brake fluid really need to be changed?

[outrun]

Labman,

Nonsense! Calipers fail because the boots fail.

I totally DISagree based on my experiance.

The internal corrosion point is valid, but I partially conceded the point since I know little of rebuilding them in this trade-in and remanuacture market

More respected sources to 2nd my opinion

http://www.ceramicbrakes.com/whitepapers/brakefluid1a.htm

comments: Fluid DOT spec and possible effects on Seal composition, Note that DOT 4's Borate Esters may not be good idea in DOT 3 sepc'd systems)

http://www.imperialclub.com/Repair/Brakes/brakefluid.htm

comments: excellent discussion on brake fluids!

excerpt: "Many people, however, don't realize that any brake fluid has an additive package just like gasoline and oil. The two additives that come to mind are "swell" agents and anti-foaming agents
Swell agents react with the rubber components of the brake system to keep them supple and promote good sealing.....

 

[labman]

Wet brake fluid can lead to problems, but seldom does. I have torn apart hundreds of calipers that failed because of leaking or sticking. In most cases, the piston was corroded, or at least cruddy, out beyond where it contacts the brake fluid. Your links may be valid, but have nothing to with common causes of brake failure. Either admit they are irrelevant or find some that relate wet fluid to failure of parts not wetted by it.

 

[sprintman]

In olden years gone by here brake fluid was changed regularly. Not so much now but heck when my brake guys will remove all four wheels, full brake inspection/report, lube caliper sliders, bleed/replace brake & clutch fluid for $A36 it's a no-brainer. A mates Mazda needed nearly a $A1000 brake repairs (rust in master cylinder/wheel cylinders etc). Simple brake flush would have saved him a fortune. He now uses my brake place and gets annual changes.

 

[hal26]

My wife and I are Corvette nuts.Hers is a 2001 automatic with 9,500 miles and mine is a 2001 6 speed with 15,00 miles.These cars are driven approx.3,000 miles annually in dry conditions only and are garage queens.The manual says change fluid at 3 year intervals.Do you folks think that this is about right?

 

[hal26]

My wife and I are Corvette nuts.Hers is a 2001 automatic with 9,500 miles and mine is a 2001 6 speed with 15,000 miles.These cars are driven approx.3,000 miles annually in dry conditions only and are garage queens.The manual says change fluid at 3 year intervals.Do you folks think that this is about right?

 

[outrun]

Regardless of component life brake fluid (unless talking about the Silicon DOT 5 I believe) will hygroscopically gain H20.

This water will eventually render the Fluid below DOT specs on dry/wet boiling points.

It is no longer withing appropriate tolerance.

Labman you are not arguing with me.

GM, BMW and other auto makers specify changes now.

I see no credible argument against purging fluid older than 30mo/30k bearing the physical properties of DOT III and the severe environments it operates in.

If anything the knowing that my 1000$ Bosch ABS modulation unit, my expensive Austrailian 2-piston PBR race calipers, etc are kept clean from aged fluid,particles, water more than justifies 35.99 for a flush.

I treat my ABS fluid like aviation hydraulic oil...absolutely crucial to safety, overkill of a belief or not.

Neglecting fluids crosses that line for me.

 

[Big Jim]

quote:

---

Originally posted by labman:
Nonsense! Calipers fail because the boots fail. Will somebody please explain to me how having new fluid inside the caliper, protects the boot on the outside? The real slackers are those that think changing the brake fluid will keep the the boots from getting old and fail to replace them and the seals in a timely manner.

---

My experience also does not match this belief of yours. I have also overhauled many calipers (and wheel cylinders) that were sticking because of sludge and corrosion from old fluid, and most nearly all of the calipers still had reasonably good boots.

For what little it costs for a quart of brake fluid and as little time as it takes to flush the system it is just plain good maintenance.

 

[labman]

A boot may look fine, but if the piston is all corroded between it and the seal, the boot failed. And I am still waiting for my explanation of how changing the fluid on the other side of the seal protects the area on the outside. If you want to change the fluid, do it. Just do the maintenance that is needed too.

 

[XS650]

quote:

---

Originally posted by labman:
A boot may look fine, but if the piston is all corroded between it and the seal, the boot failed. And I am still waiting for my explanation of how changing the fluid on the other side of the seal protects the area on the outside. ....

---

Changing brake fluid doen't protect the tires, keep you oil fresh, clean your windows or improve your sex life either.

It does protect the parts kept wet by the fluid.

 

[labman]

My 6 decades of experience included a few years in a brake shop where I disassembled failed calipers all the time. The outer part of the piston always was at least crudy, if not corroded.

 

[bowez]

Change it as often as other hydralic fluids are changed. Any heavy equipment opperaters here?
Vaporiaztion can and will and does occur yet will not be a problem if system if bled proply every time the brakes are serviced (water being denser than brake fluid it will be one of the first fluids out).
If plead is mushy, bled all the clyinders/calipers.
Being acidic neither water or Brake fluid are good protectents--boots will fail no matter, though temperature differentals are more of a problem than pH.

My advice, when serviceing brakes and the fluid that comes out looks like mud replace it.

As for down hills, downshift before braking, better to use a bit extra gas and be able to stop than heat soak the rotor/drum.

 

[Horatio]

huh...never noticed that plead and pedal have the same letters before

Greg

 

[SWS]

I think that changing the brake fluid periodically is good preventive maintenance, especially on cars with ABS. I have had this service performed on various cars for ~25 years. Sometimes I only have the brake fluid changed with no other brake work or adjustments. I am always surprised and pleased at the better "feel" of the brakes afterward - smoother & firmer pedal. Why this happens - I don't know, but I have experienced this on several makes of cars that I bought new.

I have a '03 Civic and can confirm that Honda now recommends changing the brake fluid every couple of years.

On my recent cars with ABS, several mechanics have preferred to perform a "gravity bleed" to avoid putting any unusual pressure on the ABS unit. This takes more time, and is probably not as efficient in flushing the system more vigorously, but I am OK with it. They don't want to bust the ABS unit and I don't blame them. Nobody seems to know how to properly change brake fluid in ABS cars - I have looked in shop manuals and there is usually little or no reference to it. However, some cars have special procedures and electronic adapters that actually use the ABS pump to flush the system. Interesting, but not even the dealer had that adapter and he also said that he did not want to run the ABS pump that long (30 sec continuously), so he used gravity bleeding.

 

[Razl]

I think the folks that say they can "feel" the difference after changing their oil are

But, I swear, when I change the DOT4 fluid in my Saab, I can feel the difference. The pedal is firmer and the braking just feels more responsive.

I flush every 2 year or 20,000 miles. It fast and easy using my one-man pump. Brakes saves lives, so I tend to err on the conservative side of the recommended service intervals.

 

[labman]

quote:

---

Originally posted by XS650:
snip...
It does protect the parts kept wet by the fluid.

---

-

But it is the ones outside the caliper that fail first even with never changing the fluid.

 

[XS650]

quote:

---

Originally posted by labman:

quote:

---

Originally posted by XS650:
snip...
It does protect the parts kept wet by the fluid.

---

-

But it is the ones outside the caliper that fail first even with never changing the fluid.

---

There are many of us with decades of experiance that know it ain't necessarily so.

It depends on whether or not you live in a corrosion test chamber like environment or not.

 

[Lumberg]

How's this for an argument:

Flushing the brake fluid doesn't hurt. Not flushing it could hurt.

Sorta like the argument my dad used to make for believing in God:

If you believe in God and it turns out he exists, you go to heaven. If it turns out he doesn't, what have you lost? If you dont' believe in God and it turns out he does, you go to **** . If it turns out he doesn't, what have you gained?

Less possible downside to not bleeding/flushing the brakes regularly. Not that this should take the place of regular inspection of exterior brake components. But you can't see the insides.

 

[XS650]

quote:

---

Originally posted by Kestas:
In the number of brake fluid threads we've had this past year, it appears that all members but one agree on the value of regular brake fluid flushes.

---

I've noticed that too.

The Lone Ranger does have a valid point on the potential for crud and corrosion in the non-wetted area. Many of us could potentially benefit by taking a look at those areas each pad change if we aren't already doing it.

Brakes should still be bleed on a regular basis. My normal interval is every two years. If the fluid comes out real cruddy looking, the interval goes to one year.

[ November 24, 2004, 01:17 PM: Message edited by: XS650 ]

 

[XS650]

quote:

---

On my recent cars with ABS, several mechanics have preferred to perform a "gravity bleed" to avoid putting any unusual pressure on the ABS unit. This takes more time, and is probably not as efficient in flushing the system more vigorously, but I am OK with it. [/QB]

---

I don't understand your mechanics concern with unusual pressure. The pressure with conventional pressure bleeding of the brakes can be less than a good hard stop.

Just bleed them like any other brake system, then use the brakes hard enough to activate the ABS a couple of times to dilute the bit of old fluid that was left in the ABS pump. Not perfect but pretty good.

 

[cos]

I firmly believe in bleeding brakes, it's just good preventive maintenance. I've repaired/replaced just about every brake component, including a proportioning valve (what a pain!!!) on old abused junkers but never on a vehicle that I, a family member, or friend owned since new, when I've bleed the brakes every 1-3 yrs. If you ever get a chance to ride a late model sport bike, and then change the out the old fluid, you'll actually feel the difference! It still amazes me each spring. Most motorcycle mfrs recommend bleeding the brakes every 1-2 yrs and they use the better DOT4. That, IMO, speaks volumes.

[ November 24, 2004, 10:26 PM: Message edited by: cos ]