Crank Trigger Crossover Switch Failures

Discussion in 'Manton Push Rods Top Alcohol Tech Questions' started by Mike Canter, Feb 2, 2016.

  1. Mike Canter

    Mike Canter Top Dragster

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    Over the past several years we have been plagued with Crank Crossover Switch failures. Normally these failures result from the switches internal contacts bouncing due to engine vibration. Our switches are no longer hard mounted to the front plate and are attached to something soft such as a wiring bundle. We have tried both the MSD switches and the Electrimotion Switches with the same bad results. It has cost us wins numerous times such as this last weekend. We have talked to several other racers who are experiencing the same problem. Has anybody found a switch that does not have contact bounce or have a better way?
     
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  2. HootersFunnyCar

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    Leave the switch in the tool box next to the timing light. You are never going to "switch it" going down the track so it is redundant to have it on the car. If it won't fire on the line swap the plug ins and send it.
     
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  3. overkill69

    overkill69 Member

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    We ran a FIE that seemed like a well thought out piece but deleted while troubleshooting misfires and never looked back.
     
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  4. jody stroud

    jody stroud ZOMBIE Top Dragster

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    I've had a case where the starter batteries were weak. We were able to start on mag and then switch to trigger and make the run. I like them and use them even if I don't totally trust it to last.
     
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  5. jay70cuda

    jay70cuda Member

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    Get stronger batteries. Larger cables. When I had small cables it wouldn't spin fast enough to fire the mag. So in the pits I'd start the car on mag let it warm up and then go back to the trigger before the round. Come to find out the cables were burnt up inside and full of corrosion. New cables. No more switch.
     
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  6. Mike Canter

    Mike Canter Top Dragster

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    Putting the switch in the toolbox is NOT an option. We use a 24 volt starter and still have an occasions that it will not start on the crank trigger. We just can't take that chance of losing the race because the car will not start. It is two evils of either not starting or have the switch contacts bouncing going down the track and causing misfire.
     
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  7. jay70cuda

    jay70cuda Member

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    Dumb questionn but is the mag phased. Billes came over and rephrased mine because i paid Electrimotion to don't and it was wrong. He phased it and been awesome ever since
     
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  8. lucky devil

    lucky devil Member

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    Mike ,
    can you run an offboard starter. It sucks to be number one and then cant start
     
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  9. Mike Canter

    Mike Canter Top Dragster

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    Yes mag is phased. And no we cannot use an off board starter. The problem is the crossover switched are failing
     
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  10. kosky racing

    kosky racing Comp Eliminator

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    Mike check into aircraft suppliers their switchs are way better quality------Mike
     
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  11. Mike Canter

    Mike Canter Top Dragster

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    Thanks Mike, that was exactly what I was thinking was to get a mil spec gold contact switch with a toggle lever that you have to pull out a little to switch it. So has anyone out there found a mil spec aircraft DPDT switch that has worked well?
     
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  12. tafc1445

    tafc1445 New Member

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    Have a look on skygeek website and search "Eaton toggle" and see if any of those switches may suit your application. They are all mil-spec aircraft hardware switches.
     
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  13. blownapex

    blownapex Member

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    just like the msd mag kill switch
    mike mine has never failed I zip tie it to the blower bag by the lower strap
    but I don't race like you guys
     
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  14. HootersFunnyCar

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    Ok so you need to add a second set of plug in wires from the trigger to the mag. leave disconnected until the car fires then connect them. Run them in parallel with the switch and it creates a second path for the signal incase the switch fails. I can draw you a diagram if you don't understand the wording.
     
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  15. Mike Kern

    Mike Kern New Member

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    Get a better starter! Either way you still lose the race. Better to have it not start than misfire and maybe kill it!
     
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  16. Mike Canter

    Mike Canter Top Dragster

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    There is nothing wrong with the starter. We have tried three different of the best starters running off of 24 volts. The problem is as always the 7" diameter degree wheel. Sometimes the magnets don't pass the crank trigger sensor fast enough to have a high enough amplitude signal to trigger the ignition. Most of the time, maybe 98% of the time it will fire right up but if that 2% occurs during eliminations and you don't have a crossover switch then you are SOL. The problem is these crossover switches are a piece of junk and the contacts in the switch vibrate from engine vibrations and cause misfire in the motor.
     
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  17. Mike Kern

    Mike Kern New Member

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    Why don't you use a 48 volt or at least a 36 volt? Or is that not possible? I'll assume your trigger gap is ok. It is possible to reduce the gap to help. Just looking for an alternative to the switch
     
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  18. jay70cuda

    jay70cuda Member

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    I agree. Who Starter are you using. Have you tried using lithium batteries to see if it's a battery thing. I've seen batteries read 13 volts but when you zap them with the surge of 24 volts it would basically short out and would be like starting on just 12 volts.
     
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  19. Mike Canter

    Mike Canter Top Dragster

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    The trigger gap is at .045 any closer the trigger may hit the wheel which will destroy it. We have used Meziere, MSD and CSR starters. Again it starts 98% of the time on the trigger. We have used AGM batteries and right now have two brand new big CCA 12 volt batteries in series and charge them between rounds. What I need is a good quality DPDT with locking lever switch with self cleaning gold contacts
     
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  20. overkill69

    overkill69 Member

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    We did a lot of trigger testing trying to find a misfire. The standard setup is weak. The mags internal trigger produces 3 times the voltage of the crank trigger. That's why it starts better.
    A hall effect sensor will fire the mag at ZERO rpm. I found one that would fit in the RCD bracket but with my huge 11mm pulley it was going to be really tight on space.
    A lot of EFI systems have abandoned the magnetic trigger but here we are with a monkey see setup dead in the staging lanes.
     
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