From n9ads@juno.comThu Apr 24 07:34:01 1997
Date: Mon, 21 Apr 1997 15:44:24 EDT
From: Howard R Pletcher

Subject: Lock-O-Matic Hubs

A little clarification on how Lock-o-matics work--there are about 8 rollers inside the round hub body that are forced out against the body by a large "nut" on the end of the axle shaft. When the shaft turns, the rollers are wedged against the outer body by the points of the "nut". This works equally well in forward or reverse and the only parts to wear are the nylon "friction shoes" that ride on the smooth wheel bearing lock nut. This wear occurs whether you are in 2WD or 4WD. The only unlocking that happens occurs momentarily when you are shifting from forward to reverse and back (unlike some of the semi-automatic hubs that were around in the 80's that really mechanically unlocked when in reverse). They will release if you lock up the lock up the back wheels on ice or going downhill--there is no engine braking effect when the auto mode.

You aren't likely to wear out the locking mechanism (the rollers), but because the rollers are forced out against the outer body, you could explode the hub body if you were spinning the wheel on ice and it suddenly hit bare pavement, etc. I did break one once when it felt like the hub didn't engage immediately and the grabbed after the rear wheel spun a little--just on wet grass, nothing violent.

In a previous discussion here, someone said they had been plowing snow for years in the auto mode, but I'd say they are lucky--or very careful.

I think I looked it up and about 30% of the 74's had the Dana 30's--they all did have disk brakes and were even shown as 44's on the lineset ticket because this was an unplanned substitution when Dana couldn't keep up with the 44's. The 44 was standard for '74--look at the literature and you won't find the 30 (or FA-13 as IH called it) listed at all for '74 and the substitution occurred most of the year. I had one built in April and it got a 30. Production of the 74 model ended in June. There is one difference in the 30's with disk brakes vs. drums--there are (I think) 8 bolts holding the calipers to the knuckle vs 6 with disk brakes--at least these are the numbers I seem to remember from long ago. If you wanted to convert an axle rather than do a swap, you'd have to change the knuckle too.

When the GVW was raised in 75, they did drop the lightest rated springs that had been available. You could purchase an 6200# GVW at any time, it just became the standard in 75.