A4WD in snow sucks - CRASH!

[Ed H]

I cannot believe this. I had the truck in A4WD on the way home yesterday because there was snow / slush on the roads. A lot of salt too, so the driving was fine. More like rain than snow. So I pull into my subdivision and the streets had not been plowed or salted yet. No biggie, I have 4WD. So I take the first turn pretty slow, a little wide, and apply the gas again as I plan to move back into my lane.

This is what happened in 3-4 inches of snow. The drive wheel immediately spins - no traction. The rear "locks", and the front tires grab at the same time - thrusting me into a collision course with a brick mailbox. It took out a portion of the front quarter and drivers door. I know this would NOT have happended in 2HI or 4HI. I now understand prior comments about "learning how to drive these trucks".

Shit....

$1000 deductible, and I still need tires (because I have been too cheap to replace).

Just thought I would share some pain..

 

[The_Roadie]

... I know this would NOT have happended in 2HI or 4HI. I now understand prior comments about "learning how to drive these trucks"....

I'm sooooo sorry I wasn't even more vehement about my specific warnings.

A4WD mode SUCKS DONKEY BALLS.





For precisely the reason you discovered. It can engage with a boom and break you loose and cause a crash from the astonishment. Even more so on aging transfer cases especially if they weren't serviced every 50K and got grabby as a result (probably not your issue, but I have to repeat it.)

Like doing donuts on sand or snow will break your power steering pump, it's a message that can't be repeated enough.

Sorry to hear you got bitten.

 

[tblazerdude]

but then again, our whole 4WD system sort of sucks. Perfect example is when snow plowing; the street is plowed and wet, the driveway has 4 inches of snow on it, go to turn around in the street after back dragging, and their is a lot of binding. No 4x4 and you can't back up the driveway. Luckily, I have gotten by plowing 60% or so in 2wd, the G80 and the Pirelli's make that possible. I also think yearly transfer case fluid changes are my new P.M.

 

[redleg6]

what kind of balls were those?

sorry to hear you crashed, good thing it wasn't worse like someone else slamming into you that had no insurance, but you're ok...that's important

I've had mixed results using A4WD and 4HI at times. I think it comes down to knowing where you're going to drive and the limits (capabilities) of your vehicle, no matter what it is. Driver input has a lot to do with it as well...sure several members here can attest to that.

It does suck that our love 'em or hate 'em trucks came with an iffy 4WD system out of the box.

 

[DDonnie]

Like doing donuts on sand or snow will break your power steering pump

Ha, truth.

 

[Voymom]

Ha, truth.

Don't feel bad, we found out the hard way too lmao


Sorry for your mishap. I used to drive the truck in A4WD all last winter when I first got it not knowing any better, but luckily I got the warning before anything serious happened. One thing to keep in mind is that no one here will ever intentionally lead you in the wrong direction or give you bad advice.

 

[TollKeeper]

I have had really good luck with my A4WD.. But then again, I have been using A4WD since forever (Subura, Aztek, Tahoe, and a few others).

Sorry about your wreck thou man.. That does truly suck. And the 1000 dollar deduct, plus tires.. OUCH!

 

[RayVoy]

I have had really good luck with my A4WD.. But then again, I have been using A4WD since forever (Subura, Aztek, Tahoe, and a few others).

The problem is that there are two different t-case designs out there. The design that works, and works very well, is a design that uses clutches in a manor that copies the posi-traction rear-end clutches. With this design, power is applied to the front wheels in a smooth transition. The t-case used in the 4x4 trucks operates more like the driver releasing the clutch on a manual shift car, the power is applied a bit more aggressively.

 

[The_Roadie]

Our A4WD system is different than the full-time AWD systems on vehicles like Subarus. That's also why I will now use the full acronym A4WDSDB mode when discussing our system. I used to just say A4WD, but I have a better acronym now.

 

[DDonnie]

A4WDSDB

I gotta ask, DSDB?

 

[Black_tb]

I gotta ask, DSDB?

refer to the quote above auto 4 wheel drive sucks donkey balls

 

[Jkust]

You guys are too hard on the A4wd. All my 360's have only had that (Rainiers and 9-7x's) and it is very effective if you have stabilitrac. Stabilitrac won't allow the truck to do what the OP experienced. Without the stabilitrac and even worse with the G80 and A4wd (without stabilitrac) these trucks can be tough to deal with on ice especially if your tires are worn. I will go on a mission daily on our icy roads to beat the stabilitrac and it is extra hard to do even on solid ice...until you shut it off. After the first multiple rollover debacle with our early G80 equipped A4wd Rainier, I wouldn't want a 360 without the system.

 

[Denali n DOO]

You guys are too hard on the A4wd. All my 360's have only had that (Rainiers and 9-7x's) and it is very effective if you have stabilitrac. Stabilitrac won't allow the truck to do what the OP experienced. Without the stabilitrac and even worse with the G80 and A4wd (without stabilitrac) these trucks can be tough to deal with on ice especially if your tires are worn. I will go on a mission daily on our icy roads to beat the stabilitrac and it is extra hard to do even on solid ice...until you shut it off. After the first multiple rollover debacle with our early G80 equipped A4wd Rainier, I wouldn't want a 360 without the system.

I too love stabilitrac and also try to beat it going around snowy corners and hitting the gas, it's amazing how fast the Stabilitrac takes over and controls the turn. I remember pulling my trailer down the hi way around 110 km/h and as I passed under an overpass I hit ice and had a small ass end shimmy and instantly the Stabilitrac went on getting ready to take control but it was so brief it quickly turned off since control was maintained. My friend thought his Sierra 4x4 was bad ass in the snow, then I introduced him to my Stabilitrac on some test corners, now he loves Stabilitrac too. For me, traction control isn't that great sometimes I'd rather spin the tires and keep moving forward, thanks to the G80. In snow I like traction control turned off and I don't use auto 4x4, I'm either 2 hi or 4 hi.

 

[The_Roadie]

You guys are too hard on the A4wd.

GM shipped a LOT of A4WD vehicles before Stabilitrac, many of them are aging now with inadequate transfer case maintenance and grabby clutches, and many of those are combined with bad tires. I don't think I can be as hard as I want to be on the A4WD mode because I can't call for a general recall to remove that mode from the switch. When some folks get killed from accidents like yours and this one, the NHTSA might take notice.

All my 360's have only had that (Rainiers and 9-7x's) and it is very effective if you have stabilitrac. Stabilitrac won't allow the truck to do what the OP experienced. Without the stabilitrac and even worse with the G80 and A4wd (without stabilitrac) these trucks can be tough to deal with on ice especially if your tires are worn. I will go on a mission daily on our icy roads to beat the stabilitrac and it is extra hard to do even on solid ice...until you shut it off. After the first multiple rollover debacle with our early G80 equipped A4wd Rainier, I wouldn't want a 360 without the system.

Agreed, but the installed base is huge, and GM won't be giving us free Stabilitrac upgrades, so what can we do for the 2002-2005 trucks out there? Just tell them to shun the A4WD mode. 2HI or 4HI - choose wisely according to conditions.

 

[Jkust]

I too love stabilitrac and also try to beat it going around snowy corners and hitting the gas, it's amazing how fast the Stabilitrac takes over and controls the turn. I remember pulling my trailer down the hi way around 110 km/h and as I passed under an overpass I hit ice and had a small ass end shimmy and instantly the Stabilitrac went on getting ready to take control but it was so brief it quickly turned off since control was maintained. My friend thought his Sierra 4x4 was bad ass in the snow, then I introduced him to my Stabilitrac on some test corners, now he loves Stabilitrac too. For me, traction control isn't that great sometimes I'd rather spin the tires and keep moving forward, thanks to the G80. In snow I like traction control turned off and I don't use auto 4x4, I'm either 2 hi or 4 hi.

One reason I look forward snow is to go and have some fun trying to beat the system since you can turn off just the traction control system or both systems to turn it into a pre 2006 model. Also, doesn't traction control shut off when in 4wd?

GM shipped a LOT of A4WD vehicles before Stabilitrac, many of them are aging now with inadequate transfer case maintenance and grabby clutches, and many of those are combined with bad tires. I don't think I can be as hard as I want to be on the A4WD mode because I can't call for a general recall to remove that mode from the switch. When some folks get killed from accidents like yours and this one, the NHTSA might take notice. Agreed, but the installed base is huge, and GM won't be giving us free Stabilitrac upgrades, so what can we do for the 2002-2005 trucks out there? Just tell them to shun the A4WD mode. 2HI or 4HI - choose wisely according to conditions.

All good points but for those that are searching the internet or just discover the platform, I'd hate for them to broadbrush all years of the 360's since the stabilitrac (and the traction control system that was formerly only on rwd models) makes the trucks far less likely to sucumb to user error. I'd also hate for someone to choose an exploder or some other vehicle not realizing the 2006 on up years of our trucks not realizing what seems like an innocuous piece of equipment with a marketingesque name is actually a giant leap forward. The difference between our 2004 Rainier and the 2007 is so drastic it seems to defy physics...and stability control is on every car now. Even if you don't live in a climate where it rains or snows, the dreaded overcorrection of someone changing lanes into you is where the system makes the difference between life and an 8 rollover, horrible death on some highway.

 

[Denali n DOO]

One reason I look forward snow is to go and have some fun trying to beat the system since you can turn off just the traction control system or both systems to turn it into a pre 2006 model. Also, doesn't traction control shut off when in 4wd?

You must be right, I don't think traction control has ever turned on when I'm in 4wd or maybe it just has enough traction that it doesn't need to come on I don't know. From a stop in the snow, if I turn off traction control in 2 hi then the locker will lock when I lose traction and keep me moving, if traction control is on I don't even think the locker has time to lock

 

[McGMT]

You must be right, I don't think traction control has ever turned on when I'm in 4wd or maybe it just has enough traction that it doesn't need to come on I don't know. From a stop in the snow, if I turn off traction control in 2 hi then the locker will lock when I lose traction and keep me moving, if traction control is on I don't even think the locker has time to lock

In my 06 the traction and stability does stay on in 4HI but they shut down in 4LO.... I was playing with it the other day on ice and noticed that even if you shut off traction control it still kicks in when you really get to spinnin. And then when you shut down both traction and stability controls they more or less stay off, but again when you really get to spinning and swerving they STILL come in on you if you like it or not.

 

[mrphoenix80]

These trucks have A4WD????? I don't think that position works on my switch.

My favorite is the customer that comes in the July for service and the truck is in A4WD.

 

[RayVoy]

My favorite is the customer that comes in the July for service and the truck is in A4WD.

It amuses me as well, I would leave it in A4WD and don"t recommend leaving it there; but to be honest, there is nothing wrong with doing it. Some of us DO NOT USE IT at any time of the year, but leaving it in A4WD is no different than the way the Olds and Buick trucks are set up.

 

[mrphoenix80]

True. My objection to it is that the encoder engages the clutches every time there is wheel slip. To me is just seems to be a lot to ask the encoder to do.
Of course I dont like anything auto. I will tell you what I want when I want it. My favorite cars and trucks have been stick shifting, non abs havin', crank window, manual locking....... Well you get the idea.

 

[RayVoy]

Oh, I agree, there is a lot of parts turning when left in A4WD and this will result in unnecessary wear on the front drive assembly; and as well, there is a mileage penalty.

 

[mrphoenix80]

Are we going to have and agreeing argument?

 

[RayVoy]

I love agreement arguments, I'll bring the beer..........................Moosehead of course.

 

[Conner299]

I like to refer to the A4WDSDB as the that one pain in the a$$ position I have to switch past. I wish I could remember where I found it, but there is a great post on the stress the A4WDSDB causes on the TC, somewhere on ORTB. Roadie might be able to help out on that one. It's the reason you'll never find my truck in that position, or me shifting into any 4wd function higher than 5mph, and in neutral.

Edit: Just saw the last posts, that got put up before mine did. Aren't there actually no extra moving parts when left in A4WDSDB, unless wheel slip is detected.

 

[RayVoy]

Yep, skip over the auto position like it wasn't there, I'm with ya; but rethink the shift on the fly position your taking.

I don't think anyone should shift into any 4x4 gear while the rear wheels are spinning and the fronts are stopped, that transfers a lot of energy into the frame of the t-case; however, the case works pretty good when you shift into 4x4 when at speed. The reason for this, the front wheels are turning at the same speed as the rear wheels, very little energy transfer into the case.

Here is how it works, shift from 2wd into 4wd, one of the first things that happens, the front passenger axle disconnect engages. This ties the inner and outer axle halves together (yes, there is some energy transfer as the outer is moving and the inner is not); connecting both wheels to the front diff, will force one of the wheels to turn the front driveshaft. Both driveshafts should now be turning at approximately the same rpm. At this point, the t-case clutches fully engage and engine power is sent to the front as well as the rear.

There is very little energy transfer inside the t-case, and there is some, but not a lot, at the front disconnect.

 

[Conner299]

@RavVoy...My shift on the fly position, you were referring to, might have gone misunderstood. When I shift into 4WD, 4HI or 4LO, i'm always coasting in neutral, at less than 5mph. Once it shifts into 4WD, I stop, put it into D, then take the foot off the brake and turn the wheel, left to right, to make sure it is engaged. I basically shift out of 4WD the same way, in reverse.

 

[The_Roadie]

...Moosehead of course.

You know how you can tell a guy who likes Moosehead?

Spoiler

By the antler scars in his thighs.

 

[mrphoenix80]

Aren't there actually no extra moving parts when left in A4WDSDB, unless wheel slip is detected.

The front axle disconnect is always engaged in A4WD. So the front axle and front drive shaft spin at the same speed as in 4HI. This allows the TCCM to apply the transfer case clutches with the encoder motor faster when slip is detected. The clutch is applied at 100% (50/50 torque split) then steped back at 10% increments until full release or wheel slip is detected. So in high slip conditions the encoder is working all the time (apply and release) in A4WD mode. In 4HI the encoder applies the tcase clutch and locks in.


EDIT: Now you want to really confuse someone. Take an Escalade with AWD them things have no clutches at all!!!! The front and rear diffs are open and the tcase has a planetary gearset that acts as an open diff. GM then uses the ABS to detect wheel slip and applies the brakes on the spinning wheel to transfer power to the wheels with traction. You might ask how I know this. I opened up a tcase to fix a 4WD inop concern. I thought (I don't know what the heck I thought) it had a viscous clutch or something. So I open it up and it was a planetary and a chain on 2 shafts thats it. Oh and a wasted afternoon.

 

[Ed H]

Thanks for the comments guys and gals. This is the only vehicle I've owned that I did NOT take to a parking lot for practice. This was the first real snow we received all year. Live and learn, I guess. I can assure myself THIS will never happen again.

It is with great pain that I post the pictures below.

She goes in on Monday for repairs. I should have her on Thursday or Friday, all pretty again - to the tune of $3500 (initial estimate, that we all know is always low). That $1000 deductible doesn't sound so bad any more.

View attachment 26597

View attachment 26598

View attachment 26599

 

[The_Roadie]

That'll buff right out.

Looks like a typical weekend carnage for rocky offroading. Just lose the running boards next time. Hehe.

 

[Jkust]

Bummer for sure....at least it isn't a rear quarter. They can slap a new door and fender on in no tome. I've lived that scenario 100 times with my former 04 Rainier with the full time a4wd but I did it on purpose and got to know the limitations and downsides of a g80 and the rears wanting to pass the fronts. Like I said that is exactly what the Stabilitrac prevents. Bummer they didn't have it on earlier trucks since i'm sure this has repeated itself over and over.

 

[RayVoy]

You know how you can tell a guy who likes Moosehead?

Spoiler

By the antler scars in his thighs.

Haha, I was waiting for that.

 

[McGMT]

Look at what my wife did the day after I posted about the stability on this thread....

View attachment 26614

 

[Ed H]

Aw, that sucks. I feel your pain. Hopefully the damage is just the front clip?

Snow?

 

[McGMT]

Aw, that sucks. I feel your pain. Hopefully the damage is just the front clip?

Snow?

Its a front end and a bent tie rod end.. They gave us a rental, a 2012 Traverse, that bastard is big compared to our blazer, barely fits in the garage. My wife found a nice icy patch the other day coming down over the mountain.

 

[wedge1]

So is it never too late to start changing the transfer case fluid? Mine has almost never been out of 2HI. But the fluid has never been changed. 158,000+ miles. I've put it in AWD a couple of times when there has been mud on the road.

 

[HARDTRAILZ]

I cannot believe this. I had the truck in A4WD on the way home yesterday because there was snow / slush on the roads. A lot of salt too, so the driving was fine. More like rain than snow. So I pull into my subdivision and the streets had not been plowed or salted yet. No biggie, I have 4WD. So I take the first turn pretty slow, a little wide, and apply the gas again as I plan to move back into my lane.

This is what happened in 3-4 inches of snow. The drive wheel immediately spins - no traction. The rear "locks", and the front tires grab at the same time - thrusting me into a collision course with a brick mailbox. It took out a portion of the front quarter and drivers door. I know this would NOT have happended in 2HI or 4HI. I now understand prior comments about "learning how to drive these trucks".

Shit....

$1000 deductible, and I still need tires (because I have been too cheap to replace).

Just thought I would share some pain..

I simply can not believe no one mentioned that the "too cheap to replace" tires could have easily been at as much fault as the 4x4 system. In hind sight I bet tires would have been a lot cheaper. Putting off maintenence coulda killed a kid building a snowman instead of just dinging your truck. You got lucky and got to pay for it.

So is it never too late to start changing the transfer case fluid? Mine has almost never been out of 2HI. But the fluid has never been changed. 158,000+ miles. I've put it in AWD a couple of times when there has been mud on the road.

Change the fluid with AutoTrak II. ASAP. Your truck will thank you.

 

[Darkrider_LS]

I simply can not believe no one mentioned that the "too cheap to replace" tires could have easily been at as much fault as the 4x4 system. In hind sight I bet tires would have been a lot cheaper. Putting off maintenence coulda killed a kid building a snowman instead of just dinging your truck. You got lucky and got to pay for it.

I honed in on that as well. But i agree with the others that have the Stabilitrac system...it is awesome to have in our trucks. Like everyone else with it there are times that i hit the thumb switch on the shifter to disable it to have a bit of fun. With that said i think my truck spent about 3/4 of the winter in A4wd. It def was an interesting feeling the first time i matted it on ice half expecting the rear to come around a bit only to be stopped dead by Stabilitrac kicking in and the truck launching straight forward. But one thing i did learn pretty fast is that Firestone Destination LEs SUCK on ice and snow lol

 

[Ed H]

The tires aren't THAT bad - look at the 2nd picture I posted of the damage. I have thread well above the wear bars. I usually replace tires immediately after buying a vehicle but did not this time. That's why I said I'm cheap and still need tires.

If I had practiced in snow so I knew how the truck would launch forward (no "launching" on bald tires), this wouldn't have happended either. In any case, it is clearly the driver's fault when you hit a mailbox...

You are correct. Damn happy it wasn't a kid. I always stay as far away from them as possible in the snow.

 

[wedge1]

Thanks. It will be done.