Technical Pressure brake switch horizontal or vertical?

My brake lights keep sticking. I've put two hydraulic pressure brake switches on in 6 months and the car hasn't left the garage yet. Right now I have the switch mounted up vertical. Should it be mounted horizontal? I unhooked the wires the other day and tonight hooked them back up and there not sticking. Just wandered if air was getting trapped in it.

 

H-D's are vertical & horizontal
I would use a micro switch or another type ,
Pressure switch can blow out ,

 

I stopped using pressure switches. I cannot find a supplier that does not sell ones that fail, in short order.

 

They haven't been used on cars since the mid-60s, so finding decent quality units is an issue. Harley still uses them on their bikes (and I have yet to have one fail), you might try theirs.

One other thing to think about; when these were used, they were always limited to just two 'standard' 23W brake lamps. If you're trying to run more than two lamps or are using some higher wattage/halogen replacements, you may be overloading them. You might want to use the pressure switch to operate a relay to reduce the load on the switch.

 

And I would think that those bikes don't have as much pressure.

 

Sometimes if you tap them with a crescent wrench handle they start working again. But sometimes not.


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I had a similar issue with hydraulic ones so I switched to a mechanical. No issues now.

 

I mount them vertically, but with the terminals pointing down - I can't see how mounting them the other way up isn't asking for a trapped air pocket, albeit very small. Whenever I've had to replace failed units I've used late model Harley D items and haven't had one of those fail on me yet. Never ran them through a relay but I will do in future - makes sense to me.

 

I gave up replacing them. This week I installed a mechanical one.
Search other threads on here, general consensus is go with mechanical.
First time I've heard of the harley type, maybe worth a try.

 

Harley uses Dot5 fluid , this may explain why they are lasting longer , maybe not

 

Had many Harleys in the pre Dot5 era, and never had a failure!

 

Ford mounted them horizontal on the front of the master under the hood. Maybe use a real Ford switch.

 

I got a pressure switch with my SSBC proportioning valve... leaked after the system was bled. Replaced with a Napa part, so far so good. I ran old Fords for years. If I replaced a master, I put in a new switch. Never had one fail.

 

if you are doing a new system and using one, install aiming down so no place to trap an air pocket

 

another advantage of the mechanical switch is that the brake lights come on sooner if properly adjusted.

 

Ford used these switches to shut off the cruise control on most 80's and 90's cars and trucks. The problem is that they leaked. They were bolted into the bottom of the master cylinder on the end. What would happen is the fluid would slowly make its way into the connector and then cause serious problems, leading Ford to recall the cars and add a fuse inline to prevent fires. However, the reason I bring this up, is that even with the switches leaking, the only time the circuit would fail is after serious melting had occurred and either burned the wires or blown the fuse. We never had problems where the switch would stop performing it's intended pressure related function.

Ford has since updated the switch and I wouldn't hesitate to use one as far as reliability goes. They always worked, but being as how they're for a modern car, they have a molded plug on the back for a harness connector. You can either get the connector from ford or you can insert female spade connectors over the lugs inside the connector.

Otherwise, from my experience, Harley Davidson factory brake switches are both reliable and affordable. I'm still running the originals on both of my 1977 FLH's and they work great. Good luck with your problem.

 

We had a problem with a hot rod and regularly failing brake pressure switches, decided to fit a relay in the circuit to the pressure switch and the problem went away.

 

I had to replace the one on my shovel when I first got it. They are cheap but seldom need replacing.

I have run mechanical and hydraulic switches in cars and replaced more mechanical switches than I have hydraulic switches. Unless I have given it away I have one that I took out of a '53 Stude a couple of years ago that still tested and worked fine, the master was shot but the brake switch was still hangin' in there. LOL

 

More than you want to know:
http://www.sw-em.com/hydraulic brake light switches notes.htm

 

When I put disc brakes on the front of wife's 40 Pontiac coupe, I ended up putting a mechanical switch on because it stopped so good the pressure did not activate the hydraulic one fast enough. If you stopped fast it would work but not on normal braking. Gary

 

You don't have it mounted on the wrong side of a residual pressure valve do you?

 

yep this is how I lost one of my O/T lincolns the CC switch shorted out and brake fluid is flammable , the switch to stay away from is the old 2 pin orange top unit , the new designed one uses a special plug ( it encases the whole top of the switch ) and is black . airtex sells the whole kit , sometimes you can find the Ford Revised kit with the switch , pigtail with fuse , on sale on e pay . but rock auto carries the revision switch .

this is the old switch if you have one replace it

with any of these I would use a intermediate relay so the amperage doesn't go across the points inside and get hot . or use the heavier duty mechanical arm switch

 

Yep, road tested mine today,
Can't believe how much quicker they light up, so therefore more reaction time for the driver behind you..... resulting in a signifiantly smaller dent in your pride and joy.......

 

Timely thread! Working on a brake light issue on my '60 Studebaker Lark. The hydraulic pressure switch seems to sometimes continue to pass current when brakes are released. Tapping the brake pedal may, or may not, turn off the brake lights. Bought a switch last night from O'Reillys. We'll see if that works any better.

Ray

 

I set up my Ford so I can go with a pedal-mounted switch very easily. Have a '73 Ford LTD switch picked out. I may just go ahead and buy the switch and mount it now.

 

They do when some idiot makes a left in front of you........D

 

Brake fluid is flammable?!?!?! Don't think so.

 

Sure it is., not like gasoline, but spritzed on a hot exhaust manifold, like from a pinhole leak, it can ignite.

 

read the msds ,
http://ebpaving.com/wp-content/uploads/2013/09/Brake-fluid-DOT-3.pdf its point is about 30-50 * higher than its boiling point ( 250 *) and a electrical short is more than that , seen the remains of a bulk plant that blew up when the vapor ignitied and burned down due to someone leaving a steam heater on a tank of the stuff . not auto ignition but the vapor ignitied and the hot liquid will burn .
actually I should have phrased it as "combustable" if you want to get technical about it .

all I know was FoMoCo said the cause of the fire in my lincoln was from the switch shorting out due to a design flaw on there part ( power to switch on all time and not fused instead of being a KO circuit ) .the remains of the orange cap with the wire was blown clean of the switch assy .

 

I have mine mounted right off the master cylinder. Came from Orielly's. Sometimes it sticks, sometimes it doesn't. May just switch to mechanical.