changing into 4 hi

[offthepavement]

the way i read a "post" was that it read 4 hi up to 45 miles an hour does that mean u can only go 45 in 4 hi or shift into 4 hi up to 45 mph?i thought i read jeeps official statement as shift into 4 hi going any speed?is there any consesus on shifting into 4 hi. kinda new to 4×4

[DirtyComanche]

You can shift into 4hi at any speed.  I don't recall what the official literature says, up to 45mph sounds about right.  At any speed there is risk of damage (like the tcase blowing apart) if the conditions are perfectly wrong.

 

Don't drive around in 4hi on dry pavement if you have a NP231 (Part time tcase).  A NP242 or other full time tcases can do it, as long as they're in the full time position.

[Eagle]

It means shift at any speed up to 45 MPH. (Although I thought it was 50 MPH.)

 

Just checked -- the 1989 owner's manual says shift into 4-Hi "at any legal speed." They may have changed it depending on the year.

[Minuit]

Both my '89 and '91 owners manuals say at "any legal speed" as well. I take that to mean up to at least 70 mph, although I don't know what kind of situation would necessitate shifting into 4hi at that kind of speed.

[Dzimm]

Both my '89 and '91 owners manuals say at "any legal speed" as well. I take that to mean up to at least 70 mph, although I don't know what kind of situation would necessitate shifting into 4hi at that kind of speed.

I was wondering the same thing. I can't even think of a reason for it over 45 mph let alone your 70..

[Jeep Driver]

If conditions warrant 4X, you probably shouldn't be going 70mph.

[HOrnbrod]

I was wondering the same thing. I can't even think of a reason for it over 45 mph let alone your 70..

Used for ice racing.  :thumbsup:

 

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[Dzimm]

 

I was wondering the same thing. I can't even think of a reason for it over 45 mph let alone your 70..

Used for ice racing. :thumbsup:

 

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I figured for racing they would have upgraded the t-case anyway but J guess running stock you could do it. But like stated above, without upgrades I feel like the stock case would explode after some time at those speeds.

[cruiser54]

I've shifted into 4Hi at 80 MPH. Gotta be a legal speed somewhere. 

[Gene]

I've shifted into 4Hi at 80 MPH. Gotta be a legal speed somewhere. 

Can I ask....why?????

 

Gene

[offthepavement]

[cruiser54]

 

I've shifted into 4Hi at 80 MPH. Gotta be a legal speed somewhere. 

Can I ask....why?????

 

Gene

 

Because I was Service Manager at a Jeep dealership and had 13 Comanches as demos. If anything broke, which I knew it wouldn't, we could fix it under warranty. 

[DirtyComanche]

Speed isn't really the issue. It's just going to wear things out more.

 

Slamming the case into 4hi while you've got varied traction can cause issues. If the rear tires are spinning when you do it there can be a rather abrupt coupling of torque at the case. That's what will break something.

 

All in all you can be pretty abusive and it's unlikely anything will ever break.

[Gene]

Hi cruiser,

 

You are far far braver than I would have been.

 

I would have worried about silly things like wheel lockup… Skids… And death.

 

Gene

[DesertRat1991]

[HOrnbrod]

From my JK manual, 55MPH max speed while shifting into 4x4 High-Range. Max speed in 4H is 65MPH.

[offthepavement]

[Eagle]

Speed isn't really the issue. It's just going to wear things out more.

 

Slamming the case into 4hi while you've got varied traction can cause issues. If the rear tires are spinning when you do it there can be a rather abrupt coupling of torque at the case. That's what will break something.

 

All in all you can be pretty abusive and it's unlikely anything will ever break.

 

It isn't the abrupt torque that'll do the damage. In the 231, the front and rear driveshafts are locked in 4WD. That means they both spin at the same speed. If the rear wheels are under power and spinning when you shift, the rear wheels are rotating faster than the front wheels. When you try to shift, all you're going to get is a loud, alarming grinding sound. It's exactly the same as trying to shift a manual tranny without the clutch, and not matching the engine speed to the road speed.

[offthepavement]

after it stopped pouring mud from the sky(pollen and rain) pollen count 1 trillion it felt like it had to much traction so out of 4hi i went.thanks everone for their insightful imsight on 4hi command trac.whens a good time to use it and how if i might ask(newbie) haha...side note i posted on things not mine forum bout a lost comanche in a salvage yard in milan tn.here's the rims on em i kinda think i will drive the hour to rescue a piece off it says jeep and everthing

 

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[WyoCherokee]

I've shifted into 4Hi at 80 MPH. Gotta be a legal speed somewhere. 

Here in Wyoming it is 80 mph on all major interstates :bowdown:

 

haha well it was pouring rain the other day and i was going 55 so i was like hmmm lets put er 4hi yall and man did it have better traction and control i was reading about 4×4s on a forum and came across someone that was "helping" another and he said the up to 45 mph statement so it got me hesitation on 4hi at 55 mph haha jeep says any legal speed so i take that as keep it under 70

 

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You don't need 4x4 in the rain on pavement.

 

 

 

I've shifted into 4Hi at 80 MPH. Gotta be a legal speed somewhere. 

Can I ask....why?????

 

Gene

 

Because I was Service Manager at a Jeep dealership and had 13 Comanches as demos. If anything broke, which I knew it wouldn't, we could fix it under warranty. 

 

Lucky Turd

 

 

Speed isn't really the issue. It's just going to wear things out more.

 

Slamming the case into 4hi while you've got varied traction can cause issues. If the rear tires are spinning when you do it there can be a rather abrupt coupling of torque at the case. That's what will break something.

 

All in all you can be pretty abusive and it's unlikely anything will ever break.

 

It isn't the abrupt torque that'll do the damage. In the 231, the front and rear driveshafts are locked in 4WD. That means they both spin at the same speed. If the rear wheels are under power and spinning when you shift, the rear wheels are rotating faster than the front wheels. When you try to shift, all you're going to get is a loud, alarming grinding sound. It's exactly the same as trying to shift a manual tranny without the clutch, and not matching the engine speed to the road speed.

 

Precisely

[offthepavement]

 

I've shifted into 4Hi at 80 MPH. Gotta be a legal speed somewhere.

Here in Wyoming it is 80 mph on all major interstates :bowdown:

haha well it was pouring rain the other day and i was going 55 so i was like hmmm lets put er 4hi yall and man did it have better traction and control i was reading about 4×4s on a forum and came across someone that was "helping" another and he said the up to 45 mph statement so it got me hesitation on 4hi at 55 mph haha jeep says any legal speed so i take that as keep it under 70

 

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You don't need 4x4 in the rain on pavement.

 

 

I've shifted into 4Hi at 80 MPH. Gotta be a legal speed somewhere.

Can I ask....why?????

 

Gene

Because I was Service Manager at a Jeep dealership and had 13 Comanches as demos. If anything broke, which I knew it wouldn't, we could fix it under warranty.

Lucky Turd

 

Speed isn't really the issue. It's just going to wear things out more.

 

Slamming the case into 4hi while you've got varied traction can cause issues. If the rear tires are spinning when you do it there can be a rather abrupt coupling of torque at the case. That's what will break something.

 

All in all you can be pretty abusive and it's unlikely anything will ever break.

It isn't the abrupt torque that'll do the damage. In the 231, the front and rear driveshafts are locked in 4WD. That means they both spin at the same speed. If the rear wheels are under power and spinning when you shift, the rear wheels are rotating faster than the front wheels. When you try to shift, all you're going to get is a loud, alarming grinding sound. It's exactly the same as trying to shift a manual tranny without the clutch, and not matching the engine speed to the road speed.

Precisely

if i can't use 4×4 on pavement in 4hi why is it even there fir?4hi is for rain and snow...probably more for snow but i was pretty sure when its raining really hard its better to have four wheels than two

 

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[DirtyComanche]

 

Speed isn't really the issue. It's just going to wear things out more.

 

Slamming the case into 4hi while you've got varied traction can cause issues. If the rear tires are spinning when you do it there can be a rather abrupt coupling of torque at the case. That's what will break something.

 

All in all you can be pretty abusive and it's unlikely anything will ever break.

 

It isn't the abrupt torque that'll do the damage. In the 231, the front and rear driveshafts are locked in 4WD. That means they both spin at the same speed. If the rear wheels are under power and spinning when you shift, the rear wheels are rotating faster than the front wheels. When you try to shift, all you're going to get is a loud, alarming grinding sound. It's exactly the same as trying to shift a manual tranny without the clutch, and not matching the engine speed to the road speed.

 

 

It's entirely possible to do it, but you have to be abusive.  It is synchro'd, it is possible to shift it in a way you shouldn't.  I have seen it happen, granted not actually on pavement, but in similar situations where the rear is spinning and "I'll just engage the 4wd" happens.  And if you tear the synchros and the teeth off the annulus, that was still torque that did it.

[DirtyComanche]

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if i can't use 4×4 on pavement in 4hi why is it even there fir?4hi is for rain and snow...probably more for snow but i was pretty sure when its raining really hard its better to have four wheels than two

 

It's there for low traction scenarios.  That might be snow, depending.  Maybe ice.  Rain on a gravel/dirt road, sure.  Rain on pavement, probably not, unless there's enough to skimboard on.

 

The (not available on a MJ) NP242 transfer case has a Full Time 4HI position, which is for running around in situations where you might want more traction, but there is not a complete lack of traction.  Basically there is a differential in the case that allows for some speed variation between the front and rear tires.  This tcase was optional on the XJ, so some guys swap them in because it's basically a bolt in.  If I was to plan to run around in 4wd a lot, I'd get one.

 

Like I said, you can use Part Time 4HI at speed or on pavement, you will just wear the tcase out faster.  And your tires.  And your ujoints.

[offthepavement]

[WyoCherokee]

 

 

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if i can't use 4×4 on pavement in 4hi why is it even there fir?4hi is for rain and snow...probably more for snow but i was pretty sure when its raining really hard its better to have four wheels than two

It's there for low traction scenarios. That might be snow, depending. Maybe ice. Rain on a gravel/dirt road, sure. Rain on pavement, probably not, unless there's enough to skimboard on.

 

The (not available on a MJ) NP242 transfer case has a Full Time 4HI position, which is for running around in situations where you might want more traction, but there is not a complete lack of traction. Basically there is a differential in the case that allows for some speed variation between the front and rear tires. This tcase was optional on the XJ, so some guys swap them in because it's basically a bolt in. If I was to plan to run around in 4wd a lot, I'd get one.

 

Like I said, you can use Part Time 4HI at speed or on pavement, you will just wear the tcase out faster. And your tires. And your ujoints.

it is thee one where all four tires are moving together forever until it breaks haha the 242 allowed for play between the front and back wheels i see.I'm learning so much bout em prob won't use it unless its like snowing or whatnots.i know i had pretty good traction without the 4 hi.my t-case says np 231 j 272 ratio which i guess is the new venture one.i wish i had the dana 44 axles or the 8.8 but the dana 35 which everyone beats up is still good for its payload everyones just like what i can have a payload of 5 thousand pounds in a small size truck wooo dana 44 etc lmdo my comanche gets 23ish miles to the gallon yours gets ? haha its definitely a trade off on what u want with your comanche.stop beating the dana 35 up its solid for what its made to do just like the 44 is solid for what its made to do!!!

 

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the 242 can be ran in 2 modes of 4x4: full time and part time, and is the preferred transfer case for "slick on road conditions" just as DirtyComanche mentioned. The 231 case is not meant for full time 4x4 use at higher speeds with "good traction, however can be used at highway speeds in icy/snowy/ gravel type conditions." there is still plenty of traction on rain soaked pavement. don't believe me, go put it in 4hi, turn hard left and watch your front end pop and groan as you pull forward or back up, even on wet pavement. Not saying you can't do it, sure it can be used on hilly streets in say a massive downpour, but rainy conditions do not fully necesitate the need for 4x4 while traveling at highway speeds. I grew on on the Pacific coast in the rain forest, Over 100 inches of rain a year. maybe once or twice did i use 4x4 on pavement while it was raining, and that was starting and stopping in the steep steep hills of the Portland heights. What will really help you in rainy conditions is appropriate tires and good throttle control and staying out of stud ruts.