Mechanical brake light switch conversion kit available?

[movin]

Please say somebody does make a conversion kit. The hydraulic switches are problematic and a pain to access when changing. Wouldn't it be nice to just by-pass them with a mechanical, adjustable switch?

[911pcars]

Good idea. Besides not being adjustable, the pressure switches don't seem to last very long. I don't have it on a file, but maybe somebody will post an exploded illustration from an early 911 pedal assembly. They use a simple mechanical switch working off of the brake pedal actuation (master cylinder) rod.

Sherwood
http://members.rennlist.org/911pcars

[304065]

??? SWB had a hydraulic switch then they went to mechanical with the dual circuit brakes.

The early hydraulic switch is also available from VW inexpensively. The Porsche mechanical switch is like $75. I would take the generic microswitch option.

[Christien]

The older style brake light switches are far from perfect, trust me! Yes, they're easily accessible and adjustable, but the little arm that stick out that the brake pedal shaft catches and releases to activate the brake lights is extremely fragile. In the year and a half I've had this car I've gone through 3, and they're not cheap ($75).

[911pcars]

If you're going through that many $75 switches, I'd switch to a regular microswitch - same effect, fraction of the cost. Perhaps the geometry between the actuator washer to switch arm isn't ideal? YMMV.

FWIW, one can extend switch life by replacing the regular incandescent brake light/turn signal bulbs with LED-based bulbs. There are several more LED bulb designs to choose from compared to only a year ago.

Sherwood

[Christien]

What's this microswitch? I'd definitely be interested in something a little better built than the OEM switch. Although to be truthful the ones I've broken were bought used. I finally broke down and bought a new one last summer and that one's lasted so far...

[araine901]

Originally posted by john_cramer
??? SWB had a hydraulic switch then they went to mechanical with the dual circuit brakes.

The early hydraulic switch is also available from VW inexpensively. The Porsche mechanical switch is like $75. I would take the generic microswitch option.

John,

Do you have an application for the VW one that will fit a SWB?

Thanks

Aaron

[afterburn 549]

made one from a 65 chevy Pick up (5 bucks) is mechanical ,only trouble is it works by grd rather then pwr...not to big a problem to overcome

[911pcars]

Microswitch:

http://en.wikipedia.org/wiki/Micro_switch

Sherwood

[Christien]

Ah, ok, gotcha - thanks!

Chris

[Early_S_Man]

Here is the type of heavy-duty, 15 Amp microswitch I would recommend ... same standard size from the '60s as the $15 - $20 Mil-Spec ones I have used to replace the microswitch used on the left MFI stack from '69 thru '76.

http://www.allelectronics.com/cgi-bin/item/SMS-203/700500/S.P.D.T._15_AMP_SNAP-ACTION_SWITCH_.html

[SLO-BOB]

My brake lights aren't working. I'm tracing it out now. I have no power to the sockets (pedal actuated) and the fuse and bulbs are good. I've given the brake switch a visual and it appears to function mechanically. I haven't put a voltage tester to it yet.

Can someone verify-The brake switch has an un-interupted power source (not switched by ignition and always live). Correct?

TIA.

[911pcars]

The brake circuit on your '72 is always "hot". That is, the brake switch should always have source voltage on one terminal (the other goes to the brake light circuit). First check the fuse and fuse holder (make sure there's good contact). Then use a test light (~$5) to see if voltage is available at the switch. If so, you can jumper the switch with a test lead and both brake lights should go ON. If so, the switch is NG or not closing (check adjustment).

It gets interesting after this. You should have a copy of the wiring diagram to see the voltage path and ID the brake wires, then you can narrow down where the electrons have stopped. A 12V test light is minimal for this type of troubleshooting. A multimeter is better as it indicates if you're getting 12V or maybe just 8 along with other troubleshooting info.

Pelican has some electrical diagrams you can download. Here are some more (high-res and printable).

Hope this helps,
Sherwood

[SLO-BOB]

Thanks Sherwood. The diagram helps. I have the diagram on the Haynes manual but it's hard to read. The Pdf is much easier to use.

[SLO-BOB]

Just to clarify, in the case of my car, the power to the brake switch is interupted by the ignition switch. In other words, the ignition has to be on for the brake lights to work and to get voltage at the switch.

I'm posting a new step by step thread that addresses the whole topic rather than just the switch.

brake light fix thread

If this has been done already, please let me know so I don't waste my time or Pelican's bandwidth.

[Christien]

Bob, as I understand it Sherwood is right in the the brake lights should always light up when activated, no matter what position the ignition's in. However, never underestimate the stupidity of POs On my car the brake lights don't light up when activated unless the key is in the run position (fuel pump and CD running). I pulled the wires off the switch, ran a short piece of wire to connect the 2, then turned the key and the brake lights came on, so I knew I had a problem with the switch, rather than the wiring/fuse/bulbs/sockets.

edit: just read your new thread, and it seems you already knew this...

[SLO-BOB]

Yeah-I should have been more clear. My apologies to Sherwood. I'm sure Sherwood is right-for every car other than mine! The po (not sure which one) has a lot of stuff cobb-wired. The brake/running lights were also on the wrong terminals which caused the running light to look like the brakes were always on. I tested everything with the meter to identify their function and landed them accordingly. Now, because the houisings are so bad, I've decided to replace them. Thank God a local guy is parting out a car. Otherwise I would be out $700 for housings!