Jerry Scott[CO]
Viper Owner
You will need the following tools:
1/2 in. chuck, variable speed electric drill.
4 or 5 pipe stem cleaners (tobacco shop)
1/8 in. drill bit
ball joint grease
1/4-18 NPT (8203) pipe thread tap
drain bucket
7/16 drill bit
short socket extension
1/2 in. socket wrench
non-ratchet socket drive handle
4 jack stands and jack
1/4 x 13/32 in. Allen pipe plug Teflon coated
center punch
scribe
3/8 in. Allen wrench
1/4 in. Allen wrench
oil suction gun
ball joint grease
measuring scale
Put the car on four jack stands for a minimum height of 17 in. off the ground and nearly level. With a scribe, make a fore and aft line on the bottom of the differential case that is directly under the rear center bolt that holds the rear cover. Measure .670 in. toward the driver's side and make another parallel scribe line. Now measure 1.170 in. forward from the parting line of the rear cover, (as if the rear cover was removed). You will be on the raised rectangular flat that you see on the bottom. Look at the picture of the inside of the case enclosed and you see that toward the passenger side of the bolt is a thick section of the case that you do not want to drill through. This area is thick to support the rear cover bolt and would be too high in the case to get a good drain. The location selected is well away from this thick section and is well away from the bolthole for the rear cover. Using a center punch mark the case in the location described. Now remove the plastic fill plug on the passenger side of the case, with a 3/8 Allen wrench.
Drill a 1/8 in. pilot hole with a freshly sharpened drill bit (or new) at the center punched location and go no more than .450 in. deep. The case is about .600 in. thick in this area and you don't want to break through just yet. If you do, you will find that the leaking oil will make the aluminum more difficult to drill with the 7/16 in. final drill size. Now start drilling the 7/16 in. final hole (again with a very sharp bit), being very careful to keep it perpendicular to the case. Apply a fair amount of pressure, run the drill at a slow speed, and take a few pauses to cool the bit. When the point starts to break through at approximately .6 in. deep you will start to get some oil leaking down the drill bit. My advice here is to stop and wait overnight for the oil to drain into a bucket. Mine drained at about one large drop per second. If the oil is cold as was mine, it will take several hours. The reason to wait for it to drain, is that the drill does not cut as well when the oil is flowing, and it makes quite a mess on the drill and you.
Once it has drained over night, start cutting with the drill again until you break through the case. Now with the pipe stem cleaner, make a 3/4 in. L shaped bend at the end, reach into the hole and sweep the inside several times to clean up any chips that may have gone inside. You will find that the oil will help you attract the chips. Keep cutting off the dirty end of the cleaner and sweeping until it comes out clean.
Tap the hole using a 1/2 socket wrench on the square shank of the 7/16 tap with a short extension and a non-ratchet drive handle. If you have a regular t-handle and extension for the tap, use it. I found that the normal tap drive tool without an extension, did not work for me since the tap was not long enough to clear my 3 in. exhaust. If your car is stock, you may have enough room for the standard tap driver. Before inserting the tap, coat it well with a liberal amount of ball joint grease to make the chips stick to the tap and not go inside the case. Start by turning the tap until you get it started, then when it starts to get tight, make only half turns at a time, then backing off 1/4 turn. After you have gone a short distance back out the tap, clean it and reapply the grease. Each time you remove the tap, check by inserting the plug to see how far it goes in. You do not want to run the tap too far, or your plug will not seal. You want the plug to be flush with the outside bottom of the case. This way you have some room for wear as the plug is removed and reinstalled over a period of time.
After you have removed the tap for the last time, clean out the hole and inside of the case again with the pipe stem cleaner to catch any final debris. I checked inside the hole after this procedure, with a borescope and found the area to be very clean. The pipe stem cleaners worked very well for this cleaning. Install the plug with anti-seize on the threads until flush with the outside of the case. Be careful not to over torque the plug and damage the threads. Remember, you are in aluminum.
Replace the fluid with 1 1/2 quarts of Mopar High Performance Synthetic Axle Lube, SAE 75W/140, pt. no. 4874469, and 4 fluid oz. of Mopar Gear Additive (friction modifier), no. 4318060AB. Then replace the fill plug. JonB at Parts Rack (360-837-3937), should have the best price for the fluid. You will likely need a suction gun to put in the fluids, since the fill hole is in an awkward location.
I found the Teflon coated pipe plug at a company called McMaster-Carr and the part no. is: 4534K13 @ $1.34 each. Their phone is: 404-346-7000. They also have a web-site at: http://www.mcmaster.com. The pipe tap came from Home Depot and is a Hanson (Irwin) brand, part no. 42526 08203.
My thanks to Joe Chiolo in Philadelphia for his help and information on the plug, since he did the task before I tried it. He used a 1/8-27 plug, which is fine, except that it will drain much slower. If you go with the 1/8 plug, you also can use a 3/8 in. electric drill instead of a 1/2 in. electric drill. The drill bit size for the 1/8 tap is: 21/64 in. or 11/32 in. Also thanks to Dan Burch Viper Tech in Grand Junction, CO, for a photo of the inside of the differential and his advice as well.
Jerry Scott[CO]
1/2 in. chuck, variable speed electric drill.
4 or 5 pipe stem cleaners (tobacco shop)
1/8 in. drill bit
ball joint grease
1/4-18 NPT (8203) pipe thread tap
drain bucket
7/16 drill bit
short socket extension
1/2 in. socket wrench
non-ratchet socket drive handle
4 jack stands and jack
1/4 x 13/32 in. Allen pipe plug Teflon coated
center punch
scribe
3/8 in. Allen wrench
1/4 in. Allen wrench
oil suction gun
ball joint grease
measuring scale
Put the car on four jack stands for a minimum height of 17 in. off the ground and nearly level. With a scribe, make a fore and aft line on the bottom of the differential case that is directly under the rear center bolt that holds the rear cover. Measure .670 in. toward the driver's side and make another parallel scribe line. Now measure 1.170 in. forward from the parting line of the rear cover, (as if the rear cover was removed). You will be on the raised rectangular flat that you see on the bottom. Look at the picture of the inside of the case enclosed and you see that toward the passenger side of the bolt is a thick section of the case that you do not want to drill through. This area is thick to support the rear cover bolt and would be too high in the case to get a good drain. The location selected is well away from this thick section and is well away from the bolthole for the rear cover. Using a center punch mark the case in the location described. Now remove the plastic fill plug on the passenger side of the case, with a 3/8 Allen wrench.
Drill a 1/8 in. pilot hole with a freshly sharpened drill bit (or new) at the center punched location and go no more than .450 in. deep. The case is about .600 in. thick in this area and you don't want to break through just yet. If you do, you will find that the leaking oil will make the aluminum more difficult to drill with the 7/16 in. final drill size. Now start drilling the 7/16 in. final hole (again with a very sharp bit), being very careful to keep it perpendicular to the case. Apply a fair amount of pressure, run the drill at a slow speed, and take a few pauses to cool the bit. When the point starts to break through at approximately .6 in. deep you will start to get some oil leaking down the drill bit. My advice here is to stop and wait overnight for the oil to drain into a bucket. Mine drained at about one large drop per second. If the oil is cold as was mine, it will take several hours. The reason to wait for it to drain, is that the drill does not cut as well when the oil is flowing, and it makes quite a mess on the drill and you.
Once it has drained over night, start cutting with the drill again until you break through the case. Now with the pipe stem cleaner, make a 3/4 in. L shaped bend at the end, reach into the hole and sweep the inside several times to clean up any chips that may have gone inside. You will find that the oil will help you attract the chips. Keep cutting off the dirty end of the cleaner and sweeping until it comes out clean.
Tap the hole using a 1/2 socket wrench on the square shank of the 7/16 tap with a short extension and a non-ratchet drive handle. If you have a regular t-handle and extension for the tap, use it. I found that the normal tap drive tool without an extension, did not work for me since the tap was not long enough to clear my 3 in. exhaust. If your car is stock, you may have enough room for the standard tap driver. Before inserting the tap, coat it well with a liberal amount of ball joint grease to make the chips stick to the tap and not go inside the case. Start by turning the tap until you get it started, then when it starts to get tight, make only half turns at a time, then backing off 1/4 turn. After you have gone a short distance back out the tap, clean it and reapply the grease. Each time you remove the tap, check by inserting the plug to see how far it goes in. You do not want to run the tap too far, or your plug will not seal. You want the plug to be flush with the outside bottom of the case. This way you have some room for wear as the plug is removed and reinstalled over a period of time.
After you have removed the tap for the last time, clean out the hole and inside of the case again with the pipe stem cleaner to catch any final debris. I checked inside the hole after this procedure, with a borescope and found the area to be very clean. The pipe stem cleaners worked very well for this cleaning. Install the plug with anti-seize on the threads until flush with the outside of the case. Be careful not to over torque the plug and damage the threads. Remember, you are in aluminum.
Replace the fluid with 1 1/2 quarts of Mopar High Performance Synthetic Axle Lube, SAE 75W/140, pt. no. 4874469, and 4 fluid oz. of Mopar Gear Additive (friction modifier), no. 4318060AB. Then replace the fill plug. JonB at Parts Rack (360-837-3937), should have the best price for the fluid. You will likely need a suction gun to put in the fluids, since the fill hole is in an awkward location.
I found the Teflon coated pipe plug at a company called McMaster-Carr and the part no. is: 4534K13 @ $1.34 each. Their phone is: 404-346-7000. They also have a web-site at: http://www.mcmaster.com. The pipe tap came from Home Depot and is a Hanson (Irwin) brand, part no. 42526 08203.
My thanks to Joe Chiolo in Philadelphia for his help and information on the plug, since he did the task before I tried it. He used a 1/8-27 plug, which is fine, except that it will drain much slower. If you go with the 1/8 plug, you also can use a 3/8 in. electric drill instead of a 1/2 in. electric drill. The drill bit size for the 1/8 tap is: 21/64 in. or 11/32 in. Also thanks to Dan Burch Viper Tech in Grand Junction, CO, for a photo of the inside of the differential and his advice as well.
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Jerry Scott[CO]
