Mechanical Brake Light Switch

[Sledge]

Not pretty, but if you are thinking about replacing your hydraulic pressure brake light switch with a mechanical switch, here's one way to do it. Total cost less than $30. Peace of mind: priceless. Uses Brake Switch Plus #L08 from Watson's Streetworks. I am not an employee of Watson's, just a customer. I'm also not a pro photographer (as you will see).

Respond to this thread with your e-mail address and I'll send you some .jpg files and a two-slide Powerpoint file with directions. Let me know if you can't use Powerpoint files, I'll send the slides as jpg's instead.

[SantaFe66]

I have a problem with my pressure switch and want to replace it with something more reliable that doesn't require a messy job to replace. Can you send me the info you mention?

Would appreciate it much.

Paul

[FUNFER2]

I have a question about the brake switch. I have a Lone Star, and my switch is in line, on the brake line, and also has a two pin electrical harness. So, is that hydraulic or mechanical ? My brake lights went out two weeks ago.
(Think I'll need jpeg)

Thanks,
Kevin

[flwolfman]

The two pin inline brake switch is the way Ford used to do their brake line switch. It is hydraulic in that the brake fluid pressure activates the contact and connects the switch. Most modern cars use an mechanically operated electric brake light switch. You push the peddle down and the switch is activated. Look around the brake peddle under the dash in a modern car, you will see it. I would be interested in seeing what you have done. Thanks, Jim

[FUNFER2]

Hey Jim, yes most modern cars have the switch in back of the brake pedal and makes for easier adjustment and replacement. On my cobra, it's plumbed in the brake line so it is a combination mechanical/hydraulic. This will be the second time in four years with only say, 4,000 miles on the car. I'm looking for a better option or brand.

[round_midnight]

Oddly enough, I went the other way and replaced the cheesy BDR mechanical switch with a hydraulic one. It works fine, but I am thinking of putting a mechanical one in parallel, so I would like to have the info. Send it to skipa@pacbell.net. Please put the word Backdraft in the subject so I don't delete it as spam. Thanks.

[badrich]

Sledge: I haven't had a my problems with my hydraulic switch, but I like the idea of a mechanical backup. Would you please send your info to bigrich1@mac.com? Thanks, Rich.

[SkipB]

round midnight,

Boy am I confused. When I first got my car the brake lights didn't work, so Armond and I got a new switch from a Volkswagen and it worked great. But, I thought it was a hydraulic switch operated off the front of the brake master cylinder/booster. All I remember is getting brake fluid all over my hands while we switched it. Maybe later cars like yours went to a mechanical switch?

SkipB

[Cashburn]

There was a run of mechanical switches that resulted in a return to hydraulic switches that proved more effective and consistent.

[MrMagoo]

My hydraulic switch has not failed, but I have to jam on the brakes to get the lights to go on. Everyone is always saying to me that my brake lights are out.

Is there a way to adjust it, or are the contacts just worn? Any ideas?

[SantaFe66]

I just replaced my hydraulic switch ($8.50 at NAPA) because I had to jam too hard to get the brake lights on too. Works much better now. The contacts were probably a little corroded or the switch was just old. There is no adjustment for these switches. They work or they don't. For the cost, I'd just replace it and see if it's better.

This is a real easy replacement. Just unscrew the old one and screw in the new one. Pipe threads will need teflon tape, terminals don't care which one is attached to which. Very little fluid will leak as long as nobody hits the brakes while you change.

Paul

[MrMagoo]

Thanks for the info SantaFe66. I'll do that. Any of you BDR guys know where the switch is? Near the master cylinder I presume. Is it a BMW part?

Thanks.

[SantaFe66]

Here's an image from Summit:

[round_midnight]

The switch I used looks exactly like the one in SantaFe66's picture. I got mine at my local Kragen Auto Parts for under $10. The big expense was the double flaring tool that's needed to flare the brake lines, and I had to go to several places to find the right adapters and fittings. It's important to make sure that there is no air in it when you install it (fill it with fluid before installation and install it in such a way that the open end points up) because trapped air will probably not bleed out. That may be the reason why some of them don't come on very well.

My understanding is that people were complaining about the hydraulic switches, so the importer started putting mechanical switches in after the cars were in the US, but I'm not completely sure of that. If they have gone back to hydraulic switches, I don't know anything about it.

The problem with the mechanical switch was that it is a normally open pull-type switch that is connected to the brake pedal with a spring. The switch was very cheaply made, and in my case, it would hang up and the force from the spring pulling it wasn't enough to make the contact. I messed around with it a couple of times to make it operate more smoothly, but it finally disintegrated. The switches that most manufacturers use are normally closed push-type switches that are mounted on a bracket so that the plunger on the switch is in contact with the pedal arm. Unfortunately there is no suitable place to mount that kind of switch on the BDR without making a custom bracket, and I think whoever installed the switches didn't want to go to that much trouble.

Hope this helps clarify things a bit.

[Scott Hatcher]

Sledge,
Please send me the photos. My e-mail is shatcher.hcc@earthlink.net. I have the mechanical unit located on the master cylinder and have replaced it and there is no difference. I have the same issue as MrMagoo ..... everyone tells me my brake lights don't work. Please send as jpg files. Thank you.

Scott

[Sledge]

Paul, I need your e-mail address.

Skip A, Rich, and Scott, it is on the way to your e-mail addresses. Please let me know if it doesn't come through.

Sorry folks I've been out of town for a while.

[round_midnight]

Thanks for the e-mail Sledge. I like the idea of mounting the switch to the fiberglass above the pedals. Hadn't thought of that.

[Gatorac]

Email the pics to me. I will put them in my gallery and post them on this thread.

gatorac(at)tampabay.rr.com

[Sledge]

Jim:

Check your e-mail

Cheers!

[Gatorac]