Always ensure the vehicle you are working under is supported securely with jack stands, wear appropriate clothing and safety goggles.  Be weary of your clothing and the proximity to moving parts.  If you are uncomfortable about attempting an installation, DON'T......Seek a qualified service person or facility to help with your installation.  This articles contained in this site are in addition to and enhancement of existing OEM specified procedures and practices.  With regard to specifications and procedures, the OEM manual, procedure or practice shall dictate and govern.

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When you are working under your vehicle, make sure it is supported by secure jack stands.  There is always accident reports indicating someone has perished because of working under a car that was only supported by the jack.  Do not take any chances.....

Our subject car is always making some long trips to car shows and we try to change the differential fluids every 30000 miles.  On this change, we decided to do some preventative maintenance, provide some more beef with the addition of a Kenne Bell axle girdle.  The design behind an axle girdle is both convenience and support.  There is the added convenience of a drain plug, and the heavy aluminum casting has some really meat right behind the axle bearing.  There are 2 support bolts that are threaded up against the bearing caps to provide additional support to the cap under heavy torque loading.  With gobs of torque going through to the rear wheels, these caps can stretch.  This causes the pitch to change on the ring and pinion gears leading to premature wear and potentially a whining differential. 

What you will need before you start is replacement fluids (75W140 Synthetic) including the friction modifier, a tube of RTV sealer and a 5/16x18 bottoming tap.  The new cap screws provided with the kit are designed to provide as much thread contact as possible to provide the best support.  In order to do this, you must "chase" the existing threads with a bottoming tap.  A bottoming tap is different that a regular tap in that is will cut thread to the bottom of a blind hole.  A regular tap will leave the last couple of threats with a taper on the them and you will not be able to thread the new bolts to the limit until this is done.

The subject vehicle is a 2002 GT.  You will require a 3/8 drive socket set, a slot screw driver, a scraper tool and some high temperature silicone and a drain pan.  The differential is a limited slip configuration and the clutches require the addition of the friction modifier.  People who leave out the friction modifier will start to generate excessive rear end noise and will have to add it anyway.

Start by putting the car up on a lift or jacking the car up as high as possible and supporting it with jack stands.  Do not, absolutely do not attempt this procedure with the vehicle supported only by the lifting jack.

Don't support the vehicle with jack stands under the axle this time, put the jack stands on the frame rails ahead of the lower control arm.  This will let the differential hang down as much as possible and make life a whole lot easier when you are trying to get at bolts near the top.  Once you have the vehicle securely supported by jack stands, start by loosening all the bolts that surround the rear differential pan.   There will be a aluminum tag attached to one or more of the bolts that specify the gear configuration of you vehicle unless you have changed the gear ratio.  If you have these, don't loose them, we will replace them during re-assembly.  Once you have removed all the bolts, slow pry the pan away from the differential housing near the bottom, being careful to not damage the pan.  You will need just enough prying force to break the silicone seal between the two mating surfaces.  Once you have broken the seal just enough for the fluid to start running, let it run.  This is nasty smelling stuff and you don't want to get any on your clothing.

Once you have drained the differential completely, continue to pry the pan away until it is free.  Remove it completely by lifting it up over the rear sway bar.  Use the scraper to remove all the excess silicone sealant from the mating edge of the pan, and clean any fluid gunk from the pan itself.  

Re-direct your attention to the mating surface of the differential housing and clean it with the scraper as well.  There is always some differential fluid that does not drain out completely.  Take some throw away rags or paper towel and clean the bottom of the housing.

Chasing the threads will require a little bit of patience because of the limited space.  Take some time and carefully cover the guts of the differential with a rag, tucking it in where ever possible.  This will stop any small particles of threads from getting into the gears while tapping the upper bolt holes.  If you are unfamiliar with how to tap a hole, do some research before you attempt to bottom tap the holes.  When you are near the bottom of a hole, be careful not to break your bottoming tap as it will be very difficult to get this out.  Once all the hole are completed, use a can of computer compressed air and clean all the crap out of the holes.  A couple of short bursts of air is all it takes, and it will blow back into your face, eye protection is essential.

The new girdle will now need to have the RTV (Room Temperature Vulcanizing) sealant applied to it before mounting it to the differential.  We also need to apply some sealant to the bearing support bolt threads. 

Carefully maneuver the new axle girdle into position being careful not to touch the silicone surface to anything.  Any contamination could be a source for a leaky rear end.  Replace the existing bolts with the new socket head cap screw provided and finger tighten as much as possible.  With your socket, slowly tighten each bolt using a criss-cross pattern.  This will ensure a good flat mating surface between the pan and the housing.  Once all the bolts are snugged up, torque each one to 25 ft/lbs using the same criss-cross pattern as before.  The 2 bear support bolts can now be tightened against the bearing cap.  These require very little pressure to provide support, too much will cause the caps to distort.  Tighten them until they just make contact with the bearing cap inside, and torque to 3-4 ft/lbs max.  Place the aluminum tags over the ends of these bolts.  We had to snip the ends and open them up a bit so that we could fit them over.  Add the 2 jam nuts to the bolt threads that are exposed.  Restrain the bolts so that they don't tighten any further and secure the jam nuts.

If time permits, it is best to leave the pan for several hours or over night to allow the silicone to cure completely.  This really diminishes the possibility of leaks.

When the minimum time specified has elapsed, a socket driver with an extension will be required to remove the filler plug on the front side of the differential.  This is on the drivers side, just above half way.  Cut the end off of the spout provided on the differential fluid and empty 2 quarts/litres into the differential.  Now add the 2 bottle of friction modifier and the housing should be full.  If it does not already start running out, you should at least be able to stick you finger into the hole, and touch the fluid, this is adequate.  If not, you may have to add a portion of another quart/litre of differential fluid.

Replace the plug and tighten.  Over tightening can strip the thread and lead to a costly repair and a pile of wasted fluid.  I had the transmission in neutral, which allowed me to turn the drive shaft a couple of revolutions, making sure the gear surfaces where covered and to help mix the fluid and the friction modifier.  Check all you bolts and plugs are secure, slowly let the car down off the jack stands and you are finished.