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Correct way to install brake light switch

martinnitram - 3/10/17 at 05:44 PM

I've changed my Sierra master cylinder to a fiat 19mm bore one, on the Sierra master the brake light switch went straight into a spare port via a M10 x 1.0 thread.
On my new master cylinder the port threads are M10 x 1.25 which won't accept the 1.0mm thread.
so I've run a short piece of pipe into a M10 x 1.0 3 way tee blanked off one port with a tapered bung and the switch into the remaining one.

The switch is sealing on its threads as its not tapered or long enough to seal into the bottom of the tee, as a brake pipe fitting would.

I'm not convinced this is a good idea, this is how it was fitted to the old master cylinder and worked ok, but what's the correct way of fitting a brake light switch ?

adithorp - 3/10/17 at 07:42 PM

You should have a copper washer for it to seal on. Alternatively purchase a taper thread switch. You'd be better with a bleed nipple in the third T outlet, then bleed the pipe/switch via that rather than just having a bung in it.

CosKev3 - 3/10/17 at 07:56 PM

Convert over to a electric switch on the pedal

martinnitram - 3/10/17 at 08:04 PM

Would a tapered thread brake light switch go into a standard M10 x 1 port and seal properly ?
Good point with bleed nipple.

No copper washer on, so if that's the right way to do it sounds simple enough.

Thanks

Bluemoon - 4/10/17 at 07:15 AM

quote:
Originally posted by martinnitram
Would a tapered thread brake light switch go into a standard M10 x 1 port and seal properly ?
Good point with bleed nipple.

No copper washer on, so if that's the right way to do it sounds simple enough.

Thanks

Mine sealed in this way with a bit of PTFE tape (not to much and in the correct way else you could loose a bit of tape into the system not a good idea..). This is "correct" for this type of fitting but IMHO it's not ideal but with a tapered thread this is the method. Make sure it's in the front break circuit as the brake light will come on to late on the rear circuit (tends to have less pressure!!)...

nick205 - 4/10/17 at 09:02 AM

quote:
Originally posted by CosKev3
Convert over to a electric switch on the pedal

I fitted my old MK Indy with a hydraulic switch in the brake line. Whilst it worked the brakes were applied before the brake lights came on.

Building again I'd opt for an electric switch operating from the brake pedal itself. IMHO more likely to allow adjustment to ensure the brake lights come on just before or as you push the brake pedal. Might need some extra wiring in the loom, but not a big job to do.

gingerprince - 4/10/17 at 12:31 PM

quote:
Originally posted by CosKev3
Convert over to a electric switch on the pedal

This.

I never found the pressure sender worked until I was stamping, despite how well I bled the switch. With the switch on the pedal, the brake light can come on right at the beginning even before hydraulic pressure starts to build.

Brake Switch

Brake Switch

[Edited on 4/10/17 by gingerprince]

coozer - 4/10/17 at 02:58 PM

After all the chew on with the hydraulic switch onmy mnr my next one will be a switch on the pedal....

martinnitram - 4/10/17 at 07:51 PM

Ordered a push switch to go on pedal and bleed nipple for M/C.
Getting rid of the brake line switch and chance of a leak.

nick205 - 5/10/17 at 01:20 PM

martinnitram

Just noticed your username and it's made me chuckle quite a bit.

Had a pal called Martin for some years and he's always been referred to as "nitraM". No reason really it's has just been amusing.

Angel Acevedo - 27/3/19 at 01:58 PM

quote:
Originally posted by gingerprince

quote:
Originally posted by CosKev3
Convert over to a electric switch on the pedal

This.

I never found the pressure sender worked until I was stamping, despite how well I bled the switch. With the switch on the pedal, the brake light can come on right at the beginning even before hydraulic pressure starts to build.

Brake Switch

Brake Switch

[Edited on 4/10/17 by gingerprince]

I am posting on this thread to illustrate what I did to install a Brake Light Switch.
I wanted to do something like gingerprince but having a pedalbox with twin masters and balance bar made it very difficult to do it.
I instead went to a micro switch installed behind the pad and actuated via a small strip of metal with a bolt to press on the actuating lever of the microswitch.
I can´t upload photos, but I have Pics and a short video, I have the picture uploaded to my Facebook, and I´ll send the vid to anyone who wants to see it.
Part of the reasoning was to have the brake light to come on as soon as possible, on my setup as soon as I touch the pedal, brake lights come on, no need to build pressure on the lines.
This may give a fraction of a second more to the car behind to brake early too...

Angel Acevedo - 9/4/19 at 03:23 PM

To all.
While browsing this thraad http://www.locostbuilders.co.uk/forum/4/viewthread.php?tid=214615, I went to Daf picture archive and found this picture.

Description
Thanks for Daf for uploading.
Should I have seen this picture before, a lot of pain, aggravation and cursing would have been spared...
Thanks Daf,
I´m posting this to keep the solution on a thread that makes sense.