Differential ratios

[Bigdave]

What is best foolproof way to determine the differential ratio without dissassembly?

 

[Aerocraft]

Do a search on this question. It has been answered several times. Gar Williams

 

[Kurt in NJ]

mark front pulley, mark tire,or make note of position of valve stem, put in 3rd gear, roll car 1 revolution of tire, count revolutions of front pulley --little more than 4 turns=4:11 ---3-1/2 turns = 3:54 etc

 

[Tom Wesenberg]

Kurt's approach is spot on. And, if you haven't the room to move the car....maybe it's in a garage......jack up one wheel and turn it. BUT, turn the wheel only half a revolution (valve stem at 12 o'clock to valve stem at 6 o'clock) and count the revolutions of the crankshaft pulley just as Kurt suggests. The half turn bit with the car jacked up as opposed to a full revolution on the ground is due to the action of the differential and only one wheel turning as opposed to both rear wheels turning.

??
I think you mean TWO turns rather than one half, since with one tire held still the differential will double the turns of the other tire.

 

[SSsssteamer]

Correction......Therefore, the wheel in the air needs to be turned two turns to equal one full revolution of the rear axle. By halving the one wheel's two revolutions, it equals one full rear axle revolution.