View Full Version : Bonded Brake Shoes, DOT 5 Brake Fluid, and Light Switches

04-30-2018, 04:41 PM
I just returned from "Brake and Equipment" in MPLS. where I had to get some bubble flare brake lines and DOT 4 brake fluid for my Olds. I asked about the temp to remove bonded brake shoes, and Al said they use about 900 degrees to burn off the old shoes, and 400 degrees to set the bonding on new shoes. He said they do all the shoes for Little Dearborn, and never had a complaint.
I'll still keep using riveted shoes for my antique cars though.
Back in the 70's my Scorpion snowmobile needed new disc pads, so I cut some car pads to size and used JB Weld to bond the pad to the steel plates. It worked fine.

I mentioned that DOT 5 brake fluid took out the new brake switch when I bought my 50 Champion, so I installed a new switch as soon as I brought the car home. It lasted just short of 2 years and went bad also, but NAPA has a 2 year warranty, so they gave me a new one. Al said he didn't think DOT 5 caused the brake switch problem, but I'll reserve judgment until I see how long this second switch lasts.

04-30-2018, 08:31 PM
I heard that Harley Davidson has a brake light switch that is silicone resistant , But I just put a little regular brake fluid in the switch before installing it and it seems to extend their life , I guess it acts like a barrier , Ed

04-30-2018, 08:34 PM
My brake switch went out in less than one year, and so I bought a new switch from NAPA. When I took the switch out of the box there was a piece of paper in the box that said switch does not work with silicone brake fluid. I was surprised. So that could because they saw a lot of warranty claims.


04-30-2018, 08:52 PM
The best Stop Light Switch is an Electric Normally Open switch on on the Brake Pedal Lever under the floor, for under the floor Master Cylinders, or under the Dash on the Suspended Pedal Type on Avantis and '61 to '66 Larks and Lark Types. :)

A few owners have reported the Harley Davidson Switches also fail in time.

The Current Production Hydraulic Switches from Mexico, do not seem to hold up all that well with DOT 3 or 4 either. :(

04-30-2018, 09:38 PM
As StudeRich said I found the Harley switches to fail as well. When I first switched to them they seemed to old up pretty well. A few years ago the began to fail on a regular basis on both my Champ and Cruiser. I have gone to the type of switch that StudeRich suggested.

05-01-2018, 02:20 AM
The brake light switch on my Harley (which came with DOT5 fluid) is still working fine after 22 years. The pressure switches in my other bikes that came with DOT3 and I changed to DOT5 decades ago are also still working fine, some are 39 years old.

I'm wondering if it's not what fluid you're running but perhaps the line pressure is just too high for the pressure switch to last very long.

I've used pressure switches in several 4 wheel disk systems I've built and the only problem I've encountered with them is under normal conditions it took less pedal to stop the car than to turn on the switch, so I added mechanical switches to those (very light cars). The pressure switches worked fine when driving hard.

Couid be the switches available now are just crap, like everything else made in the last few years I've had to replace earlier than I should have had to. It's taken a while, but, I'm begining to learn, plan to replace it on your dime in 13 months once the one year warrenty expires, or buy the extended warrenty and let them replace it. They aren't making stuff like they use to anymore!

05-01-2018, 03:21 AM
I’ve had silicon fluid & regular switches for 20yrs. No problems as yet !

05-01-2018, 07:14 AM
When my NAPA switch failed at just under 2 years, it would still come on, but only with very heavy brake pressure. When I first installed it I only had to use very light foot pressure. I agree with Rich that the mechanical switch would have been a better idea, and it would give the added benefit of turning the brake lights on sooner.

05-01-2018, 07:35 AM
buy NOS/NORS from our vendors or Then & Now (confirm) for Dot 3 apps.

05-01-2018, 10:36 AM
The nice thing about these older cars with an ammeter is before starting the engine, all you have to do is watch the ammeter while you step on the brake pedal to check the switch. So far my second new switch is working fine with DOT 5, but the 2 year warranty isn't up yet.

05-01-2018, 08:37 PM

05-02-2018, 03:47 PM
Long ago I converted all my DOT 5 equipped vehicles to mechanical switches... no more longevity problems.