HOW TO - hot start relay

Discussion in 'How To' started by Stan, Aug 11, 2011.

  1. After my recent bout of starting funnies I eventually got around to fitting my hot start relay.

    What a difference and for peanuts! I only have to look at the ignition switch and it starts on the button just like my Beetle always has.

    So why pay more I recon its cost me about £5 in total if that and about an hour of my time.

    You will need a 4 Blade Relay 12V 40A (£1.95 from Vehicle Wiring Products ltd http://www.vehicle-wiring-products.eu/VWP-onlinestore/home/homepage.php ) some Thinwall wire (1 metre each )56/030 Brown and Red (76p each) or whatever cable you have.
    2 x ring connectors and 2 x 1/4in spade connectors with covers.

    I made up the cables - did'nt have ring connectors big enough to fit over the 13mm bolts so just soldered wire to washers.
    Soldered the connections on all the cables for extra security.
    I found a small plastic tub to put the relay in but anything such as an old vitamins bottle will do - as long as the relay will fit in. (You dont need a 40A one btw its just they are cheaper than the others so why not have a higher rated one anyway)

    Please follow the diagram below ,
    Unscrew the 13mm nut on the solenoid (which has the thick Battery fed Cable on it) and connect your new cable to it, (Terminal 30 on relay and solenoid).
    Pull off the original thin wire from the ignition, (Spade connector terminal 50) and plug that into (Terminal 85) on the relay.
    Now plug in a cable (terminal 87 to terminal 50 on Solenoid) this will be the replacement igition feed via the relay but with no voltage drop!
    I connected the Earth connection (terminal 86) to a suitable point I already had on the body (the Rock and roll bed bolts) but you can use the 17mm bolt on the starter if you want.

    Note:
    Should the relay fail in the future all you need to do is unplug the thin original spade connector cable from Terminal 85 and back onto terminal 50 on the solenoid (removing the new wire from terminal 87 to 50) at £1.95 I purchased 2 relays to have one in the van as a standby spare.



    Here is the diagram fairly self explanitory.(I did'nt bother with the inline fuse)

    [​IMG]
    I then used cable ties to seal the lid on the box and fixed it to the body just above the heat exchanger pipes - there is a handy area to tie to.

    Here are the bits (I used an old ignition lead cover for the rubber bung it pushes the relay against the inside of the tub and stops it moving about) Dont forget to tie up the cables a bit to take any stress off them.

    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]








    One slight annoyance when I had finished I tried it and nothing!!! What !!! I was annoyed - was the battery dead? Did I wire it wrong? duff earth lead?? Nope after 20 mins of faffing I found the relay was duff! I put my spare on and it was spot on perfect start every time! I called Vehicle Wiring Products and explained the situation, they were great and without any fuss said they would send me out another one.
    So tip for the day - test it before you seal everything up - school boy mistake!
     
  2. hailfrank

    hailfrank Admin esq.

    cheers stan :)
     
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  4. You should make up the kits and sell em!
     
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  7. Good point. ;)
     
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  10. Good write up stan, just done mine, slight variation following a conversation with rickyrooo1 during which he mentioned he was planning to house it in the engine bay, sounded like a top idea so I ended up putting mine in there too so if there is ever an issue I can get to the relay without any hassle..., took me about an hour and a half but that was due to not being able to find the soldering iron.
     
  11. So, pardon my technical ignorance, but what does it actually do?
     
    thetemple likes this.
  12. Well on my last 2 outings when stopping on route mu bus would not re start until it had cooled down, this stops that happening and saves me the 30-45 min wait for cooling :)
     
  13. Woodylubber

    Woodylubber Obsessive compulsive name changer

     
  14. Honky

    Honky Administrator

     
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  16. Nice write up Stan.
    Although, thinking this through, this just improves the connection to the solenoid by cutting down on the resistance by making a shorter wire feed to the solenoid. You could do exactly the same thing by installing a thicker wire to the ignition switch (less resistance). It wont make the starter motor turn faster or more powerfully. It'll just make sure the electromagnet in the solenoid makes the high amperage connection to the starter motor reliably.

    If your ignition switch isnt passing a heavy enough current to the solenoid to activate the starter motor then there will be a problem with the wiring to the front of the bus somewhere (or the solenoid!). You might have have other symptoms like dim lights etc. Fitting this relay would solve your bad connection problems to the stater motor ( a relay needs far less current to actuate than a solenoid) but wont solve the electrical problem one of the symptoms of which was bad starting.


    Cheers
    s
     
    thetemple likes this.
  17. hailfrank

    hailfrank Admin esq.

    this mod was one of the best things i've ever done!
     
  18. Why?

    All it does is make sure you're getting enough current to the solenoid which if your wiring is in good condition (clean connections etc) should be the case anyway... There are now 4 more connections and a relay to go wrong! Doesnt actually solve a wiring problem and potentially creates the possibility of more problems.

    If your getting problems with the solenoid connecting then I'd check the voltage at the ignition switch and at the solenoid from the battery and the ignition switch. If youre getting any significant diferences then youve got a problem with your connections somewhere which you could get around by running a relay which needs less current to work but doesnt solve the original problem. Or you could just go over your connections with some contact cleaner (Not WD40). If the voltages are within say 1 a volt of each other suspect the solenoid.

    I feel like I'm ruining the party but I really think that this 'solution' isnt...

    Splatt!
     
    lhu1281 and Chrisradioman like this.
  19. stevesplatto

    I think the point of this mod is so that you dont have to re-wire back to the ignition switch...


    but you are right - your technically not fixing the root of the problem, just wiring around it.
     
  20. hailfrank

    hailfrank Admin esq.

     

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