Easiest way to change Gear Oil

[Canadian1968]

I feel like this is straight forward, but then again I have been wrong !! I can't even find it in my manual !

I have the entire 8 3/4 rear axle out of my 68.  Want to chage the oil. Do I have to unbolt all the screws around the pumpkin and and seperate the case to allow all the oil to drain out?  Then of course i would have to replace the gasket if I did that?

I see what I am pretty sure is the fill nut ( large square , passanger side) . Fill here to specification??

[Ryan.C]

it is straight forward. dump and fill.
check out this link
http://www.moparmusclemagazine.com/techarticles/drivetrain/mopp_0912_installing_a_drain_plug_in_the_differential_housing/

[Canadian1968]

So it is a bit of a pain!! Lol

I like this idea much better . Can anyone explain the difference between a pipe plug and just a regular bolt ?!

[will]

 a pipe plug has a tapered thread whereas a bolt is a straight thread. The pipe plug compresses against the threads because of the taper, thus creating a seal. Use pipe dope or teflon thread sealant.

[71 SE3834V]

So it is a bit of a pain!! Lol

I like this idea much better . Can anyone explain the difference between a pipe plug and just a regular bolt ?!

Pipe threads are tapered to seal the more you tighten it. Also the thread pitch is different.

Oops, someone beat me to it. 

[A383Wing]

careful, there is not much "meat" there on the housing for a pipe plug....if you make a mistake on drilling or taping the hole, yer gonna end up with junk....you had better know what you are doing. Factory service manual says suck out the old fluid with suction gun and refill through same hole...

[cudaken]

Normally they use a suck-son pump to remove the old lube through the fill bolt. Sorry about the spelling!

Cuda Ken

[myk]

 Best way is to suck the fluid out with a pump and refill.  Is it perfect?  No, but I don't like the idea of the drain plug and I'm certainly not going to remove the entire back half of my carrier to get at the fluid...

[Fred]

careful, there is not much "meat" there on the housing for a pipe plug....if you make a mistake on drilling or taping the hole, yer gonna end up with junk....you had better know what you are doing. Factory service manual says suck out the old fluid with suction gun and refill through same hole...

You got that right. I use a suction gun to get the fluid out. No trouble at all to do it that way and safe. I wouldn't drill and tap unless you've reinforced the housing.

[Dino]

If the axle is out of the car, you can remove the plug and let it drain, although you likely won't be able to get everything out.  If the axle is in good shape then  I would still use this method, if you're unsure of what the guts look like then open it up.  To fill, set axle upright, as it would be mounted on the car, and fill through same hole until the oil runs back out.

[troy.70R/T]

if you decide to go the pipe tap route you need to know WHEN to stop tapping with the pipe tap or u will tap it to deep and the plug will go all the way in and not seal. starting a regular tap is a little tricky and starting a pipe tap by hand is even trickier. if you screw it up u can always go another size bigger. start out with the smallest size NPT size. maybe a 1/8-27 NPT.

[troy.70R/T]

BTW when drilling by hand start with a center punch and a smaller bit to drill the hole. Like a 1/8 inch drill. be steady and don't break it off when you break through. If you want I can send you a used tap. It is not new but good enough to do want u need. I would just charge u shipping.

[1974dodgecharger]

Suck and pump seems better.

[Fred]

Suck and pump seems better.

I'm with you. 

[chargd72]

Looks like I went against the grain on this one.  No problems yet.

[chargd72]

But I did paint this symbol on it which makes it stronger 

[Canadian1968]

Hahah the emblem is nice! I got a pump and I am just going to do it that way. Maybe when I decides to change the gears and have it all torn apart I might try the plug method

[Bobs69]

Very nice Chargd72.

I thought it was a great idea.  Then I read that someone thought the housing would need to be reinforced?  Is this out of fear of changing something and loosing value?

Then I looked at the size of the plug.  I'll do it sometime too.

[chargd72]

Very nice Chargd72.

I thought it was a great idea.  Then I read that someone thought the housing would need to be reinforced?  Is this out of fear of changing something and loosing value?

Then I looked at the size of the plug.  I'll do it sometime too.

Thanks, Bob.  I thought about how this area and where most of the force would be applied.  Your drive shaft is trying to spin your 3rd member.  The 3rd member is attached with 10 bolts evenly distributed around the housing.  These housings have plenty of meat on them and it's even thicker at the bottom near the weld.  I couldn't imagine what kind of power numbers you would need to see failure due to a 3/8 hole in this area.  I could be wrong, but it's not going to keep my foot off the pedal.

[Bobs69]

Yeah to hell with it.  I'm not even go to obsess with metal shavings.  I'll use a magnet and flush it a bit.  I'm going to do it sometime too.  I've owned my car since the early to mid 90's and I haven't changed the oil in the diff yet.  That's got to be closer to living on the edge then a small hole. 

[bull]

Ok, what's a suction gun? Pics?

[Fred]

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[bull]

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[troy.70R/T]

I like the "M" on the rear end. Maybe I will paint a Pentastar on mine

[1974dodgecharger]

Just finished my manual tranny and diff and yeah the pump is tiring as hell, but worth it.  My oil had to be dead per say it stunk and it was dark brown like chocolate.  It was old nasty oild......