Inclinometer for coasting

[basjoos]

I'm trying to figure out a real-time method to determine the down slopes that my car is driving on. On my usual drives, I've been able to find the downhills where I can maintain my cruising speed through trial and error when I let out the clutch. But when driving on unfamiliar roads, except for the obvious downhills, it can sometimes be difficult to tell when I'm do a downhill steep enough to effectively coast (my car can maintain 55mph on a 2% downhill). And sometimes the lay of the land can disguise the fact that I am actually going downhill.

I've tried mounting an RV style curved bubble gauge, but it is so sensitive that it overlays my gradual acceleration/decceleration while coasting on top of the slope of the road. So when I see a -2 degree reading, I can't tell whether its reading a constaint velocity on a 2 degree downslope or a gradual decelleration on a flat road. An aircraft gyro-based artificial horizon would work great, but at over $1000, is much too expensive. An aircraft vertical speed indicator (about $200) would also work, but its reading is speed dependant. Any ideas for an inclinometer that is unaffected by minor vehicle changes in speed?

[Gary Palmer]

I've contemplated trying to find some way to do exactly what you are describing. The only inexpensive idea I have is to hang plum bob from the rear view mirror, so that it has a long length and is hopefully over some area down on the console, that I can mark or something.

It seems to me like their ought to be a better way to do this and if you come up with something I'd be really interested.

[Silveredwings]

Maybe a gyroscopic pitch indicator (inertial or interferometer-based).

[white90crxhf]

how about a string with a weight attached?

[CO ZX2]

Originally Posted by basjoos

I'm trying to figure out a real-time method to determine the down slopes that my car is driving on. On my usual drives, I've been able to find the downhills where I can maintain my cruising speed through trial and error when I let out the clutch. But when driving on unfamiliar roads, except for the obvious downhills, it can sometimes be difficult to tell when I'm do a downhill steep enough to effectively coast (my car can maintain 55mph on a 2% downhill). And sometimes the lay of the land can disguise the fact that I am actually going downhill.

I've tried mounting an RV style curved bubble gauge, but it is so sensitive that it overlays my gradual acceleration/decceleration while coasting on top of the slope of the road. So when I see a -2 degree reading, I can't tell whether its reading a constaint velocity on a 2 degree downslope or a gradual decelleration on a flat road. An aircraft gyro-based artificial horizon would work great, but at over $1000, is much too expensive. An aircraft vertical speed indicator (about $200) would also work, but its reading is speed dependant. Any ideas for an inclinometer that is unaffected by minor vehicle changes in speed?

Ironic this would come up today. 3-4 days ago I started something I haven't finished. Not much to it, may try it tomorrow. Bottle is about 8 in. long, drawn line 6 in. long. W/S washer fluid with a little food coloring added. I plan to fasten it to passenger window forward as much as possible. I have 6 in. strips of Velcro to stick to window and bottle. White Velcro should give a good backdrop for visibility of the line. I will saw a thin wooden wedge on a slight angle to use under the bottle on top of the window sill to level and stabilize. To set bottle level I will have to get the car on a level surface.

I am hoping this will help me recognize level ground. It is disappointing to think I am on level ground, accelerate, shutoff to coast and have the car immediately slow down because it is uphill. I have wasted the acceleration and got nothing back. Don't know if this will suit what you need but here it is. I rotated the bottle to show the line better. Pic not great, reflections, and half dark but gives the idea. Cost: about 50 cents for Velcro.

[95_corolla]

Basjoos,

how are you getting 23mpg in your truck is it a 4.2 liter? I have a 99' f-150 4.2 MT short bed super cab I can barely get 17mpg. Today just got narrow tires on it I hope to see an improvement LT225/75/16 they can handle over 80psi and are supose to carry a heavier load. And yours is a 4x4 that is amazing

[FireEngineer]

Go on E-bay and search for inclinometer. Some used ones from old Toyota, Nissan and Mitsu trucks can be found. Many will show front to back and side to side pitch.

Wayne

[GasSavers_TomO]

I ws just going to suggest this same route. there are several Toyota 4 Runners in my old junkyard that have the inclinometer still in them. they probably could be had for cheap as well.

[Lug_Nut]

What? No adjustments for head/tail wind? Nothing to compensate for desired speed?
A 2% slope may be fine at 45 mph, but will require fuel addition at 65 mph.

Why not a simple strain gauge measuring the torque load on the motor mount? A simple string tied to the engine, run back through the firewall and fastened by a spring will be pulled as the load on the engine increases. Make a mark on the string and a corresponding mark on some fixed background with the engine off. That's zero torque. Any time the marks line up while driving indicate that the engine is not adding torque to the wheels.
Oh, and not subject to G force (or freezing temperatures) either.

[cfg83]

theclencher -

Originally Posted by theclencher

Perhaps using oil instead will dampen the unwanted side-effects of accel/decel and bumps- no sloshing or waves if the oil is heavy enough.

Perhaps if Basjoos' RV gauge is cheap enough to be expendable if this doesn't work, it could be drained of whatever fluid it has in favor of something heavier?

That's what I was thinking, but oil didn't occur to me. I was thinking of those transparent plastic encased "blocks of goo" that have little dolphins and such floating around in them. A little motor makes them rock back and forth so that it looks like slow-mo ocean waves. Probably would go bad in the summer, though.

My wife suggested a level from a hardware store. That's easy for me to test, but would probably still react "too fast" for basjoos purposes.

Here's just one of very many e-bay solutions :

79 9007 TOYOTA TURBO 4RUNNER TRUCK 4X4 INCLINOMETER
$15 + $10 Shipping and Handling
http://cgi.ebay.com/ebaymotors/79-90...QQcmdZViewItem

CarloSW2