Pinion and ring gear ratios

[JBog]

Can someone please explain when you would want one ratio over another? Particularly when it’s being used in a Ruxstell?

[TRDxB2]

Here's WHAT IT DOES
and the conversation https://www.mtfca.com/discus/messages/3 ... 1365297912

[babychadwick]

In a word "drivability" not knowing where you are, what you have, or how you drive it's hard to answer further. A lighter car with taller 3:1 instead of 3.63 will allow you to drop the rpms down and drive the same speed as before. Of course you may not have the power when you get to a hill. At least you can downshift the ruckstel. Gearing down to say a 4:1 will allow you to climb mountains without having to use low band but then once you are on the flat you will have to wind up your motor to keep up with the Ts you passed going up the hill.

[Norman Kling]

I agree with the above. I have a 22 Roadster which is a light car. It came with 3:1 when I got it and also has Ruckstell. On flat land it works very well but where I live it is in mountains. There is a 6% grade for the last 2 or 3 miles. I can go up that hill at about 35 but if I slow down, I will need to use Ruckstell and can't go back in high till I reach the top. My other 2 cars both 26's one a Roadster and the other a Touring both have the standard ratio and will go up in high at about 25 MPH. When we are on tour, many of the cars slow down on the grades and unless I am the first one in the 22, I will need to use Ruckstell all the way up. Also If I start out from a stop on a small grade, I will need to use Ruckstell because Ford low is to high for it. Anyway, If you lived in Kansas and very unlikely to go on tours out of your area, you would probably do very well with 3:1. Wyoming has a lot of hills and mountains so I would recommend the standard Ford ratio.
Norm

[AndyClary]

Bear in mind that with a 3:1 gear you carry more speed downhill, taxing the brakes.


Andy

[Craig Leach]

With a 3:1 going down hill is best in Ruckstell especialy if thats what you came up the hill in. I hear from those that have them that 3:25 is a
good ratio.
Craig.

[Allan]

The considerable down side of a 3:1 ratio is the considerable compromise of standard T brakes. I was most uncomfortable driving my speedster, with Ruckstel, anywhere in town. Open road OK, but not where you might have to make a sudden stop. I now have that Ruckstel in my 1925 roadster, with a 3.25 : 1 ratio, and it is far more driveable.

Allan from down under.

[speedytinc]

Just considering a rux, the answers could fill a book. The pro's & cons. Trade offs. Engine horse power. Topography. MAXIMUM DESIRED DRIVING SPEEDS, typical driving speeds, traffic, parades, current driving skills, car weight, passenger load, etc..

I am asked the same question when I build a rux for someone.
A recent job with a higher performance motor in a touring mostly with no passengers. Knowing this fellow was not desiring speed & would be touring with a group as well as solo, I suggested standard gears. Not good to pick a gear set that has you in rux all the time.(they dont lube well & will wear faster.)

If I lived in or near the mountains, like Colorado & enjoyed off road, a 4:1 set in a rux would be pure joy.

My T's are setup to do 65 - 70. I occasionally drive the freeways & appreciate a T that can cruse all day @ 55 & merge @ a faster speed. (3.07 ratio)
Dont get me wrong, I can go fast, but dont on a normal day.
My 14 roadster has 3.25 gears. I dont desire to drive as fast due to the weaker top regarding higher wind speeds & a windhield that self closes @ higher wind speeds. .
I also drive these on club tours with typical speeds of 35. I get out of rux as much as possible. Driving @ idle speed basically.
& ALL stops include a down shift into rux for braking. (I am using more rux than I prefer)

If you list all the variables, we could suggest a gear set that would make you & your T happiest.
The biggest one would be you desired top speed.

[BE_ZERO_BE]

 
Here are the potential possibilities of gear ratios.
 

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[JBog]

 
Here are the potential possibilities of gear ratios.
 
Model T Gear Ratios.jpg

Which one is 'standard'?

[CudaMan]

40/11, 3.64.

[ClaytonPaddison]

I originally had stock 3.63s in my roadster rear axle for years. Behind my hot T motor ans Chicago overdrive, I could do 55-65 mph tops. When I added my Ruckstell, I upgraded to 3:1s. It made all the difference on the highway. 75+mph is now attainable and I'm still not getting her top speed. In some instances (like in town), I normally leave the Ruckstell in low as 3:1s are almost a tad too tall.

When I did the rear axle in my Depot Hack, I swapped in a set of 3.25s. Once I have the Warford in it should be a nice touring rig.

[CamMan]

For the more technically minded - https://mtfctulsa.com/Tech/power_and_torque.htm