Leisure Wheels (South Africa) - - TECH -

Trans­fer cases used in per­ma­nently four-wheel-driven 4WDs (like a Toy­ota Prado and a Ford Ever­est) are de­signed to syn­chro­nise the dif­fer­ence be­tween the ro­ta­tion of the front and rear wheels (the same way a dif­fer­en­tial op­er­ates on an axle, re­ally).

On a tarred or hard sur­face, if a trans­fer case does not syn­chro­nise the dif­fer­ence be­tween the two axles (if you se­lect 4H for a 50/50 split be­tween the axles, for ex­am­ple) the re­sult will be driv­e­line wind-up.

This wind-up oc­curs when the me­chan­i­cal com­po­nents of a ve­hi­cle’s driv­e­line bind or wear, cre­at­ing a re­sis­tance in the sys­tem. That’s the bind or wear you get when you drive a part-time 4×4 in 4H on a tar road, and try to make a tight turn. There is a feel­ing of re­sis­tance, al­most like the wheels won’t turn and are be­ing braked by some in­vis­i­ble force. This is driv­e­line wind-up.

Be­sides be­ing an­noy­ing, it also has a detri­men­tal ef­fect on the me­chan­i­cal com­po­nents.

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