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4x4 Questions...

dinkster

dinkster

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Sioux Falls, SD
Ok, there's snow outside right now, but no need for 4x4 just yet... But, I had a few questions for when it does get deep...

First off, I have manual locking hubs in the front wheels of my Blazer. I've never had those before. My previous Jimmy didn't have them. I had to put the old Jimmy into 4x4 just from the cab, and drive away. Then I read in the manual to disengage the 4x4 you have to put it in 2x4 and back up about 10 feet or so to disengage the front wheels. I was told now with the manual locking hubs I can just put it in and out of 4x4 without even stopping or without having to back up like I had to with my previous truck (the hubs would have to be in the 'locked' position in the front wheels, of course)... Is this true, or am I getting some bad info?

Also, I never rode down the highway with 4x4 on as I've heard that was a bad idea. I've been told recently that any driving on dry pavement with 4x4 is bad as well, mainly due to going around corners and the front wheels needing to spin at different speeds. I thought that going back and forth to low traction and high traction in 4x4 was no big deal, and I thought the front differential compensated for the turns.... I ask this as some roads around here don't get plowed, and when it was bad out, I used to leave my old Jimmy in 4x4 until all the deep stuff was gone. So, this was a bad idea, as I was going back and forth from dry pavement to deep snow? I never had a driveline problem with the old Jimmy, but I only used 4x4 for the snow about 3 times...

I just figured I'd ask so I don't do anything stupid with my new Blazer...
 
Yeah as long as the hubs are in the Locked position you can shift into 4 wheel whenever you want. As for driving on dry pavement with 4 wheel locked in its not such a good idea. Somebody that knows more will chime in quickly im sure.
 
dinkster said:
I was told now with the manual locking hubs I can just put it in and out of 4x4 without even stopping or without having to back up like I had to with my previous truck (the hubs would have to be in the 'locked' position in the front wheels, of course)... Is this true, or am I getting some bad info?
Click to expand...

Well you'll have to stop if you want to change the transfercase at all otherwise you'll grind the gears... as far as the hubs go I leave my hubs locked if I know I might need 4wd that way if I need it all you have to do is stop, put the TC in 4wd and go... if I'm going to be back on the street for a while then I unlock them so the front axle shafts and such aren't spinning (because with manual hubs even if you aren't in 4wd the front axle shafts/ring/pinion will spin if the hubs are locked in so keep that in mind)...

dinkster said:
Also, I never rode down the highway with 4x4 on as I've heard that was a bad idea. I've been told recently that any driving on dry pavement with 4x4 is bad as well, mainly due to going around corners and the front wheels needing to spin at different speeds. I thought that going back and forth to low traction and high traction in 4x4 was no big deal, and I thought the front differential compensated for the turns.... I ask this as some roads around here don't get plowed, and when it was bad out, I used to leave my old Jimmy in 4x4 until all the deep stuff was gone. So, this was a bad idea, as I was going back and forth from dry pavement to deep snow? I never had a driveline problem with the old Jimmy, but I only used 4x4 for the snow about 3 times...

I just figured I'd ask so I don't do anything stupid with my new Blazer...
Click to expand...

As long as your front differential is open then you'll be ok going around turns (I'd let off the gas personally and just coast)... as far as going down the freeway at high speeds... well in my opinion if you're worried about needing 4wd due to the road conditions then I'd say it isn't safe to drive fast anyways...

Just use good judgement, if you know you'll encounter some heavy snow then lock the hubs before you leave and that way you'll be ready (sure the front axle shafts and ring/pinion will be spinning but its not a big deal).

On a side note the manual hubs on my truck can be a PITA somtimes so don't be surprised :D
On my truck I find it easiest if I pull onto the pavement...
Pull forward...
Put it in reverse and go back like a couple inches...
Then put the transmission and the TC in neutral...
Hop out and unlock/lock (whatever you're trying to do) the hubs...
Get in and engage the TC...
Then put the tranny back in gear...

Seems to work for me but I'm sure we all have our own methods...
 
Cool, thanks for the tips. Especially the bit about getting them locked/unlocked. I've never had them before so, I'm sure I'd be swearing at them when I go to lock them. :doah:

I figured I'd lock them and just leave them locked for the winter... I can't think of anything wrong with that, except losing a few MPG (but the Blazer isn't my DD). Then I could switch in and out of 4x4 whenever I felt like it, and just unlocked them come spring.

I'm guessing that dry pavement in 4x4 is ok as long as my front differential is open? I have no reason to believe it isn't open. I never would leave it in 4x4 for long if I'm only on dry pavement anyways, there's just no need for it...
 
Avery4jc said:
Well you'll have to stop if you want to change the transfercase at all otherwise you'll grind the gears...
Click to expand...
That depends on what T Case he is running. For example, the NP241 in my 90 (should be the same for 89) has the synchros in it for the "shift on the fly" capablity. Not sure if the 208 is like that, but the 203 or 205 I know do not.
 
I have a 208 and i can shift on the fly as long as Im not driving over 20-25mph (I have never tried it going any faster And i don't recommend it either)

But with a 208 shift on the fly is allowed
 
BIGBLAZE433 said:
That depends on what T Case he is running. For example, the NP241 in my 90 (should be the same for 89) has the synchros in it for the "shift on the fly" capablity. Not sure if the 208 is like that, but the 203 or 205 I know do not.
Click to expand...

yeah, you can shift into 4-hi while the truck is in motion on my 208. you're suppose to put the transmission in neutral when shifting to 4-lo.
 
Good point Ben I didn't notice he had a "new" truck...

I don't shift on the fly with my NP208 b/c it would grind a little bit and I don't really have a reason to...

Oh and Joshua I hear guys say that from time to time (about leaving them locked for the winter)... its really not that big of a deal and I personally wouldn't. Some guys make it seem like its a 20 minute ordeal... when you fire up the truck and let it warm up a little bit lock the hubs if need be but if not then leave them unlocked...
I probably unlocked/locked my hubs 15+ times last time we were in Pismo...its really not a big deal.
 
I've always ran mine locked in in the winter but i hardly ever use 4wd anymore so i keep them unlocked...As for shift on the fly under 25 should be alright with your setup
 
I don't know that I'd even want to throw it into 4x4 when I was moving as everything in my brain would tell me that's the wrong thing to do. :D

I'll try leaving them unlocked till we get some weather that I might need the extra grip. Then I'll unlock them again once it clears.

I used to try not to use 4x4 for snow/ice too often because it can give you a false sense of security. You can take off from a stop real easily with it on, but trying to stop suddenly is still just as ****ty on ice with or without 4x4. So, you might not know how slippery it is until it's too late. :eek1:
 
Keep it out of 4wd on dry pavement. Even dry hardpacked dirt is a problem. Puts a lot of stress on the drivetrain components as the front and rear tires do not turn at the same speed, and that unequal force has NO outlet in 4wd except tire slippage. Your manual should say the same thing.

203 is the only t-case GM used in these trucks that used a center differential which allowed "slip" on dry pavement.
 
dyeager535 said:
Keep it out of 4wd on dry pavement. Even dry hardpacked dirt is a problem. Puts a lot of stress on the drivetrain components as the front and rear tires do not turn at the same speed, and that unequal force has NO outlet in 4wd except tire slippage. Your manual should say the same thing.

203 is the only t-case GM used in these trucks that used a center differential which allowed "slip" on dry pavement.
Click to expand...

With an open front diff? Wouldn't he have to have different differential gearings for the front and rear tires to move at separate speeds?
 
I'm as lost as TSGB... he has the same gearing and tire height front and rear...
So what are you worried about? Sure he doesn't need to run it in 4wd on the dry pavement so its not really an issue but why are you worried about different driveshaft speeds?
 
Your front tires turn differently than the rears....they steer. Imagine the front and rear tire track through a corner. That's why you can't leave it in 4wd on dry stuff. Even an open diff has to put power down to one wheel. Besides, sometimes you'll see slightly different stock front/rear ratios, like 4.09/4.11

Think about how a differential works...open diff supplies power to the wheel with the least traction. If both wheels have high traction, the fact that its open means nothing.

Not sure how hard the 208/241's are to shift out of 4wd after being driven for awhile, but my 205 will easily shift out of 4wd IF I have made no turns. If you add any turns, the drivetrain binds up enough to make it a pain to get out of 4wd. My course usually involves slippery rocks, dirt/mud hill, and a turn out on dry ground. If I shift before hitting the dry ground, no problem. Shift after turning? I've got to back up to make it easier to shift out.
 
I've engaged my 4x4 at about 45mph before. It didn't engage super smoothly but it did. :rolleyes:
 
If you think there is even a chance the road may be spotty with snow and ice, then there is no problem leaving the truck in 4wd. Yes, there will be binding when turning sharp when in 4wd (on a regular part-time 4wd setup) whether the front diff is open or not. When you turn all 4 tires make a different arc, and thus have to go different distances to get the truck from point A to point B. But again, it shouldn't be an issue as the tires should always scrub/slip and release the energy way before anything in the drivetrain could break. I'm not saying you should drive in 4wd when the roads are perfectly clear and dry (no reason to), but it shouldn't hurt anything either.
 
Randy92782 said:
I've always ran mine locked in in the winter but i hardly ever use 4wd anymore so i keep them unlocked...As for shift on the fly under 25 should be alright with your setup
Click to expand...

I run my hubs locked all winter unless i go on the highway. If in 4wd i will pop it into 2wd to park or turn in tight areas then back into 4wd if needed.

I have found having locked diffs front and back makes for on-road 4wd not so fun.
 
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