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One way to get the 4R100’s gears closer is to switch to a higher ratio final drive.
The transmission ratio doesnt change with different axle gears. Higher final drive as in 3.55 gears? I have thought about this, instead of a lower ratio that limits 3rd gear usage, use a high gear like a 3.55 that lets one use 3rd gear at highway speeds. Drive a truck with 3.55 gears and its not too bad using 3rd gear, love the low rpm cruising speed in 4th. Example; 4.30 gear vs. 3.55 is a close one in a 4spd truck because the lack of a usable 3rd gear after 50mph with 4.30. The 3.55 truck has the advantage when it comes to the use of 3rd gear lockup and 2nd gear TC lockup.
One way to get the 4R100’s gears closer is to switch to a higher ratio final drive.
Originally Posted by brokestroke
The transmission ratio doesn;t change with different axle gears.
FTN said "one way to get the 4R100's gears closer" where it is understood that the product of the transmission gears times the rear differential gear produces the final drive ratio (assuming same tires).
Do the math.
A higher rear axle ratio (numerically lower) WILL get the gears closer to each other, in terms of reducing the difference between each gear as calculated through the final drive.
FTN said "one way to get the 4R100's gears closer" where it is understood that the product of the transmission gears times the rear differential gear produces the final drive ratio (assuming same tires).
Do the math.
A higher rear axle ratio (numerically lower) WILL get the gears closer to each other, in terms of reducing the difference between each gear as calculated through the final drive.
Your right about the math.
Real life it doesnt translate completely 1:1. A truck with higher gears will feel like it has larger splits than a lower gear truck, even if they are closer on paper. Less leverage and torque of a higher gear makes the split more apparent even though it is less.
@brokestroke , if 3.73 is the "standard" final drive ratio for our trucks, a higher gear ratio means 4.10, 4.30 etc etc. I think we are all in violent agreement here.
if 3.73 is the "standard" final drive ratio for our trucks, a higher gear ratio means 4.10, 4.30 etc etc. I think we are all in violent agreement here..
Compare the lowest gear ratio (granny low) to the highest gear ratio (overdrive) in a manual transmission.
In the ZF 6, the lowest gear ratio (L) is 5.72, and the highest gear ratio (O) is 0.72.
In the school of thought where I was taught, "a higher gear ratio means" 3.55, 3.42, 3.31 if the "standard" is 3.73.
My F-550 has the deepest, or lowest, rear gear ratio that Ford ever matched to a diesel engine in a light truck... 4.88.
A higher rear axle ratio (numerically lower) WILL get the gears closer to each other, in terms of reducing the difference between each gear as calculated through the final drive.
Did you state this backwards, or is my brain confused? I expected it to say “lower rear axle ratio (numerically higher).” Ex 4.30’s reducing difference as compared to 3.73’s.
My mind says numerically lower gear ratio (geared higher) would cause final drive splits to be more. Am I missing something? It was a long day at the plant.
Originally Posted by FordTruckNoob
Well ****. EJECT EJECT EJCT!!
EDIT: This is what I was taught.
Sorry FTN, that’s completely backwards from how I’ve always been taught. The sheet should switch “LOW” and “HIGH” to be correct. Where in the world did you find that?
Bit of a sidetrack but I got a pair of exhaust manifolds with the core engine. Was thinking of having them ceramic coated and selling them. No idea if they'd sell tho. Good idea or bad idea?
