Towing RV with AWD vs 4wheel

Yes, you need to know which one you have. GM has both gear and viscous
third members

The two guys I helped had vicous third members in their Escalades.

So the OP needs to ID which third member is in the vehicle


NVG 149 AWD transfer case info

BTW - GM says the viscous coupling is not serviceable. This doesn't mean the transfer case can't be fixed, just the viscous coupling needs to be replaced. This part is #2 in the first picture. So if you did happen to ruin the AWD tcase by doing a dyno, it can be easily fixed.

Escalade Awd

gm-trucks wrote:
the Escalade transfer case uses a viscous coupling type system to power the front wheels.
The vehicle is permanently in AWD, it can not be disconnected

Tahoe-Yukon forum: understanding Awd

FULL TIME AWD wrote:

NP3 (NV 149, BW 4473 viscous clutch): uses center viscous clutch to give front/back torque bias.

NVG 149 AWD transfer case info

performancetrucks wrote:
NVG 149 AWD transfer case info

How does viscous coupling work?

Viscous coupling is filled with silicone and is not computer controlled. A series of plates with holes and slots turn in the silicone fluid. Some plates are attached to the front axle driveshaft and some are attached to the rear axle driveshaft. Normally the plates turn at the same rate without relative motion. The silicone becomes very viscous as soon as it is heated by friction and shear caused by differences between the motion of the plates. This tends to lock the driveshafts. If the rear wheels and driveshaft are slipping and turning faster than the front, friction between the plates increases, slippage is reduced, the rear wheel spin is reduced and the torque from the input shaft is transferred to the front.