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Post by tomtom9 on Oct 4, 2020 21:41:52 GMT
Hi everyone!
Can anyone tell me the location of the brake switch please on my 1967 3 litre mk3?
The brake lights have failed and I suspect the switch is at fault. Is it a simple job to replace?
Many thanks. tomtom9
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Post by Phil Nottingham on Oct 5, 2020 5:01:24 GMT
On 3 Litres its hydraulic on the engine side of the bulkhead near the handbrake pulley on a T junction for the brake lines
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Post by tomtom9 on Oct 5, 2020 8:38:01 GMT
Thanks Phil,
- being of the hydraulic type, I am assuming that air will enter the system on fitting the replacement switch - necessitating bleeding the brakes?
with thanks.
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Post by djm16 on Oct 5, 2020 11:44:18 GMT
The greater danger is of dirt entering the braking system given the placement on the firewall behind the engine. Mine went wrong, and it was filthy with oil and grit. However the oil may have prevented corrosion, so you might get it apart without twisting and breaking brake lines. I seem to remember it was not easy to get too. I strongly recommend disconnecting the two cable from the switch, and connecting the two together to check that the brake lights come on. It would be a shame to spend all day replacing the switch only to find the fault was elsewhere.
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Post by Phil Nottingham on Oct 5, 2020 21:08:46 GMT
Mine actually came out easily 20 years ago! It has a parallel thread so the copper sealing washer is needed and must be good. There are similar switches used on Minis etc but these have parallel threads and will screw in but split the rare union so beware.
The one I replaced 20 years ago became sluggish with delayed operation and heavy pressure. I replaced it last year and if you are quick no bleeding is necessary but remember DoT 3 and 4 brake fluid has always required renewal every 2-3 years even from when these cars were new.
P5Bs have the common cheap mechanical switch now plastic which fit over over the brake pedal underneath the parcel shelf. If you replace the brake pedal; with a P5B one with the added operating pad then you can covert if you also have the angle bracket to mount it on
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Post by tomtom9 on Oct 5, 2020 21:46:08 GMT
Many thanks to Phil & djm16 for all the advice - much appreciated!
tomtom9
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Post by Ken Nelson on Oct 7, 2020 14:15:51 GMT
My hydraulic switch failed recently also and I replaced with the parallel thread one and copper washer (not taper thread). I had to be careful to support the T brass junction when unscrewing it to avoid twisting the brake lines, but otherwise it was easy to do with no need to bleed brakes if done quickly. These switches apparently are prone to failure easily.
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Post by enigmas on Oct 7, 2020 20:15:06 GMT
I don't know about that Ken! The original brake switch still functions perfectly on my 66 MK3 coupe. It also deactivates the cruise control which I fitted many moons ago. I believe the hydraulic switch was used across the range of cars manufactured in the UK, including my 58 ZB Magnette which also uses the same hydraulic switch.  |
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