TheSamba.com :: View topic

Sat Sep 17, 2011 1:40 am

I've narrowed down my brake lights issue to bad brake light switch thanks to previous posts. My question is, how involved is it to actually change out the brake switch. Will removing the bad switch spill brake fluid all over the place. Or is it as simple as unscrewing the old switch and replacing without creating a mess or having to bleed the system.

This is my first post on my 1971 super beetle that I got a month ago. I am totally unfamiliar to cars let alone working on them. I am learning a lot and enjoying the car. I am thankful for all the information here and to all the folks willing to help each other out.

Sat Sep 17, 2011 5:30 am

Yours probably takes two 3 prong switches. As long as you don't pump brake and leave it open for 5 minutes - loss will be minimum. Unscrew and screw in new. If you haven't changed your brake fluid in last 3 years --- its time for a complete change of fluid as it absorbs moisture which leads to rusty brake cylinders and boiling brake fluid. Did you check them with an ohm meter to ensure they are bad - new they are only $5 but quality is iffy. Have rag handy as brake fluid quickly removes paint.

Sat Sep 17, 2011 5:53 am

You don't have to bleed your brakes
unless the fluid is about 2 years old or older.
Another suggestion besides doing the parts swap
quickly is to pre-fill the new switches as much as possible
using drops off of a toothpick or something to dribble in some fluid.

Sat Sep 17, 2011 9:17 am

Thanks for clearing it up for me and for the added tip.

Sat Sep 17, 2011 11:57 am

I suggest bleeeding the system is opened. It's no big deal to do properly, and fresh fliud is a good thing, air is the enemy.

Tue Sep 27, 2011 7:29 pm

I changed out the brake light switches and now brake lights work. Thanks to all for the info and giving me the confidence to do the repair.

Tue Sep 27, 2011 9:46 pm

BornMexican wrote: I changed out the brake light switches and now brake lights work. Thanks to all for the info and giving me the confidence to do the repair.
nice work. did you change your brake fluid while you were in there? it must be changed every 2 years!

Wed Sep 28, 2011 9:28 am

where does this two year change come from - my fluid has been in there for over 15 years -
Jerry

Wed Sep 28, 2011 10:17 am

JerryMCarter1 wrote: where does this two year change come from - my fluid has been in there for over 15 years -
Jerry
owners manual of pretty much every car ever made, by any manufacturer. including the vw beetle. and bentley manual. and factory repair manuals. here it is in bold letters, in the manual for my '79:

http://www.thesamba.com/vw/archives/manuals/79bug/79BugPage55.jpg

i changed the brake fluid on a friend's 2005 acura the other day. six years old and it was the first brake fluid change. it came out absolutely black, filled with rust particles and bits of rubber seals. way way over due. dark fluid = damage has been done. when you change it, if your fluid doesn't come out crystal clear, then it was way overdue, and damage has been done.

brake fluid is highly hygroscopic i.e. the fluid absorbs water out of the air. the more humid your climate, the more water it absorbs. if you live in the desert, you can probably get away with much more than 2 years. if you live in a swamp, you'd better change it every year. most people live somewhere in between, hence the 2 years. but brake fluid is cheap enough and easy enough to change, i'd do it every 2 years even if I lived in the desert. it's cheap insurance. fyi our local race track requires that your brake fluid be no older than 90 days to use their facility. 90 days! it's that important.

waterlogged brake fluid rusts the entire system from the inside out. it also causes the rubber seals to rot. master cylinder seals, wheel cylinder seals, caliper piston seals, and rubber brake hoses. all of them.

Wed Sep 28, 2011 1:20 pm

Well you did not inform me anything - I was just talking reality
Millions of cars have old fluid- I was thinking some of the corrosion comes from the fluid itself eating at the metal.
I have six vehicles right now - i figure they all need to be changed

Wed Sep 28, 2011 1:41 pm

JerryMCarter1 wrote: Well you did not inform me anything - I was just talking reality
Millions of cars have old fluid- I was thinking some of the corrosion comes from the fluid itself eating at the metal.
I have six vehicles right now - i figure they all need to be changed
no. the corrosion is exclusively from water contamination. consider yourself informed now.

Wed Sep 28, 2011 2:30 pm

Well not necessarily so .-----There are two types of brake fluids, glycol bases and silicone based. Glycol based is most commonly used in racing applications. While glycol based fluid does have a tendency to retain moisture, at high temperatures it is less compressible than other types of fluids, and thus gives the driver a less spongy pedal. Racing brake fluids tend to retain moisture if left exposed to air. The moisture (water) trapped in the fluid bubbles when heated and forms small air pockets. These pockets are compressible and result in a spongy brake pedal. I find it rather annoying to believe that the inside of the braking system has any air in it to retain the moisture- a little at at the fill cap – but it only comes off very seldom and then moisture content in the air is not much. Still cannot swallow two years—this is more like a gimmick to get the customer to spend money –
Ya just never know whom or when you can learn somthins –

Jerry

Thu Sep 29, 2011 9:00 am

JerryMCarter1 wrote: Well not necessarily so .-----There are two types of brake fluids, glycol bases and silicone based. Glycol based is most commonly used in racing applications. While glycol based fluid does have a tendency to retain moisture, at high temperatures it is less compressible than other types of fluids, and thus gives the driver a less spongy pedal. Racing brake fluids tend to retain moisture if left exposed to air. The moisture (water) trapped in the fluid bubbles when heated and forms small air pockets. These pockets are compressible and result in a spongy brake pedal. I find it rather annoying to believe that the inside of the braking system has any air in it to retain the moisture- a little at at the fill cap – but it only comes off very seldom and then moisture content in the air is not much. Still cannot swallow two years—this is more like a gimmick to get the customer to spend money –
Ya just never know whom or when you can learn somthins –
who told you that bunch of nonsense? all dot3 and dot4 fluid is glycol based. all of it. and all glycol based fluids are hygroscopic. this has nothing at all to do with racing or temperatures. don't take my word for it, try using some science instead of rumors and hearsay - borrow an electronic brake fluid tester and test your fluid. that will tell you exactly how contaminated it is.

http://en.wikipedia.org/wiki/Brake_fluid#Service_and_maintenance

"Most automotive professionals agree that glycol-based brake fluid, (DOT 3, DOT 4, DOT 5.1) should be flushed, or changed, every 1–2 years."

but you know better than everyone else, don't you? all those foolish engineers and mechanics changing their brake fluid for no reason, jerry knows better than they do!! it's all a conspiracy! this regular changing of the brake fluid is just a scam to take peoples money!!111 :roll:

Thu Sep 29, 2011 10:26 am

Every one to two years means after 12 months'
A service mans wet dream!
Ridiculous- my guess is that absolutely zero cars have had their brake fluid changed after one year! and that includes your own cars-- admit it!

And for the majority of old cars probably never been changed !

hahahaha torsion you’re a trip ! - You just keep on suggestion to your customers to change that brake fluid right after each Christmas after visiting Santa Claus.

GWD --------I love this place ! ! ! ! !

Jerry

Thu Sep 29, 2011 10:47 am

JerryMCarter1 wrote:
Ridiculous- my guess is that absolutely zero cars have had their brake fluid changed after one year! and that includes your own cars-- admit it!

wrong jerry. i live in a humid area, i change the brake fluid on all of my cars every 12 months, and so do all the local "car guys" that i know. on my 911 track car, i change it every 90 days in accordance with the track rules.

i buy ate gold super dot4 brake fluid, one of the best dot4 fluids on the market. it's 14 bucks for a one liter can. fourteen dollars isn't much money. with my motive pressure bleeder, it takes literally 15 minutes to completely change the fluid once i've got the car on jackstands and wheels off. it's cheap, it's quick, and it's easy. in your neck of the woods, a 15 minute job and a 14 dollar can of fluid are a serviceman's wet dream? lol that's funny.

i'm really not sure why you're having such a hard time with this simple and inexpensive maintenance item. i'm not here to change your mind. after all, you are free to neglect your own cars however you see fit. signing off from this thread now!

Thu Sep 29, 2011 3:37 pm

EVERY time you apply the brakes on an ACVW a small amount of moisture enters the system through the vented cap.

Fri Sep 30, 2011 8:50 am

Moderator note:
I did some cleanup - let's stay on topic without massive arguing.

And please do not feed the troll(s).

Sat Aug 31, 2013 1:57 pm

How is any fluid physically compressible?

Sat Aug 31, 2013 3:20 pm

Toyd, look at ice. The colder water gets, the more space it takes up. Ice is frozen water that is simply really cold--but it's still just water.

It stands to reason that if ice swells, the colder it gets, that it may also shrink (or compress, if you will), the hotter it gets.

Brake fluid doesn't compress so much when it gets hot (heavy braking conditions).

Now what about steam?

Well, that's another story.

Tim

Sat Oct 05, 2013 4:22 pm

Tim Donahoe wrote: Toyd, look at ice. The colder water gets, the more space it takes up. Ice is frozen water that is simply really cold--but it's still just water.

It stands to reason that if ice swells, the colder it gets, that it may also shrink (or compress, if you will), the hotter it gets.

Brake fluid doesn't compress so much when it gets hot (heavy braking conditions).

Now what about steam?

Well, that's another story.

Tim

Water is one of those substances that defies normal laws of physics. It expands as it is heated and also expands when it is cooled.

http://hyperphysics.phy-astr.gsu.edu/hbase/chemical/waterdens.html#c2

Water at ordinary temperatures contracts and increases in density as it is cooled, like most substances. But at about 4°C it reaches a maximum density and then decreases in density as it approaches the freezing point. This decrease in density is only about one part in 10,000 as it cools from 4°C to 0°C, but this is sufficient to cause the water near freezing to come to the top. The water further expands upon freezing, so that water freezes from the top down, and ice floats on water.

Water has the highest specific heat of any common substance, 1 calorie/gm °C = 4.186 J/gm °C. This provides stability of temperature for land masses surrounded by water, provides stability for the temperature of the human body, makes it an effective cooling agent, and many other benefits. The high heat of vaporization of water makes it an effective coolant for the human body via evaporation of perspiration, extending the range of temperatures in which humans can exist.

All liquids are slightly compressible under pressure but you will not detect it in a brake system.