Read Differential Drain Plug Question

[ACR Joe]

I tried to **** the oil from the rear differential but that proved to be relatively ineffective. As a result, I decided to drill and tap the bottom of the differential case. I plan to use a 1/8" x 18 NPT plug; big enough to allow the oil to drain, but not so big that it could possibly be detrimental to the structural integrity of the case.

The OEM drain plug is plastic (I think). Any suggestions as to what material I should use for the drain plug. Brass, galvanized steel, black iron, stainless steel, etc. Any other tips would be appreciated. Thanks .....

 

[Ron]

<FONT face="Comic Sans MS">GM has always used iron plugs for their aluminum M-22 transmission fill & drain plugs. Coat with a little anti-seize and it should work fine.

Do you plan on drilling & tapping while installed in the car? If so, it seems a bit risky to me... metal shavings & all... </FONT f>

 

[Robert1994]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Ron:
<FONT face="Comic Sans MS">GM has always used iron plugs for their aluminum M-22 transmission fill & drain plugs. Coat with a little anti-seize and it should work fine.

Do you plan on drilling & tapping while installed in the car? If so, it seems a bit risky to me... metal shavings & all... </FONT f>

<HR></BLOCKQUOTE>

<FONT COLOR="Blue">Text</FONT c><FONT face="Verdana">Text</FONT f>

Do not locate the drain plug to the bottom of the differential, ground clearence is difficult enough to deal with.
Use a magnetic plug, and drill and tap to approoiate to the
plug you obtain.

 

[ACR Joe]

I've heard from a few cognoscenti that it is acceptable to drill and tap the housing while it is still in the carrier. I plan to perform these steps very carefully so as to minimize the introduction of metal shavings in the housing. I also plan to flush out the housing with about five quarts of motor oil after tapping the threads. I'm not sure how much damage, if any, soft aluminum shavings might do in the event that a few get left behind. I believe they would just get pulverized by the ring and pinion, but I'm open to any opposing points-of-view.

 

[Chuck 98 RT/10]

"Structural integrity" as you mentioned, is exactly why the plug is no longer available. However ACR Joe, I agree with you that it would be a great convenience to have the plug. Keep us updated with the results - short term and long term.

 

[Trbulnc]

You can use a female plug instead of a male, it will be flush with bottom of housing so there will not be an issue with clearance, just make sure it is short enough to provide ample clearance from gears. You can use a 1/4, or 3/8 extension to remove it, depending on which size plug you prefer. As for not damaging the gears? I worked for Bell Helicopters doing overhauls on transmissions and gear boxes, it would amaze you at what damage little slivers of metal or other contanimants can do to a set of gears.

stephen

 

[GTS Dean]

Joe,

I seriously doubt that the fill plug is plastic. My '96 has a metal plug with an internal wrenching hex socket.

If you search the old board Archives, there have been some very good photos of the diff cooler installation. Check with Woodhouse on the proper size hole to drill and tap - I'm guessing that it's probably 1/2" NPT or o-ring boss. You could buy a nice anodized aluminum plug from Aeroquip or Earl's until you decide to get the rest of the system.