Step 3: Reassembly
Now for the fun part. Getting all back together. Take the LSD unit from the Rx-7 and attach the ring gear from the Kia Sportage to it. Reuse the Kia's ring gear bolts. Ring gear bolts will need to be torqued down to
51~61 ft-lbs (75~85 N/m).
From here ensure the bearings and races are attached to the LSD and insert it into the Kia Sportage 3rd member casing. Then place the adjust screws back into their respective sides. Hold everything down will you put the bearing caps back on in the same places they came from. You probably will find yourself having to play around with everything to get it to line up and actually have the bolt start threading. Just have patience and take your time. Once you do get all four bolts threaded, you can bring the heads down but do not tighten beyond figure tight. You need to allow for the differential to move side to side while setting the backlash. As for the bearings, from neutral (where you should be at now with the adjusting screws against the bearings but not tightening inwards) add the 2-1/2 holes of preload by turning the right side adjusting screw clockwise. Your bearing preload is now set. From here on out, while chaning the back lash, you will move both sides adjusting screws the exact same to maintain the preload.
Next place your dial indicator on its magnetic base onto the casing as shown below.
Mazda states that the backlash should be around 0.009 to 0.011mm. This can make or a rather loud rear end. We opted for a tighter setup of 0.005mm. This will require the use of synthetic fluid but keep the noise down and help prolong its life span.
To set the backlash, you essentially will be moving the adjusting screws equally on either side which will move the differential side to side with the bearing cap bolts loose. When you measure your backlash, ensure the bolts are tight.
Take your initial measurement on the backlash. Doing this requires you too use your hand and slight rotate the ring gear back and forth. you will feel the play as it hits either side of the pinions teeth. Adjust the backlashing with equal movement of the adjusting screws until to achieve your desired measure. This does take a few attempts to get it. Also when i say equal movements, i mean tightening one side and loosening the the other but equal turns.
Once you get your backlash, just torque the bearing cap bolts down. Bearing cap bolts should be torqued to
27~38 ft-lbs (38~53 N/m)
Now you can just follow the standard instructions on replacing the 3rd member. Ensure that you use gasket making material (i recommend Right Stuff) to make a good leak free seal and if you have a tighter tolerance rear, a good synthetic fluid and proper LSD additives.