Automatic transmission

Does it hurt an automatic transmission to be downshifted manually to slow the vehicle?

I've been told its not a good thing by some and others disagree. What opinions do you fellows have?

No, because the governor (or powertrain control module) won't let it downshift until it descends to a safe speed. Even if you had a shift kit with full manual control, you still wouldn't hurt anything. Just don't try it at 50mph.

nope....but...if you downshift from 60mph to low, you'll know it. You'll probably wreck the transmission..the upshift is, generally, 1-10 low,10-35 2nd, 35 and up 3rd and then you have overdrive...follow the downshifts at about the same speeds.

i was told by an old transmission guy that every manual downshift was on less upshift. and then later he said a new tranny has x number of shifts in it before the cluthes were wore out, it didn"t matter if they were up or down shifts. so shift it however you want.

dont hurt a thing. if going downhill you can shift to 2nd gear and its like a standard using engine compression to slow you down.saves on the brakes!

Silly thing to me, protect trans from downshifting by putting into second when you think you are downshifting to low, but no protection when you shift to reverse at 50 mph. Have seen it done and done it quite a few times. Don't know what trans does but you can sure turn on a dime. Hard left and floor it, hit reverse, 180 degree on the spot. Dave

like dad said... yeah, use that 2500 dollar transmission to save those 20 dollar brakes.

Hey Allan we need you to settle this!

On the funny side, had a friend in high school had a old Impala. Some of us were messin around in the back seat one night putting our hands over his eyes while he was going about 55 mph. He throws it in park and turns around to take some swings at us. Heard this hi speed click click click and when park caught bout threw him through the windshield. Ya know never hurt that old Chevy one bit. LIKE A ROCK.

The only thing no one has mentioned yet is the torque converter. While it might not really hurt the transmission, per se, to do so, you can downshift all you want, but if the torque converter isn't in lock up then the slowdown capabilities are going to be nothing or next to nothing. This because the tires aren't going to be directly connected to the engine due to the two turbines in the converter spinning seperately, not connected/locked up together. When the converter locks up, or if it lockes up, is dependent on the mfg so there's no hard and fast rule as to what vehicle, speed, etc, etc it's going to happen in. In other words try the whole downshift thing unloaded, in an area where you really don't need it, to make sure it's going to work when you do.

Like others have said though the clutch packs in an automatic transmission are going to have a 'life expectancy' of x number of shifts, be they up or down, unlike a manual transmission. In other words it's just like another post suggested by downshifting manually your putting an extra load on the clutches and as a result are going to shorten their life expectancy at least some. Ultimately your putting extra wear and tear on an expensive transmission to save a 'cheap' set of brakes.

Brakes are cheap. Automatic tranny's ain't.

With all the shifting my transmission does, hauling blaes, hauling cattle, I guess its life is going to be a short one.