The Stovebolt Site Forums The Shop Area Driveline gear nomenclature.

High gear.
Low gear.
High gear ratio.
Low gear ratio.
High and Low split rear axle.
What do these terms mean to you?
These phrases are thrown all over the place, and incorrectly in many cases.
This makes discussion awkward.
Example: "My engine screams at 55 MPH. How much higher gear ratio do I need to bring the RPM down?
Answer: You don't need a higher gear ratio. You need a lower gear ratio.
A 3.73 to 1 gear set is a higher ratio, numerically speaking than a 3.55 to 1 gear set.
Where the confusion can come in, is from the discussion of transmission gear nomenclature. First gear is commonly called "low gear", while 4th gear is commonly called "high gear", even though the ratio of these two gears contradict this nomenclature.
The same is true with the High and Low range in a split rear end.
So what is the solution, you ask?
I suggest that when the word "Ratio" is used, make sure that terms "Higher" and "Lower" correspond with the numerical aspect of the term "Ratio."

Carl
I have a pet dog. He is an annoying idiot. I should have named him Peeve.

What's more, a 4.10 is a longer rear end than a 4.57.

LONGER ?????

In my line of work, which is in the auto/ commercial truck repair/mechanic.We talk of a vehicle being low geared, as in 4:10 and higher.A high geared vechicle will be 3:73,3:55,3:07 and down. Here is how i will explain by way off my 54 3100.when i got the truck back in 78, it had 4:10 gears.4 spd manual. At 55 mph the rpm was pushing 3000. A few years down the road i had some issuse and i put a diff in with 3:90. Same trans, same 55 mph, lower rpm,as such i could go a little faster when i started pushing the 3000 rpm. Many years later a diff with 3:07 ratio went in with a 4 spd Saginaw.At 55 mph,rpm was down in the lower 2000 rpm range. Step on the gas and by the time I'm back to pushing the 3000 rpm mark, im also doing 70 mph. My numbers are ball park but close. Im not too fussy on being exact. Higher the gear ratio number the slower one goes. Lower ratio numbe, the faster one goes. Trucks/ pickups built for work need to be low geared 410 and up,off road vehicles get up into the 5's thats stump pulling gears,highway cruising cars will get into the 2's. Even in hiway trucks that run the hiway,pulling a walmart trailer will will have a gear ratio in the 3's, log trucks , heavy equipment haulers will be in the 4-5 ratios,
So when i hear someone ask, my engine screams at 55 mph what higher ratio can i go to? If he tells me hes not happy with 3.73 ill tell him to go 3.55 or 3.07, or 2.56.....at that point when he gets up to 55-60 after a mile or two his engine wont be screaming be cause it only turning over at 1800 to 2150 rpm, again only pall park.

I am perfectly fine with the phrases 'high geared' and 'low geared' as long as they are not confused with 'high gear ratio' or 'low gear ratio' respectively.
The example you gave for the guy who asked, "my engine screams at 55 mph what higher ratio can i go to?", you gave him a push on his wrong nomenclature. I can understand that. The day is too short to have to educate everyone who shows up in a shop. He ended up with what he needed, and you were able to get back to work.
Carl

I'd bet the first two Italians that looked at Leonardo da Vinci's wood peg gears had an argument over whether adding more pegs on the drive wheel should be called higher or lower gearing. I gave up years ago and just call gears deep or shallow. Anything above 3.50:1 is getting deep and anything below is in the shallow range.