Coasting Downhill For Free

[Pumpkn210]

I was thinking the other day how mutch gas I save driving the Pumpkn daily. The Merc. is a pig! I live in Puyallup and go up and down the hill all the time. The cool thing is that I dont have to waste gas going down. Just turn the key back one click and relax. With the great gas mileage it gets I dont save mutch, but with the upgrayedds that I an looking to purchase, every little bit helps!

[CharlieBucket]

you acually turn it off? i often coast down hills but i never click the key off. i am going to try it, i guess no motor running at all saves even more gas. i filled my 210 up on last friday and still am pushing 3/4 tank. i am clocking the milage, i can't wait to find out the mpg.

[69FJWagon]

hahaha I did that ONCE in my old 69 mustang thinking the same thing trying to reach the next exit cuz I was almost out of gas I got off the exit and went for the brakes... nuthin.engine off, no vacuum, no brakes almost ruined my car and the truck in front of me thank god my ebrake worked and I was only doin about 10-15 mph slid sideways to a stop just short of the truck good thing I didnt have a steering wheel lock or no steering too. point of the story... be carefull if you have power brakes and a steering colume that locks :D

[dat521gatherer]

there was a guy on the news a year ago, he was getting mad gas mileage by doing little tricks like coasting on every little hill. and i mean every little hill. coasted till he was almost stopped then went slow to the next hill. seemed like he was pissing people off by going so slow.

[DAW]

I put it in neutral and let it idle which preserves the vacuum-assist for power brakes, and allows the input shaft of the trans to turn (most transmissions require this to lube the trans). There's a local hill that I can flip it into neutral at the crest at 35 mph and hit 64 mph terminal velocity at the bottom; and another, lesser grade that I can do the 45 mph speed limit steadily for 3 miles in neutral........why waste gas, wear the engine, and turn energy into heat through the friction/brake linings wear?

 

It might be against the law to drive in neutral in some states so don't volunteer that info if you get pulled over.......say, going 64mph down a 40mph hill.

DAW

 

ps: one of these days when I have nothing else to do, I'm going to rig-up an alternator driven off of the propeller shaft (pulley sandwiched at u-joint flange/belt driving an alternator mounted on differential or trans end), electronically activated by the brake switch to convert deceleration/braking lost energy into work instead of lost as brake heat ...I'll probably under-drive the engine alternator or use a smaller one and supplement battery charging with the propellor shaft unit.

...Or to drive an air compressor and store some supplemental boost to remedy turbo-lag.....

[DanielC]

I just posted on Old Datsun Pickup Lovers about towing a L-320. Same princeples apply to coasting. I have also coasted short distances in neutral, engine running with my Ford Aerostar, and also in stop and go traffic creeping along in a straight line, less than 5 miles per hour, engine off, using the emergency brake

Manual transmissions have no oil pump. They are lubricated by oil splashing around inside the transmission. The oil level is usually midway up on a large gear inside the transmission, that turns when the engine is running, and the clutch is not depressed. This large gear is the cluster gear.

All the gears, except reverse, and whatever gear is the one to one ratio, (usually 4th gear) are always in gear. These other gears are mounted on the output shaft, and all can freely spin on the output shaft. When you put the transmission into gear, a collar with teeth on it, connected to the output shaft, slides over matching teeth on each gear and connects that gear to the output shaft. 4th gear just connects the input shaft to the output shaft.

Reverse puts an extra gear between the cluster gear and the output shaft, and that makes the output shaft turn backwards.

If the engine is stopped, and the clutch is not depressed, and the car or truck is moving, or being towed, the output shaft is spinning inside the gears. The cluster gear is not turning, and it is not splashing oil up in the transmissiion, and there is not much lubrication of the bearings on the output shaft.

Most of the bearings inside the transmission are roller bearings, and do not need a constant flow of oil like the main bearings of an engine do. There is also no load on the transmission if the car is being towed in neutral, and so the lubrication requirements are also less.

The absolute safe way to tow a manual transmission vehicle is to disconnect the drive shaft. But it is generally considered ok to tow a manual transmission vehicle short distances, at slow speeds.

I would not tow a manual transmission without disconnecting the drive shaft, above about 25 miles per hour, or more than about 20 miles distance.

[datsunaholic]

I towed my '76 from Spokane to Tacoma with the rear wheels down, in neutral, 70MPH all the way over I-90, less down 18 and 167. That's over 300 miles. Didn't do any damage. I did eventually change the trans, but that was because I wanted a 5-speed.

 

Coasting:

 

Back in the early 90s I used to test drive each of my "new" cars by driving around Mount Rainier. This was before they charged entrance fees on weekdays. Anyhow, when I test drove my '78 510 Wagon in '91 I ran the mountain counter-clockwise. From about Sunrise to nearly all the way down to the park exit I had the engine off- 57 miles straight coasting. I also coasted on several smaller stretches out of the park- a 150 mile trip and I had the engine running lless than 100 of them. I even passed a couple cars with the engine off (and a bicycle through the hairpins). I wouldn't do it with a car with power steering, but the brakes were fine (just a little more effort).

[hang_510]

It might be against the law to drive in neutral in some states so don't volunteer that info if you get pulled over...

i always wondered how they could prove this???? its illegal here :fu:

 

 

unless your costing for more than ~60seconds (w/motor off) it takes more gas to restart it than idling for that long.

 

 

there is a section of muholland hwy thats about 4.5 miles downhill that i like to coast (get up to ~60mph :D ) to see how far i will go until i stop.

[Bleach]

unless your costing for more than ~60seconds (w/motor off) it takes more gas to restart it than idling for that long.

now that bit of info is not true. That has been disproven a long time ago. That may only be true for an old V8 with a carb (starting when cold)

You can start a warm L-series on fumes. A FI engine starts even easier.

With the key in the ON position, you can just put it in 4th and let the clutch in to start it up.

 

http://green.yahoo.com/blog/climate411/71/when-to-turn-off-your-engine.html

[hang_510]

That has been disproven a long time ago.

"Surprised? It's true - the 10-second rule has been proven empirically."

just my length of time was wrong, too ol'skool i guess :mellow:

[datsunaholic]

Plus the 10-second "rule" doesn't apply to coasting and compression starting.

 

Trust me- even 358ci pushrod 4-barrel V-8s can save gas doing the coast thing. NASCAR drivers who are running VERY low on fuel will shut off the engine under yellow flag conditions and coast down the banking for as little as 5 seconds just to save that timy amount of fuel (though more often thell coast the entire straightaway). Do that 3-4 times a lap under yellow could be the difference between winning and running out with a quarter lap to go (it happens!)

[Pumpkn210]

I did check the ign. switch first and found out that one click back turns everything off and leaves the steering unlocked. The cool thing is that the Pumpkn keeps the vacuum all the way down the 3mi hill and I usually use 3rd to start it and slow for the turn at the end. I was coasting down meridian the other day and had to stop for a light. Left the car off at the red light. There was a guy next to me observing my Orange coolness and when the light changed I hit the start switch, fired it up and off I went. He had the stupidest look on his face when I hit the starter!

:D

 

Just had to post about this. It is one of my favorite things about older cars.

[ssfwgn]

I did that all the time when I was going to school, you now running late so you'll fill it up on the way back. I actually figured out how to intensionally backfire the car buy doing that, I went through alot exhaust parts that year.:D

[Phlebmaster]

This guy is coasting real fast!!:lol:

 

 

I don't think it was cheap though.:eek:

[Figbuck]

I have been a coaster for a long time. If I see the light change ahead of me, I will put it in neutral and coast up to the light. This seems to really piss people off behind me. They can't wait to speed up to the light and sit there. Most of the time, I can just slip it into second and keep going because by the time I get there the light has changed and I don't have to accelerate through first gear.

 

A couple times lately, drivers have honked and then swerved around me just so they could sit at the light ahead of me. A mile later they still are still sitting at the same light I am.

 

There is a big hill up behind our house with lots of curves. I don't have a steering lock and even though the vac is gone in one or two pumps, I got to the place where I can drive it through the corners with out using brakes and go faster than if I was under power. Good thing the traffic division is under funded and this road is never patroled, because I'm going 55 through corners with 25mph yellow diamond signs. I don't do it during the day but usually late at night.

 

Cheap entertainment... :P

[djmoreron]

sometimes my truck bogs and shuts off on me, so i have no other choice but to coast :lol:

[Pumpkn210]

There is a big hill up behind our house with lots of curves. I don't have a steering lock and even though the vac is gone in one or two pumps, I got to the place where I can drive it through the corners with out using brakes and go faster than if I was under power. Good thing the traffic division is under funded and this road is never patroled, because I'm going 55 through corners with 25mph yellow diamond signs. I don't do it during the day but usually late at night.

 

Cheap entertainment... :P

 

I go out onto the peninsula every once-in-a-whyle for thier awsome roads. The speed limit is 45 and all the corners have those yellow=suggested speed signs for like 10mph. Screw that the speed limit is still 45, and I do it to it. The best thing is the locals dont seem to mind. They all haul around there too.

[fiveNdime]

I do the same thing.....my wife says I'm crazy.

I dont turn the car of though not too smart seings how I have power brakes and steering, but only power brakes on the datto of course.

 

I hate those people who do that passing crap in the morning when there late, when theres about FIVE THOUSAND other drivers in front of me going the same speed I am......hmmm I wonder where all the gas comsumption is???? Or at least some of it.