front end binding in AWD

[msandli]

couldn't find if this question has been asked before, so here goes.

i have a 2001 tahoe 5.3 with the pushbutton AWD transfer case (don't know exact RPO code), 260k miles, runs pretty well. typically, i just leave it in 2hi for normal driving. when it's raining, i sometimes will put it in auto-AWD because the roads in atlanta don't have the best drainage.

when driving at normal speeds in AWD, i don't notice that anything is different. during very low speed, high turn maneuvers (like backing out of a parking space), it feels like my front wheels are binding, almost like they were hooked to a locked diff. it seems to do it turning both ways, and when going in either forward or reverse.

i don't know the condition of the front diff fluid or the transfer case fluid, but i wouldn't guess either of them were very clean. those are both on the "round tuit" list.

i am wondering if this is a symptom of something wrong? it's been awhile since i've read up on how everything is hooked up when in auto-AWD, but i thought it was supposed to essentially be off until it sensed a large spin difference between the front and back wheels. are slow speed, very tight turns enough to cause the t-case to engage? or does this mean that something is essentially turned on all the time? i only put it auto in the rain and i don't ever take it off road, so i'm not worred about more damage or a lack of performance. i haven't tested if it acts the same way in 4hi/4lo. i remember when i drove subarus that running slow speed figure 8's was a good diagnostic test for the transfer case.

i'm open for any knowledge or suggestions.

 

[mattbta]

Has it done it since you've owned it? Have you had any front end work done?

 

[msandli]

it has done it since i've owned it as far as i know (but since i only put it in AWD in the rain, it's not always on my radar). i haven't personally done any front end work, and i don't know the status of the parts in the front end. i will say that it holds an alignment pretty well, the shocks and struts aren't totally shot, the steering doesn't wander, etc., so for 260k miles, i'd say the front end is in decent shape.

 

[PG01]

When you put any car into 4wd on pavement, dry or wet, it will act that way...when you are in snow it doesn't feel like its 'binding' or 'locked' because it is slipping so to speak on the snow... awd is a diff animal all together... if you have 2hi/ N/auto/4hi/4low you dont really have 'awd' you have 4 wheel drive

Auto 4wd basically locks the hubs so to speak and when a wheel sensor senses a slipping tire it licks the front diff so to speak so you have 4wd, it pops in and out of 4wd when needed 4hi/4low keeps it constantly in 4wd

You may have issues when the auto part of that because it shouldnt be binding when you turn unless a wheel is truly 'slipping'. Only the 'hubs' 'lock' when auto is pushed yntil 4wd is needed or a sensor acknowledges a 'slipping' wheel

 

[msandli]

ok, maybe my issue is i thought the front diff was open, even in 4wd mode. if this is not the case, then the binding in the front is normal, but i should be more careful about when i truly need to engage auto-4WD.

is the front diff open or not?

edited this post to reflect that my push buttons are like in the post above: i have auto-4WD, NOT awd, if that makes a difference.

 

[Sasquatch]

That makes a huge difference, My lack of ability to explain what is exactly going on lead me to copy this........


The name "part time" derives from its use. It can only be used part of the time - most of the time (for most uses) it has to remain in 2WD. Only "full time" - notice the name - can be used full time for all uses.

The fight between front wheels and transfer case also makes 4WD performance suffer - in a turn the front wheels are not pulling like they should. They are in effect hindered by the front drive shaft.

The slowing effect caused by front wheels stresses all components between wheels and the transfer case. It causes mechanical components to bind instead of moving freely - this situation is called "axle binding" ,"driveline binding" or "driveline wind up". First indicators while driving is a hard steering feel and the vehicle displaying jerky movement. Shifting back to 2WD will become impossible (gears and levers are extremely forced together). Continued 4WD use on dry surfaces will cause the weakest links to break (U-Joints, axles, differential gears, transfer case gears and chains, bearings, drive shafts).

 

[swathdiver]

Put it in 4HI or 4LO on unpaved roads. Use AUTO for bad weather on paved roads. A good set of tires will negate the need to move it out of 2WD for 99% of people. But do take it out on dirt every once in while to exercise those features so they'll be there when you need them. A bet a lot of Texans are finding 4WD HI and LO useful these days.

 

[Bowana]

Up here in Canada with our winters I only used auto 4 on my previous Subs and Tahoe's. 4 hi or low only when absolutely needing 4 wheel drive. Auto 4 should not change the way the vehicle reacts whether on pavement or gravel and only activates the 4 wheel drive upon slippage of the rear wheels. I would suggest getting your front end drive line checked. It may need some service work.

 

[chevy529]

^^ x 2. Auto 4wd or AWD will only engage with wheel slippage. If the sensors are working correctly. I'd get it checked.

 

[M1Gunner]

Using any setting in a dry scenario will potentially destroy your drive train. Whether it's your transfer case, front or rear diff, one of them, more than likely you front diff, is going to bind with a catastrophic effect. Even with AWD vehicles uneven low tire pressure will prematurely destroy the drivetrain.

If you're having issues while cornering or turning it is because of your differential. If you think it's the front, then engage 2wd and check for the noise. If it's only when in 4wd it's obviously your front diff and discontinue use until further diag can be done.