Mustangmaster

From what I remember on this being discussed before here, if you leave cars in gear and coast down hills to get some engine braking, it wears out the transmission. Instead of throwing it in neutral and pressing on the brakes to slow the car down when it coasts too fast going down hills. So, if you wear a transmission out, that could cost thousands. If you wear brakes out, that should only be hundreds. I would think it would take an awful lot of engine braking in gear going down hills to wear a transmission out. Just like it would take an awful lot of pressing on the brakes going down hills to wear out brakes. So, it may very well be a non issue either way.

Norm Peterson

It's not wearing out the brakes that is the concern here. Nor is it the relative replacement cost of just the wear parts.

It's fading them to the point of uselessness that is, and when that happens the thickness of the pad material becomes meaningless.

Nobody who has ever faded their brakes for any reason questions the value of engine compression braking on long or steep downgrades.

Nobody who has not faded their brakes for any reason knows quite what it's like. With the possible exception of those who have been through an episode of complete front and rear hydraulic failure.


Nobody seems to worry about powertrain wear (tranny and axle gears) when you either maintain speed going up the same hills or actually accelerate while climbing. If you're going to try playing the "tranny wear going downhill" card in this discussion, you'd best be only coasting on the way up with just enough head of steam going in to make it to the top.


Norm

Throck!

I'd be leary of coasting down hills with an automatic transmission, or at least check your fluid afterward.

People used to try that on a hill near where I grew up and ended up burning out their tranmission.

The reason for this is because the trans fluid pump is turned by the torque converter which is bolted to the flexplate. If your engine isn't turning fast enough, it's not pushing enough fluid through the trans and radiator to cool everything down. But when you're going down hill there are still parts turning in your trans, with clutches wearing against plates, because the packs aren't engaged when they should be.

Anyway, go and talk to a local auto transmission shop and they'll be able to describe it better.

Again if you decide to coast down a hill with an automatic, at least check the fluid afterward, if it smells burnt or is a dark red and feels gritty, go talk to a trans shop and at least change the fluid/filter.