Quote:
Originally Posted by cRiPpLe_rOoStEr
Seems like the decoupling only works with the engine on. Well, I never held my breath for those "automatic 4WD" systems, unless they had a proper center differential which IIRC some SUVs from the '90s didn't resort to and relied mostly on sensors input to engage and disengage the front drive. And once the clutches wear out, it may become worse to drive on pavement.
That sounds good.
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There's no electric involvement in the center differential. It's a set of clutches with a gerotor pump. When there is a speed difference between the front and rear output shafts, the gerotor spins to pressurize the clutch pack.
There's no preload on the clutch pack when it's new, but I suspect incorrect fluid usage or water contamination makes the clutch pack drag. I've seen an identical transfer case with even more resistance than mine.
Same system was in the front and rear axles (now replaced with air-locking differentials).
Pressure is regulated by a simple metal tab over the pressure relief orifice. Subsequent version used a solenoid to control pressure in both front and rear clutch packs and could act almost like lockers if the solenoids held pressure high and long enough.
It's a good system for mild off-roading but it requires wheel speed difference to work and it still allows for slip between sides. I couldn't have made it up that obstacle in the video I posted with the standard traction system.
Another bonus with the transfer case swap is that fluid changes (every 20k miles) cost $8 instead of $30. No need for special fluid.