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Differential drain plug drilling difficulty?

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Old Apr 11, 2015 | 01:28 AM
  #21  
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Originally Posted by mtwoolford
So what exactly is the size of the tap? I did mine on the bench, inconjuction with pulling the batwing for poly mounts and new u-joints; I drilled and tapped for a 1/8th inch pipe plug wit a recessed allen head;


of course this was AFTER I pulled the lowest batwing / differential mounting bolt and then wondered why no fluid drained out
I assumed/guessed that the OP was supplied the 1/8 NPT plug - the same as you installed.

You aren't the first and I'd guess NOT the last that has done this. Some have actually modified the housing to use that bolt as a drain-plug BUT I believe it's not a good choice.
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Old Apr 11, 2015 | 12:21 PM
  #22  
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I have never had an issue with removing the tap after about five turns into a material that I do not want the cut material to pass thru the hole. You just gently thread the tap back in, just like you would start a bolt.

If I am taping large quantities, I have a tapping head that fits in my drill press and I can tap a 1/2-16 hole in less than a minute. That is tap and extract the tap. I also using a tapping fluid to lubricate the tap.
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Old Apr 11, 2015 | 02:50 PM
  #23  
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Originally Posted by WVZR-1
You want to "rinse" the housing it seems. Flush in an automotive conversation generally implies a "run through and drain". You could do as you mention just rinse it with maybe a motor oil product, and maybe the differential fluid would do well. I'd keep anything that hinted cleaner out of it.

Use a heavy grease to lubricate your tap and the "trash" will/should stay pretty much with the tap.
Yes, just rinse it out, my word choice was unclear. I bought some more 75W-90 just to be sure I get everything out before I fill it up. I also went ahead and got some Lucas heavy lubricant. I appreciate the pointers! My goal is to have the car back on the road by Monday with a new window regulator/plug wires in tomorrow and the diff done tonight, but after a month of not working on the door panel and regulator there will probably be some head scratching at my screw organization.
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Old Apr 11, 2015 | 02:55 PM
  #24  
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Originally Posted by mtwoolford
glad to see you're not afraid to do some work on your car and welcome to the forum ;

btw, one of the first things I did to my vette was to install a drain plug in the differential...couldn't believe they didn't come from the factory with one
Thanks! I hope to be a bit more mechanically inclined after I do all of the minor work on this car that I want to do. I really don't understand why they wouldn't just manufacture the differential with a drain plug, and I would guess it discourages owners from changing fluid. I don't even want to know how long that old oil was in there for and wish I'd done this job sooner.
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Old Apr 11, 2015 | 03:12 PM
  #25  
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Originally Posted by mtwoolford
So what exactly is the size of the tap? I did mine on the bench, inconjuction with pulling the batwing for poly mounts and new u-joints; I drilled and tapped for a 1/8th inch pipe plug wit a recessed allen head;


of course this was AFTER I pulled the lowest batwing / differential mounting bolt and then wondered why no fluid drained out
too many bolts under there! It's a 1/8 in. but I'll be doing it from under the car. Hopefully there's no issue with the Y-pipe getting in the way, or I'll need to find something to extend the tap. I was just barely able to get off the fill plug with WD40, a sledgehammer, and the hex wrench. Otherwise this would've become an interesting situation!
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Old Apr 11, 2015 | 03:16 PM
  #26  
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Originally Posted by THE 383 admiral
Use Kerosene. On the Tap, a quality tap. It is a very easy mod. Just be patient. Drill straight tap straight. The method above is a machinist. Use light turns just enough to cut.
Will do, thanks.
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