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Brake pressure switch - which way up???
Sloan85 - 30/4/13 at 09:03 PM

Just thought about something I read some months ago and was wondering whether there was any truth to it?

I have installed the brake pressure Switch with the terminals facing upwards but I read that this can get air trapped and its best the other way up? You can see how I mounted mine in the photo below. Will it be ok like this or should I change i? It will mean moving bracket up about 30mm but I could do it before I get the brakes up and running.

Cheers


big-vee-twin - 30/4/13 at 09:12 PM

Change it, they do trap air, also may hit gearbox in that position.

Just noticed you building a bec so gearbox not an issue

[Edited on 30/4/13 by big-vee-twin]

watsonpj - 30/4/13 at 09:13 PM

Dont know about the air getting trapped but it will work better in the front circuit as there is more braking effort on the front end. I had mine in the back originally and someone stop me and said my brake lights werent always coming but work fine on front circuit.

Pete

loggyboy - 30/4/13 at 09:17 PM

Why not turn it at 90 degrees.

wilkingj - 30/4/13 at 09:41 PM

Yes, mine and a few others started sticking in this (The upright) position.
I suspect the air bubble could allow some minor corrosion (over time) causing it to stick.

Also an air bubble to be compressed on braking makes a less firm pedal, OK only a small amount, but it all adds up.




EDIT:
Just flip it thru 180 degrees, and hang it downwards, just a nut n bolt job, and no new flares or piping work to be done.
Just my 2d's worth.

[Edited on 30/4/2013 by wilkingj]

bi22le - 30/4/13 at 10:18 PM

I have mine with terminals up. Its at the highest point so is used as a method to bleed the line.

Not to sure about the corrosion and sticking story but it may actually be true. I have had to replace my switch once as is stopped being sensitive enough.

£5 later all fixed and bled.

loggyboy - 30/4/13 at 10:50 PM

quote:
Originally posted by bi22le
I have mine with terminals up. Its at the highest point so is used as a method to bleed the line.


I dont think all air would work its way to the top, most we be trapped in various points so all 4 corners should still be bled when the need arises.

rx7locost - 1/5/13 at 01:13 PM

Your switch location is virtually the same as my MGA's brake switch; very low on the chassis and terminals pointed up. I rebuilt it with all new hoses hard lines etc, never thinking about trapped air. I never had any soft pedal. I later replaced this switch without having to re-bleed the system by filling the switch body with fluid before swapping it out. I think you will be just fine.