Dana 44 Drain Plug

[Dean Barker]

Does anyone have the exact dimensions or the exact location on where to drill a hole in the Dana 44 to install a drain plug. I'd rather not have to buy a kit.

 

[Eightysix]

Hello Dean,


Your differential has a drainplug. If you are looking at the diff from the rear it's on the right side and looks like a large allen head with a flange. It should have a rubber tag on it with fluid specs, but may not. You'll want to use the correct GM fluid and two bottles of limited slip additive. I used a hand pump much like a grease gun to completely drain the diff and used it to refill also. Just make sure you add the limited slip first and then fill with diff gear oil to the top of the drain hole.

 

[Ken]

I think Dean''s referring to the aftermarket addition to the differential, where one drills into the bottom of the differential case. I can't find any pictures that depict it better, but here's what mine looks like, it should give you an idea of where to drill the hole.

You can see where I drilled slightly (about an inch) to the left of the center bolt on the differential cover plate. Be sure to flush the case thoroughly after drilling and tapping in order to remove all traces of metal. ​

 

[G Winter]

Ken , you say an inch to the left of the center bolt. Is this a critical measurement ? How far forward. Also is there any danger in hitting something inside when I break through? I have mine on stands getting ready to change fluids and some exhaust work.

BTW the 90 with the 6 speed has the 44 , right ?

 

[Ken]

Yep, you should have a 44. The hole is drilled just to the left side of the ring gear and centered in the case; you don't want to go any farther than the case thickness, which is a little under a half-inch or so. Wrap the bit tape or use a stop to prevent you from drilling too far. It wouldn't hurt if you hit the meat of the ring, but if you hit a tooth ... :eek

 

[8388]

I prefer not to drill any holes, you might end up compromising the structure. It's not just a cover, as you know.

I use a pump to remove the oil. After all, how often do you change out the fluid ?

 

[G Winter]

My understanding is that the case gets drilled not the cover. I feel that if you have any wear material in the bottom , pumping it out isn't going to get that . I want that out. I also intend on installing a magnetic plug.

 

[Ken]

Ah yes, the magnetic drain plug, aka "an oily Chia Pet" as someone once described it:

 

[8388]

My understanding is that the case gets drilled not the cover. I feel that if you have any wear material in the bottom , pumping it out isn't going to get that . I want that out. I also intend on installing a magnetic plug.

Drilling the case would be even worse in my opinion. I've seen what these cases do under a real load. The right way, is to remove the cover. If your making some serious power and putting it to the ground, I would not want to drill any part of that case.

 

[G Winter]

Ken , you make some serious power . How long ago did you drill your case?

 

[Eightysix]

I agree with 8388 100% , that's why I chimed in. To be honest I was just hoping to prevent someone that may not have realized there was a plug from making a costly mistake. I'm no metallurgist but I do know that drilling cast aluminum is probably not a good idea if it's a stress bearing member. Personally I would not alter a part that's as expensive or hard to find as a D44 rear end. Just my .02

 

[Bob86ZZ4]

When I had mine apart I drilled a small hole into the base of the hole that the bottom bolt threads into. I drilled the hole from inside the case just into the bore of the original hole that the bolt threads into. Then when I want to drain the fluid I just remove the bottom bolt off the back cover and the fluid comes out the hole. I put thread sealer on the bolt when putting it back in. This has worked fine for me for a few years. There's no way that drilling here can have any effect on case strength or integrity. It sure is easier than sucking the fluid out the fill hole. Just another idea for you.

 

[Ken]

I'll be sure to let y'all know when mine breaks in two. :eyerole

 

[Dean Barker]

Thanks to all who replied. Bob86ZZ4 had a neat solution, I thought. All gave me something to think about.

 

[ZRXMAX]

Thanks to all who replied. Bob86ZZ4 had a neat solution, I thought. All gave me something to think about.

Though it seems like a good solution... the lowest part of the housing is to the left of the bottom center bolt... about one inch from the center of that bolt... You also have depression in the casing to the right of the bolt... We don't need to address that...
A previous owner drilled a drain hole in the rear cover... it was to high for complete drainage... and it leaked... so... When the cover was off the car I had it heli-arced shut... guess what ? It still leaks... So... I bought another cover to polish up real pretty... When I change housings and gear ratios next time... the new cover will go on... See what a hassle it turned out to be ? Maybe it is just me...

I did a Dana 36 differential housing side drain plug install one time as per Corvette Fever instructions... it never leaked and never cracked... Seemed like the right thing to do at the time...
I wonder if the current owner thinks so ?

 

[PLRX]

My first Vette had a drain plug, I followed Corvette Fever's directions and it worked well.

Ken, I see you have a different size of drain plug, what size is that one?, magnetic?, where can I get one? After last week's pumping out gear oil adventure I wished I had an axle drain plug!

 

[Ken]

It's just a magnetic plug like you'd find for the oil pan. Any parts store will have several sizes.

 

[G Winter]

One last question for you on this Ken. How much room is there above where I install the plug? The plug I found has a magnetic pin that sticks up so that the total length of the plug form the contact point to tip is .750 in. Do I need to find a shorter plug ?

 

[Ken]

The case itself is about a half-inch thick or so at that point, and there is probably a quarter-inch between the case and the ring gear. The plug, with a washer, should fit. I'm guessing that mine is about three-quarters of an inch long all in all.

 

[G Winter]

The case itself is about a half-inch thick or so at that point, and there is probably a quarter-inch between the case and the ring gear. The plug, with a washer, should fit. I'm guessing that mine is about three-quarters of an inch long all in all.

Thanks a bunch Ken. I drilled the hole and and tapped it while it was draining. A bit messy but sure tapped nicely that way . Pumped some ATF through it and left it set. I will put the plug in and refill with Royal Purple tomorrow. Then for the trans. Can't find the right oil around here.