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Re: [Land-speed] Inertia Switch Specs...

To: <drmayf@mayfco.com>, "LSR" <land-speed@autox.team.net>
Subject: Re: [Land-speed] Inertia Switch Specs...
From: "Rick Byrnes" <Rick@RBMotorsports.com>
Date: Thu, 4 Dec 2008 13:09:58 -0500
First
The impact to knock out the "inertia" switch is considerably higher than the 
bumping of a push truck.
How many push trucks have triggered this switch?
Have anyone with anything manufactured in the past 16 or so years 
experienced this other than in an accident?
Quit worrying.  Mount it like the OEM did, and make sure it is accessible to 
you.
Hell, mine in the liner is under the seat, and the seat shell has to come 
out to reset it.  Thats how much confidence I have that it is not 
accidentally going to be tripped.
SCTA is not going to tell us what to use but will look in inspection for the 
presence and proper wiring.  It will be hard to prove that it works without 
removal or banging into the race car Really hard.
The Ford switch has been in production since the late 70's basically 
unchanged, and has very proven reliability.

I have used the Ford switch on each of my cars, and never had a problem. 
Wire in series with the activation of the relay or solenoid that controls 
voltage to the fuel pump.  If you are not using a relay you should be.  My 
Weldon pump draws almost 20 Amps at working pressure and flow. (Methanol- 
100psig)

My inertia switches came from junk yards and work just fine.  They have the 
connectors too.

Ricky B
----- Original Message ----- 
From: "drmayf" <drmayf@mayfco.com>
To: "LSR" <land-speed@autox.team.net>
Sent: Thursday, December 04, 2008 11:40 AM
Subject: [Land-speed] Inertia Switch Specs...


> One of th eapproved rule changes, required for the 2010 season is the 
> implementation of an inertia switch to shut down an electric fuel pump in 
> an upset condition.  I think this is a greeat idea. BUt seems that there 
> may be some open issues with that, at least it seems that way to me. One 
> is what is the requirement for impact to trigger the switch? It needs to 
> be higher that the bump of a push car yet low enough to be effective. Can 
> a switch be placed in a control line of a relay or does it need to be in 
> the primary line? I can purchase one from Pegasus for about 60 bucks that 
> is for 10 - 12 g's and it is used in the circuit course racing. But is 
> that too much? Too little?  And that begs the question of where and to 
> what the switch should be mounted. Chassis / framework? Inside the cockpit 
> area? Does it for some reason need to be accessible to the safety crew?  I 
> suspect more questions could be asked but this is enough for me now, lol. 
> Have any of you chatted with club officials as to what they might actually 
> be looking for during tech inspection?
>
> Input is appreciated and no I wont bend over, lol...
>
> mayf
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