Rearend advice

[lts70]

When I put my new inner axles in I plan on changing the gear oil to a full synthetic. Before I button it back up and fill it with the new oil how should I clean it out besides draining it? Brake clean? Is there any thing else I should do or check while I have it pulled apart? Bearings or seals? Right now I have no problem with my posi slipping, no noise, no leaks. I am hoping I can just swap the axles out and be done with it with out more time and cost. But if there is something I should do while I have it all apart I want it done right.

Thanks guys

[Tx Firefighter]

If you have no problems right now, I'd pop the lid, swap the axles, brake clean it on the inside, and button it up with new synthetic fluid.

By the way, be sure to smear a bit of grease around the axle seals as you slide the new axles in place so they don't run dry initially.

[special-K]

I agree with TX.Did you just upgrade to hardened shafts?Just curious about the purpose of installing the new axles.You weren`t in there for any problems,right?

[LONGHAIR]

I am curious about the term "inner axles"?

[elkynova]

while you have the old axles out, spend the time and put new axle seals in. They don't take much time and are well worth not having to take it all apart again. If you have a posi, don't forget to add the conditioner, it will blend with synthetic as well as hypoid.

[lts70]

Tx Firefighter, Thanks for the advice, especially about the grease on the seals, I will be sure to do that.

LONGHAIR, I have always used that term to describe the axles, is it wrong?

special-K, I am switching my 70 from 6 lug to 5 lug to fit some new wheels I got for Christmas. And yes they are the hardened ones from summit racing , links below.

http://store.summitracing.com/partde...5&autoview=sku

http://67-72chevytrucks.com/vboard/s...d.php?t=318405

elkynova , I bought Valvoline Syn Power Full Synthetic 75W-90 Gear Oil and Lucas synthetic Oil Stabilizer Pure Synthetic that I use for my motor but on the back it says, " Adds additional lubricity and extra protection for any racing application; use in engines, transmissions and differentials". I figured I would go half and half. Is there a better option for Posi rearends?



Thanks Guys

[lts70]

How much capacity does the rear differential have? What ratio of oil to additive would you guys use? Would you use some thing else besides what I got for an additive or oil?

My shipping confirmation said I will get the axles today or tomorrow. I will be posting pics as I go.

[elkynova]

Hey there, When I rebuilt the rear end in my 69 blazer with the 12 bolt posi, I went to chevrolet and bought a bottle of posi conditioner. You just put the whole bottle in and fill the rest with your gear oil. The stock gear oil weight is 85-90. When using syn. make sure it is equal to the 85-90 viscocity. The bottle of additive was only about 6 ounces or so. Just fill the diff through the side plug until the gear oil is level with the plug and your good to go. Enjoy the posi, good luck....

[dirtball]

This is the additive you want to use. http://www.drivetrainspecialists.com...duct-5229.html Should be able to get it at your local GM dealer.

[lts70]

Thanks dirtball and elkynova, I will go get that additive at lunch. Will the 75w-90 I have work in place of the original 85w-90? Or do I need to get different oil?