98arrunner

Hi All,

I jacked up the rear axle for brake shoe replacement, and noticed that when I turn on the engine, with gear in neutral, the two wheels turns slowly (probably 2 revs per min). If i step on the gas (gear still in neutral), they turn a little faster, but slower than if in gear.

Why would the wheels (propeller shaft) turn when the gear is in neutral?

I have 98 4runner, v6, 4wd, 5spd, no mods.

Thanks in advance.

mike_d

there's probably enough drag caused by the gear oil that tranfers just enough torque through the transmission to turn the wheels slowly.

TechWrench

That is exactly what is happening. You can grab the drive shaft, and it will stop, but the gear oil in the trans will provide enough 'drive' between the main and countershafts to turn the output shaft if there is very little resistance in the drive line.

kyle_22r

kind of like the same idea behind a torque converter in an auto tranny or the fan clutch on the motor.

WATRD

Ah... a beautiful lesson in fluid dynamics. What a great way to start a Sunday!

TechWrench

In a very abstract way, I suppose. The torque converter and fan clutch are specifically designed to provide a fluid coupling in a 'drive' line. What is happening in the manual trans is more like an undocumented feature.

Years ago, I had a '79 Chevy K10 with the old 4 speed manual with the 'granny' 1st gear. Where I usually parked at my home was on level ground, so I didn't normally set the parking brake. I learned the gear oil drive lesson very well when I left it idling one VERY COLD morning (about 15 below) before I went to work. I had started it to warm it up, and went back in to get my road coffee. When I came out, the truck was gone..........
I found it on the front lawn next door. The 90 weight was so stiff, it 'drove'
the truck about 80 feet until it decided to stop on its own. Used the parking brake a lot more after that