8 3/4 housing drain

[Pool Fixer]

I changed out my 3.91's for 3.23's today. While I had it apart, I drilled and tapped a hole for a small drain plug. I looked inside and it does not protrude into the housing any more than the weld in the center of the housing. I mounted it off center to pass side of car a bit so I don't think it will even come close to hitting anything. Hopefully it does not leak. I just sealed it with RTV.

I realize the interval in draining the fluid is prob more than I'll ever reach but this might not be the last pumpkin change I do. I hate breaking the seal and hoping it all gets into my drain pan.

Quick performance 489 case. 3.23's with eaton trutrac

 

[dadsbee]

Great idea! My dearly departed Lab helps me with mine...

 

[Pool Fixer]

Great idea! My dearly departed Lab helps me with mine...

I don't have the brain power to come up with that... stole that idea from some people on the web.

 

[khryslerkid]

Good idea. You'll need to change the lube after 500 miles on a new gear break in. I used a siphon pump when I've done mine the last couple of times.

 

[Pool Fixer]

Good idea. You'll need to change the lube after 500 miles on a new gear break in. I used a siphon pump when I've done mine the last couple of times.

good idea till it leaks and I can't stop it... I always let perfect be the enemy of good.

The break in only says to run it gently for 15 min, let rest 45 min... and do that 5 times. and no suregrip addative. I like your idea of changing it in 500 miles.

 

[Don Frelier]

I doubt it will leak.
You can always hit it with the welder.

 

[supergluehero]

I had my driveline shop weld a half coupling to the bottom of mine so I didn't have to worry about it sticking up internally too far. It also gives more meat for the threads since the housing is too thin. Too bad their weld was crap and it leaked. I'm in the process of resealing it with some JB Weld to try and avoid rewelding it. Not the best picture, but it's the best I have right now.

 

[j-c-c-62]

I changed out my 3.91's for 3.23's today. While I had it apart, I drilled and tapped a hole for a small drain plug. I looked inside and it does not protrude into the housing any more than the weld in the center of the housing. I mounted it off center to pass side of car a bit so I don't think it will even come close to hitting anything. Hopefully it does not leak. I just sealed it with RTV.

I realize the interval in draining the fluid is prob more than I'll ever reach but this might not be the last pumpkin change I do. I hate breaking the seal and hoping it all gets into my drain pan.

View attachment 1605774

View attachment 1605775
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Quick performance 489 case. 3.23's with eaton trutrac

I used a magnetic plug on mine and also shifted it slightly to avoid any direct contact with ground debris, and to get it out of the direct ring gear swung flow of lubricant to help the magnet retain whatever it collects.

 

[Pool Fixer]

This whole drain plug and changing diff was in prep for dr diff rear discs. tackling that tomorrow or the next day. have the parts laid out. seems doable. directions aren't that great but there is a guy who did one on youtube. hopefully he knew what the F he was doing lol

 

[PurpleBeeper]

I like the idea. I’ve added drain plugs to automatic trans pans for the same reason. Why not?

 

[R413]

1960-62 full size Chryslers have drain plugs factory installed like you did to yours, offset to the side.

 

[j-c-c-62]

I don't remember that on our 1960 300F. Actually, I never remember seeing that on any Mopar's, anybody got any pics, I'm curious.

 

[hdwrench]

we’ll it’s a great idea , it sure be nice to avoid the mess . you could weld a ring around it to act as armor if ya think you might catch it on something…

 

[j-c-c-62]

This is my magnetic oil pan plug for the rear end. I might slightly deburr/round the sharp corners to reduce its ability to snag any debris. It's been almost 20 years, but I believe I built up the threaded hole inside to give plenty of meat to tap into.

 

[493 Mike]

I did the 8 3/4 on my 65 Coronet and used a 1/8" pipe plug. Most tap and die sets come with a 1/8" tap so tap the hole until the plug will screw in about 3 1/2 turns by hand and use pipe dope to seal. Pipe thread is tapered so it will seal mechanically also. It looks like the OP used a straight thread set screw for a plug?
Mike

 

[Pool Fixer]

I like the idea. I’ve added drain plugs to automatic trans pans for the same reason. Why not?

Trans is next. I bought a drain plug kit for that

 

[dvw]

Weld a very short piece of 3/4 pipe contoured to fit the bottom. plug using an internal allen head pipe plug. Drains quickly. doesn't stick down far enough to bother anything. That being said 8 3/4 housings are plenty thick enough to tap for smaller thread size. The brake line retainers used on my street car are stainless. The housing is drilled and tapped for 1/4-20 bolts to hold them on. Been that way 30 years.
Doug

 

[j-c-c-62]

Weld a very short piece of 3/4 pipe contoured to fit the bottom. plug using an internal allen head pipe plug. Drains quickly. doesn't stick down far enough to bother anything. That being said 8 3/4 housings are plenty thick enough to tap for smaller thread size. The brake line retainers used on my street car are stainless. The housing is drilled and tapped for 1/4-20 bolts to hold them on. Been that way 30 years.
Doug

I mostly disagree, even with a 1/4" drain in 1/8" metal. A brake line retention bolt has few downsides if it dislodges. The same cannot be said for a drain plug.
I found pics of my internal drain plug reinforcement from years back below. For those with a keen eye you may also notice my rear end cooler pick up point before it was enclosed with a welded baffle, and a finished pic with fill/view port and all the internal slosh baffles and housing stiffeners.

 

[#41]

I mostly disagree, even with a 1/4" drain in 1/8" metal. A brake line retention bolt has few downsides if it dislodges. The same cannot be said for a drain plug.
I found pics of my internal drain plug reinforcement from years back below. For those with a keen eye you may also notice my rear end cooler pick up point before it was enclosed with a welded baffle, and a finished pic with fill/view port and all the internal slosh baffles and housing stiffeners.

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Baffles are interesting. Where did you get that idea?

I agree that it's better to weld on a bung or something other than just relying on the the threaded thickness of the housing. It would not take much effort to strip the threads.

Here is my 8-3/4 modified with a cooler and temp gauge.

 

[DPeltz]

Just curious, what type of use are your cars seeing requiring a diff cooler?

Never had an issue with 83/4 rears but the occasional pinion, or axle seal.