you seat the gear, the holes in the carrier line up with the holes in the gear. Like so:
But anyways, the first thing that you need to do is lightly sand the surface of the carrier that the ring gear will seat against and the back side of the ring where it seats against the carrier in order to insure a perfectly flat mating surface. I used a sanding stone to accomplish this
Next I placed the ring gear in a pot of hot water in order for it to expand slightly. I then pulled the ring gear out of the hot water (using thick rubber kitchen gloves) and placed it over the carrier while making sure that the bolt holes were lined up. It takes some force to press it over the carrier, but it doesn't need to be seated completely by hand. Instead, pull the gear into position by installing 5 of the 10 bolts. After the ring is completely seated, remove the 5 bolts that you just installed
The reason that I did not leave the bolts installed is because I wanted to give the water in the bolt holes time to dry so that nothing would rust over time.
Install the carrier bearings while you wait for the water to dry. Luckily, the carrier bearing installation was MUCH easier than the removal.
1. Start by heating the bearings in boiling water
2. I lubricated the bearing seat with some bike lube that I had around the house. I don't know how much it helped, but I figured that it couldn't hurt.
3. Then I pulled the bearings out of the water (using tongs and gloves) and placed them over the bearing seat (make sure they're on the right way)
4. Seat the bearing straight and pound it on using the bearing race and seal driver.
5. The bearing will eventually be seated flush with the top
of the carrier, but it needs to be seated further. The bearing driver can't get it any farther because the lip of the carrier actually sticks above the inner race about 1/8th of an inch when the bearing is fully seated, so I improvised. I adjusted the bearing separator so that the inner diameter of the separator rested on the inner bearing race, but not on the carrier lip, then I placed a large metal chisel over the center opening in the bearing separator to act as a surface to pound on and gave it a nice whack with a hammer.
in this picture you can see three concentric rings, the inner most ring is the carrier, the second ring is the inner race, and the third is the roller bearing cage.
Then I placed the chisel
Then I hit the middle of the chisel pretty hard with a hammer. If you tap it lightly then you just have to readjust the whole set up because it bounces off after you hit it, so just give it a whack. There shouldn't be any space between the bottom of the inner carrier bearing race and the carrier bearing seat when the bearing is fully seated.
Repeat this process for the other carrier bearing.
Next install the ring gear bolts. Install these bolts with thread locker and hand tighten all 10 of them, then torque them progressively in a star pattern. The torque progression should be 20 ft-lbs, then 40ft-lbs, 60ft-lbs, and finally 85ft-lbs. remember to torque in a star pattern. Also, I placed my metal pipe through the center of the carrier to hold it stationary as I torqued the bolts.
Next re-install the pinion gears and the side gears.
1. The first thing to look at is the traction loc set up which is the series of splined steel discs and the friction clutch plates.
There are two different stacking orders for the traction loc that I have seen. First is the set up that comes from ford. Which is: shim, friction disc, 2 steel splined discs, friction disc, 2 steel splined discs, friction disc, side gear.
The other is something that I found on one of the install websites that I found and the author says that he found it on the internet as an "upgraded" stacking order, but I can't say anything about the validity of this statement. The order is: shim, friction disc, 1 steel splined disc, friction disc, 1 steel splined disc, friction disc, 1 steel splined disc, friction disc, side gear.
You will notice that in the alternate order you use fewer splined steel discs and one more friction disc. My install kit did not come with new friction discs and they were very expensive to buy from ford, so I did not have the option of using 4 friction discs. If you buy a rebuild kit, you will still need to re-use one of the old friction discs to have 4 on each side gear. I don't know whether or not there are positives or negatives about either stacking order, but I stuck with the ford factory setup.
Another thing that I did not have in my installation kit is new traction loc shims, which determine how tightly the 4 gears mesh. I don’t know what difference the tightness makes, if someone does, feel free to chime in. Even if I did know what difference it makes, I didn't have the shims to adjust it, so I put it all back how it was.
When I pulled the side gears out, I found that one of them had a broken tooth, so I replaced it and it wasn't a huge deal.
2. After deciding which stacking order you would like, stack the traction loc assembly on the back of the side gears
If you have a rebuild kit that included new shims of different sizes, start with trying to install the thickest shim offered, which is usually about 0.045"
3. place the side gear assembly into the "bottom" of the carrier, with the tabs of the friction discs lined up to fall into the slots in the carrier. If you have kept track of it, install the side gears back into the sides that they came out of.
4. Place the other side gear into the "top" of the housing in the same way and hold it in place with your hand.
5. Install the pinion gears but MAKE SURE YOU HAVE THE SHIMS ON THE BACK SIDES OF THE PINION GEARS WHEN INSTALLING
Place the pinion gears directly opposite each other between the two side gears. To make sure they are lined up, look through the holes in the center of the pinion gears and sight that they are lined up.
Rotate the pinion gears into place.
Check that they are lined up by looking through the pinion shaft bore. If they are not, remove them, realign them, and rotate them back into place. If you sight the alignment before rotating them into place it can save you some time.
Because my install kit did not come with new shims or new friction discs, I reused the old friction discs and shims on the side gears. I called ford about getting new friction discs, but they were incredibly expensive and the parts department said that if the friction discs still had a decent amount of clutch pad remaining that it really wasn't necessary to replace them, so I didn't. Because I reused the old setup, I had no problems simply rotating the pinion gears in place with my hands. If I was going to do this again I probably would have just paid for the new friction discs, but c'est la vie. If you have the option (i.e. your install kit provided the shims), use the thickest shim offered on the side gears (typically .045"), and try to install the pinion gears. You may find that you cannot rotate the pinion gears in by hand, but that's okay. Place the gears opposite each other and lightly tap on the pinion gear with a punch and hammer to rotate them into place.
Don't hammer excessively, but don't give up with the first slight tap. If you find that you cannot get the pinion gears in place, drop down to the next smallest shim on the side gears and try again.
Re-install the S-spring. I had some difficulty with this step, but just be patient and it will eventually go in. The reason that installing the S-spring can be somewhat difficult is because the ring gear prevents you from getting the desired "angle of entry" if you will. As you upgrade to a taller gear ratio, the ring gear actually gets thicker, making the minimum angle of entry greater, if that makes any sense. Basically, you have to distort or compress the spring in order to get it to install and the thicker the ring gear, the more distortion or compression you need to get it in.
What I did was I used a pry bar leveraged against the ring gear to distort the "front edge" of the S-spring as a tapped the spring into place with a hammer.
This process is probably easier with two people, and the hardest part is getting the spring started. Remember which way the spring is supposed to be installed. I say this because I had to double check. It should end up looking like this:
next install the pinion bearing races into the differential housing. What I did was I placed the races into the bore and placed the old
bearing into the new
Then I used the bearing race and seal driver to hammer against the old bearing.
Outer pinion bearing race fully seated
I then repeated the process for the inner pinion bearing race. For me the outer pinion bearing race went in without issue, but the inner bearing took time and a whole lot of pounding. Again I lubricated the bearing bores, and again I don't know how much it helped, but it can't hurt.
Inner pinion bearing race:
lubricate the new
outer pinion bearing and place it in the race.
put the pinion oil seal in its place and drive it in with the seal driver. be careful not to damage the oil seal.
replace the axle oil seals. Apparently oil seal pullers are capable of getting these seals out, but either I'm not smart enough to use one or the seals are in way too tight to get out with a little hook on the end of a bar, so what I did was I rented an axle bearing puller and a slide hammer and pulled out the whole axle bearing and seal. Then I hammered the bearing back in place and replaced the seal.
Removing the bearing and seal:
Simply hammer the bearing back in with the race and seal drive, then do the same with the new oil seal.
Mock up installation
There are a few reasons that you will want to do mock installations.
First is because you want to practice torqueing the pinion nut. During final installations, the pinion nut torque sets the bearing pre-load and crushes the crush collar, but the problem is that when you crush the crush collar, you cannot back off the pinion nut to lessen bearing preload, should you over step the required measurement, because then you have over-crushed the crush collar. Therefore, I recommend installing the pinion nut and checking bearing preload once or twice as practice before you place the crush collar and make your final installations.
Second, the wear pattern is determined by the depth of the pinion head, which is set by placing a certain sized shim between the back side of the pinion head and the inner pinion bearing. But, the inner pinion bearing needs to be pressed on using an incredible amount of force, and if you go through the process of pressing on that bearing only to check the wear pattern and find that you need a different shim thickness then you are going to really frustrate yourself. To avoid this frustration, shave out the inner diameter of the old
pinion bearing using either a dremmel or a file so that the bearing can be easily slipped on and off of the pinion. So on with instructions.
I've been throwing around the term bearing preload a lot, so I guess now would be a good time for me to explain it if I haven't already. Bearing preload is simply the amount of torque that it takes to turn the pinion gear. You measure this by turning the pinion with a beam or dial style in-lb torque wrench and reading the output on the wrench.
Shave out the inner diameter of the old
inner pinion bearing so that it can be slipped on and off by hand. be sure you don't take off any of the thickness of the bearing, because that would effect your pinion depth, and then you're working with two variables, which is a mess.
you can see the scratched look on the inner walls of the bearing in the picture above.
Assemble the new pinion using the shim thickness that you calculated earlier (with the thickness of the old pinion head and shim) and the old, bored out inner pinion bearing. Lubricate the inner bearing and drop the assembly into the housing. Install the pinion flange and the pinion nut hand tight.
Now is where you can practice installing the pinion and pinion nut. You will not be able to use air tools when crushing the crush collar, so there's no point in doing it now. Just practice using your breaker bar and metal pipe. Install the pinion nut as shown in this video:
**Note: Because you are doing a mock-up installation without the crush collar, it will not take that huge amount of force shown to reach the required bearing preload**
Ford specifies 10-14in-lbs of preload if you are reusing the old bearings, and 20-28in-lbs of preload for new bearings
Use the in-lb torque wrench to measure bearing preload as shown above. Whenever I checked the bearing preload, I removed the metal pipe from the pinion flange because it would have made a significant difference in how much force it took to turn the pinion. It was somewhat of a pain to remove the bolts every time I wanted to check preload, but air tools made that less of a problem. The reason that it made such a significant difference is because of the length and weight of the pipe. Inertia would be the technical explanation, I think, but I'm not a doctor.
once the bearing preload is set, you can start setting the backlash.
This would probably be a good time to define backlash. Backlash is the measurement of how much space there is between teeth of the pinion and the teeth of the ring gear. When the ring and pinion are meshed together, there is still some play left in the mesh. You can see this by holding the pinion in one place and wiggling the ring gear back and forth. You will hear the teeth click together. In other words, only one side of the teeth are contacting at any one time, either the drive side, or the coasting side and say for example the drive side of the teeth is in contact, then the space between the coast side of the ring and pinion teeth is the backlash space. Backlash is probably the most important measurement in this whole install, because if the teeth are to tightly meshed, then they could heat up, expand, and seize while you are driving, if they are too loosely meshed, then you run the risk of breaking the teeth. So yeah, mildly important.
the backlash is determined by how far right and left the carrier sits in relationship to the pinion head. The closer that it sits to the pinion, the tighter the teeth mesh, the tighter the backlash, the smaller the backlash reading. Before we can start adjusting backlash, first you have to put the carrier in the housing. you want to start by gathering the new carrier bearings that came with the install kit (the carrier shims will have a different inner diameter than the ones that came from the factory so just find the ones with the same outer diameter) and coming up with a group of shims that is equal in total to the total shim thickness that you measured before. So in my case, the factory shims added to a total thickness of .539", therefore, I collected shims that were in total .539" thick or there about. For me, this was all of the shims in the install kit. Divide the shims up into two equal groups. Place the groups on the outside of the carrier bearing bores (I placed the thickest shims in the group on the inside so that as I was dropping the carrier in, I didn't run the risk of crushing or bending one of the very thin shims). Then, cover the carrier bearings with the races, and place the carrier into the bearing bores on the inside of the stacks of shims
Now it is time to measure the backlash. You need your dial indicator with the magnetic base for this. I could explain to you exactly how to set it up and run the test in words, but I'm thinking that would be a bit tedious so I'll briefly describe it and show pictures and a video.
1. First you have to set up the magnetic base of the dial indicator on the lip of the housing as shown below
2. The following video shows how to measure the backlash, but it isn't for the 8.8 differential in our mustangs, so don't follow the procedure for adjustment or the recommended specs for backlash, only notice how the dial indicator is set up and how he wiggles the ring gear to get a reading.
3. Ford recommends a backlash of between 0.008" and 0.012" of backlash for the 8.8 rear end, so if you are not within that range, you are going to need to make adjustments (I would be willing to be that everyone will need to make adjustments).
4. to adjust the backlash in the 8.8 rear end, you have to swap shims left and right to make the carrier sit further left and further right. Yes, this does mean that you need to lift the carrier out, swap shims side to side, and put the carrier back in. Be careful lifting the carrier out because the races and shims can fall into the bottom of the housing and get mixed up meaning you have to re-do your previous backlash measurement, so go slowly and do it right. To increase the backlash reading, you need to move the ring away from the pinion, which in the mustang is moving the ring towards the driver's side of the axle. Obviously it's the opposite to decrease the backlash. It takes mental math, patience, and practices to get the backlash within spec, so don't get frustrated. Remember that this is the most important measurement.
5. After swapping shims and re-installing the carrier, take a new backlash reading, and repeat the process until the proper backlash is achieved.
"Finally!" you might be saying, but not so fast, because you still need to check the wear pattern before you declare everything set for final installations. To check the wear pattern, even though you don't need to for setting the backlash, I think it's a good idea to have the carrier bearing end caps in place since you will be turning the gears.
To check the wear pattern, use the gear marking compound that came with your install kit, and brush a VERY SMALL AMOUNT of compound onto 4-5 ring gear teeth in 2 places on the ring gear. You really need very little marking compound. I realized that I used WAY too much after I had finished. After applying the compound, turn the ring and pinion past each other a couple of times in both directions until the pattern becomes visible.
What you want to accomplish isn't seeing how excess marking compound gets deposited on other teeth, but how the thin, almost dry layer of marking compound gets worn away by the gear contact. Look at the video below to get an idea what you are looking for in checking wear pattern and how much compound to use
you want to evaluate the dark spots among the yellow (or whatever color compound).
To figure out what the wear pattern that you have just established actually means, look at this website under the "checking the pattern" section
If you find that the wear pattern isn't correct and the pinion depth needs to be adjusted (which I did... twice), you need to pull out the carrier, pull out the pinion, remove the inner pinion bearing (that's why it's a good idea to have the old one bored out for easy removal), swap for a different shim depending on what you determined from your wear pattern, re-install the pinion, re-install the carrier, reset the backlash because it will have changed with the new pinion depth, then redo the wear pattern test. I know that that sounds like a colossal PITA but you get pretty efficient at it after the first time, and plus, it's really important to get it right.
Just remember **the backlash needs to be set correctly before determining the wear pattern**