Base Model Rear Locking Differential

[Rocketeer Rick]

I would also advocate for a mechanical LSD front, depending what becomes available, for folks that don't opt for the Sasquatch package on the trim levels that don't otherwise offer the front locker. To me, that might actually be more useful then one in the rear, especially if a buyers does choose the rear locker. That too makes a good combination.

Sponsored

 

[Rednek]

hopefully powertrax or eaton will make a locker for the m190,way cheaper to just put in place of pinion and side gears then replace carrier.

 

[Austin26]

My $0.02 - the fundemental differential will absolutely be different between the open and locker; they will be different differential carriers, made from different castings. My perspective comes not only from being with a manufacturing company, but one that actually builds differentials (though not these diffs).

The open diff is a very simple mechanism, and will have a very pared-down carrier. It'll be just enough to get the spider gears into it and have the needed strength for the axle's rating. Anything more than that adds cost, and Dana will be building 100s of 1000s of these a year, since they sell them to other customers than Ford. There is no need to add anything not required, and they're doing enough volume to justify different tooling needed to make different versions.

The locker, OTOH, will need a carrier that has unique features that open won't have - it'll have to accommodate the magnetic coil that actuates the lock, it'll have to have provisions to the lock's dog clutch, and it might even a different set of spiders gears to make room for the other stuff. So it will absolutely be a different carrier than the open model. And it goes without saying that if the diff carrier has to accommodate all those parts, it has to have those parts too. That is all extra cost that would only be added if needed.

Again, at the volumes that we're talking about here, making different versions is no big deal. They will need multiple sets of tooling to meet the overall volume anyway, so its no problem to make them different.

Where they might have a common link is the outer carrier, the "pumpkin" housing that contains the diff and ring & pinion. This is likely to be a common casting, with the only machining differences being a port for the e-locker's wiring. But that doesn't buy you a lot if you can't remachine it yourself to allow for an aftermarket wiring harness.

So, short version: if you buy a truck with the open diff, you will have a stictly-speaking open diff. It will not be able to be turned into a locker with just some wiring.

Thanks for the detailed response. Would the base open differential allow for a LSD / Torsen in the aftermarket?

 

[Rocketeer Rick]

It would, but as I've noted in a couple places, the hang up with be with the ring & pinion gearing. On open-diff equipped axles, the ring is welded to the diff case (instead of the traditional bolts). So, installing the LSD means replacing the ring gear with one that can be bolted to the aftermarket LSD (no aftermarket company will expect you to weld on, I promise). But ring & pinion gears are almost always mated for life, so replacing the ring means replacing the pinion too.

This is all very do-able, but adds cost and complication to the install. So, for that reason, locking axles will actually be technically easier to swap diffs into, even if that might mean you'd sacrifice the locking aspect of it. In a perfect world, someone clever would introduce an LSD that also retains the OEM lock feature. Then you have all of usage cases covered, though such a diff might be a tricky package to design.

On the other hand, if you had a notion of regearing the axles someday anyway, well, the diff swap will be the perfect time to do it... But either way, I'm certain that aftermarket gearing will be available to support the aftermarket diffs that will also eventually show up.

 

[Austin26]

Thank you for the response @Rocketeer Rick . I understood most of what you said though still struggling with how or why one would weld instead of bolt. Only differential experience I have is replacing a Ford 7.5" solid rear with 3.27's, with a Ford 8.8" rear with t-lok and 4.10's.

 

[Rocketeer Rick]

Thank you for the response @Rocketeer Rick . I understood most of what you said though still struggling with how or why one would weld instead of bolt.

Its pretty simple, really - cost savings.

For starters, the time to install the ring gear on the assembly line is reduced, since there's no need to place 10 bolts in place, run them down, and then torque them. There's no line fall out if one or more bolts fail to reach torque properly. That's all replaced with a few seconds of having a weld laser pass over the part. Tied to that, there's no need to continuously buy bolts and threadlocker (probably pre-applied to said bolts). There's also a minor savings in materials on the diff case itself, since the ring gear flange can be made smaller. So, the casting is cheaper, theoretically the finished part is cheaper. Though, in my experience, adding a laser weld requires complex, tightly toleranced machined features to provide exactly the right shape for optimized weld penetration. So, that'll probably offset some of the savings...

But all together, that theoretically generates a noticeable cost savings in producing the axle assembly. When you multiply that 100s of 1000s per year, it all adds up. That's the same reason why automakers make all sorts of other seemingly stupid minor changes to their products that we all bitch about. A few bucks here and there adds up to very real money in high volume. If that complicates service or aftermarket upgrades post-purchase, well, so what? Such is the way of the industry, I'm afraid.

 

[Austin26]

@Rocketeer Rick what is welded to what exactly? Is the open differential of the base similar to the "old" style which is ring and pinion with spider gears to turn the axles? Or can you share photos or links to an article? Not sure if I'm being dense today or my brain is mush from a math test today.thank you.

 

[Rocketeer Rick]

The basic configuration of the differential is same as it ever was. As you noted, this is similar to a conventional arrangement, where there's a ring gear attached to the diff case, and inside the diff case, spider gears mounted on cross-shaft are used to drive side gears that in turn, rotate the axle shafts. So, torque is transferred from the ring gear to the diff casing, then from the casing to the spider gears, and then through the side gears to the axle shafts. None of that changes. What has changed is simply the method of how the ring gear is attached to the diff casing.

This is a representative image that I found on google. Basically, instead of having those bolts that are shown here being torqued down, there is a weld where the flange (which is shiny here) and the ring gear (which is dark colored) are butted together. Looks like this (this image comes from EMAG, manufacturer of laser weld machines):

That is what is different between the open and locking versions of the Ranger & Bronco axles.

 

[Hey19]

The ring gear is welded to the carrier for a weight savings from what I’ve read on the Spicer Dana site. It’s a minor savings but it all adds up.

 

[Austin26]

And to add, say, a Torsen one would need what?

 

[Rocketeer Rick]

OK, so when the ring gear is welded to the diff case, it is a permanent fixture on that diff. So, to install another differential, you also need another ring gear too. I found this image, again, on google:

The catch here is that the ring & pinion gears are matched sets (at least normally). They're married for life. So, not only do you have to replace the ring to facilitate the diff swap, you also have to replace the pinion, because they're a set. What's more, installing a fresh ring & pinion set requires proper set up to get the meshing correct. This is done typically with shims under the pinion head and shims next to the diff case bearings, and the process to do it requires a bit of experience and skill.

So, that makes the swap a bit more complicated and costly then just a simple diff swap would normally be.

 

[Austin26]

OK, so when the ring gear is welded to the diff case, it is a permanent fixture on that diff. So, to install another differential, you also need another ring gear too. I found this image, again, on google:

The catch here is that the ring & pinion gears are matched sets (at least normally). They're married for life. So, not only do you have to replace the ring to facilitate the diff swap, you also have to replace the pinion, because they're a set. What's more, installing a fresh ring & pinion set requires proper set up to get the meshing correct. This is done typically with shims under the pinion head and shims next to the diff case bearings, and the process to do it requires a bit of experience and skill.

So, that makes the swap a bit more complicated and costly then just a simple diff swap would normally be.

Thank you, again. I did look up terms like welded differential before asking but only got search results of goobers permanently locking their axles ha.

I want to say I paid $600 for a proper ring and pinion install and I swapped the differentials out. That wouldn't be terrible though the same would be needed for the front.

 

[grimmjeeper]

The "Lincoln Locker" (welded spider gears) has been around a long time. So that comes up with most "welded differential" searches. Welding the ring gear has been around a long time as well but it's not nearly as common in the automotive axle end of the industry. If you search on "welded ring gear" in your favorite search engine, you'll get better results.

Beyond that Rocketeer Rick has pretty well covered the subject and I don't have much to add beyond what he's already said.

 

[Rocketeer Rick]

Thank you, again. I did look up terms like welded differential before asking but only got search results of goobers permanently locking their axles ha.

I want to say I paid $600 for a proper ring and pinion install and I swapped the differentials out. That wouldn't be terrible though the same would be needed for the front.

Well, the same would be needed in the front only if you are either A) installing an LSD up there too, or 2) you were changing ring & pinion ratios, so both axles need to be changed to match regardless. But if your interest is simply installing an LSD in one axle, while keeping the same ratio you already have, then there is no need to dive into the other axle as well.

 

[CarbonBronco]

I plan on adding a Truetrac lsd to a base.

after owning a Detroit tru trac and currently on a Auburn Posi in my rig they both work great but have their limitations. they are both not rebuildable due to internals on both of these posi's. The tru trac failed on me after 4-5 years of mixed use. the worm gears were toast. currently the auburn unit is doing ok and the only exception is that i have to run/add friction modifier in the 3rd member. besides that its been good so far.

Sponsored