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Old 11-04-2008, 01:10 AM   #1
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Default Clutch switch override... Best way to go about it...

What would be the best way to go about making a Clutch switch override? I never really got under there to see what is going on. Is the FM unit worth it? Can I just zip tie it pushed in or jumper the switch?

Flyin' Miata 1 800 FLY MX5s
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Old 11-04-2008, 01:29 AM   #2
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aha, my project this week may be worthwhile to someone, better yet the guy who shared his vents.

I didn't want the wear associated with the clutch-in starts, but I also didn't want to hand the keys over to anyone (read, wife) who might happen to turn the key with the car in gear and the clutch out. So, I chose to install a toggle switch running from the OEM switch wires under the clutch pedal. That assembly comes out with a couple of 8 or 10 mm nuts, and the wires have a clip into a harness. I used a razer to remove about 1/4 inch of insulation from the OEM wires, and soldered two long wires to the exposed wire. I ran those two wires up to the steering column cover, where I installed the toggle switch. When the toggle switch is off, the clutch switch works normally. you can't start without depressing the pedal. When the switch is on, you can start it in neutral without depressing the pedal. after the car is started switch the toggle back to off.
Even better would have been a momentary switch, but I didn't have one. I think that paranoia might stop me leaving the switch engaged AND forgetting to not have it in gear when starting up clutchless. The switch itself is in a position where you can't easily see it for people that like to flick switches, and your knee won't get it. Just my solution, hope it helps.
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Old 11-04-2008, 01:42 AM   #3
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Quote:
Originally Posted by tronik View Post
aha, my project this week may be worthwhile to someone, better yet the guy who shared his vents.

I didn't want the wear associated with the clutch-in starts, but I also didn't want to hand the keys over to anyone (read, wife) who might happen to turn the key with the car in gear and the clutch out. So, I chose to install a toggle switch running from the OEM switch wires under the clutch pedal. That assembly comes out with a couple of 8 or 10 mm nuts, and the wires have a clip into a harness. I used a razer to remove about 1/4 inch of insulation from the OEM wires, and soldered two long wires to the exposed wire. I ran those two wires up to the steering column cover, where I installed the toggle switch. When the toggle switch is off, the clutch switch works normally. you can't start without depressing the pedal. When the switch is on, you can start it in neutral without depressing the pedal. after the car is started switch the toggle back to off.
Even better would have been a momentary switch, but I didn't have one. I think that paranoia might stop me leaving the switch engaged AND forgetting to not have it in gear when starting up clutchless. The switch itself is in a position where you can't easily see it for people that like to flick switches, and your knee won't get it. Just my solution, hope it helps.
That's a pretty good idea. I have thought about going the momentary switch route myself, which would enable you to still use the original switch to activate launch control on a MS.
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Old 11-04-2008, 01:43 AM   #4
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Just d/c the plug going to the switch, the upper switch. Make a jumper with 2 male disconnect terminals. Insert both ends into the the connector your pulled from the switch.
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Old 11-04-2008, 01:44 AM   #5
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thanks....I like soldering. I also soldered a toggle switch to my diagnostic port ten/grd, just to save like 5 seconds every so often. Thinking of soldering up a megasquirt this winter
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Old 11-04-2008, 09:06 AM   #6
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Just d/c the plug going to the switch, the upper switch. Make a jumper with 2 male disconnect terminals. Insert both ends into the the connector your pulled from the switch.
That. Any other way is sort of moronic. It's a 30 second mod.

Frank
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Old 11-04-2008, 09:34 AM   #7
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Ok thanks guys, I think i know what ill do...

It's going to be a... tronik inspired Paul bypass of sorts. Switch is getting unplugged two male spade connectors are getting jammed in. The other end is going to be connected to a momentary push button. So if you don't know about the switch u cant just push the clutch in to get the car to start. Kinda a security measure and an engine saver...
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Old 11-04-2008, 09:47 AM   #8
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can you still use the cruise with the clutch switch disabling?
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Old 11-04-2008, 10:29 AM   #9
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Originally Posted by hustler View Post
can you still use the cruise with the clutch switch disabling?
Good question.


Where is the thrust bearing they mention? Im having a tough time imagining what exactly by passing the clutch switch is supposed to save.

Also, no more launch control for those who have it.
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Old 11-04-2008, 11:27 AM   #10
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Quote:
Originally Posted by boileralum View Post
... which would enable you to still use the original switch to activate launch control on a MS.
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Originally Posted by hustler View Post
can you still use the cruise with the clutch switch disabling?
There are two separate switches on the clutch pedal.

The one which interrupts the starter is a large unit mounted at the very end of the clutch travel (ie: at the firewall.) This switch is normally open, and closes to complete a path from the keyswitch to the starter solenoid when the pedal is pressed all the way to the stop. This switch is highlighted in red in the attached drawing

The one which deactivates cruise and parallels the neutral switch to the ECU (which is the same one we use for flat shift and launch control on the MS) is a smaller switch, mounted to a bracket under the dash. When the pedal is at rest, this switch is depressed and thus open. When you push in the clutch pedal just a bit, the switch is released and closes to ground. This switch is shown in green below.



You can bypass the starter interrupt switch (either with a clip or by shorting the wires together) without affecting cruise, launch, or flatshift.
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Old 11-04-2008, 11:33 AM   #11
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Originally Posted by fmowry View Post
That. Any other way is sort of moronic. It's a 30 second mod.

Frank
disagree, funny man. Taking an extra five minutes to significantly lesson the chance of someone trashing a trans, this causing many hours of work plus significant costs us not moronic. It's kind of the opposite.
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Old 11-04-2008, 01:20 PM   #12
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I have an FM clutch override switch I never used. PM me your addy and I will send it to you..................it's just a clip.
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Old 11-04-2008, 02:23 PM   #13
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Isn't it the thrust baring between the block and crank that's at issue, not the transmission? There's no axial force being placed on the transmission input shaft since the clutch slides freely on the input shaft's splines. There is, however, an oil starved thrust baring in the block.

In the grand scheme of things, I wonder how huge of an issue this really is on daily driven cars. It's not as if it's completely bone dry of oil for cars that get driven most days of the week. On a track car that barely gets driven, I can see the point...kind of.
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Old 11-04-2008, 03:26 PM   #14
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Originally Posted by miatamoxie View Post
Isn't it the thrust baring between the block and crank that's at issue, not the transmission?
Anytime the clutch is being pressed (when the throwout bearing is loading the pressure plate) the thrust bearing is being loaded. So the idea is to be able to start in neutral without depressing the clutch to keep from loading a 'dry' thrust bearing during startup.
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Old 11-04-2008, 03:40 PM   #15
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Wouldn't disengaging the clutch lower load on the engine?

This all sounds like snake oil to me in all honesty, but id love to hear a debate on the issue.

Where exactly is the thrust bearing? Someone said between the block and the crank? Are we talking about the fluid bearings the crank sits on inside the block?

The clutch\pressure plate is attached to the flywheel? What exactly are we removing load off from starting in neutral? Which still leaves the transmission attached to the engine?
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Old 11-04-2008, 04:00 PM   #16
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Not a miata pic, but here's a thrust bearing:

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Old 11-04-2008, 04:10 PM   #17
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I think the issue is exaggerated the heavier the pressure plate clamping force gets...

IMO it's convenient, I can lean in and start my car if I'm say tracking down an exhaust leak and keep having to turn my car on and off to see if it's fixed...
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Old 11-04-2008, 04:12 PM   #18
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disagree, funny man. Taking an extra five minutes to significantly lesson the chance of someone trashing a trans, this causing many hours of work plus significant costs us not moronic. It's kind of the opposite.
What are you talking about? It's a 30 second mod. 2 male spade connectors. Clutch switch overridden. Ran this way for 6 years with no problems.

Someone who trashing the trans? I don't let idiots try and start my car. If you do, then you've got other problems. Maybe you should buy an automatic.

Frank
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Old 11-04-2008, 04:13 PM   #19
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What exactly are we removing load off from starting in neutral?
Equal and opposite reactions my friend. when you push in the prerssure plate not only does it compress the clamping springs but it literally tries to push the crank straight out the of the engine... of course the thrust bearing and block keep that from happening. The heavier the clutch the more force that is trying to "push" the crank out.

Get it?
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Old 11-04-2008, 04:45 PM   #20
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What Mike said. The thrust bearing definitely gets loaded when the clutch is pressed in, no debate there.

What may be debatable is whether or not the ability to start the engine without the clutch pressed in significantly increases the life of the thrust bearing. But, since the mod is relatively easy, then why not? I may do this myself and if I do I will probably use a momentary bypass switch mounted under the steering wheel that I can push with my left hand. To each his own.
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