OK Gurus, I am about to build my 57 Ford 9". I have already narrowed it and finished the suspension out, so it's time to put it back together. I am thinking it's a good idea to go back with 31 spline axles, since I intend to replace just about everything anyway. Am I correct that the 28 spline carrier has a smaller ID through the center than what I will need for 31 spline axles? Thanks!
You are correct that the carriers are different, but don't go scrounging for a 31 spline carrier, bore the 28 spine unit out to fit the 31 spline axles. I have done far to many, and there is no problem in doing it.
Bearing size is different for the carrier bearings on 28 spline and the "bigger" 31 splines...pretty sure the carrier is the same...but the housings (drop ins) would be different.
The smallest sized 28 spline bearing can be bored out to the 31 spline size, the factory did it themselves.
I plan to drop in a Power Trax Lock-Right. That replaces the side gears, so I can order the 31 spline unit. Drive Em, What do you use to bore the hole? Machine shop, or simple trick? I'm also wondering if my early open diff housing is a 3 spider or 4 spider, and does it matter? I can get an empty diff for $100, but added to the cost of a Lock-Right and I might go with a Detroit Locker. Thoughts? This is what I am asking about... I.D. where the axle p***es through to mate with the spider gear.
LM501349/LM501310 or LM102949/LM102910 depending on the OD/ID needed for the carrier bearings. If it's on an original chunk and carrier, you can match with common bearings. Two tools needed, calipers and a bearing spec book. The carrier bores are smaller on the 28 splines carrier and can be bored. Downside, I've seen 30 spline 10 bolt Chevy carriers using the same part number carrier bearings having the ring gear side of the carrier break off in daily driver pickup and van applications. I haven't seen it on a 9" Ford yet. Somebody told me an 8.8" carrier will fit and bolt up to everything correctly into a 9", haven't seen anybody trying. Some 8.8's have Trac-Locks from the factory, and some good aftermarket stuff is available. I'm curious.
If you want a Detroit Locker and know how to drive with one, do it. The original 4 pinion spider diff's were the strongest factory stuff. If you're going to buy a used carrier, don't lay a penny down until it's split apart to inspect for wear. Even with Ford's original Trac-Locks, combined with mud and beer, the carrier halves are bad to wear out between the axle gears/thrust washers/halves. Ford quit installing 9" rearends in 85/86. And today it's 2008. Dirt trackers, drag racers, and hot rodders have made a dent in supply of OEM good and good used stuff.
I hear you. There are several dealers that have new cases, w/o spiders, etc for $100. With the the latest Lock-Right, that get's up close to $600, so now I am wondering. Everywhere I look, I see cases for mid 70's on up, but no mention of these very early units. It makes me wonder if it's good for anything. It's in good shape, but I won't do much good with an open diff.
I just put in a True-Trac carrier in my 9" it uses gears instead of clutches, it Acts like a locker but is smooth like a clutch posi. No clanking or hoping around corners but when you get on it posi all the way.
I stick them in a lathe and bore them. FWIW, I have been doing this for 20 years and not one of them has ever broken.
$600 is close to buying a complete carrier with a warranty instead of some new will-fit stuff. I know Lock-Rights work, but why not buy a complete carrier for a few dollars more? The Detroit True-Trac diff works very well also and is very streetable. If anybody remembers, it used to be the Gleason Torsen torque sensing differential. Neat for rods and even very good for 4x4's too. You can also buy a new clutch type Trac-Lock diff for about the same money. Pick your poison.
I need to price out a few options, but all of the complete units I've seen start at $800+. I like the True-Trac and the Detroit is legendary, but bang for the buck is in the Lock-Right. I don't know that I will ever get enough traction to hurt any of these. I have about 430 hp planned, but at 2400 lbs on skinny tires, it isn't likely I will ever stress anything I use.
We have a winner! The True-trac is readily available for just a few bucks over the Lock-right, under $500. It uses it's own carrier rather than replacing the internals of an open carrier, It's about $100 or so less expensive than a detroit locker and advertised to run smoother/quieter. I'll let you know if I run into any install issues. The only question remaining is that there seems to be potential that my '57 case may have odd sized side bearings. I'll be home to measure in a couple of weeks. Thanks guys!
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