On a 26 how much oil should be in the diff, level with the bottom of the fill plug or?
Ford recommended a third of the diff housing filled, so on post '18 axles with the lowered filling hole, filling to the edge of the hole would be about right.
What is correct way to check oil level ? I stuck little finger in to check mine and began to panic when it got stuck. Will never try that again!
With the low fill hole you shouldn't have to put in the little finger deep enough to get stuck, just an easy touch inside should tell you if you have enough.
I haven't tried to check the level in an older axle with the hole halfway up, but if you don't want to push in your finger down 1-1/2" to check the level, then maybe a bent piece of electrical wire could be used as a dip stick?
You don't need much. That ring gear is pretty close to the bottom of the housing. In addition, how would you like oil running out you axle tubes?
I have a rebuilt diff with the modern replacement type axle seals. On a good long run, 90 miles or so the left axle seal starts leaking along with oil dripping from the axle tube rivets near the differential housing.
Wondering if too much oil could be the cause ? particularly at high speeds....(Well high for a T)
I have filled the lube until it runs out the fill hole.
From the 1926 owners manual:
What about Lubricating the Differential?- Answer No 104
Do not make the mistake of putting to much grease in the differential housing. The housing should not be more than one-third full. The differential is supplied with the required amount of lubrication when the car leaves the factory. The oil plug should be removed about every 1000 miles and more grease added if necessary. If a fluid grease is used the level should be approximately one and one-half inches below the oil hole.
Henry usually had all specs right, but an 1-1/2" below the hole will only have about 1/2" of lube in the bottom, not in my world!
Good axle seals and fill to the plug hole.
Going through owners instruction books, yes the high plug is 1"to 1-1/2" below the plug but our Canadian T's dropped the plug height in 1915 and fill to the plug. That 1926 answer No 104 would be the failure to up-date for the plug change.
That's one of the few mistakes in the Ford Manual - the 1/3 full bit is correct, but the 1-1/2" below the fill hole remark came from the days in the teens when the fill hole was half way up at the RH housing.
Doubt you need much oil in the differential as long as the ring gear is dipping into it. I expect those teeth are doing a fine job of slinging what is there all around. I made up a little wire gauge that lets me fill the rear to 1" below the filler plug on my early cars and have never had an issue. I do have to check it frequently as I do not want it to fall below that level. On my later cars I fill to 1/2" below the plug.