4CV Brake light Switch
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  1. #1
    Tadpole HeyCharger's Avatar
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    Default 4CV Brake light Switch

    Hi Guys. Just found out that the brake lights only come on if I really stand on the pedal. Elsewhere, someone suggested that it is easier to install a switch that activates when the pedal is depressed, as opposed to a pressure switch (which would require bleeding). Has anyone done this or had problems with the pressure switch? Thanks. Rod.

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  2. #2
    Too many posts! JohnW's Avatar
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    Quote Originally Posted by HeyCharger View Post
    Hi Guys. Just found out that the brake lights only come on if I really stand on the pedal. Elsewhere, someone suggested that it is easier to install a switch that activates when the pedal is depressed, as opposed to a pressure switch (which would require bleeding). Has anyone done this or had problems with the pressure switch? Thanks. Rod.
    The pressure switches are pretty reliable but I think, from my experience, that their diaphragm stiffens up with age (20 years plus) and then you have to press harder before the lights come on. I've replaced both R8 and 4CV switches, both being over 30 years old, and still working but not at as low a pedal pressure as I wanted.

    Personally, I'd not consider doing anything other than fit a new pressure switch. They are available.

    You should change the brake fluid from time to time anyway, unless you're on silicone, so the bleeding isn't a huge deal. Actually, if you pull off the old switch and screw the new one most of the way, then depress the pedal slowly, you might be able to bleed it adequately past the not quite tight tapered threads. Mine is, if I recall, a bog standard VW one, about $15 about 20 years ago and just fine still.

    Cheers
    JohnW

    Renault 4CV 1951
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  3. #3
    1000+ Posts J-man's Avatar
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    My R10 is exactly the same. I must do something about that before someone gives me a R8 rear end ! Shorten it that is
    cheers,

    John

  4. #4
    Tadpole HeyCharger's Avatar
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    Default

    Is the switch on the master cylinder?

  5. #5
    1000+ Posts alan moore's Avatar
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    The switch is screwed into the end of the master cylinder, and is a pressure type switch, that as has been said, the diaphragm stiffens up over the years.
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  6. #6
    VIP Sponsor 59 Floride's Avatar
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    Yep the switch is on the master cylinder and isn't that difficult to replace..

  7. #7
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    Go into a motor cycle shop and get a water proof switch and attach via a light spring to the pedal. Has worked fine on Kermit for over 8 years.

  8. #8
    Fellow Frogger!
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    Default Brake switch

    The R10 switch is the same connectors are a little difference, they are easy to get, I got one from Colliers in Sydney, some time ago. come up on ebay regularly, try ebay.fr if you are having trouble getting one locally. Dafco at Kingsgrove may have one also.
    Hope that helps
    Renosprite

  9. #9
    Too many posts! JohnW's Avatar
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    Quote Originally Posted by RENOSPRITE View Post
    The R10 switch is the same connectors are a little difference, they are easy to get, I got one from Colliers in Sydney, some time ago. come up on ebay regularly, try ebay.fr if you are having trouble getting one locally. Dafco at Kingsgrove may have one also.
    Hope that helps
    Renosprite
    This is one of those "there are actually two types of switch" situations. The earlier ones are a tiny thread switch, whereas the R8/10 ones are much bigger and hold the banjo union onto the end of the master cylinder. Both easy to get.

    Daisy Tour article under preparation.

    Cheers
    JohnW

    Renault 4CV 1951
    Renault R8 1965
    Renault Scenic 2005 (wife's)
    Renault Scenic 2007 (mine)
    Renault Scenic 2006 (daughter's)
    CitroŽn CX Pallas 1980

    National Co-ordinator, Renault 4CV Register of Australia

  10. #10
    My Supermodel 63-1092's Avatar
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    Just make sure the centre copper washer of the master cylinder doesn't slide down when you screw the switch out.

    Or you might put the new one in and find liquid flowing out, then when you rectify and try again even more brake fluid will leak all over the grass at the caravan park because you pinched the washer when you tightened it up the first time, and don't think you can find a 2mm copper washer on a Sunday in Brisbane at a auto shop.

    Not that it matters as you'll blow your engine getting home and seven months later the car is still in pieces and you haven't touched it in months.

    I'm due to fly home soon aren't I ? Shite three weeks to go still.
    John
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  11. #11
    VIP Sponsor 59 Floride's Avatar
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    I'm due to fly home soon aren't I ? Shite three weeks to go still.[/QUOTE]

    Best you have a Bex and a lie down now John......

  12. #12
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    Default those copper washers

    as a lad i was always told to heat those washers up till there red then quench them in water, do that a couple or three times will make the copper nice and soft again so it seats properly and seals ,think its called, anealing just hang it on a bit of wire over the gas ring, if you overheat it, the washer will melt PUGS

  13. #13
    Too many posts! JohnW's Avatar
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    Quote Originally Posted by pugwash View Post
    as a lad i was always told to heat those washers up till there red then quench them in water, do that a couple or three times will make the copper nice and soft again so it seats properly and seals ,think its called, anealing just hang it on a bit of wire over the gas ring, if you overheat it, the washer will melt PUGS
    My understanding is exactly the same. Get a good green flame and don't get it to red heat or something like that. The correct advice is new washers as it is a bit fiddly and best to seal first time. I had a master cylinder out three times one afternoon and don't wish to repeat that.

    Annealing it is. My experience is that these washers will stand 3-4 retightenings before they don't seal without annealing. I presume they work harden with the shearing and high pressure when tightened up.
    JohnW

    Renault 4CV 1951
    Renault R8 1965
    Renault Scenic 2005 (wife's)
    Renault Scenic 2007 (mine)
    Renault Scenic 2006 (daughter's)
    CitroŽn CX Pallas 1980

    National Co-ordinator, Renault 4CV Register of Australia

  14. #14
    Tadpole HeyCharger's Avatar
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    Well,the gods must have been smiling on me. Bought an early VW switch on ebay and fitted it today. All went extremely well. probably took me about 20mins. No hassle at all.
    Each time I did this little girl, I'm so impressed with the performance of it. What a machine!
    Rod.

  15. #15
    Too many posts! JohnW's Avatar
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    Quote Originally Posted by HeyCharger View Post
    Well,the gods must have been smiling on me. Bought an early VW switch on ebay and fitted it today. All went extremely well. probably took me about 20mins. No hassle at all.
    Each time I did this little girl, I'm so impressed with the performance of it. What a machine!
    Rod.
    Glad it worked. It's relatively easy (but for location eh?) and sometimes goes smoothly! The earlier ones are much easier as you don't disturb the banjo union.

    Cheers
    JohnW

    Renault 4CV 1951
    Renault R8 1965
    Renault Scenic 2005 (wife's)
    Renault Scenic 2007 (mine)
    Renault Scenic 2006 (daughter's)
    CitroŽn CX Pallas 1980

    National Co-ordinator, Renault 4CV Register of Australia

  16. #16
    Too many posts! JohnW's Avatar
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    Quote Originally Posted by HeyCharger View Post
    Hi Guys. Just found out that the brake lights only come on if I really stand on the pedal. Elsewhere, someone suggested that it is easier to install a switch that activates when the pedal is depressed, as opposed to a pressure switch (which would require bleeding). Has anyone done this or had problems with the pressure switch? Thanks. Rod.
    Well, time to eat humble pie!

    I had brake light switch failure in the R8 and fitted my spare hydraulic switch. No joy as with my light pedal pressures with very free calliper pistons mean that I had to brake too hard to get the lights to show. At least with drum brakes you need more hydraulic system pressure to start braking than with dics.

    I've finally reverted to fitting a mechanical micro-switch. Details and photos will follow when i've got it adjusted and working.
    JohnW

    Renault 4CV 1951
    Renault R8 1965
    Renault Scenic 2005 (wife's)
    Renault Scenic 2007 (mine)
    Renault Scenic 2006 (daughter's)
    CitroŽn CX Pallas 1980

    National Co-ordinator, Renault 4CV Register of Australia

  17. #17
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    I fitted my Floride S with a mechanical switch but was told at Junee it was often on so guess I need to readjust it a bit. I got one for a Holden of some sort from local spares place as I didn't have time to get a proper hydraulic one from Ken and needed the car for an event. At least I've slotted the mounting so shouldn't be too hard.

  18. #18
    Too many posts! JohnW's Avatar
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    Quote Originally Posted by Sunroof View Post
    I fitted my Floride S with a mechanical switch but was told at Junee it was often on so guess I need to readjust it a bit. I got one for a Holden of some sort from local spares place as I didn't have time to get a proper hydraulic one from Ken and needed the car for an event. At least I've slotted the mounting so shouldn't be too hard.
    Mine is a microswitch from Jaycar with a spring steel bit pushing the switch in, with the option of pushing it in ether switching it on or off. Photos tomorrow if I finish it before a few days in Adelaide.
    JohnW

    Renault 4CV 1951
    Renault R8 1965
    Renault Scenic 2005 (wife's)
    Renault Scenic 2007 (mine)
    Renault Scenic 2006 (daughter's)
    CitroŽn CX Pallas 1980

    National Co-ordinator, Renault 4CV Register of Australia

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