Damned BRAKE LIGHT SWITCH sucks in a dangerous way. Any better solution???

[xlr8]

I got mine from the local auto parts store a couple of years ago. The bulb comparo site discusses vendors:

"Vendors?

This particular bulb is OEM for many parts vendors like Honda, Sylvania, G.E. Lighting and are easily found at almost all automotive parts stores (PepBoys, Advance Auto, NAPA, AutoZone, etc.).

They will be in the package labeled #3496. It may be in a GE or Sylvania blister package but the bulb(s) on the inside the package will be stamped "STANLEY" and will have a SILVER base. These are made by Stanley Electric Co., LTD., a subsidary of Yokahoma Electric Corp. of Japan.

UPDATE: In recent years; GE and Sylvania blister pkg's have contained bulbs now mfg'd in TAIWAN and are silver base. They do not have the manufacturer name of Stanley stamped on the bulb, nor is the wattage or CP indicated there either. Only the #3496 number. I was informed by a Sylvania sales representative that it is indeed a true identical bulb, simply made in Taiwan and not Japan. My comment to him was, if this is indeed an identical bulb, why did Sylvania neglect to publish CP and WATTAGE spec's for this bulb on the package, like they do on all their other bayonet based automotive replacement lamp products. He had no answer to this question.

Now, K-Mart sells a Phillips #3496 but this does not have the same light output spec's and I have yet been unable to obtain a white paper on this bulb from Phillips. Since there is no CP info on the product package, I surmise its just a standard 32 CP bulb or 1157 replacement. I would not waste my money on these.

This bulb is available through Honda parts as well. The Honda part number is 34906-SL0-A01 and retail for about $5.00. You can even find these bulbs at your local WALMART store under the GE or Sylvania labels in the automotive lighting parts area.

Look at using these bulbs and the LBM-II bucket mod for Impala/Caprice to drastically increase the light power output of your rear lighting system without overloading the wiring or control switches (brake, stalkswitch, etc.). Up to 300% increase in power can be obtained on some aspects of the rear lighting. "

[terryb]

Thanks Russ. I saw the descriptions on the comparo site but for some reason thought you had just purchased your bulbs and was curious to know up-to-date info.

So back to the switch, has anyone else found that pressure bleeding fixes the issue as it did for Ken911?

[pmajka]

Jack, see the pics that are behind the wood board and up on the Brake shaft to the Master cylinder (cant kick those), also, I only disconnected 1 Hydraulic switch, so in the event of Mechanical failure, i still have the better of the 2 Wet switches.

Originally posted by Jack Olsen
Any redundant solution is a plus. And I like Andrew's switch since when it fails the lights go on, rather than a failure where the lights don't go on. If Andrew's switch could be wired in parallel with the pressure switch (so that if either failed the other still triggered the brake light), I think it would be a big improvement. Any switch down by the pedal cluster that I could cause to fail by deliberately kicking is a no-go, in my book. Over time, lots of stuff can bounce around down there.

I bought the LED/inertia switch unit a couple of years ago. I actually bought it as a brake indicator for in-car videotaping, and put it somewhere... I have no idea where it is now, and I never ended up using it.

[Formerly Steve Wilkinson]

Terry, as for pressure-bleeding fixing the problem, I bleed my brakes a couple of times a year, since I use the car mainly for DEs, and entirely change the brake fluid once a year or so. And I use a Motive power bleeder. Hasn't made any difference for me. And see my slightly earlier post re. "bleeding" the brakelight switches. That didn't help either.

[47silver]

my 75 has the old style and it does not look to difficullt to put a bracket on the cluster and the factory switch. I'll try to take some pics later.

[Formerly Steve Wilkinson]

I just ordered the '70s mechanical switch from Pelican and will make a bracket to fit it onto my '83 SC. If that's the way Weissach, or even downtown Stuttgart, decided to go back then, it's good enough for me. And at $80 per OEM switch, it better not be Brazilian.

And while I'm at it, if anybody has a few words to spare as to roughly where on the pedal cluster I should be planning to affix that bracket, advice beforehand would be appreciated.

[toolman]

You could also attach the "buttton out=on" switch to the back of the foot board to keep the wires and hardware out of the way.

[47silver]

http://www.pelicanparts.com/911/911_Parts/1974-75/7-1.JPG

check this parts diagram out. the bracket has 2 holes drilled to allow the screws to go through and tighten onto the switch. the lever on the switch moves over to contact the brake pedal

also the tech manual on rebuilding the 914 brake cluster has a explanaton and some pictures of the cluster.. the pictures are not very clear though,
on the picture the rod has a bolt and a washer that is the physical device that moves the brake lever arm.

http://www.pelicanparts.com/techarticles/Mult_pedal_cluster/Mult_pedal_cluster.htm

[Dennis Kalma]

I have had a neverending battle with my switches, I am now on my 5th set.

I have tried it all, GHerman switches, Brazilian and now VW (which are the exact same part by the way). I have worried that it is my silicone brake fluid, but I hear so many problems with other folks that I have concluded that the fluid doesn't make the difference.

I always replace the switches "in situ", the fluid leaks out, I try to fill them before I thread them in....no difference. Walter Fricke (a Rennlist friend) sliced one of my dead switches in half, and here is what he found out, and I quote:
"I did receive the defective brake light switch you kindly sent me. Tested it with an ohmmeter after figuring out which lug was the common and which the NO and NC from a wiring diagram (handy that the terminals had number labels). The NC route showed about zero ohms resistance, as it should. The NO (brake light) circuit showed, under 100 psi of air or so, a varying resistance in the 500 to 1,500 ohm range. Of course, under heavy braking the hydraulic pressure could be as much as 1000 psi, but we want our brake lights to come on with any braking, seems to me.

I cut it apart. No brake fluid inside or other evidence of failure there. I used a 20X magnifying glass. One side of the NO contact (a flat plate) had a little smudging on it at the contact line which wiped off with my finger. Don't know what that was - didn't really look like material from burned contacts. The other side of that contact - a rectangle roughly like the end of a male spade lug connector - looked like it was a bit irregular - the contact surface was maybe only 40-50% of what it should be, the rest being less smooth and a hair lower (well, probably less than a hair). Not burned or anything. I'd have thought it was enough for brake light purposes, but that was the only explanation I could see for the relatively high resistance.

Maybe a little quality control problem, or the metal stamping process which leaves an edge which is too uneven for its purpose?"

No real joy there.

I have not checked, but is there any other vehicle which uses hydraulic pressure to activate the brake lights? According to Fred Puhn's book "Brake Handbook", using hydraulic pressure to activate the lights is a fairly typical way to do it and he shows a few in the book. He is not big on them for racing, there is a risk of leakage, but I think things have improved in terms of parts since he wrote that book.

So all we need to find is a Japanese car that uses a hydraulic brake light switch with the same thread.....anyone want to spend an afternoon at a junk yard or parts warehouse to find out? I think there is no hope that Porsche will ever make a switch worth the powder to blow it to...wherever.

Dennis

[kide]

As for dim brake lights, you could install a third LED brake light in the air vent for 3.2 coupes and Turbos. Check this out:

(all links in Japanese but lots of photos)

http://911sc.fc2web.com/mainte060404.html
http://911sc.fc2web.com/mainte060418.html

This guy did a similar mechanical fix for the slow response of brake lights based on fluid pressure.

http://911sc.fc2web.com/mainte050716.html
http://911sc.fc2web.com/mainte060521.html

He added an LED on his steering column corresponding to the brake light, so that he knows when the brake lights are on.

http://911sc.fc2web.com/mainte050721.html

Very cool.

[Craig 930 RS]

EXCELLENT idea!

[Quicksilver]

The whole brake light arrangement on these cars has always bugged me. You have god's own brakes with dim little bulbs that come on after you press on the brakes. Not good.

A few subjects:

Bulbs...
You can use standard 1157 bulbs in the rear of these cars. The only difference between the 1157 and stock bulbs is the shape of the solder contacts. Stock is oval and an 1157 is round. It is very easy to find higher wattage halogen 1157 bulbs. They are about twice as bright. No one will miss the brake lights on my car.

LED replacements...
A while ago I saw an 1157 replacement that used a 5 watt Luxeon Star. This would be WAY brighter then the stock bulb. I haven't been able to find it again because I would like to try one. One good thing about LEDs is they turn on instantly unlike incandescent bulbs.

Bleeding the brake light switch...
Bleeding the switch won't make a difference. It won't change the pressure on the switch. The pressure in a hydraulic system is always equal through the complete system. The delay in pressure from having to push a tiny bit of fluid into the switch would be measured in milliseconds. Air in the brake system increases the required master cylinder input for a given pressure. It doesn't reduce the system pressure unless the MC bottoms out before the required pressure is reached.

Mechanical switch location...
The brake lights are supposed to give an early warning that someone is stopping. By the time you see that the car is slowing you don't really need any more brake lights. The fact that the pressure switch only comes on after the pressure is building is silly. You want EARLY warning so let's get the thing to turn on as early as possible.

You need movement to trigger a mechanical switch. The rod going up to the master cylinder doesn't move very far so it won't give a real fast reaction. Lets put the switch on the pedal where it moves at least twice as much as the brake linkage. If you look on most of your pedal switch enabled cars you will find that the switch is about twice as far away from the pedal fulcrum as the MC's linkage. This will require a little different linkage because are pedals aren't hanging under the dash. A pushrod from the pedal going under the floorboard might do the trick.

I would leave the stock switches in place and run them in parallel. For use with higher wattage bulbs I would add a relay so it doesn't toast the switches.

[xlr8]

Here is an electronic device that allows you to use your turn signal bulbs as running lights/brake lights along with your regular brake lights.

[Quicksilver]

Originally posted by kide
As for dim brake lights, you could install a third LED brake light in the air vent for 3.2 coupes and Turbos. Check this out:
(all links in Japanese but lots of photos)

http://911sc.fc2web.com/mainte060404.html
http://911sc.fc2web.com/mainte060418.html

. . .

This guys lights are a little similar to what I did with my car. I don't have any pictures of the finished product on this computer but I will see if I can find some later.

Here is a picture of the initial setup/fabrication.

I fit grommets into the ends of the slots of the air vents. The front bottom of each grommet had to be trimmed with a flat bottom to fit. I inserted all of the LEDs backwards and then soldered them all together with the load limiting resistors so it was one complete unit all the way across the rear.

The next step was to put it inside through the zipper for the sunroof. The screaming hard part was to pull then unto the grommets from the rear. I put a bit of glycerin on each LED and used a hooked piece of piano wire to put them in place.

It looked great!

... but ...

The metal around the slots is perpendicular to the rear glass. This means the LEDs are aimed downward along the line of the car. The end result is the LEDs were extremely bright after you were so close that you would have already hit the car.

In this picture from the Japan site, I see that this guy had to adjust for the angle in his setup.


I don't like the rough look of his external mounting. What I am thinking of for my next attempt is a Luxeon Star with light piping or something...

[Jack Olsen]

I'm not a big fan of the way LED lights look. But then, I'm even less of a fan of somebody plowing into my tail. So I added a third light (yes, LEDs) up high. It's invisible to me from the driver's seat, but much more visible to distracted night-time SUV drivers than just my 911R lights.

[toolman]

Jack, I like your idea with the slim LED, which is much better than the stocker that blocks your rear view. What type of light did you use and where did you get it?

[Jack Olsen]

Pelicanite UTKarmann_Ghia did it first, and he wrote out how to do it here.

[xlr8]

"Intellibrake" system

[Craig 930 RS]

Jack's idea:
http://www.brakeflasher.com/cycle.htm

I am IMPRESSED with this unit. I received mine yesterday, and ran a test on it the past hour or so. Unit can be adjusted by a slight tilt or internally bending the wire mounts for the mercury switch. Tilting the unit yielded great results - lights right up until a near-complete stop.

Internals - mercury switch:


Uncle Waldos "coke bottle glasses? These pups are BRIGHT!


Whole unit:

[Formerly Steve Wilkinson]

Outstanding! I ordered two of them a few days ago and am considering something like industrial-strength Velcroing them to the bottom of the whaletail rubber lip, one on each side.

Of course, I may then have to go the full lowrider route, get some Pesco pumps and make that SC jump.