05 Silverado 1500 5.3 LM7 4l60e

04BlackMagic · January 29, 2019

Is manually downshifting going down a steep grade instead of using brakes in snowy/icy conditions damaging the fragile 4l60e transmission? I have been doing this downshifting a few times a day and began to think about negative affects if any?

Also, is there a proper way to manually downshift with these trucks to avoid damage? Do I need to be going a certain speed in order to downshift to lower gears or just shift the lever down?

Thanks

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sefiroxx · January 29, 2019

In theory, no. Bbbbbbuuuuttttttt

The torque converter would typically provide some sort of cushion for speed difference. However, the TC was engineered to drive the output shaft, not be driven by the output shaft.

So, if the speed differences are great, something is going to give , eventually. Be sure to get the car speed down to the range of the target gear to minimize the impact of speed difference on the components.

carkhz316 · January 31, 2019

It doesn't hurt anything unless you somehow manage to bounce the Tach off of redline all the time, but in reality, it won't shift to lower gears if you're beyond the range of them. It's not as conservative as the newer trucks (ie: your truck WILL downshift sooner/ higher RPM when it finally does). That all said, I would use extreme caution doing this in snow and icy conditions as its a quick way to skid out of control when the resistance of the engine braking overcomes the traction of your tires and causes you to start fish-tailing. Try it some place quiet and open with glare ice and you'll see what I mean. Use your brakes. At least you (and your ABS system) can predict/ sense when your tires start to lockup. Lastly, the 4L60 isn't that fragile. The only difference in component operation during manual downshifting and standard driving is the application of the overrun clutch (the part that gives you the engine braking, which is the only time it's used. Literally designed for that purpose).