Transfer Case Technical Discussion

[Laminar]

Yeah... true, was trying to avoid the super long explanation.

You aren't going to find automatic locking hubs on modern off-road vehicles, just not reliable. On pickup trucks and especially heavy duty trucks, yes, you will still find locking hubs. But off-road vehicles have all gone to FADs or just leaving the axle in neutral in the transfer case.

Is the Raptor not an off-road vehicle?

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[NC_Pinz]

Not sure what the love affair with lockout hubs is. I've had a few very reliable, old school rigs that had no lockout hubs (auto or manual). One less thing to go wrong or to explode when you put too much power through it. I've got one with lockout hubs in my garage. They are fine, work fine, but I can't say I look forward to disassembling if I need to do front brake replacement or repair...not that I do that very often.

 

[RagnarKon]

Is the Raptor not an off-road vehicle?

It is an off-road oriented vehicle but it definitely should not have auto locking hubs in my opinion. I actually thought I remember reading they removed the locking hubs in 2022, but I didn't bookmark the article so can't say for certain.

Either way. The IWE was one of the most common failure points on the F-150... so common that many companies sell kits to permanently lock the hubs. I could see the need to include locking hubs on the "normal" F-150 so they can meet their fuel economy targets, but definitely shouldn't be on the F-150 Raptor.

(Obviously just my opinion.)

EDIT— Seems like the locking hub was removed on some 2022 F-150s but not all. Don't know about the Raptor.

 

[Mattwings]

The modern equivalent of disengaging the hubs is disengaging the hubs. F-150s have had vacuum hubs for decades and the latest generation swapped to electric actuation, but they still disconnect the hubs when 4x4 is off. As has been mentioned, these frequently cause issues, but when they're working they're nice.
I am going by the initial development of the case and the terrain management modes. That was developed for the Raptor and was at least partially carried over to the Bronco.


Link? The Raptor has dual engagement - clutch pack for 4A operation plus a locking ring for locked 4H operation. This is unique to the Raptor TC.

The 4A F-150 transfer cases all have a clutch pack only, which can overheat with extensive use and can slip if its torque rating is exceeded. The non-4A transfer cases just have a locking ring so there's never any slip.

The info in this thread on the Bronco's 4A case made no mention of dual engagement style like the Raptor:

I wasn’t aware of the “locking “ ring in the Raptor case. My understanding was that the 4A and “terrain management “ used by the Raptor was the basis for the Bronco case and approach overall. I haven’t followed the Bronco Raptor that closely, is it spec’s the same as the “regular “ 4A case? I wheel a fair amount, but don’t have plans for significant HP or tire size changes, so it probably makes little difference for my use case, but interesting for sure.

 

[Razorbak86]

I wouldn't think the sway bar would reconnect in the middle of a flexed obstacle though to reestablish a load on the system, unless you failed to disengage it before hand so it might still be ok until you flattened out

Ya, I am certain it has a means of re-centering itself, otherwise you would have a frt suspension that looks like a broken low rider w/a wierd lean. There was a good thread on here about how the SB disco works, can't find it atm. But either way once the tires cross roughly the center position it will be locked again. The computer just shuts off the solenoid. I could here it click when I unplugged the WSS

Sorry, found the details here . It's all hydraulic, and when disconnected solenoid valves are open, when closes solenoid valves are closed. Fail-safe is open though if control is still maintained, it may fail-safe closed. This is because it automatically closes the valves when going over 20mph, but I bet if the car can't detect speed it would have to try and close the valves. Otherwise, you would have stability issues at highway speeds. I would be shocked if a single WSS failure could impact this, but you never know.

Did you happen to see what happens if you unplug the sway-bar? I wonder if the front locker would work, what trouble codes popped up . Curious as to what the result would be if the sway-bar was completely removed if it failed outside of warranty

I did not, but that's something I would like to check. I don't see any reason to lock out the locker if the disco has failed tho. I guess I'll add that to my list of things to try!

According to an updated thread posted in June 2021...

Bronco Stabilizer Bar Disconnect Operational & Service Information

NOTE: In case of electrical failure, the system will default to the connected mode with the solenoids closed.

NOTE: In case of a loss of hydraulic pressure, the system will default to the disconnected mode, and a warning light will be displayed in the IPC. Vehicle handling characteristics will be degraded.

 

[mike8675309]

According to an updated thread posted in June 2021...

Bronco Stabilizer Bar Disconnect Operational & Service Information

Unfortunately, it doesn't describe what happens if it can't determine vehicle speed. I assume it is determining vehicle speed from the vehicle speed sensor, not wheel speed sensors.

 

[Bmadda]

Unfortunately, it doesn't describe what happens if it can't determine vehicle speed. I assume it is determining vehicle speed from the vehicle speed sensor, not wheel speed sensors.

It doesn't have a VSS. Most vehicles now don't anymore. This is what has come from CAN, it's simplified some things (less sensors and less wiring) but now your ABS is not just an add on system, it's essential. That's why it acts the way it does, and why I think Ford could probably make the software a little better so the ABS module deals w/the failure, and figures out that it still has 3 good inputs and can determine speed from those. But I totally get the way failure mode is now, and I can say from experience other manufacturers do it the exact same way. Just the way of the world these days!

 

[JT58Bronc]

Not sure what the love affair with lockout hubs is. I've had a few very reliable, old school rigs that had no lockout hubs (auto or manual). One less thing to go wrong or to explode when you put too much power through it. I've got one with lockout hubs in my garage. They are fine, work fine, but I can't say I look forward to disassembling if I need to do front brake replacement or repair...not that I do that very often.

Locking Hubs were a great thing in their day and highly encouraged. I had manual locking hubs on my Toyota Land Cruiser, Jeep CJ, my best friend on his K Blazer, on most of my 80's and 90's Toyota pick ups. My 80's Ford Bronco even had them- automatic locking ones- where you had to back up to unlock them. Warn was amongst the best brand. When full time 4WD became available on Jeeps, Ramcharger, etc. back in the 80's it was problematic. Lots of drag, leaking oil and terrible gas mileage. The locking hubs worked great, I never had any failures and the front wheel bearings were so easy to disassemble and re-pack with grease.

Only people who could not think or plan ahead to lock and unlock their hubs when 4 wheeling, or in a in snow storm had trouble. I came across many people stuck in mud holes and I had to ask were your hubs locked, or people would wait until they were stuck, then try lock the hubs and curse. And then when your are done 4 wheeling, unlock the hubs. Not rocket science- so easy and saves so much drag and wear. I still today see so many F250's driving around on pavement with the hubs locked, see the U joints spinning. I will always love those locking hubs- to me it's backwards having the front end engaged all the time. I may need a pick up to go with my Bronco- haul my damn kayaks due to all the issues with and obtaining a roof rack LOL. I'm going 70's or 80's.......and I'll get my locking hubs!

 

[NC_Pinz]

Locking Hubs were a great thing in their day and highly encouraged. I had manual locking hubs on my Toyota Land Cruiser, Jeep CJ, my best friend on his K Blazer, on most of my 80's and 90's Toyota pick ups. My 80's Ford Bronco even had them- automatic locking ones- where you had to back up to unlock them. Warn was amongst the best brand. When full time 4WD became available on Jeeps, Ramcharger, etc. back in the 80's it was problematic. Lots of drag, leaking oil and terrible gas mileage. The locking hubs worked great, I never had any failures and the front wheel bearings were so easy to disassemble and re-pack with grease.

Only people who could not think or plan ahead to lock and unlock their hubs when 4 wheeling, or in a in snow storm had trouble. I came across many people stuck in mud holes and I had to ask were your hubs locked, or people would wait until they were stuck, then try lock the hubs and curse. And then when your are done 4 wheeling, unlock the hubs. Not rocket science- so easy and saves so much drag and wear. I still today see so many F250's driving around on pavement with the hubs locked, see the U joints spinning. I will always love those locking hubs- to me it's backwards having the front end engaged all the time. I may need a pick up to go with my Bronco- haul my damn kayaks due to all the issues with and obtaining a roof rack LOL. I'm going 70's or 80's.......and I'll get my locking hubs!

I hear you...just know that some 60s and 70s didn't bother with lockouts for reliability reasons. Not automatic hubs mind you, just engaged all the time and running neutral in the transfer case. That is bulletproof, just not efficient.

I always locked in before ice or snow storms hit because you sure didn't want to mess with them once they were frozen.

 

[Jdc]

It doesn't have a VSS. Most vehicles now don't anymore. This is what has come from CAN, it's simplified some things (less sensors and less wiring) but now your ABS is not just an add on system, it's essential. That's why it acts the way it does, and why I think Ford could probably make the software a little better so the ABS module deals w/the failure, and figures out that it still has 3 good inputs and can determine speed from those. But I totally get the way failure mode is now, and I can say from experience other manufacturers do it the exact same way. Just the way of the world these days!

While getting wheel speed from 3 wheels is better than none it's still going to cause issues given that if you have a wheel that's slipping or in the air, and has a faulty sensor, the computer has no way of knowing and therefore can't act.

Also, awesome job on testing these failures.

 

[Bmadda]

While getting wheel speed from 3 wheels is better than none it's still going to cause issues given that if you have a wheel that's slipping or in the air, and has a faulty sensor, the computer has no way of knowing and therefore can't act.

Also, awesome job on testing these failures.

Right...I totally get that ABS/TRAC has to be disabled if it loses a single WSS (trac is off anyway in 4L), but I think they could write a "limited operation strategy" that allows front locker and disco operation based on the fact that the computer can assume a single WSS is damaged and the remaining 3 are giving valid speed data. This would give a guy a more sporting chance of completing the trail if a single sensor gets damaged. Just an idea, I understand why it does what it does now, but I can see where they could make this improvement.

 

[dgorsett]

Ok, so I got to a good stopping point at the end of the day today, and decided I wanted to do some "test failures" on my own Bronco (2dr BL Sas, 7mt, other models may be different). I put it on a rack, 1st put it in rock crawl mode w/both lockers locked and SB disco on. I then started it and put it in crawl gear (so it was easier to observe whatever happened...I redid the test in 1st as well). I unplugged LF wss 1st. What happens is the front locker unlocks and the disco reconnects instantly. I DID NOT lose drive to the front wheels. Stayed in 4L, and rear locker stayed locked (this is good I think...I can live w/this). Tried RF WSS and LR WSS, same results. Even if reconnected the frt locker and disco will not work for the remainder of that ignition cycle. Key off, then restart w/wss plugged in and they work again. Tried same configuration in normal mode, same results. Tried in 4H, and, of course frt locker is not allowed in 4H, but disco is, and the results are the same, never lost power to the front wheels tho...I am relieved at that! Took some pics at the code fallout from testing. Disregard PSCM codes, those were set during my failed rack swap experiment!

All the other modules on that CAN tree had the same "invalid data from abs code" so unfortunately losing a single WSS causes all kinds of dash warnings and chimes, but, at least on my vehicle, DOES NOT cause a loss of 4wd...and I am glad!

Great info. You do not loose 4wd, but if you start in 2wd does the loss of a WSS prevent a 4wd shift? My sons Tacoma would not shift into 4wd with a faulty WSS.

Also, regarding manually shifting the TC. I suppose I would remove the shift motor and rotate whatever it attaches to. Anybody tried this? Anybody know the "shift pattern"?

 

[dgorsett]

I hear you...just know that some 60s and 70s didn't bother with lockouts for reliability reasons. Not automatic hubs mind you, just engaged all the time and running neutral in the transfer case. That is bulletproof, just not efficient.

I always locked in before ice or snow storms hit because you sure didn't want to mess with them once they were frozen.

You're right. I've had every type of locking hub or no hub there is since my 1945 GPW and really they are all fine. The automatics of the 80's and 90's were probably the weak link. With those on snowy days I'd 'preengage' them to avoid that violent first engagement at speed. I also preengage manual hubs before needing them. No problem running them engaged while in 2wd, even all winter. People should get over the idea that they need to be engaged/disengaged at every 4wd/2wd shift. I've never had an issue with the semi automatic hubs on a couple Ford Super Dutys. My LJ and current Bronco had/have no axle disengagement at all (just at transfer case) and work great. For some reason my BB with 4.27's is the only part time without FAD which is fine with me. It still averages 23mpg.

 

[VoltageDrop]

There is a path to give this feedback to Ford. Though you may need to experience a failure to do so. I haven't seen a failure like this documented anywhere, but whoever had it should be writing to Ford, or working with their dealer service department to get Ford involved. If one of the larger youtube channels covering the bronco were to just disconnect a speed sensor and see what happens, that would be helpful in getting it addressed.




I'm sure it had to do with cost combined with engineering decisions. I don't know how the weight of the Bronco front driveline parts differs from the F250's but I bet it is significant. The rotational drag of the Bronco front driveline must not be high enough to add the additional complexity of an auto-locking hub. Manual locking hubs would be a complete nonstarter in today's society.
If the Bronco is around long enough and makes enough units, someone will come up with a manual front locking hub kit for it.

The F250 still uses u-joints which are not constant velocity so their lockout hubs probably have more to do with vibration than MPG, especially since those trucks are exempt from MPG testing. The Bronco has CV joints on the axles and drive shaft so you shouldn't notice the front drive being engaged.

I'd so much rather have the M190. Which models have this? Those without the different 4 X 4 driving modes? Maybe base non Sas? This might explain why some of the base models with the smaller tires are getting the best gas mileage- upper 20's to 30's- less front axle drag, light weight and smaller tires.

It's too bad that the technology back in the day had locking hubs- and the vehicles then were just plain inefficient. Today we have the technology and the vehicles are so much more efficient. I'm getting 21.8 in my Sas right now I bet I could get at least 25 if the front end was disconnected. And performance would improve as well. I wish we had a choice in transfer case selection- I still want Sas with froth and rear lockers but forgo the driving modes in lieu for the M190 transfer case.

I doubt you'd see even a 1 mpg improvement unless you do lots of city driving where accelerating that mass becomes a factor. There are Broncos getting 30 mpg?!

 

[mpeugeot]

A little earlier someone told me that a Bronco with the "Advanced 4X4 Transfer Box" should not be flat towed. Only manual transfer boxes can be towed safely. Yet in the above material there was a reference to "Neutral Flat Tow Activation and Deactivation (307-07B Four-Wheel Drive Systems - Advanced 4X4 with 4A Mode, General Procedures).

Any chance we can see this document (and any updates or cautions regarding flat towing a 2022 Black Diamond). Thank you. I printed out this data and it will reside in my center console.

I have flat towed the Advanced 4x4 transfer case equipped Bronco with 0 issues. It behaves as one would expect.

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