Coasting with an Auto

[kickflipjr]

Today was the first time i tried drifting down a hill (engine not on). I just put into N, killed the engine, coasted down this one hill for about a mile, and then restarted when it was needed. I have heard that this can be bad for certain auto trannies. I have also heard that it isn't bad on saturns (i don't plan on doing this too often because it is hard on the starter).

[MetroMPG]

yay - another convert!

a mile is a long coast (by local standards). one of my longest around here is maybe half a mile - IF there are no trains coming AND the light after that is green.

[Compaq888]

this is the reason I stopped coasting with engine off. It can kill the tranny easy, and starter. I hate auto.

[kickflipjr]

I used to do it with my old car (5 speed). It just seems dumb with an auto.

Yeah, that hill is nice, long, and not too steep. I have bee coasting it in nutral for years.

[Compaq888]

I don't think coasting with engine on in neutral will damage anything, there will be less resistence but the problem is you can't put it into the gear you want

[rh77]

So, today I tried the coast/engine off in a few places. With the driving I do, I ended up doing it approx. 15 times. If I don't let the transmission kick-down to first gear before a light, then the N-to-D shift is jolting once things get going again. I coasted down a hill, engine off for half a mile and started back up. I've been using the N-idle feature at long lights if I know it isn't planned to change within 20 seconds. Otherwise, I've been trying the shut-down. I have to pay close attention to the traffic pattern, or else I get stuck dead in the water until things get back up and running, and irritated people behind me. Cutting the power deactivates the turn signal for a second or two -- I may look into the engine cut if I get decent evidence that I'm not trashing the transmission. So yes, MetroMPG, I have seen the light, and I'm now converted.

RH77

[Compaq888]

rh77,

so let me get this straight, you coast in N then put it into D? Wouldn't that N bomb the transmission???

Can you make it work like this... See a red light ahead, flip to N, shut down engine. Stop at red light, green hits restart engine, put in D and keep going??

Can you put the shifter from D to N without causing any damage?

[Compaq888]

Here is what I did this morning. When I drive and see a yellow or red light I put in N and let it coast to the light. If I know it's going to be a long light when I put it into N I shut the car down too. When I get to the light I stay there till it turns green and restart the car and put back in D. If the light will be soon I just coast up to the light in N and leave it in N and wait for the green. When the green hits I put in D and drive off.

[rh77]

Originally Posted by Compaq888

rh77,

so let me get this straight, you coast in N then put it into D? Wouldn't that N bomb the transmission???

Can you make it work like this... See a red light ahead, flip to N, shut down engine. Stop at red light, green hits restart engine, put in D and keep going??

Can you put the shifter from D to N without causing any damage?

As far as I know, you can't damage the transmission from shifting to D-N or N-D without throttle input. N-bombing the tranny is putting the car in neutral when you're moving, say 65 mph, then in N go full throttle and shift into D. Since it's not a standing start bomb, it probably wouldn't tear things-up immediately, but a few times and it's shot.

RH77

[rh77]

So, I took a VAC up to Calgary and their National Parks in the Rockies over a long weekend. Down a long hill on the Trans-Canada Highway 1, I put the rental Chrysler 300 into N and shut off the car. It coasted at the speed limit down the mountain. When it was time to start it back up, it wouldn't! Dead in the water, we coasted to a conveniently located turn-out on the side of the road. I had to turn the key to the complete OFF position and then start the car! If I did that moving, it would've locked the steering, potentially screwing us even further. I have some Canadian car stories to tell in a separate thread, but MetroMPG, I saw my first Pontiac Firefly!

RH77