4x4 hub design questions

I've owned a bunch of 4x4s, but they were all either auto hubs (88 and 98 chevy) or IFS Fords and Dodges with no unlocking feature at all. They were just always connected to the CV axles.

My 94 B4000 had broken auto hubs that I converted to manual. How long can I leave them engaged on dry roads? What is it about the manual hubs that requires them to be disengaged when my F150s were always engaged with no option to disengage?

'Splain me the difference.

I don't mind unlocking hubs, but (for instance) this past week we had a day of about 6" of snow, then dry roads for a day or so, then another inch. In anticipation of maybe needing 4wd for my driveway, or the unmaintained roads on the way to work, I just left the hubs engaged for three days. I didn't feel like getting out in 5 degree weather three times in 20 minutes every time I turned onto unmaintained pavement.

AFAIK its more about mileage and keeping wear off the front end bits. I know most of the Early (same ish era) Toyotas were the same parts weather manual or auto hubs came on them. Wheel bearing and CV wise etc.

I lock and leave them in situations like that, and just shift the T case as needed.

Leaving them locked for a day or so shouldn't be a problem, particularly if you're staying slow.

An old company truck was an OBS F250. I was in and out of mud all day so I generally left the hubs locked, but at highway speeds I was getting horrible vibrations and noises even though I put the transfer case back in 2wd. That's the only thing I know to be bad about making them locked. 

Ok, good to know.  I remember an old Scout 2 we used to have and the owner's manual put the fear of god in you about leaving the hubs engaged.

It's a mileage thing. Unlocking them lets the front axle and driveshaft not turn. Less drag on the engine. Better mileage. 

I have heard that a lot of the northern folks lock them in at the first snow and leave them lock for the duration.

When I'm riding around, I usually lock the Samurai axle when I leave the house and I may or may not remember to unlock them when I get home. 

Unlocking hubs were a luxury in the early days.   saved driving the font axles, differential and drive shaft.   Good for app. 2 mpg.

 There were thousands of 4x4s with standard hubs roaming the roads with no problems.

In other words you should be able to drive with your hubs locked without a problem.   Just make sure the transfer case is in  2 wd.

My KJ ran 80k miles with out hubs.

Makes no difference.  All you are doing is rotating a few more parts that were designed to rotate anyway.

When I lived in Upstate NY I locked the hubs in in the fall and unlocked them in the spring.  When I sold my last truck it had 280k miles on it with all of the original front driveline parts including u-joints.

my disco is full time 4x4, there is no way to lock or unlock the hubs, so far I am at 114,000 miles with no issues with them.

APEowner said:

When I lived in Upstate NY I locked the hubs in in the fall and unlocked them in the spring.  When I sold my last truck it had 280k miles on it with all of the original front driveline parts including u-joints.

This practice probably saved the U-joints, on reflection.  The typical failure mode isn't so much wearing out as it is rusting from lack of motion.

Used to be really common for TTB Explorers to get extremely stiff steering, or steering that wanted to index, because the U-joints rusted.

When I was running manual hubs on my Samurai I'd only unlock them if I knew I wouldn't be doing any offroading for a while. Unlocking them only means that the front diff, axles, and driveshaft don't have to turn, making a miniscule reduction in wear and improvement in mileage. IMO the real advantage of manual hubs is as a survivability mod - if your front diff binds up, you can unlock the hubs and limp out in RWD.

This is all good info.  I was wondering if it had to do with the suspension design.  Most IFS 4x4s use CV axles (like your Disco, Mad Machine) and most solid axle trucks use u-joints.  I thought maybe you had to unlock with u-joints for some reason but it makes sense that CV joints can spin forever.

Knurled. said:

APEowner said:

When I lived in Upstate NY I locked the hubs in in the fall and unlocked them in the spring.  When I sold my last truck it had 280k miles on it with all of the original front driveline parts including u-joints.

This practice probably saved the U-joints, on reflection.  The typical failure mode isn't so much wearing out as it is rusting from lack of motion.

 

Used to be really common for TTB Explorers to get extremely stiff steering, or steering that wanted to index, because the U-joints rusted.

I believe that to be the case.

what is interesting.. the disco is not IFS, but it still uses CV joints. The trouble with their suspensions is the double cardan joints on the front driveshaft wear out and go bang with little warning. I am due to replace my front shaft this spring as they say to do it between 100 and 120k to avoid an expensive repair

Early Jeep vehicles used CV joints enclosed in a housing.   Later on they went to U joints.

Curtis said:

This is all good info.  I was wondering if it had to do with the suspension design.  Most IFS 4x4s use CV axles (like your Disco, Mad Machine) and most solid axle trucks use u-joints.  I thought maybe you had to unlock with u-joints for some reason but it makes sense that CV joints can spin forever.

It's been many years, but I seem to remember on dry pavement the u-joints were slightly more prone to binding with the hub locked than unlocked when making very tight turns.  

There's also the axle disconnect system, which I have yet to understand the purpose of.  

Ian F said:

Curtis said:

This is all good info.  I was wondering if it had to do with the suspension design.  Most IFS 4x4s use CV axles (like your Disco, Mad Machine) and most solid axle trucks use u-joints.  I thought maybe you had to unlock with u-joints for some reason but it makes sense that CV joints can spin forever.

It's been many years, but I seem to remember on dry pavement the u-joints were slightly more prone to binding with the hub locked than unlocked when making very tight turns.  

There's also the axle disconnect system, which I have yet to understand the purpose of.  

Yeah, I'm just learning about that as well.  The diff side of the axle shaft has a sliding collar that engages or disengages splines on the axle shaft.  CAD.  Central axle disconnect.

In reply to Curtis :

yeah, I know how it works. I'm having trouble understanding exactly what it's supposed to accomplish.  The hubs still turn. The diff still turns. The front driveshaft still turns. It's just not getting power from the transfer case.

There are a couple of rear axles that can be converted to have lockout hubs as well.  I've seen it on vehicles being flat towed behind rvs.

Ian F said:

In reply to Curtis :

yeah, I know how it works. I'm having trouble understanding exactly what it's supposed to accomplish.  The hubs still turn. The diff still turns. The front driveshaft still turns. It's just not getting power from the transfer case.

As I understand it, the hubs turn, but the diff and shaft don't.  The CAD sleeve is between the CV axle and the diff, so once it disconnects, the only thing turning is the CV shaft.

Curtis said:

Ian F said:

In reply to Curtis :

yeah, I know how it works. I'm having trouble understanding exactly what it's supposed to accomplish.  The hubs still turn. The diff still turns. The front driveshaft still turns. It's just not getting power from the transfer case.

As I understand it, the hubs turn, but the diff and shaft don't.  The CAD sleeve is between the CV axle and the diff, so once it disconnects, the only thing turning is the CV shaft.

That's not how it worked on my '95 Dodge.  All it does is split the shaft between the hubs to the right of the pumpkin.  But the left hub was still connected to the differential and turned the driveshaft. 

Ian F said:

Curtis said:

Ian F said:

In reply to Curtis :

yeah, I know how it works. I'm having trouble understanding exactly what it's supposed to accomplish.  The hubs still turn. The diff still turns. The front driveshaft still turns. It's just not getting power from the transfer case.

As I understand it, the hubs turn, but the diff and shaft don't.  The CAD sleeve is between the CV axle and the diff, so once it disconnects, the only thing turning is the CV shaft.

That's not how it worked on my '95 Dodge.  All it does is split the shaft between the hubs to the right of the pumpkin.  But the left hub was still connected to the differential and turned the driveshaft. 

The driveshaft stays still, the left axle just spins the side and spider gears, so the right axle's inboard half will be spinning backwards at road speed.

mad_machine said:

what is interesting.. the disco is not IFS, but it still uses CV joints. The trouble with their suspensions is the double cardan joints on the front driveshaft wear out and go bang with little warning. I am due to replace my front shaft this spring as they say to do it between 100 and 120k to avoid an expensive repair

Jeep Grand Cherokees with all wheel drive/full time 4WD would get CV axles.  Part time vehicles would get U-joints.  I figure it was so there'd be no annoying kickback in the steering during parking lot maneuvers.

Some of those JGC transfer cases had a silly number of positions.  I vaguely remember one that had 2wd, full time 4wd (center diff, and I think a VLSD), standard 4wd (locked center differential), Neutral, and 4-Low.  And 90% of them probably stayed in 2wd...

Knurled. said:

mad_machine said:

what is interesting.. the disco is not IFS, but it still uses CV joints. The trouble with their suspensions is the double cardan joints on the front driveshaft wear out and go bang with little warning. I am due to replace my front shaft this spring as they say to do it between 100 and 120k to avoid an expensive repair

Jeep Grand Cherokees with all wheel drive/full time 4WD would get CV axles.  Part time vehicles would get U-joints.  I figure it was so there'd be no annoying kickback in the steering during parking lot maneuvers.

that's interesting to know.