4H on the highway safe???

[Joaquim]

Why would you want to? That lock on the transfer case says it's locked. Having raced on ice I can tell you a locked xfer case is like locking an axle. You're guaranteed it's going to cause the wheels to loose their static friction and go into a spin. At highway speeds you get less stability. On dry pavement you're putting enormous stress on you driveline.

Next time it snows go to a parking lot and test it out.

If you get the option for full time 4 WD that doesn't add a lock to the xfer case on the console, that's another story.

Get 4 studded tires and leave it in 4H.

4H is locking the center diff… what are you trying to say?

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[word302]

4H is locking the center diff… what are you trying to say?

There is no center diff on the standard transfer case. If you have 4 auto or AWD there is a center diff and it would not be locked in auto mode. That’s why you can use it on dry pavement.

 

[word302]

Okay you drive at low speeds and get rear ended by a semi or other traffic that is going much faster and cause an accident then - I don’t think you completely understand the dangers of not moving with the flow of traffic, are you saying a jeep is incapable of it?

You’re trying to tell me semis drive 60+mph in winter storms? Methinks you and I define winter storms differently.

 

[Joaquim]

You’re trying to tell me semis drive 60+mph in winter storms? Methinks you and I define winter storms differently.

I’m referring to snow falling and slick conditions varying but for the most part you can see the highway - not snow piling up where it is unsafe to go beyond 30 mph -

 

[Joaquim]

There is no center diff on the standard transfer case. If you have 4 auto or AWD there is a center diff and it would not be locked in auto mode. That’s why you can use it on dry pavement.

Ah okay I must be misunderstanding how the standard command trac system works (it is command-trac right?) - Correct me if I’m wrong but this is the argument against 4H on highways, with power being split exactly 50/50 between front and rear axles - even the slightest turn on the highway could cause a situation where power needs to be split differently - and thus the inability of the vehicle to do so could cause it to spin out/slip out of traction?

 

[Remorseless]

Ah okay I must be misunderstanding how the standard command trac system works (it is command-trac right?) - Correct me if I’m wrong but this is the argument against 4H on highways, with power being split exactly 50/50 between front and rear axles - even the slightest turn on the highway could cause a situation where power needs to be split differently - and thus the inability of the vehicle to do so could cause it to spin out/slip out of traction?

Personally, I'm less worried about losing traction and more binding up the t-case. If you've got good enough traction to be moving highway speeds safely, it's probably enough traction that you're running the risk of binding and damaging the t-case or something else in the driveline. Running 4H on a straight road isn't an "instant grenade" thing on the t-case, but you really want to be only engaging the system when wheels can slip freely.

 

[Heimkehr]

The last thing I'd want in snow is a FWD car with no ground clearance.

That's not my first choice, either, but I managed the lake-effect snowstorms of western Pennsylvania pretty well with my VW Golf. Granted, it wore quality 3PMSF tires and its driver knew how and when to use the Go pedal. That car didn't have ABS, either. Good tires and common sense carried the day.

The car that preceded the Golf was a RWD 260Z that wore Cooper Cobras. That car acquitted itself pretty well in the same weather. To be fair, the FWD Golf with winter rubber had the obvious advantage.

 

[word302]

Ah okay I must be misunderstanding how the standard command trac system works (it is command-trac right?) - Correct me if I’m wrong but this is the argument against 4H on highways, with power being split exactly 50/50 between front and rear axles - even the slightest turn on the highway could cause a situation where power needs to be split differently - and thus the inability of the vehicle to do so could cause it to spin out/slip out of traction?

Yes the possibility. With practice and experience it’s no big deal.

 

[Joaquim]

Yes the possibility. With practice and experience it’s no big deal.

And by this you mean avoiding turning beyond a few degrees in 4H?

 

[blnewt]

Thought this was a simple answer, but 69 posts now has me confused ?

 

[Steph1]

It is safe to be in 4hi on the highway in straight lines, entering a curve you should shift back to 2wd otherwise your driveline will bind. In 4hi, both sides have to turn at the same speed. So you need a loss of traction if you want to leave it on in a curve.

 

[Remorseless]

And by this you mean avoiding turning beyond a few degrees in 4H?

I'd say more avoid 4H on typical asphalt/concrete road surfaces. The manual states this as well:

The transfer case is intended to be driven in the 2H position for normal street and highway conditions, such as hard-surfaced roads. In the event that additional traction is required, the transfer case 4H and 4L positions can be used to lock the front and rear driveshafts together, forcing the front and rear wheels to rotate at the same speed. The 4H and 4L positions are intended for loose, slippery road surfaces only and not intended for normal driving. Driving in the 4H and 4L positions on hard-surfaced roads will cause increased tire wear and damage to the driveline components.

Basically - any time the road is normal, 2H. Any time it's actively slippery, 2H/4H/4L are acceptable. Any time road surface is moving between slippery and dry, make sure you're in 2H when on a dry section. If you're unsure if it's slippery or dry, be in 2H and use caution. If the ground's coated in snow and you're not breaking through to the road surface, 4H should be fine.

 

[J0E]

Personally, I'm less worried about losing traction and more binding up the t-case. If you've got good enough traction to be moving highway speeds safely, it's probably enough traction that you're running the risk of binding and damaging the t-case or something else in the driveline. Running 4H on a straight road isn't an "instant grenade" thing on the t-case, but you really want to be only engaging the system when wheels can slip freely.

Exactly.
I've done plenty of ice/snow racing with studded tires. Once I hit triple digits (over 100 MPH) and the studs started coming out.

 

[cmcclintock]

If I am in the mountains going up an down hills, snow on the road, snowing I may wil put in 4H when I feel It is safe to drive 20-30 mph. Any signs of pavement it is back in 2H. I have been doing this for 30+ years.with never any issues.

 

[J0E]

If I am in the mountains going up an down hills, snow on the road, snowing I may wil put in 4H when I feel It is safe to drive 20-30 mph. Any signs of pavement it is back in 2H. I have been doing this for 30+ years.with never any issues.

Safe to 50 MPH
Gets squirreley in corners over 60
Assuming you're not on pure ice, otherwise 30

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