locoboy
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| posted on 1/8/07 at 06:37 AM |
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brake pressure switch
I have installed a brake pressure switch to activate my brake lights and having filled the system and bled it through last tnight it seems the brake
pedal needs to travel a fair way in order to activate the lights.
The switch is in the rear circuit, in hind sight i would have placed it just after the MC at the front.
Its all wired in and im NOT re wiring it!
can i bleed the switch by unscrewing it whilst the ezebleed is attached to the car?
Is there a chance that there is air in the T piece that holds the switch?
ATB
Locoboy
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RazMan
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| posted on 1/8/07 at 07:39 AM |
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The switch should be perfectly ok in the rear circuit. Long pedal travel might not mean that air is in the system - does the travel reduce after a few
pumps? I doubt that air can get trapped in the switch either.
I would suggest a manual bleed (Eezibleed always gives me problems) and see if the pedal improves - the switch should not change things imo.
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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saigonij
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| posted on 1/8/07 at 08:02 AM |
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i noticed that on my first car, it took about 1cm ro more of pedal travel before the switch turned the lights on, so i was thinking of using a switch
on teh pedal this time
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iank
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| posted on 1/8/07 at 08:14 AM |
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Which way up is the switch. Can a bubble be trapped in the t-piece? Logically they should be installed with the wire pointing down.
Since they work on pressure the pedal has to have moved enough to start braking, a switch on the pedal can trigger before the master cylinder has even
started working.
It's only a problem with feathering the pedal, used as normal the brake lights will be fine.
--
Never argue with an idiot. They drag you down to their level, then beat you with experience.
Anonymous
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nick205
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| posted on 1/8/07 at 08:14 AM |
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I had the same issue with a hydraulic switch mounted ina 4 way T piece in the rear circuit. The switch was in the top of the T piece (i.e. highest
point) and bleeding it did improve things a bit, but not as much as I'd like.
I too am not about to move it, but am considering wiring in an electrical switch to work off the brake pedal (as per most tin tops).
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MikeR
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| posted on 1/8/07 at 08:14 AM |
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there are two types of switch (well, one type but activated at two different pressures).
Can't rememebr the figures but it should be marked on the switch, see if you can get one with a lower activation pressure.
Or at least that is what i was told at a show a couple of years ago on a stand.
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britishtrident
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| posted on 1/8/07 at 09:53 AM |
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Brake adjustment ----rear self-adjusters need run up
Usual cautions about leaving enough slack in the hanbrake cables for the adjuster to work.
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gingerprince
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| posted on 1/8/07 at 10:18 AM |
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quote:
Originally posted by MikeR
there are two types of switch (well, one type but activated at two different pressures).
Can't rememebr the figures but it should be marked on the switch, see if you can get one with a lower activation pressure.
Or at least that is what i was told at a show a couple of years ago on a stand.
If anyone can provide part numbers for the 2 different pressure types I'd be interested. My switch is in the front circuit but only comes on
under moderate-hard braking, not under gentle braking. I have bled (manually) the switch to no avail, so I'm hoping I have the higher pressure
switch.
Of course I could put a switch on the pedal, but it seems to me a pressure switch operating properly is a better solution.
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RazMan
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| posted on 1/8/07 at 10:59 AM |
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My one came from CBS and is quite sensitive - comes on with a light dab.
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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BenB
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| posted on 1/8/07 at 02:04 PM |
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The problem is usually a combination of what has been mentioned- a relatively high pressure needed to activate the switch combined with most switches
being plumbed in so the wires point up. This allows an air bubble to sit under the switch, cushioning the action....
I've always thought that accelerometer activated brake lights were a better idea. After all, engine braking alone can catch out the person
behind you if they're not used to following such a light car......
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locoboy
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| posted on 1/8/07 at 03:10 PM |
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Good thread and suggestions fellas,
Is this likely to cause an SVA fail or not?
Technically my brake lights DO work.
ATB
Locoboy
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Angel Acevedo
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| posted on 1/8/07 at 06:43 PM |
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Pedal actuated switch is better IMHO due to the fact that you can "Show" your braking intentions before the actual braking action....
Don`t know about racing, but you could use this as advantage to make the car behind brake sooner....
LOL...
I don`t think you can do this more than a couple of times before it gets noticed....
Beware of what you wish.. for it may come true....
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bobster
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| posted on 1/8/07 at 07:32 PM |
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there was a similar thread on the dax forum a few months back. the general consensus there was that a pedal mounted switch was best otherwise mount
the pressure switch wires hanging down as has already
been mentioned.
http://forum.rushowners.co.uk/phpBB2/viewtopic.php?t=1843
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