Sorry for the most likely dumb question but here goes.

When I am going down a big hill or coasting into a stoplight off of the interestate is it hard on your automatic transmission to bump it from drive into neutral and coast it to a stop or less than 15 miles an hour? I feel like the transmission actually slows my truck (05 F150) significantly when going down hill or coasting into a stop sign or light.

Next question is it hard on the transmission to shift it back into drive from neutral while coasting? Does the speed matter or what should the speed be when doing it?

Thanks all who answer as I am truly an amateur when it comes to fixing and wear/tear on a truck. Just feel like I could get better gas mileage if I was able to coast into some intersections and down hills. Thanks again.

Mas Salsa

 

It won't hurt it a bit, and just to add to your knowledge, it's illegal.

 

I'm confused... You don't want the engine to slow you down? Won't hurt, cept your wallet for increased brake wear.

Adrianspeeder

 

all i can say is wtf

 

to coast or not to coast...that was the question....

I asked about coasting because I have a decent couple of hills in my everyday drive...one lets me coast out to a stop sign and usually at the end of the coast i am going about 20 mph and it is a mile or so hill and the other case is an exit ramp that is off of the beltway here in mn. it is an uphill ramp and if i coast then at the top for my right hand turn i am going about 15 mph versus having the engine slow me down and then having to give it gas to the top of the hill. I dont know if it is all trucks or just my twisted brain but it feels as if my truck (05 screw kr) wants to slow down when i take my foot off the gas (do not have overdrive off btw) to slow down up a hill or to a light. I am averaging about 16 mph while not towing anything....

Anyway...that is why I coast...appreciate all input...thanks...

Mas Salsa

 

Yes it does slow you down. Called compression braking, by using the slowing down engine and coast clutches in the tranny to slow the wheels. Those of us with stickshifts even install exhaust brakes to get more engine braking power. I'm not an expert on auto trannys, but it doesn't seem like a good idea. Safety comes to mind in an emergency you wouldn't be able to move quickly out of the way without remembering to shift to drive, or if you would lose brakes, you wouldn't have the help of the tranny/engine to slow you down without remembering to shift to drive. Also shifting to neutral and back to drive are just two more wear operations on the tranny.

Adrianspeeder

 

Not to take over the post, but adrianspeeder, do you know where I could get an exhaust brake for a 2002 F-150, and do they sound anything like a big rig, I love that sound

 

As far as I know not for gasser engines. Even the ones available for light truck diesels don't make that classic big rig sound. That is known as a Jake Brake, and works by opening the exhaust valves a little longer to slow down the engine. Physically part of the engine that can't be added.

Adrianspeeder

 

i coast down hills all the time in whatever i drive

saves fuel
better cooling thru the radiator seeing as the rpm drops and the wind has a better chance of cooling the fluid down also as the pump is "in idle mode"
and its a good "game" on certain roads to see how far you get

 

Again why are we discussing this? It is ILLEGAL!!!

 

In the manuals it's not recommended to tow a auto trans for more than 7 miles or something like that with out dis- the drive shaft, I would say It could, I have worked on a few over the years with blown seals because the kids seem to think shifting the auto trans is a cool thing. leave it in gear 'you are not saving anything. let the trans and computer do the shifting for normal driving.

 

That is because when towing in neutral the engine is off not spinning the cooing pump in the tranny. Engine on solves that.

Adrianspeeder

 

Not a good idea. Not safe. Vehicle control is more important. That is why it is illegal.

 

Just leave it in drive, your going to kill your trans. I don't know if it is bad to shift from drive to nuetral, BUT NEVER go from N to D while coasting. From what I understand it is hard on the bands. The bands hold the planetary at the same speed so a gear change can be made. There is alot of speed difference when coasting in N (internally) so when you go back to drive the bands have to bring everything to the proper speed in engage in to drive.

It is alittle more technical than that but basically don't do it.