4 WD high (how fast can you go)?
11-22-2009, 12:27 PM
#1
Junior Member
Thread Starter
Join Date: Jan 2009
Location: Alberta
Posts: 4
4 WD high (how fast can you go)?
Hi all, just wondering… Can’t get a straight answer on this.
Yesterday during a snow storm in Northern Alberta I was out on the highway. Cruising speeds were (loike in most Canadian cities in the winter) variable. There were some parts of the highway that called for 50-60 KM then others 80-90.
My question is this…my manual for my ’09 Sahara Unlimited says that I can shift into 4 WD high as long as I’m under 88 km. ONCE I’m in 4 WD high can I go 90, a 100?
Please no one write back “if you need to be in 4WD you shouldn’t be going faster then 80 anyway”. Sometimes 90 or even closer to 100 with snow on the ground happens, especially when passing, or when an 18-wheeler is up your butt doing 110 etc.
This is all I can find from Jeep in their FAQ: QUESTION... How fast can I drive in 4WD High Range?
ANSWER...You should not go faster than road conditions permit.
Anyone have an answer for this? Thanks
Yesterday during a snow storm in Northern Alberta I was out on the highway. Cruising speeds were (loike in most Canadian cities in the winter) variable. There were some parts of the highway that called for 50-60 KM then others 80-90.
My question is this…my manual for my ’09 Sahara Unlimited says that I can shift into 4 WD high as long as I’m under 88 km. ONCE I’m in 4 WD high can I go 90, a 100?
Please no one write back “if you need to be in 4WD you shouldn’t be going faster then 80 anyway”. Sometimes 90 or even closer to 100 with snow on the ground happens, especially when passing, or when an 18-wheeler is up your butt doing 110 etc.
This is all I can find from Jeep in their FAQ: QUESTION... How fast can I drive in 4WD High Range?
ANSWER...You should not go faster than road conditions permit.
Anyone have an answer for this? Thanks
11-22-2009, 02:10 PM
#2
Senior Member
Join Date: Nov 2008
Location: Somewhere between NE and SW Alberta
Posts: 1,216
Re: 4 WD high (how fast can you go)?
You can do highway speed in 4 high. When the rear wheels slip the T/C starts to transfer power to the front axle. It's kind of like having a "partial" all wheel drive system. That's why you can drive on bare pavement without hurting the T/C. g/f does 120km/h in the ZJ with it in 4H and have never had a problem with it.
11-22-2009, 03:06 PM
#3
Senior Member
Join Date: Oct 2008
Location: St Catharines
Posts: 347
Re: 4 WD high (how fast can you go)?
No offence, but there is no reason at all to be doing that speed in 4WD unless it is AWD. If the roads are bad enough to need 4x4 Slow the hell down. I have a 2500 series Dodge 4x4 that is almost never in 4x4 on the street and if it is I am not going that fast.
11-22-2009, 03:18 PM
#4
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Thread Starter
Join Date: Jan 2009
Location: Alberta
Posts: 4
Re: 4 WD high (how fast can you go)?
See (LOSTSOUL) I knew there would be one in every group!!! So you're the pain in the butt guy doing 60 when traffic is going 90...Ya...again thanks for the input but you didn't answer the question. There are tons of reasons to do 90 in 4 WD, my question is will it hurt the mechanics of it.
Please note that I'm not hauling butt doing 100 in a snow storm. Must of the time I'm in 2 WD, but IF it calls for it can I do the 100km an hour in 4WD?
Please note that I'm not hauling butt doing 100 in a snow storm. Must of the time I'm in 2 WD, but IF it calls for it can I do the 100km an hour in 4WD?
11-22-2009, 06:45 PM
#5
Member
Join Date: Oct 2008
Location: port colborne ont
Posts: 50
Re: 4 WD high (how fast can you go)?
it wont hurt it if u do a hundred km in for wheel high or even more its just low range that would do damage
the manual tells u not over a certan speed in high range to protect them self if not u would get pepole doing 120 in a blizard cause the manual said they could u know?
the manual tells u not over a certan speed in high range to protect them self if not u would get pepole doing 120 in a blizard cause the manual said they could u know?
11-22-2009, 08:59 PM
#6
Moderator
Join Date: Feb 2009
Location: New Brunswick
Posts: 889
Re: 4 WD high (how fast can you go)?
Its all about knowing how to use your transfer case... and which transfercase you have
Some Transfercases have locked front and rear drive shafts in High mode, so its important to know what transfercase you have, and what mode you need.
Select Trac thats in my WJ (NV242 transfer case)
2wd, i was asked if it was front wheel drive ONCE... and couldn't believe it...
4wd Full time or is for your highway driving where you want the power transfer only when needed, otherwise its RWD with a slight load on the front tires ready to go at a moment of a slip. If the roads get as bad as they do in New Brunswick being able to go highway speeds in full time is a good option. we run studs and everything, and the potholes get so bad (i never saw ANY in ontario as bad as the mellow ones in NB!) if you have to swerve into the center track thats not down to the pave, or off into the gravel you'll be fine so long as you don't drive like a idiot and yank the wheel around.
I use Full time when im on my way out on the trails, no point to crawl if im not crawling over anything, and if im tackling terrain i rather stand the chance of not slipping, steep loose gravel i'll put it in 4 part time.
This is what some transfercases consider to be 4wd High. you really wouldn't want to put it into part time at those higher speeds (driveshafts locked even power split, just not going thru the planetaries for gear reduction) thats for when your at a higher speed afraid of slipping, going up a steep gravel hill where you could expect it to slip at any time. Part time is what you want to use when you have low traction... getting out of a mud hole is a prime example... no need to multiply torque if you have no traction!
4 low is for when your having a hard time getting over something, best when you have maximum traction... and crawling out of the hole if you cant drive out easily in High or part time.
the proper way to shift in and out of gear is to let your vehicle roll at 2-3mph, shift the tranny into neutral, shift the transfercase into gear while rolling (this allows the gears to catch interface with the moving bits of the driveline with no load on them, reducing the chance of damaging it), then shift the tranny back into gear. they say you can shift some t-cases on the fly, as in grabbing the leaver and just putting it into gear... but i've heard a few grinding teeth when people have thrown it into part time/high... soo i dunno your call.
it's always best to be in gear before you need to be...
As far as causing damage, well take a guess what happens if you've got a locked and limited slip or any locker engaged, and that wheel doesn't slip when it has to and builds up a ton of pressure/torque... it finds the weakest link and breaks it...
when taking a sharp turn and driveshafts are locked, and the limited slip is engaged and locked together the wheels cant rotate at different speeds, and you get that wheel hop, driveline bind whatever you want to call it, if that doesn't happen cause the conditions are good for traction, she's going to pop something...
weak links are CV joints, U Joints, and in some cases the ring and pinion.
Some Transfercases have locked front and rear drive shafts in High mode, so its important to know what transfercase you have, and what mode you need.
Select Trac thats in my WJ (NV242 transfer case)
2wd, i was asked if it was front wheel drive ONCE... and couldn't believe it...
4wd Full time or is for your highway driving where you want the power transfer only when needed, otherwise its RWD with a slight load on the front tires ready to go at a moment of a slip. If the roads get as bad as they do in New Brunswick being able to go highway speeds in full time is a good option. we run studs and everything, and the potholes get so bad (i never saw ANY in ontario as bad as the mellow ones in NB!) if you have to swerve into the center track thats not down to the pave, or off into the gravel you'll be fine so long as you don't drive like a idiot and yank the wheel around.
I use Full time when im on my way out on the trails, no point to crawl if im not crawling over anything, and if im tackling terrain i rather stand the chance of not slipping, steep loose gravel i'll put it in 4 part time.
This is what some transfercases consider to be 4wd High. you really wouldn't want to put it into part time at those higher speeds (driveshafts locked even power split, just not going thru the planetaries for gear reduction) thats for when your at a higher speed afraid of slipping, going up a steep gravel hill where you could expect it to slip at any time. Part time is what you want to use when you have low traction... getting out of a mud hole is a prime example... no need to multiply torque if you have no traction!
4 low is for when your having a hard time getting over something, best when you have maximum traction... and crawling out of the hole if you cant drive out easily in High or part time.
the proper way to shift in and out of gear is to let your vehicle roll at 2-3mph, shift the tranny into neutral, shift the transfercase into gear while rolling (this allows the gears to catch interface with the moving bits of the driveline with no load on them, reducing the chance of damaging it), then shift the tranny back into gear. they say you can shift some t-cases on the fly, as in grabbing the leaver and just putting it into gear... but i've heard a few grinding teeth when people have thrown it into part time/high... soo i dunno your call.
it's always best to be in gear before you need to be...
As far as causing damage, well take a guess what happens if you've got a locked and limited slip or any locker engaged, and that wheel doesn't slip when it has to and builds up a ton of pressure/torque... it finds the weakest link and breaks it...
when taking a sharp turn and driveshafts are locked, and the limited slip is engaged and locked together the wheels cant rotate at different speeds, and you get that wheel hop, driveline bind whatever you want to call it, if that doesn't happen cause the conditions are good for traction, she's going to pop something...
weak links are CV joints, U Joints, and in some cases the ring and pinion.
11-22-2009, 09:17 PM
#7
Moderator
Join Date: Feb 2009
Location: New Brunswick
Posts: 889
Re: 4 WD high (how fast can you go)?
To answer you specific assuming you have a JK (as this is in the JK forum) you have a Command Trac 241 or Rock Trac 241
your 4 High is locked driveshafts... so if you opted to have limited slip diff's, it wont be so much fun at high speeds, just avoid tight turns that cause the binding/wheel hop since the limited slip would try and kick in. if its a Rubicon with the E locker you should be fine, since i think it only engages the locker in Low, unless you mod it to engage when you want... so yea
oh and even an open diff under some road conditions act as locked diffs and cause the bind...
to answer your specific question, no real speed limit in High, since its not going thru the planetary's its just engaging the front driveshaft at the same rate as the back. (and you'll be able to tell)
as soon as you start to maneuver a tight turn, you could end up in big trouble... moose jumps out onto the road, you better hope you can stop, cause maneuvering could be tricky. all depends on the drive line and how it wants to play at that point.
your 4 High is locked driveshafts... so if you opted to have limited slip diff's, it wont be so much fun at high speeds, just avoid tight turns that cause the binding/wheel hop since the limited slip would try and kick in. if its a Rubicon with the E locker you should be fine, since i think it only engages the locker in Low, unless you mod it to engage when you want... so yea
oh and even an open diff under some road conditions act as locked diffs and cause the bind...
to answer your specific question, no real speed limit in High, since its not going thru the planetary's its just engaging the front driveshaft at the same rate as the back. (and you'll be able to tell)
as soon as you start to maneuver a tight turn, you could end up in big trouble... moose jumps out onto the road, you better hope you can stop, cause maneuvering could be tricky. all depends on the drive line and how it wants to play at that point.
11-26-2009, 09:17 AM
#8
Junior Member
Join Date: Jun 2009
Location: Dawson Creek, BC
Posts: 4
Re: 4 WD high (how fast can you go)?
There actually is a reason the manual states a specific speed limit for 4wd usage. The most obvious has been stated by lostsoul. Secondly the transfercase uses a chain drive system that is not meant to be driven above a specific speed (heat issues). I have used my t-case at hiway speeds numerous times, but intermitently. I see alot of high mileage t-cases here that are run for extended hiway miles. The only real issues I see are burnt fluids and excess synchro wear and damage.
11-26-2009, 11:04 AM
#9
Junior Member
Thread Starter
Join Date: Jan 2009
Location: Alberta
Posts: 4
Re: 4 WD high (how fast can you go)?
This is what I'm hearing from the dealership also. Two or three mechanics saying not a problem, then two or three of them saying keep it under 88kph. I think to be safe keeping it under will be the best avenue. Thanks for the input everyone to this unresolvable issue.