Qiken

I remember a thread in regards to the installing of a drain plug in the pumpkin.....suggestions please

blkzr1

hi, i put one in my 1986. i leveled the car on jackstands then i removed the exhaust system, then, with the oil still in the pumpkin, i drilled a 21/64 hole in the rear of the pumpkin. the hole was drilled 3/4" to the left of the center lower bolt and 1/2" forward of the flange where the batwing is attached. this area is a low spot in the casting. yes, the oil will flow out but if you place a rag over the drill and drill slowly, it isnt to messy. i used one of my older battery driven drills. then i put greese on a 1/8 npt tap and ran the tap in the hole. the greese will catch the thread cuttings. go about 1/3rd of the way into the hole, then pull the tap and replace the greese and do it 2 more times. then run a quart of thinner oil through the rear end to ensure that no cuttings are in there. use an allen type 1/8" npt plug with thread tape on it for the plug. a square head plug will stick out and rub the exhaust. see ya

Jagdpanzer

Here are some pics of a 1/4" drain hole I put in during the 4.10 gear install I did last year. The brass plug was replaced with an anodized aluminum allen socket type I picked up from the local speed shop.

DanZ51

I put a plug in my batwing years ago when I upgraded my gear ratio. The batwing was removed at the time.

I just eyeballed where I wanted to put the hole(center, low as possible, clear of any moving parts) and started drilling. It's only aluminum so it's real easy . Use care when tapping the hole; NPT taps are tapered so the deeper you go the bigger the hole becomes (tap alittle then test your drain plug.) IIRC my plug also also used a seal washer (like an oil pan drain plug) so I "dressed" the surface of the hole flat with a mini-grinder.

dan6712cc

Bill at ZFdoc says not to as in his experience they will eventually end up leaking most of the time.

WVZR-1

I don't know that I would "dispute" your comment but I'd guess it something to be considered. I'm quite confident that "done right" there should be "little" concern for the leak.

I believe I would consider "metrics" rather than NPT only because the "tools of the day" are metric. A conversational install would be a "magnetic" plug.

neat

The bottom bolt hole is what I use. I drilled into the cavity of the bolt hole from inside the case. The bolt hole is much deeper than the bolt is long, so if you look at what you are doing you can drill a hole into that extra space and not mess with the threads the bolt uses. I use some sealant on the bottom bolt and have had no issues.

WVZR-1

That's a quite interesting and I might say "novel" approach to the task. It accomplishes all but a few/couple ounces of the complete drain or do you angle the bored hole? I assumed a "vertical" approach to the existing bore. Again "interesting"! It doesn't though seem to be maybe as "tidy" for the drain. A straight "down" shot is quite easy to collect. After removing the bottom center bolt I would imagine the weight and force of the fluid creates a stream that might be more difficult to collect.

If the differential is on "the bench" it looks quite simple.

I've generally assumed that those who have asked were actually trying to accomplish the task while the differential was still in the car!

Did I mention: "Interesting"!!!

The only complication I could see with this solution is the original bolts are "tri-obal" and self tapping. I would probably clean/chase the threads in the housing and replace the bolt with a regular threaded fastener.