silicone brake fluid proof brake light switch

[Sal]

The silicone brake fluid I use in my early Ford ruined the original stop light switch. Some one said Harley Davidson has a switch that will go on the master cylinder that holds up to silicone brake fluid. Does anyone know the H-D part number for it?

[flathead48]

Sal, I have been using the HD for years, can't remember the part number but bring the Ford switch in and they will match it. If I remember the ends on your wires will have to be changed for the HD switch. Regards, Rick

[Sal]

Thank you for the information.

[38 coupe]

How did the stop light switch fail? Quit switching, start leaking, plugged up with gunk? Several of the local guys are running silicone fluid and I'd like to know what to look for.

Thanks!

[V8COOPMAN]

Originally Posted by Sal

The silicone brake fluid I use in my early Ford ruined the original stop light switch. Some one said Harley Davidson has a switch that will go on the master cylinder that holds up to silicone brake fluid. Does anyone know the H-D part number for it?

Suggestion below! DD

Ron Francis sells a silicone compatible switch that has been mentioned here several times.

http://www.ronfrancis.com/prodinfo.asp?number=SW%2D32



Item Number: SW-32Unit Price: $28.95In Stock

[ken tx]

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H D brake light switch #72023-51C made in USA.

[V8COOPMAN]

Originally Posted by ken tx

H D brake light switch #72023-51C made in USA.

The info I've read suggests that 72023-51C has been superceded by a -51D in 2006 because of this very issue......MY understanding only. DD

[TJ]

I always use the mechanical lever switch that was used on the older Chev. pickups. Never had a problem with them.

[alanwoodieman]

I have had two of Ron Francis's swithes fail, so far none of the HD switches have failed? when they failed the silicon got thru the seperation and hydro locked making the switch not work-how do I know this, I drilled on of the switches and fluid ran out, after letting the fluid out the switch worked

[Sal]

I want to thank all of you who replied.

[37 Coupe]

Originally Posted by alanwoodieman

I have had two of Ron Francis's swithes fail, so far none of the HD switches have failed? when they failed the silicon got thru the seperation and hydro locked making the switch not work-how do I know this, I drilled on of the switches and fluid ran out, after letting the fluid out the switch worked

My situation exactly the opposite two failed Harley D switches and been running the Ron Francis switch successfully last 5 years. Odd. Make sure the ron Francis switch is the silicon compatible one.

[RandyZ]

I went through 2 or 3 of those Harley switches as well. Soon as they leak a little, it contaminates the contacts. I finally gave up and rigged a mechanical switch in front of the brake linkage. Problem solved!

[Binx]

So the moral to this thread's story like others similar is DOT-5 silicone brake fluid sucks and don't use it in your old vehicle. Keep using the lesser DOT spec and change it periodically like you do your other fluids. Got it.

Lonnie

[Gary in La.]

I've had silicon brake fluid in my '46 for 25 + years and have had no issues. Replaced brake switch one time due to being inop. I use NOS Delco 4766 switches. Have'nt used the new replacements.

[Tony, NY]

I've had silicone brake fluid and same switch for over 12 yrs and no problems. Can't remember where I got the switch. Probably NAPA.

[TagMan]

I bought an original '37 Chevy in 1993, flushed the system and installed Silicone brake fluid. I never changed the brake light switch at that time or since. I drain & install new DOT5 fluid about every 7-years or so, changed brake shoes and one drum in the interim, but I still have the same brake light switch installed.

I have no idea if it's the one that came from the factory, but I do know it was old when I got the car in '93 and it's never missed a beat in 21-years and thousands of miles of driving.

[37 Coupe]

Originally Posted by Binx

So the moral to this thread's story like others similar is DOT-5 silicone brake fluid sucks and don't use it in your old vehicle. Keep using the lesser DOT spec and change it periodically like you do your other fluids. Got it.

Lonnie

Well you make it sound easy to eliminate the brake switch problem but I think silicon brake fluid is well worth the glitch. Try to make a long story short but I know it won't happen. Forty years ago when I had my block garage shop built and I didn't get it properly insulated or heated at first I had a lot of issues with moisture especially during "January thaws". Actually the "46 Ford coupe I had at the time had issues sweating in the damp condensation when high and low temps meet. I had problems with every wheel cylinder sticking in a very short period of time,one time I burnt paint or bubbled it off the wheel itself around wheel stripes before I got back home. Went through a lot of brake line cleaning,reworking cylinders etc. Really didn't know much about silicon brake fluid back then and never used it on the 46 but I did on the next project a '53 F-100.By then in the early eighties some info like in Old Cars Weekly addressed its merits. Just recently the man who bought the '53 from me in 1990 called and asked about the electric fuel pump that went bad. I told him it was probably the ethanol gas that probably ate it up,surprised,shocked actually when he told me the gas in the tank was what I had put in,he never drove or even started the engine. So fuel problem issue is a no brainer.His pole barn was uninsulated or heated truck had other issues it sounds like,rodents etc,what a shame. Finally the moral to my story, brakes he said seems to be fine,nothing stuck as rolled truck outside. Silicon brake fluid I installed in the eighties,not one cylinder (piston) stuck. I doubt if the original type switch works as at that time I wouldn't have had an option. I will accept the once in awhile failure well over a complete brake rework. Again the only failures I have had were a couple original switches and two HD ones.

[FlatheadTed]

We are going through this same problem ,wheel cylinders were sleeved in stainless new cups but the silicone fluid is leaking past ?? We think to course of a honing pattern .Ted

[Ian NZ]

I had a lot of problems with the brake cylinders, I had to even replace the master cylinder as the bore was so rusty with using the ordinary brake fluid in our 1947 Ford coupe in the 1970's, as the car was not used regularly. So I replaced the brake fluid with silicone fluid and have had no trouble since. I also have had trouble with the brake light switches and since I have replaced it with a Harley Davidson switch I have had no more problems. What I have found since our coupe is not used very often every month or two it is best to give the brake pedal a pump up to bring the pedal up and to make sure every thing is ok.

[JSeery]

Originally Posted by FlatheadTed

We are going through this same problem ,wheel cylinders were sleeved in stainless new cups but the silicone fluid is leaking past ?? We think to course of a honing pattern .Ted

Bad cups? Have you considered a residual valve to maintain some pressure on the wheel cylinders?

[Ian NZ]

Originally Posted by JSeery

Bad cups? Have you considered a residual valve to maintain some pressure on the wheel cylinders?

Do you think you really need to run a 2-lb residual valve in the Ford V8 hydraulic brake systems, i thought that was already incorporated in the V8 master cylinder.

[JSeery]

Originally Posted by Ian NZ

Do you think you really need to run a 2-lb residual valve in the Ford V8 hydraulic brake systems, i thought that was already incorporated in the V8 master cylinder.

Depends on the master cylinder, some have them and some do not. Not having them can be a source of wheel cylinder leakage.

[FlatheadTed]

Thanks for the tip ,The duel M cylinder is a modern one so I would think maybe there is a valve in the out let only , ? disk and drum M/C

Originally Posted by JSeery

Bad cups? Have you considered a residual valve to maintain some pressure on the wheel cylinders?

[JSeery]

Maybe, maybe not, depends on how the system was set up. As an example might have had a combination valve that served that function.

[Automotive Stud]

Originally Posted by V8COOPMAN

Suggestion below! DD

Ron Francis sells a silicone compatible switch that has been mentioned here several times.

http://www.ronfrancis.com/prodinfo.asp?number=SW%2D32



Item Number: SW-32Unit Price: $28.95In Stock

I know this is an old thread but I'm running dot 5 and I'm on my second one of these switches in two years. Does anyone really offer a true dot 5 compatible switch?

[JSeery]

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I thought the Harley switches were, but not positive.

Update: Genuine Harley Davidson, part # 72023-51D

OK, second update! This was already covered in detail earlier in the thread!!!!

[38bill]

I was running the Harley switch and it failed too. I ended up switching back to DOT3 when I did a total rebuild of the brake system.

[nelsb01]

So, does anyone have an answer? I was over reading the Harley boys forum and they are not buying HD switches because they are not made by HD and fail. They suggested Accel 181101.
Anyone using that one? I am gettting tired of the 9 month and replace $9.99 ones that I now buy 10 at a time.

[tiger.1000]

I agree with BINX. Don't use silicone fluid. Stay with DOT 3 and perhaps every two years or so bleed the system and renew the fluid. £5 will buy you a brake fluid tester which will determine if there's any water in the system and it's water that's the killer.

[richard crow]

i use the chevy lever switch the reason is they can be adjusted to be more senative the hydl switch requires pressure. the lever switch puts the lights on sooner giving the car behined you more time to know your stopping .plus i use dot five if your car sits it,s the best way to go

[deuce lover]

I'm with Richard.To me the hydraulic ones are a waste of time.The lever switch is the only way to go.Its foolproof. Just touch the pedal slightly and the brake lights come on.Used it on last 5 cars I built.Speedway has them pretty cheap.


Here it is $6.99 at Speedway



https://www.speedwaymotors.com/Speed...itch,1972.html

[TJ]

I've used the lever switches for years. Never had one fail so far. It's a simple solution when using dot 5 fluid. Depending on where you buy the switch they cost between $10-15 and it's a one time purchase.

[Tony, NY]

Yeah. Give up on the hydraulic switch and go to one off of the pedal, as said.
https://www.amazon.com/Allstar-Perfo.../dp/B003C01FFY

[Ronnieroadster]

Years ago when i had the same failure with silicone fluid and the original style brake light switch i spent time trying to figure out why they fail. I found the seal in the brake light switch was the problem its not compatible with silicone. Once the seal fails the two contacts inside the switch are now flooded with the silicone fluid. The fluid now is causing a high resistance to make the contacts work correctly if i pressed really hard on the pedal the brake lights would work. Any heavy duty brake light switch would still have the same problem there called heavy duty to handle more load not a change in brake fluid type. My solution is exactly as others have written a mechanical brake light switch problem solved.
Ronnieroadster

[d.conrad]

HD switch is smaller and cheaper than Ron's ( about half the price).. Works great and I'm told HD uses silicone brake fluid.

[alanwoodieman]

I have a HD switch on my wagon for almost 30 years! bought a ron francis switch for my 41 truck and it lasted about 10 years. silicon molecules are so small they sneak past the disc in the switch effectively neutralizing the switch

[Yoyodyne]

I don't think it's the silicone fluid making them fail. I started having those switches fail 40+ years ago before there was silicone fluid. old ones lasted for years, newer ones failed in a year or so with DOT3. American made, etc.

[vanhammer]

Originally Posted by alanwoodieman

I have had two of Ron Francis's swithes fail, so far none of the HD switches have failed? when they failed the silicon got thru the seperation and hydro locked making the switch not work-how do I know this, I drilled on of the switches and fluid ran out, after letting the fluid out the switch worked

I know this post is old, but I got one of the Ron Francis switches in 2016. Did not install it for a year or two and I have not even put 100 miles on the car. I dont have any brake lights now unless I press very hard on the pedal. I am running less than 3 amps through the switch. Warranty is out of course, but they would not even knock off a small percentage to get another one. I think I will go with the HD one.

[Automotive Stud]

Yeah I've switched to the lever switches on all of my cars after having two Ron Francis switches fail. Never tried the Harley but I was tired of messing with it. I only had one lever style switch eventually wear out and it was 20 years old.