Final Drive(s) Drain and Refill

[TallCoolOne58]

Working my way down my list, with the last stretch of warm weather last week I decided to pull the final drive pans, replace the pan gaskets, and refill with fresh 80W-90. Ordered the gaskets from TM, bought a gallon of gear oil (finally smartened up since between the trans/diff and final drives you're talking close to a gallon anyway, and much more cost effective) on sale, and a tube of black permatex. After gaskets arrived, out to garage I went.

I was a little apprehensive due to some of the horror stories here (pans full of dirt etc.) but all went well. The old gaskets had obviously been seeping for some time as the pan bolts were filthy. With drain pan in place, and latex-gloved hands, I removed each one (side bolts first) I made sure each one had a lock washer, and dropped them one by one into a separate container for a kerosene 'bath'. My prior experience dropping tranny pans as an auto tech came in handy, as I knew what to expect when the pans started to drop. Front bolt next, slowly, and sure enough the pan began to separate from the bull gear housing. The key is a controlled separation to minimize the mess. I let it drain to the top of the pan level, then removed the front bolt. Removed the rear bolt very slowly to let most of the oil drain out of the pan, then removed completely with one hand holding the pan.

The old fluid was surprisingly clean, about what you would expect after 1 season of use. The old gaskets scraped right off, and I used a wire wheel to clean up the pan flanges that the gasket rests on. Washed the pans in kero, wiped dry. Wiped outside with acetone, primed and repainted IH Red. Gave the paint 24 hours to dry, then a thin layer of black rtv on pan gasket surfaces. Assembled gaskets on pans, started each clean bolt with lock washer in each hole, then torqued down each bolt in a criss cross pattern, to tighten evenly. I like to use a nut driver for gaskets that really don't require a torque spec. The object is not to crush and distort the gasket which is a guaranteed leak, but to compress it. A nut driver helps prevent overtorquing, versus a ratchet.

I let it set for 24 hours (per the rtv tube instructions), and refilled both sides. No leaks, no seeping fluid, even after a test drive. One more thing off my to-do list, and the satisfaction of knowing it's done and done right. I like knowing what I got underneath me.

[BigBill]

I often wondered why IH engineers didn’t put drain plugs on the final pans. They could of used flush hex plugs. And made the filler access plug larger.

When I worked for the engineering group the new fresh out of school engineers worked with me. The first thing I taught them, when designing something think of the mechanic who has to work on it, make his job easy.

[TallCoolOne58]

I often wondered that my own self, BigBill. Sure would have encouraged more maintenance in this area. As it is, it's a messy tedious pain in the neck.

[IHCFan1950]

I often wondered why IH engineers didn’t put drain plugs on the final pans. They could of used flush hex plugs. And made the filler access plug larger.

When I worked for the engineering group the new fresh out of school engineers worked with me. The first thing I taught them, when designing something think of the mechanic who has to work on it, make his job easy.

I honestly don't know why you couldn't modify them to have drain plugs. Just drill a hole in the bottom the right size, tap it to the correct thread pitch, and there you have it. I know the pan metal is a little thin, but it may be worth experimenting on a "scrap" pair.

[John *.?-!.* cub owner]

I think IH did that for 2 reasons. 1 was price, and second was reliability. A drain plug sticking down that close to the ground would prone to being damaged or knocked out in actual farm work which is what it was designed for. A boss to allow the plug to extend inside the pan would require the pan to be lowered to give room, the gear runs very close to the pan.

[BigBill]

When I restore the finals I’ll make changes. I like to change gear oil often.

[JimCub48]

Welding, brazing a short nipple to the bottom of the pan to accommodate a plug would work so your plug would not interfer with the gear. One could also weld, braze a buffer shied to protect the bottom of the pan. I think it is duable.

[TallCoolOne58]

A quick drain and refill with an occasional pan gasket replacement when necessary would sure be a heck of a lot quicker and more convenient, as well as reduce down time.

[Larry in WNY]

Put the drain plug on the back curved side to protect it and raise the front end to help it drain.
Larry

[Mrblanche]

When I worked for the engineering group the new fresh out of school engineers worked with me. The first thing I taught them, when designing something think of the mechanic who has to work on it, make his job easy.

I have a brother-in-law (well, ex-) who was a maintainability engineer for a large computer company. Yes, such a thing actually exists.

[SDiver40]

When I changed my drive fluid on the super A, I installed some drain plugs. The long bolt was just for holding until I got everything welded.
Afterwards I used 1/2 oil pan bolt with Brass crush washers. It's never leaked and dont stick out much at all.

[Slim140]

When I changed my drive fluid on the super A, I installed some drain plugs. The long bolt was just for holding until I got everything welded.
Afterwards I used 1/2 oil pan bolt with Brass crush washers. It's never leaked and dont stick out much at all.

One thing I see wrong with that is all the metal shavings, dirt, grime, etc will settle in the bottom and it looks like it’s about 3/4” from the bottom of the nut to the bottom of the pan.

If you take them off and clean them you get everything out. How often does the oil get changed there anyway, when someone has a bearing go bad or fixing a leak? Realistically, I’d bet one of those two scenarios.

[MilGunsmith]

Any difference in doing the change on a Lo Boy? I have a 55 and I don't think it's ever been done. Need to do the brake bands also.

[staninlowerAL]

Because the LOBOY finals are rotated, the oil is sitting in the lower half of the pan. Makes a super mess when you drain it unless you have prepared to catch it in a drain pain.

[BigBill]

If you use a 1/2”-20 fine thread nut then a 1/2”-20 drain plug will work with the copper washer. If there’s room between the bull gear and the pan maybe a magnetic drain plug will fit.