places to electronically monitor gear position

[Guest teigan]

i've acquired the correct sized LCD panel to replace the lotus installed clock. apart from passengers watching television/maps on it, i want to display the current gear position. the reverse gear has an electronic switch, but where is a good place to locate switches to accurately know when the other gears are engaged?

[DanR]

Why?

[Guest teigan]

because i can

[markt]

because i can

<{POST_SNAPBACK}>

Can't argue with that logic... One of my mottos.

[GSimpson]

You can use 4 microswitches to detect the motion of the gearstick.

eg Forward #1 switch, central 1 & 2 switches off, rearward #2 switch

left #3 switch, central 3 & 4 switches off, right #4 switch on

Feed switches to microcontroller which can work out what gear is selected from switch combination and also drive the LCD screen.

Could use microchip 16f84 or Basic stamp

[Guest teigan]

thanks for the input. already have the pic controller and serial interface ready. considered the gear stick option, but tripping the microswitches accurately and consistently would not be possible, even with an individual levered switch at the 6 possible corners. mounting the switches on the stick would be worse, giving false readings more often than not. lever motion would be more dependable. best location is the question.

[jimmybondi]

You could use a ceiling-mounted CCD camera which will monitor position and movement of the gearstick. A complex computer programme, as used in automated industrial assembly lines could translate the video images to the different gears, which could be displayed on your TFT??

Goddammit! If you want to know which gear you are in, look on the gearlever - 'because I can...' does not count here

[Guest teigan]

when i'm arguing with the screaming passenger, i sometimes forget if i'm in third or fifth.

[jimmybondi]

They tend to scream at ~ 120mph, but they get very quiet at 155mph...

[Guest teigan]

they scream at all velocities, but it's impossible to drive over 100 where i live.

[jimmybondi]

Ahh, c'mon Teigan - we all have seen the 2 sexy Ladies in their Countach in 'Cannonball Run'...

[USAndretti42]

because i can

<{POST_SNAPBACK}>

Are you sure?

You could take a tacho signal and wheel/car speed signal to a microprocessor and calculate the overal gear ratio and work it out from that ( as long as the clutch is engaged).

[Guest teigan]

that method would be prone to error by 1 gear. i will be saving tach data though, which will be downloadable from the serial interface.

[DrieStone]

Maybe mark both axis of the linkage optically and have an optical reader for each. Use bits from a USB mouse and read the position of the linkage as an X/Y position.

[Guest teigan]

i like that. optical would be slicker, apart from the pain of keeping it clean. i guess the plan would be to first have someone observe the linkages when i'm in the car shifting.

[USAndretti42]

that method would be prone to error by 1 gear.  i will be saving tach data though, which will be downloadable from the serial interface.

<{POST_SNAPBACK}>

I can assure you, from experience, it would not.

[Guest teigan]

maybe you have a doublecheck routine. do you have a flow charted algorithm i could copy?

[USAndretti42]

I will check when I am back in the office.

[WayneB]

Tiegan, I assume your car is missing its original wooden shift knob which has a small cast metal diagram of gear positions on it.

This is where the gears are:-

1 3 5

2 4 R

Memorise this chart and in time you will master the technique

[Guest teigan]

it isn't necessary for anyone to be relevant or instructive or funny in reply to a technical question.

[williamives]

can you explain why you think that monitoring speed&rpm won't work ...

Clearly I have too much time on my hands, but i had some rpm-speed data from my car sitting on my desktop (sorry Kato - I've still got to finish writing the review...), so i plotted this graph in excel of speed/rpm against time. Looks pretty good to me, you can see all 5 gears clearly!

just my thoughts....

Will

'99 Sport 350

[madmezza]

can you explain why you think that monitoring speed&rpm won't work ...

Clearly I have too much time on my hands, but i had some rpm-speed data from my car sitting on my desktop (sorry Kato - I've still got to finish writing the review...), so i plotted this graph in excel of speed/rpm against time. Looks pretty good to me, you can see all 5 gears clearly!

just my thoughts....

Will

'99 Sport 350

<{POST_SNAPBACK}>

Sorry - might have missed this - but where did you get the speed data from? Tach I guess is inductive from the spark plug leads or directly from the coil, but speed - do you have something on the gearbox speedo output? (an optical sensor or something)??

[williamives]

mine's a 1999 V8. So speed & rpm are both available on the ODBII interface. Thats what I used to log the data.

Will

[Guest teigan]

i think all the cars with computers use speedo and tach data to help regulate other functions. never got to look at a car with an electronic gear position indicator to see how it was calculated. on a normal shift sequence from zero, the delineations would be clear, but downshifting for turns or driving low gear downhill would confuse the equation.

[scooter]

i think all the cars with computers use speedo and tach data to help regulate other functions.  never got to look at a car with an electronic  gear position indicator to see how it was calculated.  on a normal shift sequence from zero, the delineations would be clear, but downshifting for turns or driving low gear downhill would confuse the equation.

<{POST_SNAPBACK}>

In my rally (that's 'pro-rally' for the Seppos) car, I have an aftermarket computer (Autronic SM2) that uses this basic algorithm to calculate what gear you are in (that is by comparing engine revs to tailshaft speed), and it works very successfully for those that have used it. I haven't set it up myself, though. In fact I haven't even bothered to connect a tacho or shift light as they're not really necessary.