Transfer Case Technical Discussion

[flip]

What I want to know is why the transfer case is not disconnected from the front driveshaft and axle when in 2WD? The front end spins- including differential, driveshaft, axle gears, half shafts, etc. when in 2WD. The transfer case is not transmitting any power, it all spins freely but creates drag.

Are all Ford trucks like this (Except F250, see below)? My past 2019 Silverado the transfer case disconnected the front driveshaft and axle so there was not that extra drag of the driveshaft and the main gears, at least. The half shafts still spun though. At least minimized some of the drag.

I was really surprised (and disappointed) that the front axle, etc. is always engaged.

Locking hubs are what is needed to completely disengage the front end when in 2WD. Ford has them on the F250's- why on them and not the Bronco?

Valid point and glad you brought it up. There is definitely some rotational drag through the CVs, front diff, front drive shaft and through the transfer case. The reasoning they may have done it like this is consolidating the engagement points to the clutch pack in the advanced 4x4 and blocking gear in the part time. You eliminate the need for locking hubs (which have been problematic for Ford in the past), manual hubs which require you to physically engage them and in the case of the advanced, no need for a front axle shift motor/fork/locking ring to put power to the front axles. All of these add weight and expense and maybe they figured out the setup they're using now is more cost and weight effective than one of the other methods.

Maybe my gripe is why not just put the M210 in everything along with the advanced transfer case? You could still up charge for front locker like SAS and BL, lower the number of service parts, it's at least serviceable compared to the 190 and would eliminate the front axle engagement motor on the part time setup. It would still be possible to "dumb down" the transfer case to offer 2H, 4H, 4L on part time with no need for all of the other inputs to make 4A or some of the other traction assist work. There might be a little more input cost to the vehicle but you cut down on a lot of part combos for the entire model, are able to upcharge for a few extra options and leave the door open for end user upgrades down the road. I dunno, not on the inside or know what their costs are but this just makes sense to me.

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[Bmadda]

This diagram shows a axle disconnect. Is this only on some models? and why? I heard M210 gets no disconnect, but M190 does. Strength/durability? Note Jeep does the same...higher end models typically don't have the disco. Good old fashioned manual lockouts were a great way to go, it's too bad people didn't like them. Yukon gear was making lockout conversions for Jeeps (I have on my YJ), maybe they will consider doing them for Bronco?

 

[flip]

 

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[mike8675309]

I don't think any choice was made. I think it's a bug plain and simple.

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.

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Locking hubs are what is needed to completely disengage the front end when in 2WD. Ford has them on the F250's- why on them and not the Bronco?

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.

 

[JT58Bronc]

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.

 

[Bmadda]

So all have CAD except Raptor? I honestly didn't see it on mine. Could be the CAD is disengaging and not the xfer case...that would explain 2L accidentally happening. Think what I wana try when I get some time is put my Bronco on a rack, start it, put in 4L and put in gear (low speed idle) and disconnect an abs sensor. We should be able to verify if it's going into some weird failure mode, and what it's doing that way. Could try it in 4H and the rest of the goat modes too, but won't work if traction control isn't off.

 

[flip]

Using my BL VIN, it does not show a front axle disconnect. I think the shop manual and Microcat are missing some parts and/or descriptions.

 

[Felix808]

Here's a better pic of the advanced setup with the chain from the WSM.

A lot more going on in the part time.

Interesting that the part-time case has an oil pump.

 

[Bmadda]

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.

M190/M210 are the diffs. M210 is the heavy duty one. Center axle disco is not really a feature you want. Doubt it saves much gas, and it's another point of failure (and ya they fail constantly). I do wish we had a choice in xfer case though...I doubt the part time case is having these problems, and Ford forced us to take the 4A to get sas, or higher end trims...probably to sabotage the Bronco program so they don't have to sell these things anymore (ya I know, I love conspiracy theories!)

 

[Bmadda]

Using my BL VIN, it does not show a front axle disconnect. I think the shop manual and Microcat are missing some parts and/or descriptions.

Mine's a BL...and I don't remember seeing anything like that on it when jagging around w/the rack.

 

[mike8675309]

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.

You are driving a heavy brick, that's why you don't get 25mpg. I feel you are overestimating the impact of the rotational mass of the driveline.

 

[Bmadda]

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!

 

[Felix808]

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!

Thank you for putting in the work. It's good to know it doesn't completely lose the front axle.

 

[jbellousux]

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!

Thank you for putting in the work to disprove “fake news.” Your post is incredibly important.

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