The Stovebolt Site Forums The Shop Area Driveline 50 3/4-ton Positraction or Locker

I see from the scanned pages of the 1959 Truck Shop Manual Supplement that Positraction was first available in 1/2-tons without 4 wheel drive that year. What was the first year it was available for 3/4-tons (with the Eaton HO-series)?? I want to improve the 2WD traction in snow, ice, mud and sand of my 50 3600. Should I look for a later-year third member with posi (as well as 4.10 gears) or try to find a locker? Randy's R&P used to sell a Detroit Locker for that axle. Is a locker better for overall driving, including dry pavement cornering or is it more suited for high-performance applications? Thanks!

Some of the later years H052/72 had a "No Spin" option, which was really a Detroit Locker. It is possible to install a locker from a 14 bolt into your diff. You have to use the 14 bolt axles and spider gears and may need to cut down the length on the axles slightly.

The No-spins (17 Spline) actually make driving in ice a little more interesting. If the truck doesn't go forward then the rear goes sideways. I too am looking for a No-spin differential, but in the 5.14 flavor rather than the 4.10.

As for installing a Detroit locker, (30 Spline), requires the 14 bolt shafts to be cut down or I can cut you a spacer to shim them out. Cutting down the splined portion of an axle shaft compromises its strength much more than people realize. You just need the 14 bolt detroit itself as it will replace the stock spider gears inside of your currently open carrier.

On dry pavement its usually not noticed unless you dog the throttle while turning. If you do, it will give you some tire chirp. Another thing that they are known for is the detriot "bang". If the locker is loaded partially engaged, you can sometimes get a spring back action as the locker teeth seat in place under load and the rear of the vehicle will shift side to side fairly hard and you will hear an audible BANG from the rearend.

Thanks for the responses. After I posted this I did a search for "locker" and got about 100 hits with lots of good info. I also did some other internet research including on www.eaton.com. Apparently lockers have gear teeth that engage (and disengage) rather than clutches. Others have warned that traction on ice may not be as good as with an open diff.
This is my goal: to make the 50 3600 my year-round daily driver by the end of this summer - including the Wisconsin winters. So traction in snow is my primary concern.
Other comments?
Thanks!

More research on the net including other truck forums: the consensus is that the only traction aide available for the Eaton HO52/72 axle as used in Chevy and GMC trucks from 47-72 was/is the NoSpin/Detroit Locker. Available as a factory option from 60(?) to 72 and in the aftermarket. Eaton owns the Detroit Locker brand now and ones for the HO axle are no longer manufactured. There's lots of discussion about using a Locker made for the GM 14-bolt, as mentioned above, but the 30-spline axles have to be modified...
Oh, well. Thanks for the comments.

I put a "locker" in my ford. I say locker but it does unlock on dry pavement. It has gears rather than clutches.

It's an after market thing which I got from Randy's ring and pinion.

It works well and the little clunk it makes sometimes when going from reverse to forward is of no bother because I understand what it is.

When on grass it stays engaged so turning will chew up the grass a little.

I like it and it only took 45 min. to install.

With both wheels turning your rear end would get a little loose on slippery pavement though, but hey, so does my Corvette with a factory installed posi.

Dan

Your better bet would be to find a 14 bolt rear end with a limited slip center section. Those are EASY to find in the 4.10 gear ratio. You may need to get it narrowed, which a hot rod shop can usually point you in the direction. Its a shame you aren't closer to me as I have a friend who narrows axles and does a very good job for very cheap. Moser can respline shortened axle shafts for about $75 each.

Another option though to running the 30 spline 14 bolt detroit is to simply have a set of custom shafts made of the proper length. There are plenty of aftermarket companies that cut 14 bolt shafts for aftermarket applications.

Here is a link to some 14 bolt information. A Cab and Chasis DRW housing could be used at 63" WMS and will yield you a narrower axle closer to that of the current Eaton.

http://www.pirate4x4.com/tech/billavista/14b_bible/index.html

Thanks for the link Alexj. Lots of info. Thanks for the other responses.