Drivetrain

Bryan Lott published on
3 min, 427 words

Drivetrain

Engine

Transmission

Manual

Automatic

CVT

Transfer Case

  • Part-time 4WD
  • Engages the (almost always) front driveshaft
  • Front and rear driveshaft spin in step with one another
  • If rear driveshaft goes, can drive out in FWD w/ the transfer case engages
  • Various gear reductions are available at the transfer case
    • Jeep Wrangler Rubicon: 4:1
      • Can roughly treat 4-low - 2nd gear as 4-low - 1st gear in other Jeeps
    • Other Jeeps: 2.6:1 or 2.72:1

Center Differential

  • Full-time 4WD
  • Locking the center diff locks the front and rear driveshaft in step with one another

Driveshaft/Propshaft

  • Rzeppa Joint
    • Continuous Velocity (CV) joint
    • Consists of 6 large ball bearings running in grooves along with a containing "cage"
    • Allows 45-48 degrees of articulation while some can give up to 54 degrees
    • Can be a weak point in the front driveshaft of lifted Jeeps as the front driveshaft angle changes significantly more than the rear when lifting.
  • Birfield Joint
    • CV joint
    • Consists of 6 large ball berings running in eliptical tracks.
    • Improved efficiency upon the Rzeppa joint
  • Continuous-Velocity (CV) Joint
    • Need to be matched or driveshaft loping occurs
  • Cardian (also called double cardian) Joint
    • Consists of two paired CV joints and a centering mechanism that prevent loping and tend to be stronger at larger angles.

Axle (L/R) Differential

  • Locking the axle differential locks the left and right axles/wheels in step with one another

Solid Axle

Full Float

  • Axle shaft only serves to transmit rotational force from the differential to the wheel
  • "Fully floats in the axle housing"

Semi Float

  • Axle shaft serves to support the weight of the vehicle and transmits rotational force
  • Axle shaft is held in the housing by a c-clip at the differential. This c-clip can be a weak point and upon failure the entire axle, wheel, and brake assembly will walk out of the housing.
    • Trail fix for this is to use a long rigid "bar" (hi-lift standards work well for this) strapped to the vehicle to keep the wheel from walking out of the housing.

IFS

Other

Portal Hubs

  • A planetary gear set is located at the wheel and provides the final gear reduction.

Pinzgauer

  • Youtube: Pinz Driveline Operation
  • 2 differentials "merged together"
  • 2 ring gears offset with a center set of spider gears
    • TODO: understand how the spider gears interact with the ring gears
  • Allows each side of the axle (halfshaft) to rotate independently
  • Can bust 1 pinion and a ring gear and still keep going w/ lockers engaged