Master cut-off wiring

Scott Haynes

Scott Haynes

hello
So I have one final thing left to do in order to go through an annual inspection. I need to wire my master cutoff switch. From what I can tell I need to have it cut power to the ignition and not allow the car to restart. I have a main power wire that runs from the battery to the fuse panel. I can cut into this and it will accomplish both. Will that be sufficient? I know there is some debate on the wiring. I just want to make sure my car is legal and safe. Any help is appreciated.

TIA
-Scott
 
Scott, not sure how your car is wired but here is what I did with mine.
I bought a 4 pole cutoff switch.

The main terminal is for the positive battery cable.
Most cars if you cut off the 12+ battery cable it will not kill the engine. The alternator will allow the car to continue to run. You can test this by disconnecting the positive battery cable while the car is running. My daily driver E30 beater I swapped batteries with my tow rig while it was running when the rig would not spin over.

The other is for the 12+ from the alternator to the battery. Careful here you may need a diode to protect the alternator. BMW has this built in from the factory. If you look you can find diagrams. Maybe on a VW forum? Someone else has gone through this.

If done the way above not only will the switch kill the engine but will kill power to the entire car which is the goal safety wise. It is not about "restarting" it is about power killing to everything in event of throttle stick, fire, etc.

Also try to mount it where it is easy for the workers/safety people to get to. They need easy access more then you do. Needs to be accessible if your car is upside down or on its side also.

Mine is not perfect but is on the top of the dash just inside the passenger door window opening and is clearly marked and very visible. I hope to run a second switch in the same place but on the driver's side. That way no matter how the car is laying or which side is responded too the switch is there for them.

I have seen an expensive but very trick setup using 1 main cut off switch operated by a solenoid. You mount this anyplace and then run as many small 12v toggle switches as you like where ever you like. Internet search will find them for you.

I don't know VW's but with my car BMW had already put the battery in the trunk so both positive cables battery-alternator were already there to tap in to. And since BMW puts "jumper terminals" in the engine compartment it was really easy.
So you might want to see if your car has something similar. They are both German;)
 
Scott is EXACTLY right...

The idea is to 'KILL" all electric power to the car including ignition, fuel pump (if electrical), lights, dash, etc.

The best way to do this is to interupt battery power to EVERYTHING and if you have an alernator, kill it also.

Option 1 no alternator:

http://www.pegasusautoracing.com/productdetails.asp?RecID=1465

Option 2 with alternator:

http://www.pegasusautoracing.com/productdetails.asp?RecID=1464

Option 2 includes a resistor and an extra set of terminals to shut down the alternator.

LOCATION:
YES, Scott is right again. You want to be able to reachd this switch yourself in case of a problem AND have it in CLOSE proximity to the window so workers can reach it easily. The location 'must' be identified with the appropriate decal on the exterior of the car close to the location of the switch using this decal:

http://www.pegasusautoracing.com/productdetails.asp?RecID=1011

NOTE:
Second reason for wanting to reach the switch yourself is, they are not 10,000% reliable. Sometimes they can 'vibrate' or get knocked to off position (rare but it happens).


For battery interuption, you can use the hot or ground side wires. Either one will interupt the battery circuit (you'll find cars wired both ways).

Use the SAME SIZE wire for the switch as your main battery cables. Unless your battery is like in the trunk on a front engine car. Then I'd use one size larger for the switch wiring as you're gonna put the switch in the cockpit somewhere.

NOTE:
For 'total loss' electrical systems there's one other thing you want to do. But I don't think it's applicable to your car.
 
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I was actually considering putting window nets on both sides of my car for 2010 Lynn. May look a little goofy, but boy would I be safer, especially after I replace my 2 year old practically brand new $300.00 6 point belts!
 
I do believe the drivers voted down the 2 year replacement rule, but the E-board overturned that.
I think the wording from Steve in his recap said the "belts expire when they expire" but what that means exactly I'm not sure.
If we purchase FIA certified belts with a 5 year rating do we still have to replace them every 2 years? That's the way I read it.
 
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Hey folks, don't forget about that crusty old Texan at Armadillo Racing for your parts needs. Andy is there for us every weekend and his prices are not that unreasonable.

I'd rather buy from one of our own than a company many miles away. (even if he is a Texan)
 
westipton said:
I do believe the drivers voted down the 2 year replacement rule, but the E-board overturned that.
I think the wording from Steve in his recap said the "belts expire when they expire" but what that means exactly I'm not sure.
If we purchase FIA certified belts with a 5 year rating do we still have to replace them every 2 years? That's the way I read it.
Click to expand...

SFI belts expire 2 years from their manufacture date, which is (I believe) on the belts somewhere. Whenever that date is, to the day, is when they expire. FIA belts have a 5-year expiration date on them, which is when those expire. It's pretty cut-and-dried this way.

So, yes, buying FIA-rated belts is potentially cheaper, amortized over 5 years, than buying "cheaper" 2-year SFI-rated belts.
 
For the price difference a 5 year belt is the logical choice from what I've seen with current pricing. I feel better already Steve, thanks.
 
Wes,

If you decide to go FIA, check with Keith Averill. He usually makes a buy in Jan/Feb so you get a FULL 5 year set rather then ones sitting on some big suppliers shelf for a year.
 
Averill Racing Stuff
((248) 585-9139

WELL known upper midwest formula car prep shop. Also knows EVERYTHING there is to know about Reynards. Good all round guy who can answer tons of questions.

http://racing-stuff.com/

Give him a call and he'll be sure to get the color you want (red?).
 
For battery interuption, you can use the hot or ground side wires
Click to expand...

ummm... I seem to remember that the Secret Sports Car Club now doesn't allow ground
lifting... not that it matters much in the current case...

t
 
If you use the cutoff on the ground side it is possible for the ground side to be punctured before the switch. The switch will be rendered useless. For safety reasons I put the cutoff switch on the + side of the battery. G
 
gordon_jones said:
If you use the cutoff on the ground side it is possible for the ground side to be punctured before the switch. The switch will be rendered useless. For safety reasons I put the cutoff switch on the + side of the battery. G
Click to expand...

If you use the cutoff on the HOT side it is possible for the HOT side to be punctured before the switch and in contact with the frame. The switch will be rendered useless as your battery will be in a dead short across the battery terminals (BIG SMOKE).

Either way there's a risk of something happening that isn't 'normal' and rendering the switch useless.
 
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