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Discussion Starter · #1 ·
Hey guys, I'm trying to figure out the proper speeds for switching into and driving in 4H and 4L. I've checked the 2006 Xterra Manual http://www.nissanusa.com/pdf/techpubs/xterra/2006/2006-Nissan-Xterra.pdf at 5-16. If I'm reading it right, the speeds are really high for driving in.. What do you guys know of for proper speed to switch into/out of 4H and 4L and also what is the max speed you can go for both?
 

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NEVER shift to 4L while moving...
Well, you can sure try ... it just won't go. The logic in the t-case control computer is such that you must have the shifter in neutral and your foot on the brake (clutch in, for a manual) for it to engage 4L.

As long as you're not excessively loading the t-case, you should be fine to switch into 4H up to 50 or so ... I know I've done it on the highway many times.

Once in 4L, I've been up to 3rd gear for sure, maybe even 4th (I've got a manual) ... probably 30 or 40 mph for short stretches, with no ill effects. I've had it up to 65 or 70 in 4H.

If I can sustain speeds that high for any extended driving (more than a few hundred yards), then I take that as I sign that I need to switch the t-case.

Exceptions to that rule are running washes out in the desert, where 4H does help with handling; and with the right suspension, higher speeds (40-50 and up) can be maintained as long as you have the visibility for it.

Your t-case is very robust ... as long as you're not being dumb, it'll be fine.
 

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Discussion Starter · #5 ·
So it is safe for the vehicle to drive at 65 mph in 4H and switch into/out of it at like 50 mph?

4L should be done while stopped in neutral? Max speeds of.. ? I have an automatic
 

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If you're concerned about it, follow the recommendations in the manual ... they're all there, I'm sure of it.
 

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Discussion Starter · #9 ·
If you're concerned about it, follow the recommendations in the manual ... they're all there, I'm sure of it.
Yup, it was in there. I was confused on the wording on for one section and thought that was what I was looking for but it sounded wrong. The section I was looking for was a few pages down.
 

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These answers sound about right, I have shifted into 4H going 40+mph a lot. Just let off the gas to unload the T Case and it will pop right in.
 

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Max 4L speed of 31 MPH according to the manual. If you're going that speed you don't probably really don't need 4L.
Read the manual again. 31MPH in low range is the upper speed that you should not manually shift an automatic into 3rd, 2nd, or 1st gear.

If you make your way to page 5-16 you can see a recommended max speed with a stick shift is 57MPH in 5th gear in low range. They don't list what it tops out at in 6th.

For the most part the system is idiot proof. If you are moving it won't shift in or out of low range. You have to meet all the correct criteria (stopped, brake on, transmission in neutral, foot OFF the clutch pedal if applicable). It won't let you exceed the capacity of any gearing combo. Eventually you will reach the rev limiter on the engine. I've played in the dunes before. Put it in low range and go. When it flattens out you can go faster, when it gets worse you slow down. Never needed to leave low range the whole time in the dunes. You can get plenty of speed in low range.
 

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Read the manual again. 31MPH in low range is the upper speed that you should not manually shift an automatic into 3rd, 2nd, or 1st gear.

If you make your way to page 5-16 you can see a recommended max speed with a stick shift is 57MPH in 5th gear in low range. They don't list what it tops out at in 6th.

For the most part the system is idiot proof. If you are moving it won't shift in or out of low range. You have to meet all the correct criteria (stopped, brake on, transmission in neutral, foot OFF the clutch pedal if applicable). It won't let you exceed the capacity of any gearing combo. Eventually you will reach the rev limiter on the engine. I've played in the dunes before. Put it in low range and go. When it flattens out you can go faster, when it gets worse you slow down. Never needed to leave low range the whole time in the dunes. You can get plenty of speed in low range.
So dont use first gear with 4lo because its bad on the tcase? Do you get stuck a lot?
 

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Just so the OP knows, you should not be driving in 4hi on paved roads. We do not have a center diff and the drivetrain will bind if you try turning in 4hi on a road that has good traction.
 

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It always bothers me that manuals on just about any 4wd vehicle use the word traction. 4L just gives you more torque. If two wheels aren't getting any traction you can switch between 4H and 4L all day and it won't help you one bit. This is evident to anyone who understands the way spider gears work. If you don't know how they work there are more than a few links on this forum to explain it. Locking diffs make a huge difference if you are ever stuck in 4wd. That being said pretty standard numbers to live by with 4wd speeds is 45mph in 4H and 30mph in 4L. even then do you really want to be maxing out the speed rating?

Doing higher than 45 in 4H tells me it is not necessary to be in 4H at all. If you feel like you need to be in 4H and are doing 60 mph then you are going way to fast for conditions IMHO. 4wd is not going to help you stop any better than 2wd.

There was a trend in motorcycles for a while to ping the rev limiter to say hi and I used to tell guys how dumb that was. often followed by "why?" because the rev LIMITER is the point just before the engine blows up. do you really want to be that close to max RPM's on your motor frequently.

4wd repairs can get very pricey. It's a great option to have in a vehicle but you need to use it with caution as intended unless you are made of money.
 

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i've been up to 60 or 65 in low range for short periods while driving on the beach, it didn't sound like it was coming apart, only thing that really let you know it was in LO was the planetary singing away.

i found on my last trip that in LO the converter fully locks up in 5th gear at about 20mph and 1200 rpm or so. in HI it'll lock up in 4th at about 30 and in 5th at about 36-37. if you're cruising faster than 30 unless you're in sand and need the gearing of low range, you should probably be in HI range.
 

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It always bothers me that manuals on just about any 4wd vehicle use the word traction. 4L just gives you more torque. If two wheels aren't getting any traction you can switch between 4H and 4L all day and it won't help you one bit. This is evident to anyone who understands the way spider gears work. If you don't know how they work there are more than a few links on this forum to explain it. Locking diffs make a huge difference if you are ever stuck in 4wd. That being said pretty standard numbers to live by with 4wd speeds is 45mph in 4H and 30mph in 4L. even then do you really want to be maxing out the speed rating?



Doing higher than 45 in 4H tells me it is not necessary to be in 4H at all. If you feel like you need to be in 4H and are doing 60 mph then you are going way to fast for conditions IMHO. 4wd is not going to help you stop any better than 2wd.



There was a trend in motorcycles for a while to ping the rev limiter to say hi and I used to tell guys how dumb that was. often followed by "why?" because the rev LIMITER is the point just before the engine blows up. do you really want to be that close to max RPM's on your motor frequently.



4wd repairs can get very pricey. It's a great option to have in a vehicle but you need to use it with caution as intended unless you are made of money.

X1000. If you are worried about how fast you can go, you probably don't need to be in 4wd at all.


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