Rear Gear Oil Change and New Seal 1973 Dart

[Mike's Dart]

Gave the /6 a new filter and 4 1/2 quarts of fresh oil today! Now on to the rear end and an oil change and a new seal! Any advice on the best rear gear oil to use and how much I'll need? Anything I should know prior to getting into this rear gear oil change? Thanks in advance!

Mike

 

[Marcohotrod]

what size rear? does it have a crush sleeve?

 

[Mike's Dart]

what size rear? does it have a crush sleeve?

Wow! Did not know there was so much to this rear gear? I'm not an automotive technician, so I guess I'll have to do a bit of research. Owners manual, VIN number? Stamp on the axle/rear end?

 

[66fyssh]

It's a little easier if you just want to change the gear oil and not the pinion seal. If the pinion seal (around the area where the driveshaft attaches to the rear diff) is not leaking, there's no need to go into the hassle of replacing the pinion seal.

If it's an 8 1/4 (8.25) you remove the differential cover off the back and the fluid will drain out. Remove any remaining gasket material on the cover and the differential housing and replace the cover gasket with a new one. It should take about 2 quarts of 85W90 and if you have a locking rear, you'll want to add 6 ounces of limited-slip additive before the gear oil. There's a fill hole about halfway up the side of the differential. Add gear oil until it runs out the hole!

...and in the words of our friend Del (67Dart273), head over to MyMopar - Mopar Forums & Information - Service Manuals and download a service manual.

 

[kiss]

just get 80w90 gear oil at the autoparts store
if you have sure-grip get the kind labeled "limited slip"
alternatively you can add the limited slip fluid separately

this is the kind I bought:
Amazon.com: Valvoline 831 Gear Oil: Automotive

 

[Mike's Dart]

It's a little easier if you just want to change the gear oil and not the pinion seal. If the pinion seal (around the area where the driveshaft attaches to the rear diff) is not leaking, there's no need to go into the hassle of replacing the pinion seal.

If it's an 8 1/4 (8.25) you remove the differential cover off the back and the fluid will drain out. Remove any remaining gasket material on the cover and the differential housing and replace the cover gasket with a new one. It should take about 2 quarts of 85W90 and if you have a locking rear, you'll want to add 6 ounces of limited-slip additive before the gear oil. There's a fill hole about halfway up the side of the differential. Add gear oil until it runs out the hole!

...and in the words of our friend Del (67Dart273), head over to MyMopar - Mopar Forums & Information - Service Manuals and download a service manual.

Thanks for the Service Manual down load guidance and rear gear advice! Much appreciated!!!

Mike

 

[Mike's Dart]

just get 80w90 gear oil at the autoparts store
if you have sure-grip get the kind labeled "limited slip"
alternatively you can add the limited slip fluid separately

this is the kind I bought:
Amazon.com: Valvoline 831 Gear Oil: Automotive

Got it! And they actually had the cover gasket in stock! Thanks for the advice!!

Mike

 

[Mike's Dart]

The cover on my 73 Dart's rear gear has 10 bolts, so what size differential do I have? Thanks!

Mike

 

[66fyssh]

Should be an 8.25

 

[Mike's Dart]

Should be an 8.25

View attachment 1715021313

That is the one!! U DA MAN!!!!!!!!!!!!!

 

[66fyssh]

You're welcome. Let us know how it goes! There's nothing quite like the smell of old school gear oil

 

[Mike's Dart]

You're welcome. Let us know how it goes! There's nothing quite like the smell of old school gear oil

Will do! Fellow at the parts store said to be sure and not get it in my hair! The look on his face lead me to believe his advice was "spoken" from experience!