Hydraulic brake pressure switch not working

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Model T Ford Forum: Forum 2014: Hydraulic brake pressure switch not working
Top of pagePrevious messageNext messageBottom of page Link to this message  By Willard Revaz on Monday, August 11, 2014 - 07:59 pm:

The pressure brake light switch on my newly installed disc brakes needs heavy pressure to activate the brake light. More than I really want to use to bring my Touring to a stop. Other than supplementing with a parallel mechanical switch, Are there other pressure switches requiring less pedal force to activate. I was told there might be an adjustable version.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Keith Gumbinger, Kenosha, WI on Monday, August 11, 2014 - 08:34 pm:

Hi Will - I suggest that you contact the vendor that you got the new disc brake from as they may have encountered this problem before.

Best wishes to you and Barbara.

Keith


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ricks - Surf City on Monday, August 11, 2014 - 09:03 pm:

I never had a problem with old VW switches.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Monday, August 11, 2014 - 09:17 pm:

Having no experience with hydraulic brakes on a Model T, I ask this question. Do you still have the internal transmission brake? If so, it is doing some of the braking, and so your hydraulic system is not being used at the same pressure you would have if it was only hydraulic. You might use the mechanical switch which every vendor supplies. That way it will operate your light whenever you push the pedal, whether hard or soft.
Norm


Top of pagePrevious messageNext messageBottom of page Link to this message  By jeff cordes on Monday, August 11, 2014 - 09:39 pm:

A typical hydraulic brake switch requires about 100psi to complete the switch. Of course that varies slightly from switch to switch.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Chester W. Lowery TN on Monday, August 11, 2014 - 10:19 pm:

William, I wasn't going to say anything but since Norman mentioned the mechanical switch I thought I would.... I installed the disc brakes on my T and decided to leave the mechanical switch because I have it adjusted to a very light touch of the pedal which I like in traffic here where I live......Tailgaters are very common no matter what you drive and now the cell phone drivers even make it worse.... Although this is not the answer to your question.....Chet


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bill in Adelaida Calif on Tuesday, August 12, 2014 - 12:49 am:

Some of the modern replacement hydraulic switches are problematic in this area. I followed a friends 39 Mercury last year and I mentioned that the brake lights were only coming on when he was braking heavily. He replied that he was having a problem with the new switches not activating under moderate pressure and he had changed the one on his car twice in 3 months.
They may look the same but they don't work the same.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Rick Goelz-Knoxville,TN on Tuesday, August 12, 2014 - 10:15 am:

Willard, i had a problem with one of my cars and called TTP and they gave me the NAPA part number SL134SB it was not expensive, i carry a spare so i will never need one again.

Rick


Top of pagePrevious messageNext messageBottom of page Link to this message  By Charlie B actually in Toms River N.J. on Tuesday, August 12, 2014 - 10:26 am:

Yeah, it's the switch. Especially if your brakes are working normally. I have no idea about how you'd find one that has a lower operating pressure though.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Charlie B actually in Toms River N.J. on Tuesday, August 12, 2014 - 10:27 am:

Contacting the vendor as suggested is a good start. I'll lay you $5 he's heard about it.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth from NC on Tuesday, August 12, 2014 - 11:07 am:

I like my mechanical switch from Fun Projects anyway because then you can touch the brake pedal and light up your brake lights without actually using your brakes yet - I do a lot of my decelerating by putting my spark and throttle all the way up. It doesn't slow the car down quite as much as stepping on the brakes but it's enough that I've almost been rear-ended: the guy pulled up beside me and said "Hey I think your brake lights are out, you slowed WAY down but they never came on." I realized it was because of how I normally drive. So now I touch the brake pedal to light up the brake lights while using the throttle and spark to slow down. People realize that I'm slowing down and I still have the actual brakes left to bring me to a stop. Just my 2 cents, YMMV.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Aaron Griffey, Hayward Ca. on Tuesday, August 12, 2014 - 11:56 am:

DOT 5 brake fluid will mess up a new brake switch so it will take too much pressure to work right.
I only use '50 Chev mechanical switches.
But to replace your hydraulic switch you need to get one for a Harley Davidson motorcycle. They will do the job.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Willard Revaz on Tuesday, August 12, 2014 - 12:46 pm:

Thanks to all who replied with many suggestions. My pressure switch is most likely from a modern car set up which uses power braking, thus more pressure is available to activate. I too, slow before applying the brake but am careful to observe who is following too closely. A quick tap on a brake light will signify your intentions graphically, which most drivers need today rather than following at a safe distance. If I cannot get a H-D switch to work with just a touch, I will go with a reliable mechanical switch.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Charlie B actually in Toms River N.J. on Tuesday, August 12, 2014 - 03:45 pm:

I doubt you'll have to go that far. Myself, if I had a purchased hyd. system I'd want it to work as advertised. That being said if you simply must go mechanical don't fail to get the Fun Projects Brake Light Switch Kit. Worth every penny. it's nice to buy something that actually works!


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