If you changed gears from say 3.42 to 4.10, what would happen to your stall speed on your torque converter? Would it stall slightly higher? How about tire diameter, what affect will going to a taller tire have?

 

Interesting question. I will be going the apposite way as you, 4.10 to 3.42. Look forward to hearing some answers.

 

My converter felt looser with 3.42s and tighter with 4.10s. It probably has to do with the change in shift points.

 

It will feel tighter but dont really know if it will stall higher or lower, good question

 

True stall speed will remains the same, but flash stall might be a bit lower with 4.10 gears. Lower gearing like that won't load the drivetrain as much, so the converter won't stall as high. Now if you're brake stalling, it's going to stall the same because the tires are locked.

 

same brake stall, lower flash point.

 

It will "feel" tighter with a lower gear because you've increased mechanical advantage over the driveline and you're causing the engine and trans to do less work for the same amount of movement. Basically loading the converter less. A higher gear should make a converter feel looser overall due to the engine having to work harder to move the vehicle. Same concept as shorter and taller tires. Shorter tires will make a converter flash lower than a taller tire with generally more traction and everything else being equal.

This is why in a lot of turbo setups a taller gear and/or tire is selected to load the turbo (and converter) harder, making boost faster and making boost easier to maintain and keep linear.