When to use/not use 4x4? Overheating diffs, transfer cases etc.

[Reddog]

Lately I've been hearing more and more about overheating transfer cases, diffs, and transmissions while off-road. I recently listened to a podcast where the host was saying to stay in 2H until you need it, and if you do need 4x4 to use 4L and in leave your trans in 1st or 2nd. They stated 4H is for inclement weather at 30-50mph, not for slower speed off-roading, you'll over heat your transfer case or front diff running in 4H on the trails.

On that same token I've also heard to stay in 4H on trails because you don't want to find yourself in a situation where you need it but it's too late to engage it, and always engage 4L before entering anything that might warrant the need.

What say you?

Stop listening to generalized videos done to make money by people who are reading their source material from some text. . I have never had a single problem from overheating either the t-case or diffs. That goes for the V-8 powered jeeps Ive had two. Its what they are made for. Going up grades off road, then use 4x4. Not talking about rock crawling here cause I don’t do any. But I overland a lot and most of time Im in 4x4h. Overlanding in 4x4 h doesnt hurt anything. You are going slow to begin with. I just put it in 4x4h and go, up grades off road and down, road or not. Rarely use or need low range. Go use your jeep and enjoy the over priced money pit that they are.

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[OldSarge]

Lately I've been hearing more and more about overheating transfer cases, diffs, and transmissions while off-road. I recently listened to a podcast where the host was saying to stay in 2H until you need it, and if you do need 4x4 to use 4L and in leave your trans in 1st or 2nd. They stated 4H is for inclement weather at 30-50mph, not for slower speed off-roading, you'll over heat your transfer case or front diff running in 4H on the trails.

On that same token I've also heard to stay in 4H on trails because you don't want to find yourself in a situation where you need it but it's too late to engage it, and always engage 4L before entering anything that might warrant the need.

What say you?

have driven for days in 4H with some 4L mixed in. Never had an issue. This includes some moderately challenging trails in Moab. FWIW anyway.

 

[ShadowsPapa]

No I don't need 4HI to drive down a dirt road or 4LO and lockers because I have to drive over a decent sized rock. You can shift into 4HI at freeway speed, just how slow are your hands and how nearsighted are you that you'll be cruising down a forest road and suddenly it's too late to put it in 4wd? I've also found in decades of experience that the guy over using every tool in the tool box is the one who gets stuck the worst......................
.......................

One of the best explanations ever.
Your bottom line nails it.

 

[ShadowsPapa]

Not talking about rock crawling here cause I don’t do any. But I overland a lot and most of time Im in 4x4h. Overlanding in 4x4 h doesnt hurt anything. You are going slow to begin with. I just put it in 4x4h and go, up grades off road and down, road or not. Rarely use or need low range.

These are capable even without using all of the "tools at hand".
I was pulling my JTMX into a spot with really pretty high concrete blocks and not the normal curbs to prevent vehicles from going a bit too far. The spot was narrow, I couldn't make the turn as i'd have liked to, and the silly thing thought it was on some rocky trail or something and started walking right up the concrete barriers. I thought - imagine what it would have done if I had other things engaged.
Down, boy! It's a parking lot!

 

[MoxiesDad]

I guess it all depends on where you go off-road. I don't have experience yet with my JTR off-road, but use my 2004 TJ Rubicon off-road regularly. We put it in 4L and keep it there. Basic guideline is 4L under 15mph, 4H when faster. Had several newbies with JK's over the years that stayed in 4H then later got on the radio saying they had trans hi-temp light come on. Just told them to put it in 4L and trans temp dropped back to normal within minutes.

 

[ShadowsPapa]

I guess it all depends on where you go off-road. I don't have experience yet with my JTR off-road, but use my 2004 TJ Rubicon off-road regularly. We put it in 4L and keep it there. Basic guideline is 4L under 15mph, 4H when faster. Had several newbies with JK's over the years that stayed in 4H then later got on the radio saying they had trans hi-temp light come on. Just told them to put it in 4L and trans temp dropped back to normal within minutes.

I wonder if they understand manual mode on these transmissions?
(and the fact that if the engine is running hotter - so will the transmission in many cases)

 

[Zachanadandy]

I guess it all depends on where you go off-road. I don't have experience yet with my JTR off-road, but use my 2004 TJ Rubicon off-road regularly. We put it in 4L and keep it there. Basic guideline is 4L under 15mph, 4H when faster. Had several newbies with JK's over the years that stayed in 4H then later got on the radio saying they had trans hi-temp light come on. Just told them to put it in 4L and trans temp dropped back to normal within minutes.

That's a very technical trail if speeds are never above 15mph? In that case I'd agree that 4LO is probably best. That's not your typical trail run though. And the JK is a terrible example as the 1st gear ratio was bad in the later models and absolutely atrocious in the early autos. You mean a 2.86-1 1st gear means you need 4LO pretty often? With the 2.86 1st gear, factory 3.55 axle gears, and 2.73 transfer case a non-rubicon early JK had a whopping 27-1 crawl ratio in low range. The 8 speed with the tcase in HI still gives you 19.3-1. Not even on the same planet.

 

[Sweetums]

Lately I've been hearing more and more about overheating transfer cases, diffs, and transmissions while off-road. I recently listened to a podcast where the host was saying to stay in 2H until you need it, and if you do need 4x4 to use 4L and in leave your trans in 1st or 2nd. They stated 4H is for inclement weather at 30-50mph, not for slower speed off-roading, you'll over heat your transfer case or front diff running in 4H on the trails.

On that same token I've also heard to stay in 4H on trails because you don't want to find yourself in a situation where you need it but it's too late to engage it, and always engage 4L before entering anything that might warrant the need.

What say you?

I go to 4High and I air down when the pavement ends.

• It helps with control of the vehicle on slippery surfaces to have power to the front.
• If road conditions change suddenly I'm not caught out in 2WD and getting stuck.
• Airing down helps preserve the trail surface by improving traction and softening the tires. Going too fast and running highway pressures are leading causes of washboarding.
• 4WD also helps preserve the road by reducing the chance of spinning one tire and digging a hole on climbs. It also spreads the load across all tires so the fronts are not being pushed through softer terrain, which also causes washboarding.

I've been driving with these guidelines for over 20 years and I've never overheated a diff, transfer case, or transmission. In most of my 4WD vehicles the diffs would be turning anyway since I didn't have freespooling hubs - so any heat concerns would be the same regardless of whether you were in 2 or 4 high. If the front diff could handle cruising down the highway in 110 degree weather at 80 mph all day, it can handle lower speeds on a dirt road.

 

[ShadowsPapa]

I've never overheated a diff, transfer case, or transmission. In most of my 4WD vehicles the diffs would be turning anyway since I didn't have freespooling hubs - so any heat concerns would be the same regardless of whether you were in 2 or 4 high.

I have tried to think through this and see why, how, where, there'd be any heat concerns in a front differential.
On the highway or in the city, with a FAD, you are always spinning the left axle, spider gears and carrier side gears. It's how they prevent turning the whole carrier/ring gear/pinion.
On a trail in 2 wheel drive, same thing, only much slower.
They used to say "engage 4 wheel drive every few months to lubricate the spider gears in the carrier" or words to that effect in the owners manual. Otherwise, without the ring gear carrying lube up and the splash lube effect, those gears inside the carrier were theorized to eventually run dry.
So 2 wheel drive has the effect of spinning those small gears - the side or axle gears and the "spider" gears, inside of the carrier without benefit of the ring gear splash lube effect.

4H - the axles will be under the same load and same conditions as 4L. They will be turning the same speed in either case. If you go 15 in 4H as far as the whole axle assembly is concerned - axles and the differential parts - it's the same as going 15 in 4L.

As far as the transfer case - from the output clear through the driveshafts, pinion, ring gear, carrier and out to the axles, everything is the same - 4H and 4L if you are running the same speeds. The loading is the same, the RPM of the parts is the same if you go the same ground speed.

The difference comes at the input side of things. 4L will require higher engine RPM to go 15 mph ground speed as opposed to 15 mph ground speed in 4H.

 

[Stan H]

When 4H struggles I go to 4L . Love @Zachanadandy explanation also .
Proper tool for the Proper job

 

[KevinC]

To stay on subject. Jeep Beach/I was exiting the beach and found a 392 just coming onto the beach with his rear tires buried and sitting on his axle. The lifeguard was yelling at him through a megaphone to put it in 4WD. I got out and approached him and he said his Tazer must be glitzing and wasn't allowing him to engage 4H/L or even 4 FullTime. At this point if he did manage to get his 4WD system working he wouldn't have gotten out. In my experience it takes a few revolutions of the front tires to fully engage the front axle. If you are stuck in 2WD with free spinning tires, how can your front tires turn a few revolutions to engage? It can't. So...I am a advocate to engage the transfer case in the proper gear before the obstacle prevents you from getting a clean couple of rotations from the front tires.

I hooked a strap to his rear tow hook and pulled him out backwards. I was in 4H with OffRoad + turned on because I was going to drive through some really thick sand for a few miles exiting the beach. Rear locker was off. Pulled him out without spinning a tire.

So to stay on point; I feel the Offroad + allows you to utilize the computer to pick a gear that enhances performance while not overheating any components.

 

[Janster]

…….social media pushing FEAR across society again. These people need to find something better to do with their time.

Jeeps have been around almost forever. They’re the most equipped, capable, & experienced offroad consumer vehicle you can get. You don’t get that kind of reputation because your equipment can’t handle it.

Just DRIVE!!!

Surely…if you’re doing something stupid ON or OFFROAD, in any gear….. you’re gonna have more problems (and more things overheating) than worrying about the diffs overheating.

 

[Sweetums]

I wonder how they would react to systems like the Land Cruiser that are full time 4WD?

Our front diff is also down on the axle, so it gets way more airflow and less engine heat than an IFS setup. Even my IFS vehicles never had a problem with the diff, t-case, or trans overheating unless you also were cooking the engine. Our Jeeps have temp sensors, you can even pull up the Off Road pages or use the instrument cluster to watch your trans temp.

If it gets too hot the computer will pitch a fit, I guarantee you would know about it.

This whole thing of overheating diffs sounds like someone needs to take a Xanax and lie down for a while, maybe breathe into a paper bag.

 

[ShadowsPapa]

I've never found it to require 'a few revolutions' but that doesn't matter - if it's up where a top of the tooth on the sleeve is hitting the top of a tooth on the "gear", it's not going to engage. Normally it takes only an inch or so of tire rotation - you only need to get the sleeve to the point it's not hitting the other shaft "spline teeth" directly head-on.

You'd literally have to move at least some to get the tooth to go into a slot between teeth on the sleeve. Maybe just a few degrees of rotation (5 to 10?? depending on number of splines) is all that's needed. It's like trying to get into low or reverse on a manual transmission - sometimes the teeth hit each other wrong and something has to move - at least some amount. An inch or two does it if you are not actually moving on the road. It takes longer at road speed than when not moving or barely moving in my experiences plowing and trying to get 5,000 pounds of trailer and car through rocks and gravel, up a hill, or through a washout and wet grass.
I have been able to engage mine into 4H from a dead stop and pull myself out of a rut more than once. I'm more of the "let's see how far I can get in 2 - even plowing snow, I take it as a challenge just to see how capable the truck is.

 

[ShadowsPapa]

Our front diff is also down on the axle, so it gets way more airflow and less engine heat than an IFS setup. Even my IFS vehicles never had a problem with the diff, t-case, or trans overheating unless you also were cooking the engine.

Like my car - differential/axle bolted to the engine mounts, hanging up next to the engine, with the exhaust passing just inches over the housing, and buried up behind a cross member, further hidden by a huge piece of steel - skid plate. You can't even see the thing without pulling the skid plate, then you see just the bottom edge behind the cross member.

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