40inches
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| posted on 15/5/09 at 11:03 AM |
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BEC electric reverse control, opinions
The mechanics are now worked out, so I am sorting the electrics.
The simplest way to control the motor would be a push button near the gear lever or on dash,however, seeing that we have to have a reverse, like it or
not  , it would be nice if it was usable on a daily basis, so here are my thoughts on the subject:
The control needs to be usable when reversing using mirrors or turning around in seat, so a button on dash or by gear lever is a poor compromise.
A foot control using a switch on one of the pedals would be more intuitive and close to the way we already reverse, but, which pedal?
Accelerator?; The most logical, but engine would need switching off to avoid revving it's rocks off.
Brake?; Not as daft as it sounds, if the switch activates before brakes are applied the brakes could be used to modulate car speed, engine could be
left running.
Clutch?; A good compromise, but might be awkward using right foot.
I favour the accelerator, but needs a way to stop the engine revving 
Thoughts, ideas, preferences welcome.
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Mr Whippy
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| posted on 15/5/09 at 11:10 AM |
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personally I’d have a short spring loaded (possibly with a catch so it can't accidentally be operated) lever on the tunnel that you can reach
with your left hand. The lever just pushes the switch at the opposite end to the handle.
Fame is when your old car is plastered all over the internet
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tegwin
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| posted on 15/5/09 at 11:13 AM |
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Convert the throttle peddle to "fly by wire".... when you flick a switch it stops talking to the engine and talks to the electric motor
instead to activate reverse?... Sounds like a nice simply solution
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Would the last person who leaves the country please switch off the lights and close the door!
www.verticalhorizonsmedia.tv
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afj
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| posted on 15/5/09 at 11:15 AM |
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id go for the motor control connected to the shift light how about a small micro switch on the throttle pedal like the brake light switch
on my truck
eerrrrrrrrrrrrrrrr
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Howlor
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| posted on 15/5/09 at 11:17 AM |
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Why not use a floor operated dip switch, have it wired so it can only work when in neutral which should be easy to do.
Steve
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40inches
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| posted on 15/5/09 at 11:30 AM |
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quote:
Originally posted by tegwin
Convert the throttle peddle to "fly by wire".... when you flick a switch it stops talking to the engine and talks to the electric motor
instead to activate reverse?... Sounds like a nice simply solution
Why didn't I think of that
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smart51
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| posted on 15/5/09 at 11:34 AM |
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I'd have a switch on the clutch pedal so that the electric reverse can only be operated with the clutch pedal fully down. A separate switch to
enable the reverse can be placed wherever convenient, by the gear lever or on the dash. I'd also interlock it with the neutral light.
With the reverse switched on, and the box in neutral, when the clutch pedal is pressed, you reverse and when lifted, you slow down. Engaging a gear
disables the reverse. It leaves your right foot free to put a few revs on the engine to provide a bit of electrical power too.
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40inches
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| posted on 15/5/09 at 11:37 AM |
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quote:
Originally posted by Howlor
Why not use a floor operated dip switch, have it wired so it can only work when in neutral which should be easy to do.
Steve
The reverse switch will be wired in with the gearbox neutral switch.
I thought about a foot dip switch, but aint a lot of foot room in a 7 , I like the idea of trying to replicate the way we already do it; right foot
on accelerator to move, switch over to brake pedal to stop, nothing to learn or get confused about
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40inches
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| posted on 15/5/09 at 11:49 AM |
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quote:
Originally posted by smart51
I'd have a switch on the clutch pedal so that the electric reverse can only be operated with the clutch pedal fully down. A separate switch to
enable the reverse can be placed wherever convenient, by the gear lever or on the dash. I'd also interlock it with the neutral light.
With the reverse switched on, and the box in neutral, when the clutch pedal is pressed, you reverse and when lifted, you slow down. Engaging a gear
disables the reverse. It leaves your right foot free to put a few revs on the engine to provide a bit of electrical power too.
This is the way I am thinking at the moment, how about linking through the stop light switch so you can keep foot down on clutch pedal and use brake
pedal to stop, cutting power to motor? Just trying to hold on to the accelerator option, as afj pointed out some sort of rev limiter would work.
Keep the ideas coming ;
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Howlor
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| posted on 15/5/09 at 11:54 AM |
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How about a simple button on the steering wheel or somewhere that engages the reverse system, it kills the engine using say the side stand switch. You
could then use the accel to go backwards, then here comes the clever bit! Could you get it so that it restarts the engine as you fully lift off the
accelerator similar to the BMW with the clutch depress?
No idea how to do it though!
Steve
If it was a button on the steering wheel that cuts the engine when you pressed it then as soon as you release it, it restarts the engine. The speed
control could then be on the accelertor but does nothing while the engine is running and in gear.
[Edited on 15/5/09 by Howlor]
The only failure I could see would be if you were coasting along in neutral, then push the steering wheel switch and press the accelerator. That would
cut the reverse in whil moving forward but what are the chances of that happening.
[Edited on 15/5/09 by Howlor]
[Edited on 15/5/09 by Howlor]
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hoots_min
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| posted on 15/5/09 at 12:09 PM |
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What about a button on the handbrake? You can then use the handbrake for braking if speed to much and would work when you have to turn round. As you
say, this would only work when in neutral so shouldn't engage when going for handbrake turns? 
Today is a good day: I achieved new heights of ineptitude.
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BenB
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| posted on 15/5/09 at 12:13 PM |
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I wouldn't switch the engine off whilst running the reverse motor. You'll kill your battery in milliseconds.
Starter motors draw current turning over an engine. How much juice will it take moving the whole blooming car?
On my brothers DIY reverse mech (based upon a starter motor / ring gear system) he had to rev the engine a bit whilst pressing the reverse button
otherwise the engine would stall due to a severe lack of volts going to the ECU / coils.....
Don't forget you need a way of engaging / disengaging the starter. Having it wacking round all the time (passively) will nacker it in no time
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andyd
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| posted on 15/5/09 at 12:29 PM |
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Use a servo from a radio controlled system usually used in scale models and rig it up as a fly-by-wire to the throttle.
The throttle is then, most of the time, making the servo push/pull the actual throttle linkage on the engine then when you "engage
reverse" it switches over to driving the reverse starter motor.
I would say you should engage it not unlike you would in a "normal" car via the gear lever or maybe just a on/off push button.
Put in all the checks about needing to be in neutral etc and job's done.
Andy
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Howlor
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| posted on 15/5/09 at 12:30 PM |
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quote:
Originally posted by BenB
I wouldn't switch the engine off whilst running the reverse motor. You'll kill your battery in milliseconds.
Starter motors draw current turning over an engine. How much juice will it take moving the whole blooming car?
On my brothers DIY reverse mech (based upon a starter motor / ring gear system) he had to rev the engine a bit whilst pressing the reverse button
otherwise the engine would stall due to a severe lack of volts going to the ECU / coils.....
Don't forget you need a way of engaging / disengaging the starter. Having it wacking round all the time (passively) will nacker it in no time
Good point, I wonder how it would cope with a car battery rather than the bike unit?
Steve
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mark chandler
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| posted on 15/5/09 at 12:38 PM |
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Car battery may kill the engines generator windings, use with care !
Thats why you are not supposed to jump start bikes from car batteries.
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ReMan
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| posted on 15/5/09 at 12:44 PM |
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I don't see what's wrong with the switch on the tunnel?
If you gan reach the gearstick/handbrake, when driving you should reach the switch.
Definatley keeps it simple and your feet can carry on doing what they should.
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ReMan
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| posted on 15/5/09 at 12:46 PM |
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quote:
Originally posted by mark chandler
Car battery may kill the engines generator windings, use with care !
Thats why you are not supposed to jump start bikes from car batteries.
I don't understand why this should be true?
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sammy
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| posted on 15/5/09 at 03:12 PM |
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Switch in tunnel combined with the brake-light circuit:
When in "reverse" mode lifting your foot off the brake pedal (brake-light off) engages the reverse, and when you apply the brakes
(brake-light on) it disengages the reverse.
Build diaries...
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40inches
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| posted on 15/5/09 at 05:19 PM |
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quote:
Originally posted by ReMan
quote:
Originally posted by mark chandler
Car battery may kill the engines generator windings, use with care !
Thats why you are not supposed to jump start bikes from car batteries.
I don't understand why this should be true?
Me neither! There are a few on here using car batteries in a BEC, Nitram springs to mind for one. I doubt that a bike battery would have enough grunt
to run a reverse motor, I have bought a 80ah calcium battery, but have toyed with the idea of fitting a bike battery as well and split charging to
isolate the the engine and reverse.
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40inches
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| posted on 15/5/09 at 05:23 PM |
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quote:
Originally posted by sammy
Switch in tunnel combined with the brake-light circuit:
When in "reverse" mode lifting your foot off the brake pedal (brake-light off) engages the reverse, and when you apply the brakes
(brake-light on) it disengages the reverse.
That sounds like a possibility
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dmac
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| posted on 15/5/09 at 07:43 PM |
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how about a lever to engage the system and an interlock on the neutral light to stop it working while in gear and then the activation switch attached
by a spring to the accelerator pedal so that the first half inch or so of travel activates the switch and then the spring allows the accelerator to
continue to travel without damaging the switch.
this gives you your natural operation and allows you to slightly rev the engine to help out the battery.
Some sort of warning light on the dash might be an idea so that you don't accidentally leave reverse engaged and rev the engine while in
neutral. Even better, you could have a push button to engage and have this latch a solenoid which is positively disengaged when you put the car in
gear so you can't accidentally leave reverse engaged while driving.
Duncan
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lsdweb
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| posted on 15/5/09 at 08:18 PM |
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Presumably there's a throttle pot so you could use the output of this to control the on/off of the motor via some simple electronics, with a
neutral switch and other dash switch. You could ensure this was set to a minimum voltage to ensure the engine was running fast enough to keep the
charge up.
Wyn
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andyd
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| posted on 15/5/09 at 08:28 PM |
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Slighty OT but...
Hasn't any bright spark engineer come up with a usable mechanical solution to reversing a BEC?
And no I don't mean using a full Quaife type extra box.
Something that is possibly in-line with the drive but "semi-disengaged". Might be more expensive than a starter motor but far less hassle
to operate.
Andy
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tilly819
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| posted on 22/5/09 at 01:58 PM |
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Im working on it at the moment
just picked up a prop shaft last night, have a couple of ideas il put a proper post up when iv come to a solution
Tilly
F20C Haynes roadster 440 BHP/Tonne www.youtube.com/handmadeextreme
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