Differential drain plug install instructions is wrong

[GTSnake]

Well, I used the illustrated instruction on installing the differential drain plug and the part number it refered to is wrong.

The instructions said to use the McMaster Carr part 4534K13 plug. That plug is too big. It won't fit into the hole made by the 1/4" tap. After looking on the McMaster website it turns out the correct plug is one size smaller than the one referenced in the instructions. I think this has been discussed before but the instructions have not been updated.

The correct part number is 4534K12. I had to take a guess based on the size given and ordered it. It cost a whopping $0.89 but shipping cost me $13 for next day air.

BTW, if you do this make sure you have some way to catch all the aluminum shavings when you drill. A 7/16 hole through 0.6" of aluminium makes a LOT of shavings. I had it all over the place. On my shirt, face, arms & hair. It may be worth it to have someone with a shop vac catch all the shavings as you drill or else you will be sweeping for a long time.

Another tip is when you fill the oil back in. I used Royal Purple so I wedged the oil bottle on top of the half shaft and connected the tube to the fill hole. I let it drain overnight so I didn't have to constantly squeeze the oil uphill.

 

[SEASNAKE]

I use a little hand pump (like a hand soap pump) to fill the differential. Starting with the limited slip additive then filling with the oil. It works well.

 

[Tom F&L GoR]

An alternate is to drill through the bottom center bolt hole into the differential. Then the bolt itself is also the plug. It's consequently a smaller hole, so will take longer to drain, but no tapping.

 

[FE 065]

Did you add the Mopar additive? Can't remember what's it's called- but it's a friction reducer I think.

Too bad you were a rush, McMaster stuff usually comes quick to my place. One or two days, and the shipping seems to always be only $4. Even the 12"x12" steel plate (1/16" thick) that came today was only $4.26 shipping or something like that.

Can't believe the shipping's so cheap.

Thanks for the plug size error reminder

 

[RoadiJeff]

GTSnake,

I did the drain plug install two weekends ago and discovered the wrong part number listed in the how-to but only after I'd received the wrong plug and had to ship it back. I emailed the <font color="blue"> Illistrated Instructions Editor </font> link at the bottom of the page and reported it but apparently no one has corrected the error.

It also says you have to use a 1/2" drill chuck with the 7/16" drill bit but I found one with a 3/8" shank. I email them that correction as well. Plus, I included the part number for the 1/4-18 NPT tap that works for the recommended drain plug. Both the tap and plug can be purchased through the McMaster-Carr website.

They have VERY fast service. Although it came from Chicago and I live in St. Louis, nearly 300 miles away, the sales person assured me that I would have it the next day using regular ground delivery. I thought "yeah, sure" but by gosh it was sitting at my front door the very next day.

Also, a question about this NPT (National Pipe Thread) designation that no one I've asked from Home Depot to several journeyman pipefitters have been able to answer. What does the 1/4-18 stand for in the drain plug reference? I assume the 18 is for 18 threads per inch but the 1/4 sure does not mean it is a 1/4" diameter plug. I figured that out when they said to use a 7/16" drill bit prior to the tap.

I even Googled the info and several online charts have strange sizes when it comes to the NPT standards. For instance, a 3/8-18 NPT tap uses a 9/16" drill pilot hole. On the more common threads, an NC 3/8-16 tap uses a 5/16" drill bit. I don't get it.

 

[mntngts99]

NPT 1/4-18 = Pipe size ID - treads per inch
shaft size, hole size, ID, OD. Its all messed up.

 

[Chuck 98 RT/10]

NPT 1/4-18 = Pipe size ID - treads per inch
shaft size, hole size, ID, OD. Its all messed up.

LOL

It makes sense to a "pipe" guy. They have to engineer flow through a pipe.

 

[GTSnake]

I thought about emailing the editor as well but I figured with all this remodeling going on it would end up getting lost. Also I tried to do a search on previous experiences but came up with nothing. So I thought I'd just post it.

I probably should have just used the regular shipping. They're usually really fast. But I ordered it after hours and I wanted to get it finished so I opted for the next day shipping without knowing how much it would be.

 

[Supercharged Vipermad]

I don't update the Illustrated Instructions on this site any longer...but I will note the update and make the proper changes elsewhere. Thank you.

 

[Fast Viper Dan]

Note: When using a tapered pipe tap, stop at 7 threads from the top!
Happy taping,
Dan

 

[RoadiJeff]

I just did like the how-to suggested and screwed in the drain plug after every couple of turns with the tap. The hardest part for me was keeping the drill perfectly perpendicular with the case. It didn't help that I was laying on my back with the car up on jackstands.

The other not-so-fun part was that I had to remove most of the Corsa exhaust due to clearance issues with the tap wrench. I bought a huge T-handle wrench because I couldn't see me getting it straight with a ratchet and a 1/2" socket. I figured the extra effort kept me from messing something up and having to take the differential to a machine shop to correct any mistakes. There was a loose clamp I discovered on the exhaust anyway.

One other correction in the how-to that I didn't mention is that it says to refill the differental with 1 1/2 quarts of Mopar High Performance Synthetic Axle Lube and 4 fluid oz. of Mopar Gear Additive. Since there's 32 oz in a quart that would mean 52 oz of total fluid. The service manual says that 45 oz is the total recommended fluid level and overfilling can cause foaming.

Here are the McMaster-Carr part numbers that should be in the how-to:

1/4" PTFE coated drain plug - 4534K12 ($.89 ea)
1/4"-18 uncoated taper pipe tap - 2553A13 ($18.94 ea)