Collision Sensor Part 2

[bullfist]

Mounted a (new) Ford Sierra/sapphire inertia fuel cutoff switch on the hood at the weekend, bolted tightly to the chassis.

 

However, wacking the chassis hard with a hammer would not cause the switch to trip.

Two questions:

 

A bit absurd, but perhaps I should mount the switch upside-down (more sensitive upside-down).

Or maybe I should mount it on something less rigid i.e. the scuttle.

 

Any opinions?

Thanks,

-Steve

[fry61]

Morning Steve, the switch in Florin is mounted on the bulkhead & that still needs a good thump to make it trip. Would suggest you are not able to get enough movement under test with switch on chassis; but please don't hit harder to prove.

[richyb66]

 

However, wacking the chassis hard with a hammer would not cause the switch to trip.

 

 

It won't, depending on how close to the switch you hit, you probably couldn't hit the chassis hard enough to get the ball in the switch to move and trip the switch. A good tap close to the switch or a sharp tap on the switch with a piece of wood should get the switch to trip out.

 

 

A bit absurd, but perhaps I should mount the switch upside-down (more sensitive upside-down).

Or maybe I should mount it on something less rigid i.e. the scuttle.

 

No and no again. You need it mounted solid to the chassis and in the same orientation to it's fitting on the Sierra.

 

With any luck it will never be needed.

[Guest MarkB]

Early mondeo cut off switches were fairly easy to trip, hundreds of call outs to mondeos that wouldn't start after a wheel change ( sensor in spare wheel well)

[Guest MarkB]

Early mondeo cut off switches were fairly easy to trip, hundreds of call outs to mondeos that wouldn't start after a wheel change ( sensor in spare wheel well)

[Jez Morton]

I think the clues in the name. Inertia. Whacking the chassis won't trip it, its not a shock sensor. A change in velocity is what trips them or a rapid decelleration, the inertia of the weight inside the switch causes it to continue moving and trip the switch. If its not moving then the force required to dislodge the ball is huge. I've got mine mounted solid to the chassis and never had a miss trip, in the hand it seemed really easy to trip.

 

Jez

[Snapperpaul]

A "how to" document

 

http://www.oemautoparts.net/downloads/IS31.pdf

 

I've got 10 to 12G in my head as a inertia switch activation point, that's a big impact

[bullfist]

Thanks for the (good) answers.

Will leave it where it is, and stop wacking the chassis.

Cheers,

-Steve

[Guest bob13]

I know mine works!! Did a spirited junction start, a little sideways should we say. When everything had finished going sideways the car just stopped dead. There's me thinking I have killed my car, tried to start it, nothing. Then i thought the inertia switch, my little tool box in the boot had hit it, and killed the engine.

 

So I went from O dear tow home time to thank god just push the button!

 

 

 

[Guest peter2b2002]

as above did the same when i was down south after spinning comming out of a roundabout a bit too quick in the wet

peter2b