2003 Escalade AWD question

[bzzh8c]

It's been reported that when using engine braking down an incline in an Escalade, one does not get as much resistance as in a Tahoe in 4WD mode, and thus tapping the brakes to maintain speed is needed whereas in the Tahoe it wasn't. Is this because of a fundamental difference between AWD and 4WD?

 

Is there a way to force an Escalade into 4WD mode?

 

Thanks for advice.

[chris_kucia]

IIRC, that model year Escalade uses a viscous clutch AWD system, similar (but different xfer case) than was used on the awd Astros, Syclones, and Typhoons.

 

It is not "disable-able".

 

As I understand it, is the rwd drivetrain is essentially solid as normal, but in the xfer case there is a chain drive off the driveshaft that attaches to a viscous clutch. The front driveshaft is powered by the viscous clutch.

 

How it works is the fluid in the viscous clutch has the peculiar property of becoming thicker (more viscous) as it warms and as you try to move parts through it. So it works sort of like a torque converter, but a fast-reacting one.

 

When both the input drive and the output drive of the viscous clutch are moving at the same speed (no slippage), the fluid is "runny" and there is no power transmitted so the front drivetrain is coasting. When the input and output are different, due to a traction difference between the front and rear drivetrains, the internals of the clutch begin to slide and the fluid gets really thick really fast, which couples the front driveshaft to the input of the clutch and transmits power to the front.

 

Its pretty cool technology - it engages and disengages as seamlessly as an automatic transmission shift, but still is able to transfer a significant percentage of torque to the front wheels. Best part is that no driver input is required.

 

 

I believe that some other AWD models have the ability to disable AWD using an electrically-actuated planetary gearset, but frankly, I don't know all that much about them, only what I've read on the web. I think the 2003 Escalade had a single-year transfer case that was revised on the later models.

 

 

This is all off the top of my head, so please correct me if someone has better info.

[hcvone]

It's been reported that when using engine braking down an incline in an Escalade, one does not get as much resistance as in a Tahoe in 4WD mode, and thus tapping the brakes to maintain speed is needed whereas in the Tahoe it wasn't.  Is this because of  a fundamental difference between AWD and 4WD?

 

Is there a way to force an Escalade into 4WD mode?

 

Thanks for advice.

 

<{POST_SNAPBACK}>

 

 

 

I had 6 Suburban's and now have an Escalade AWD, I notice no difference in towing between the trucks, and we tow large snowmobile trailers in the mountains.