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mike100 · 05-19-2014

A chassis dyno won't take the gear ratio into account except that some gear selections may have more friction than others. Lets say your engine makes 300 lb/ft of torque and you run it through a 3.08 diff. The axle will see over 900 lb/ft of torque (and of course 3 times slower rpm for a conservation of energy). The chassis dyno won't read 900 lb/ft, it's a separate system with its own diameter and speed calculation. All you get is the engine torque minus the frictional losses (and whatever other fudge factors are in the mix for the dyno).

I always felt individual trans gearing would always be more useful than just the final drive, but that is not too practical in production transmissions. Take a look at the MT-82 trans in the new mustangs... 1st gear is nearly 4:1 and the 1:1 gear is actually 5th (not 4th). That's about 1/2 the reason those new Mustangs scoot so well in the 1/4. I wish the ZF had tighter ratios sometimes.

It is a time-to-distance mod, not so much a seat-of-the-pants mod. I'f I had the budget, I'd do 3.73's myself.

05-19-2014	#29
mike100 Join Date: Feb 2011 Location: San Marcos CA Posts: 1,786	Re: 4.10 gears...not what I expected. A chassis dyno won't take the gear ratio into account except that some gear selections may have more friction than others. Lets say your engine makes 300 lb/ft of torque and you run it through a 3.08 diff. The axle will see over 900 lb/ft of torque (and of course 3 times slower rpm for a conservation of energy). The chassis dyno won't read 900 lb/ft, it's a separate system with its own diameter and speed calculation. All you get is the engine torque minus the frictional losses (and whatever other fudge factors are in the mix for the dyno). I always felt individual trans gearing would always be more useful than just the final drive, but that is not too practical in production transmissions. Take a look at the MT-82 trans in the new mustangs... 1st gear is nearly 4:1 and the 1:1 gear is actually 5th (not 4th). That's about 1/2 the reason those new Mustangs scoot so well in the 1/4. I wish the ZF had tighter ratios sometimes. It is a time-to-distance mod, not so much a seat-of-the-pants mod. I'f I had the budget, I'd do 3.73's myself.