Hot Rods Quick change Detroit Locker

I have what I believe to be an early Detroit locker for a quick change rearend the ring gear flange is much closer to center than most other diffs similar to the early ford banjo rears,it has 12 small ring gear attaching bolts and is 31 spline for the axles,thats why I don't believe its for early ford they were coarse spline weren't they?Does anybody know a way to determine if it is for a quick change and which kind?I originally thought maybe 9.3 Olds/Pontiac but the flange is way to close to the center for that.

 

Photos will assist those more knowleable than me.

 

Yes, pictures are required, but what you describe could fit the 3/4 ton based QC.
31 spline units were available.

 

I have an 80's vintage Winters stock car qc (what they now call their heavy duty rear). It has a 31 spline locker in it and I think it does have 12 bolts on the ring gear. Look on Winters web page,as they have good pictures of their products and still listed a locker the last time I was on their site.

 

last year's winters catalog. Does it look kind of like this?

 

Jim,

I think he is probably describing one of these, in 31 spline.

 

Yes it looks like the one you show gearhead,I'll try to get some pics of it today.

 

Here's some pics

 

Mine doesn't use a crosspin the housing internal is splined along with the external of the locker mechanism is that an early vs late thing?

 

It's not the earliest, but it is old. The real early ones look like this:

 

That early style one you show there looks like the internals of the locker they used in the old Eaton HO52/72 rears used in 50's/60's chevy and GMC 3/4 ton trucks except they use 3 pins instead of 4.Mine has splines on the same surface that has the pins on yours and the ID of the housing has splines that they engage.Does anybody use these in their builds because I'll never have one.

 

Technically, I think the one I showed is a 'No-Spin' insert. They replaced the differential internals with the cross and splined pieces. Available for several carriers, not just QCs.

The one you have is a whole assembly, made by what is now Eaton.
Generically, 'Detroit Lockers'.
They generally are loud, make some popping sounds and make the rear of the car feel twitchy. Kinda like it 'walks' around a corner.

But when you stand on it, it truly 'Locks'.

Don't know if it's still true, but it WAS the ONLY differential allowed in NASCAR cup cars. Occasionally, one would get the drive dogs disengaged during a pit stop and when the car was dropped it would just sit there. That's why you would see the crew guys pushing, just in case.
The only application I would recommend them for today, is a drag car that had to be driven on the street (occasionally)!

The TruTrac style is just sooooo much smoother.

 

I used a locker on my street/strp car for a bunch of years, defiantly made some noise, would scare passengers much to my amusement. Went to a Ford traction loc which works ok as long as both wheels have bite. Now a days my choice would be the Eaton Tru Trac. Ever think of how they make all those gears inside?

 

Yes,that is exactly what the old Chevy truck rears used it just replaced the spider gear assembly in the normal diff carrier.My old truck has a little plate attached to the dash that says it is equipped with a no spin differential.I've found if you let it coast while going around a corner it stays fairly quiet,but if you give it power it pops and jumps a little.So if it is based on the 3/4 ton rear is it the 8 3/8" or the 10" rear?

 

1938-1952 Ford 3/4 ton. The ring gear is 10" with 12 bolts. Also known as a Timken because they made them for other car manufacturers. I don't know if Ford made their own or not but I would think so.

 

Truth. I run those in my street cars, have run them in the front axles of my on/off road 4x4 stuff.

 

If the tru trac is a development of the gleason torsen diff then it can trace its roots back to the gleasman dual drive from the 50's,Ford actually offered it as a racing part in 1962 before they switched to the Detroit locker a couple of years later,actually saw one in a very early nodular case third member 30+ years ago at a swap meet.

 

Gleason TorSen for a Quickchange TorSen is short for Toque Sensing.


The TruTrac operates on the same principal, but the planet gears run parallel to the axle shafts. This one is a Dan Press (DPI) Gold Track. There are many others with different names and colors

I can't find a picture of this one apart, but have one on the bench. If anyone wants to see that. I can takes some pics tomorrow.

 

YES!

 

I used a DPI and had it machined to fit my Champ.

 

Yes, x2. I have not been able to get to mine yet, to see if I can swap gears, to run it backwards.

 

Here's the guts of a Stock Car Products TruTrac:


I tried to mock them up to show the interrelationship of the gears.
The ring gear and carrier rotate causing the planet gears to turn the sun (or axle) gears. Driving in a straight line everything rotates at the same speed. When you enter a corner the outside axle has to turn faster than the inside one. If you apply power the side gears are forced apart into the thrust plates in the end caps. Depending on the torque applied and the traction available, the torque is split proportionately between the axles.

DPI made these as standard, half tight, tight, and adjustable, which was a measure of how much preload was built into these units. This let the unit to be tuned for driver feel and rear tire stagger. Adjustable was not an 'at track' deal.

The unit that Lynn Pew posted above was narrowed to fit in a Halibrand case with the H852 adapter side plates. Halibrand made these originally, I reproduced them in both 11 and 12 bolt variations.

These TruTrac type differentials can be cut enough to fit with a narrower (3 3/4") Frankland type center section.

 

Gimpy,

You can definitely swap the gears side to side. The question I have is, "Does it make a difference if the gears try to push inward as opposed to outward?"
The surface area is the same either way.

 

@Pewsplace,
Did the ring gear bolts interfere with the side plate? They look quite long. There are shorter bolts available, and the latest ring gears are threaded so the bolts go thru from the back side.

 

I am trying to wrap my head around potential thrust wear issues.

I am going to swap mine. I don't want to have to take it back apart, and do it over later.

 

YES, makes a difference. In tractor pulling the guys tried to run the rear ends backwards and when the pinion pulled in the backlash would go away and turn into the gears binding; sucking up all kinds of power and sometimes breaking the carrier.

 

I don't think the planet gears work by side thrust but by binding in the bores they run in. More load, more bind, more drive to that axle but shouldn't let the other axle over speed because the planets are tied together..Tractors had the same arrangement and worked very well until the planet bores wore too much for the Planets to bind, straight cut gears though [cheaper] but same principle. My tractor was the same stacking of gears but the planets didn't fit in bores but had their own axles. Worked by load/binding also but because the tooth mesh was purposely made not smooth.

 

I am not planning on running a standard ring and pinion backwards.

I will be using a reverse rotation ring and pinion.

The plan here is to swap the sun and planet gears in the carrier, so they are turning the intended direction, in my application, instead of backwards.

 

I am certain that they would work fine, even in reverse. I am just concerned about the bevel in the gear pushing the planets and sun in the opposite direction from intended, applying thrust where it may not necessarily be intended.

I might be over-thinking it, but it looks like swapping left for right won't be a huge challenge.

 

Seb,
I wouldn't argue with you, but I have probably had close to 100 of these apart. The only wear has always been on the end plates. Never any sign of wear on the bores for the floating planets.

The DPI adjustable units had screws that preloaded the plate into the planet gears. Different manufacturers used different helix angles on the sun and planets. That tells me that they were trying to optimize the end thrust.