Rear Differential Fill Question - M1009

[cmroles]

I just changed the fluid in my rear differential. According to the LO the rear 10-bolt should take 5.4 pints of 80/90. I got almost, but not quite, 5 pts in before the new GO started coming back out of the fill plug. At this point its closed back up, but am I going to have problems if I leave it filled to the bottom of the plug-hole?

I know most people say to leave it 1/2" or so below the plug, so I'm just curious if I've created a potential problem.

Thanks

 

[mistaken1]

Isn't there a special additive for the posi that needs to be added as well?

 

[cmroles]

Isn't there a special additive for the posi that needs to be added as well?

The LO only specifies additive for the front differential on M1031 and M1028. Doesn't say anything about the M1009. I could be wrong though.

 

[DokWatson]

Gov-bomb differential doesn't use clutch packs like a regular limited slip, no additive required.

Its supposed to be filled up to the fill hole. Axles have breathers, you can't hurt it by 'overfilling' it.

 

[Westech]

I just fill it up till she blows .. let it drain out till its just at the top of the fill. Plug her and go.

 

[mistaken1]

Gov-bomb differential doesn't use clutch packs like a regular limited slip, no additive required.

I did not know that. Thank you.

 

[cmroles]

I just fill it up till she blows .. let it drain out till its just at the top of the fill. Plug her and go.

Perfect. I was just worried that I'd damage by overfilling.

The truck only has 26,000 miles on it, and the gear oil that came out looked like vintage 1984...

 

[gvaneck]

I need to drain out my rear fuild and i was wondering what gasket I should get for the m1009 and if the front and rear seal is different

 

[Blue2actual]

I need to drain out my rear fuild and i was wondering what gasket I should get for the m1009 and if the front and rear seal is different

I JUST did this to my 1009- the front and rear have different seals.

Front-Gasket GM# 458860
Rear-Gasket GM# 26016662

I went to Oreilly's and gave them the GM numbers and they had them in stock...hope this helps.....

 

[DokWatson]

I need to drain out my rear fuild and i was wondering what gasket I should get for the m1009 and if the front and rear seal is different

I use black RTV

 

[gvaneck]

Thanks for the help guys

 

[ChiefMinion]

Front Rear Differential Gasket

1986 M1009

If it helps anyone, the Fel-Pro gasket numbers for the axle housings are:

Front: RDS 55075
Rear: RDS 55028-1

Note that when I walked in to NAPA, and asked for the front gasket, their computer specified the rear. Not a problem since I needed a rear anyway. They are NOT the same.

 

[ryan77]

Most gear oil has the additive in it! look on the bottle unless you get the cheap stuff like costal, valveoline at autozone has it in it.

 

[idM1028]

Yep, love the valvoline. Mostly because I can use it in the rear AND the front of the M1028
You shouldn't have any problems with overflowing. I just changed out my front and rear diff fluid. I've always just filled up my fluids till they start pouring out the fill plug and have never had a problem.