I got this idea when installing new gears and posi in my wife's 92 Camaro "project car" last weekend, which I posted about in a different thread in this forum.

The stock 10 bolt is kinda annoying for lube changes since you have to yank the cover to drain the lube. No fun at all. There's gotta be a better way. Please forgive if this has been suggested many times before, but it's a new idea to me.

I noticed that there is a seemingly ideal location to put a drain plug. Along the bottom of the housing, just slightly to the pass, side of the pinion, is a rectangular area with a slightly v-shaped bottom to it, as viewed from the outside of the housing. You might be interested to know that this area is TOTALLY OPEN inside the housing. Also, it is the very lowest point in the housing. Ideal for a drain plug location!

Although I have not done it (yet!) it should be a simple matter of drilling and tapping this area for, say, a 3/8" NPT plug and screwing it in. I'd put the plug about 1-2" from the front edge of this rectangualr area to keep it well away from the spinning ring gear (although I really doubt it would come close to the ring gear even if you put it all the way at the back edge).

 

The 10bolt cover I have is a stock style that has a drain plug fitted on it. I think it is an SLP cover. I believe the drain on my cover is in the same place that you are describing.

 

No, the drain plug location I'm talking about would be on the bottom of the housing itself, not in the cover. The bottom edge of the cover is not the lowest point in the unit, either.

 

I wouldn't drill and tap the housing for a drain plug. Its already weak enough in regards to flexing. Although it my not be the absolute "low" spot... drill and tap the cover... not the housing. I just wouldn't trust a 10bolt case w/ a "hole" in it.

 

87- you raise a good point. I'm not sure if this is what you would call a "high stress" area or not. It certainly doesn't look like it does much supporting of anything but you never know what the factory was thinking when they built these odd cavities into the housing.

 

It's quite commonly done. In fact, I did one of my cars that way not too long ago; a 8.5" 10-bolt. I used a 1/8" pipe plug, with an Allen head (wouldn't want a raised hex or square head getting caught on something and ground off), as it seemed wise to keep the hole small.

 

I don't believe in drain plugs in automatics or differentials. If you're gonna inspect the inside (which I do always,) then you might as well pull the cover. Your mileage may vary.

 

I dunno about doing this to the rearend, but I think drainplugs for the transmission pan are cool because you can drain the pan first and then drop the pan with no spills. I mean spilling on the floor isn't the end of the world or anything, but for some people that dont have a nice working area it makes cleanup much quicker. The only thing I'm afraid of is the pan eventually cracking from being drilled. I havent seen this personally, but I did hear about it happening. I've never heard of this being done on the rearend, but if SLP does it then its prolly safe (just a guess though).

 

Ive seen it done of a few different rear ends over the years. Gear oil doest make too much of a mess if you have a drain pan so I never botherd with it. Now with an automatic transmission it makes draining the fluid sooooooooooooooo much easyer. The $6 B&M drain plug was the only item Ive ever purchased that I dont regret.