Differential Oil & Flush Questions

[motive]

The Shop Manual says to drain and flush the differential with light engine oil before re-filling with new gear oil and not to mix different brands of gear oil. Since I'm draining and replacing the oil, the mixing issue is not my concern, but just for information purposes, does this still hold true for modern hypoid gear oils, or is it an old recommendation from a time when the old gear oils each had "special additives" that might not have been compatible.

But the manual doesn't say what is involved in flushing it. I was planning on dropping the drain plug, letting it drain until most everything has dripped out, then squirting some 10W30 motor oil in through the filler hole and letting it drain out, then replacing the plug and filling it with new oil. It won't be much of a flush, but would it be sufficient? Any advice will be greatly appreciated.

Mike with Speedster

[Guido]

I don't have much experience with Studebaker rear axles, but when I was fooling with tractors I used kerosene to clean out transmissions and rear ends. Before embarking on using this method, wait for some others to respond. There may be issues with a limited slip differential as well as seals.

Guido Salvage - "Where rust is beautiful"

1946 M-16 fire truck
1948 M-16 grain truck
1949 2R16A grain truck
1949 2R17A fire truck
1955 E-38 grain truck
1957 3E-40 flatbed
1961 6E-28 grain truck
1962 7E-13D 4x4 rack truck
1962 7E-7 Champ pickup
1962 GT Hawk 4 speed
1964 Avanti R2 4 speed
1964 Cruiser
And various other "treasures"
Hiding and preserving Studebakers in Richmond & Louisa, Va.

[DEEPNHOCK]

What you need to do is go to your flaps and get a new cover gasket.
Remove the cover (drain pan at the ready_ and let it drain overnight).
If you let it drain overnight, you shouldn't need to flush it, unless you have metal floating around in there, which means you should look further and fix it while it is open...
Scrape and prep both the gasket surfaces and using a high quality gasket sealer (Permatex Ultra-Black) put a small amount on the mating surfaces and install the cover....
...A small amount means a small bead run around the outer edge of the gasket that is 'smoothed' with your finger... It does NOT mean a 1/4" bead that squeezes out when you tighten the cover bolts. Remember... If you are squeezing silicone sealer 'out'...you are squeezing silicone sealer 'in'...and that is bad news..
Reinstall the cover and let it set overnight.
Re-fill with good differential lube (and Twin Traction additive if so equipped)...
Do it right and you will have a dry and clean pumpkin.
Good question!
Jeff[8D]
DEEPNHOCK at Cox.net
Ocala, FL.
'37 Coupe Express
'37 Coupe Express Trailer
'61 Hawk

http://community.webshots.com/user/deepnhock

[Sonny]

What Jeff said, but I wanted to add, do NOT use ANY solvent based cleaner/oils/whatever to clean inside the rear end, unless you're in the process of totally rebuilding it. IF you use a solvent based cleaner, (diesel fuel, mineral spirits, etc.), you WILL be rebuilding it, (trust me [:I])!

I use fresh El Cheap-O gear oil, thinnest you can find, squirted into the gear sets after it drains all night, run your "magnet on a stick" through the bottom of the housing, wipe it out thoroughly, (especially digging in under the ring gear where all the metal sits), with as lint-free cloths/towels as you can find. Refill with Red Line gear lube for posi-traction rear ends, ("open" rear ends benefit from using the Red Line posi grease too).

Oh! You can forget using high pressure air to "get into/clean all those little hidden corners) too. It's not necessary, a rear end needs just a drain, wipe and flush, be gentle back there! (Hey, that sounds familiar.... D'oh! )

Oops! Almost forgot, and it seems like like a small point, but one many get wrong. The vehicle MUST be sitting on the ground, (or in it's normal stance, with the suspension "loaded"), to correctly refill/check the gear lube! Yep, most everyone over fills the rear end 'cause they fill it on the jack/jackstands, with the ass-end sticking up in the air, which means that you'll probably be replacing, (at least), the pinion seal soon too, (too much gear oil over-pressurizes the rear end, gears beat the oil into foam too)!

Sonny

http://RacingStudebakers.com

[blackhawk]

quote:do NOT use ANY solvent based cleaner/oils/whatever to clean inside the rear end, unless you're in the process of totally rebuilding it. IF you use a solvent based cleaner, (diesel fuel, mineral spirits, etc.), you WILL be rebuilding it

Hmmm... I am curious. Tell me more. I just drained the TT differential and transmission on my '64 Cruiser and flushed them with kerosene. I've done this before on other studerbakers and never noticed a problem afterwards. Dale