I have been tracking down a horrible grinding noise on decel. I started to notice this noise after all the rear subframe work and rebuilding the driveshaft. Now that all of this was new and in good working order, the noise leads me to the rear differential. I started reading the manual and found that there was an easy test to check the total backlash of the diff. When I performed this check I got a .5 inch of backlash. The Service limit is .2 inches, sssooooo I have somehow obtained 2.5 times the amount of acceptable backlash. With this information and an angry tiger in my hatch on decal, I embarked on this next adventure of going through the rear differential. This particular rear is 3bolt LSD out of a 1990 AWD Talon.
When working on the rear, I find it easier to remove the whole subframe. Yes you can remove just the rear and axles, but I am going to drop the whole subframe. Start by draining the rear diff and catching all the fluid to examine for metal chunks. Support the car as high as possible on jack stands. Getting the car high is the key to being able to clear the gas tank once the subframe is down. Remove the tires, e-brake cable, and calipers. Attach the calipers to the shock via a zip tie or other material to prevent brake line damage.
Remove the exhaust and be careful not to scratch your expensive pieces of tubing.
Note: There are very few bolts that hold the subframe in, so you will want to support the diff via a floor jack and be prepared to balance the assembly with your free hand once it is loose.
Remove the lower shock absorber bolts.
Remove the 10mm brake line bolt that is easily accessible.
Do not forget about the 10mm bolt holding the brake line from the top. This bolt is not easily accessible and can be removed later, BUT you must remember this bolt or your subframe will be dangling by your e-brake cable.
Make mating marks on the drive shaft and the pinion flange. Then remove the four bolts and separate the driveshaft from the pinion flange.
This is a good time to test your LSD if you have one. Slowly rotate one tire in a forward motion and the tire on the opposite side should move in the same direction. If it does that is one test down, If it does not, then that starts to point a finger at the LSD. This test can also be referenced in the FSM. Also in this picture, you can see where I made the marks to measure the backlash of the rear diff.
The bolt on the right in this next picture should be removed first. There is one of these on each side.
Now there are only four bolts left holding the subframe on. IF YOU HAVE NOT SUPPORTED THE SUBFRAME YOU NEED TO DO IT NOW. The nut on the left in the picture above holds the front portion of the subframe on. There is also one of these on each side.
The last two nuts are for the differential support.
Once these are out, your subframe will be free. You will now need to remember about those upper e-brake cable bolts if you did not remove them before. Also, be aware that the sway bar will catch the drive shaft!!!!! The trick is to lower the subframe just enough to clear the mounting bolts, then slide it towards the gas tank. Then, while balancing the subframe with one hand, push the driveshaft towards the transfer case to clear the rear sway bar. After the driveshaft is clear, you just have to wiggle the subframe and pull it out on your rolling jack. This is of course easier said than done.
Now removing the diff is quite simple. Remove the 6 axle nuts (3 on each side for this 3 bolt). To separate the axle from the cup, use a metallic (metal) hammer. TAP on the cup while pulling on the axle and the shock from the hammer will make them separate. Now that you have both axles separated, you can remove the two side bolts holding the diff in. The bolt is already taken out in this picture, but gives a reference of how to find it.
This access hole is between the lower and upper control arms.
Now remove the two upper bolts holding the diff in.
Now the differential will be loose. If it is still on the jack, just roll it out. Be sure to support the rest of the subframe when removing the diff.
Now you will need to separate the axles. It may have been smarter to do this with the diff still bolted up to the subframe, but as you can see I did not. Get your favorite pry bar and place it as shown in the next picture. Apply some pressure to avoid slippage and give the pry bar a good whack with your free hand. This will pop the retaining clip loose so that you can remove the axles.
Take your axels and store them to avoid damage. Tape the splines as a precautionary measure with masking tape.
Now the fun begins 
Start by placing the diff inside of your vice. This is not the most conventional way as they do make a stand to hold differentials, but not everyone is going to have that special tool, so the next best thing is a vice with some cardboard spacers to prevent case damage. Also, make sure if you use the vice that you have it locked down nice and tight. Any time you are using a hammer, be sure to check the diff every few whacks. IF YOU DO NOT THE DIFF COULD FALL OUT OF THE VISE!!!!! Ask me how I know 
Start by removing the 14mm outer case bolts.
The cover will be sealed on and will not just lift off. Grab your hammer and a punch. There are two holes that go through the diff housing where you can insert the punch to push on the back side of the diff cover. This makes easy work of removing the cover.
You will end up with something like this. YUM!!!!
After the cover is off, you will need to start a battery of test. The first one I chose was drive gear run out. The Service Limit for run out on the Ring Gear is .002 of an inch. You will need a magnetic base of some kind, a dial gauge good to at least a .001 and some patience. Clean the surface where you plan to make your measurement to insure accuracy. Setup the dial gauge so that it is as close as possible to 90* of the part you are measuring. On my gear there was a shoulder that was perfect for the task.
When working on the rear, I find it easier to remove the whole subframe. Yes you can remove just the rear and axles, but I am going to drop the whole subframe. Start by draining the rear diff and catching all the fluid to examine for metal chunks. Support the car as high as possible on jack stands. Getting the car high is the key to being able to clear the gas tank once the subframe is down. Remove the tires, e-brake cable, and calipers. Attach the calipers to the shock via a zip tie or other material to prevent brake line damage.
Remove the exhaust and be careful not to scratch your expensive pieces of tubing.
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Note: There are very few bolts that hold the subframe in, so you will want to support the diff via a floor jack and be prepared to balance the assembly with your free hand once it is loose.
Remove the lower shock absorber bolts.
You must be logged in to view this image or video.
Remove the 10mm brake line bolt that is easily accessible.
You must be logged in to view this image or video.
Do not forget about the 10mm bolt holding the brake line from the top. This bolt is not easily accessible and can be removed later, BUT you must remember this bolt or your subframe will be dangling by your e-brake cable.
You must be logged in to view this image or video.
Make mating marks on the drive shaft and the pinion flange. Then remove the four bolts and separate the driveshaft from the pinion flange.
You must be logged in to view this image or video.
This is a good time to test your LSD if you have one. Slowly rotate one tire in a forward motion and the tire on the opposite side should move in the same direction. If it does that is one test down, If it does not, then that starts to point a finger at the LSD. This test can also be referenced in the FSM. Also in this picture, you can see where I made the marks to measure the backlash of the rear diff.
The bolt on the right in this next picture should be removed first. There is one of these on each side.
You must be logged in to view this image or video.
Now there are only four bolts left holding the subframe on. IF YOU HAVE NOT SUPPORTED THE SUBFRAME YOU NEED TO DO IT NOW. The nut on the left in the picture above holds the front portion of the subframe on. There is also one of these on each side.
The last two nuts are for the differential support.
You must be logged in to view this image or video.
Once these are out, your subframe will be free. You will now need to remember about those upper e-brake cable bolts if you did not remove them before. Also, be aware that the sway bar will catch the drive shaft!!!!! The trick is to lower the subframe just enough to clear the mounting bolts, then slide it towards the gas tank. Then, while balancing the subframe with one hand, push the driveshaft towards the transfer case to clear the rear sway bar. After the driveshaft is clear, you just have to wiggle the subframe and pull it out on your rolling jack. This is of course easier said than done.
Now removing the diff is quite simple. Remove the 6 axle nuts (3 on each side for this 3 bolt). To separate the axle from the cup, use a metallic (metal) hammer. TAP on the cup while pulling on the axle and the shock from the hammer will make them separate. Now that you have both axles separated, you can remove the two side bolts holding the diff in. The bolt is already taken out in this picture, but gives a reference of how to find it.
You must be logged in to view this image or video.
This access hole is between the lower and upper control arms.
Now remove the two upper bolts holding the diff in.
You must be logged in to view this image or video.
Now the differential will be loose. If it is still on the jack, just roll it out. Be sure to support the rest of the subframe when removing the diff.
You must be logged in to view this image or video.
Now you will need to separate the axles. It may have been smarter to do this with the diff still bolted up to the subframe, but as you can see I did not. Get your favorite pry bar and place it as shown in the next picture. Apply some pressure to avoid slippage and give the pry bar a good whack with your free hand. This will pop the retaining clip loose so that you can remove the axles.
You must be logged in to view this image or video.
You must be logged in to view this image or video.
Take your axels and store them to avoid damage. Tape the splines as a precautionary measure with masking tape.
You must be logged in to view this image or video.
Now the fun begins 
Start by placing the diff inside of your vice. This is not the most conventional way as they do make a stand to hold differentials, but not everyone is going to have that special tool, so the next best thing is a vice with some cardboard spacers to prevent case damage. Also, make sure if you use the vice that you have it locked down nice and tight. Any time you are using a hammer, be sure to check the diff every few whacks. IF YOU DO NOT THE DIFF COULD FALL OUT OF THE VISE!!!!! Ask me how I know 
You must be logged in to view this image or video.
Start by removing the 14mm outer case bolts.
You must be logged in to view this image or video.
The cover will be sealed on and will not just lift off. Grab your hammer and a punch. There are two holes that go through the diff housing where you can insert the punch to push on the back side of the diff cover. This makes easy work of removing the cover.
You must be logged in to view this image or video.
You will end up with something like this. YUM!!!!
You must be logged in to view this image or video.
You must be logged in to view this image or video.
After the cover is off, you will need to start a battery of test. The first one I chose was drive gear run out. The Service Limit for run out on the Ring Gear is .002 of an inch. You will need a magnetic base of some kind, a dial gauge good to at least a .001 and some patience. Clean the surface where you plan to make your measurement to insure accuracy. Setup the dial gauge so that it is as close as possible to 90* of the part you are measuring. On my gear there was a shoulder that was perfect for the task.
You must be logged in to view this image or video.
You must be logged in to view this image or video.
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