Can changing my brake fluid improve my braking?

[SteveD2]

My jeep stops like it's in a rain storm...on DRY pavement.

I do know that it wasn't very good to begin with, and I probably need to replace my pads. I have checked the level of the brake fluid, but not the condition. Is it possible that replacing the fluid might help the braking?

 

[9c1]

Yes, it will - but if you are asking if it will cure your braking problem - probably not.
Depending on how old the brake fluid is, there can be a noticeably firmer pedal with fresh fluid. I change brake fluid every two years and I can tell a difference in pedal feel with the fresh fluid.
Sounds like you need a brake inspection and diagnosis.

 

[labman]

Unless the fluid is completely compromised with moisture and it is boiling in normal braking, no. I think it takes a strong imagination to see any difference in braking due to the fluid except under high heat. Even a little air in the line will give you a low pedal, but as long as it doesn't bottom out, you will still stop. Even then, you could pump it up. Don't let anybody divert you from the basics, good tires, good lining, and clean, new hardware to allow things to move as they should. Rebuild the cylinders and calipers as needed to avoid developing leaks. If the pistons don't push back fairly easily, rebuild or replace the caliper. I rebuild. Kits are cheap, and it isn't that much work.

 

[pgtr]

If the fluid somehow has air in the system then yes, bleeding will certainly help a lot.
If you are not comfortable doing this or don't know how - I would find someone to help you (you need a helper or special tools anyway) or take it in to an automotive shop.

If you had to make an emergency stop can you apply sufficient pressure to put the tires to the limits of adhesion? E.g. 'just' on the edge of locking up or actually lock up the wheels?

Warn pads against rotors, unless really worn, won't in and of themselves degrade brake performance. Of course ultimately if so worn that you have metal against metal - that's a different story but then you should be hearing that.

 

[VaderSS]

I know that labman and I differ on our opinion of brake fluid life and pedal feel, etc..., but I agree that changing brake fluid in this case would result in only a slight improvement, where you are in need a quantum leap. It may be as simple as a pad change or as complicated as a full rebuild. Unless you are mechanically inclined, or have someone who can show you the ropes, I'd suggest you seek proffesional help.

 

[SteveD2]

How long is brake fluid usually recommended to be good? I'd be willing to bet it's never been changed in 99k and 13 years. I can still lock up the wheels and skid if I want to...but the brakes could definately use improvement. I'm also going to be towing a 2,000lb boat with this truck for the first time as soon as the weather gets nice again...and I'm really worried about stopping that.

 

[digitaldrifter91]

if its that old you will see some improvment but no miricles. possibly get some better pads for your rotors.

fluid looses itself over time, i think the life span is 2 years till it should be bled...

i would try to check up before you tow that boat

 

[ChrisW]

Don't forget that your tires are probably the most important part of the "braking" system. I would get the other parts of the brakes checked besides just changing the fluid. Perhaps the old rubber lines are too soft and have too much flex. Or the seals on the caliper or master cylinder pictons are worn. Your brakes will lock up if your brakes are stopping faster than your tires can grip the road.

 

[labman]

Brake fluid does eventually go bad, but not for a very long time. I have seen brake fluid that had turned to solid granules. This was usually in something very old that may have set exposed to air and moisture for 20 years or more. Something old enough that that it didn't have a modern DOT 3 or better fluid in it. When I worked in the brake shop, with many older, poorly maintained vehicles, I never remember replacing the fluid alone as fixing any problem or heard anyone suggest it would prevent problems.

Starting out new and kept sealed, the brake fluid will outlast the other brake components except for the actual castings. Whether you follow the good practice of rebuilding/replacing every lining change, or only every few changes, the fluid will all be replaced long before it would go bad. Leave the calipers go until they start to leak, and you are asking for problems. In that case, you may as well start with a rebuilt caliper. If and when you you get the piston out, likely it will be corroded and need to be replaced, running the price of the job at least near if not over the price of a rebuilt one. A corroded piston that was forced back into the caliper, may not pop out with a shot of air. At the brake shop, we had a bench set up the more difficult pistons yielded to. I have heard of people using adapters to fit a Zerk fitting and using a grease gun to extract pistons. Yeah, there are tools made for the job, and they do work on ones that aren't too bad.

At 13 years old, take a close look at the hoses and lines. If the hoses look like old, OEM ones or just old, replace them. Don't forget the one to the rear brakes. Look at the steel lines. Pay particular attention to the hardest to see places. That is where crud collects and rusts the line. I don't remember any of the many brake lines I replaced, looking like they rusted from the inside. Often you could hardly see where it was leaking for all the rust and crud on the line.

Any time you replace lining, clean up all the hardware and replace any that isn't like new. Replace all springs and O-rings. I use graphite on metal to metal moving surfaces and silicone grease on rubber on metal to rubber, internal and external. Bleed screws get silicone. Your shoes and calipers must be free to move to apply and release the brakes. This makes a real difference, not an imaginary one.

 

[VaderSS]

quote:

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Starting out new and kept sealed, the brake fluid will outlast the other brake components except for the actual castings.

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The problem is that you cannot truly seal a brake system. Moisture will always get past the seals, plastic, and rubber components, and turn the fluid corrosive. While brake fluid sitting in a can may have an indefinite shelf life, brake fluid in a system does not.

Another problem you may have is frozen rear adjusters. I'd give the entire system a good inspection. I usually usually buy factory rebuilt calipers and new wheel cylinders as they are often almost as cheap as buying a kit. A rebuilt set of front calipers for my car is $22 ($11 each) with a lifetime warranty.

[ December 05, 2003, 01:06 PM: Message edited by: VaderSS ]

 

[labman]

quote:

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Originally posted by VaderSS:

snip....The problem is that you cannot truly seal a brake system. Moisture will always get past the seals, plastic, and rubber components, and turn the fluid corrosive. snip....

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Maybe not completely, but well enough to make changing brake fluid more bother than it is worth.

 

[VaderSS]

From this link;
http://www.buckeyetriumphs.org/technical/Brakes/Fluid/Fluid.htm

code:

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Brake Hose Moisture Absorption Test - Moisture Content of Fluid

Before Test After 7 days Emersion After 35 Days emersion

glycol-based Fluid 0.15% 3.03% 6.9%

silicone Fluid 0.01% 0.03% 0.03%

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Now granted, this is an emersed hose, but you get the idea...

That artical mentions DOT 5 fluid. I consider DOT5 to be for very specialized purposes, and not suitable for daily drivers or ANY ABS equipped cars.

Something I never even thought of, but it apears that salt is also absorbed through the lines;

code:

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Brake Hose Cl Absorption Test - Cl Content of Fluid

Before Test After 6 days Emersion

glycol-based Fluid
silicone Fluid

---

 

[Kestas]

Anybody who stores classic cars knows that the brakes need attention every 10-15 years, regardless of use (similar to the 13 years on ZmOz's Jeep). This is because the hydraulic components degrade over that time for any number of reasons, that is, before we've been recently educated about the importance of flushing brake fluid on a timely basis (~every 2 years).

Though I agree with labman on a number of his thoughts, I disagree with the thought of leaving brakes alone until something is wrong. Flushing the fluid in brakes should not be a big trouble or expense, yet goes a long way in protecting the hydraulics of the system, delaying hydraulic component replacement, and reducing susceptibility to fluid boilover which can result in scary loss of pedal pressure under some circumstances.

 

[satterfi]

I change the brake fluid in my motorcycle at least once per year and sometimes twice per year.

I can always feel a difference after changing fluid. However, I also extend and clean the pistons and I think this helps with brake performance.

Of course with a motorcycle you use your hand to activate the front brake so you would expect to detect small differences in brake performance versus stomping a car brake pedal with your leg.

 

[Robbie Alexander]

quote:

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Originally posted by ZmOz:
it's never been changed in 99k and 13 years [/QB]

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change egvery 1-2 years... Cheap fluids every year, high grade stuff maybe longer 1.5-2 years...
Most fluid is considered WET I think in 1- Year, although IMO in most applications you can PUSH it a while longer... Hey most people don't do this every 3-4 years, but that doesn't mean it should not be done... Do it every year or two regardless.

 

[labman]

quote:

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snip.... Hey most people don't do this every 3-4 years, but that doesn't mean it should not be done... Do it every year or two regardless. [/QB]

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Outside of this board, I never heard of anybody ever changing brake fluid except the people converting to silicone.

 

[Robbie Alexander]

quote:

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Originally posted by labman:
-*-*QUOTE]Outside of this board, I never heard of anybody ever changing brake fluid except the people converting to silicone.

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Thank goodness for the board then.

Have you ever gotten over 80K, 90K, 100K out of a set of pads? Do your Rotors last 200K with heavy breaking? Have you EVER LOST your brakes on the expressway?
Yes, Yes, Yes.

Brake Fluid Absorbs moisture, and like a paper towel, becomes saturated. There is a point where the water will cause problems.

 

[9c1]

We teach our students (Automotive Technology at a community college) to change the brake fluid every two years. Some auto manufacturers have begun to recommend this interval lately. We do a lot of fluid flushes. We have converted empty 30 pound R12 and R134 containers to hold vacuum, and use those containers to draw fresh fluid through the wheel bleeder screws. First draw the old fluid out of the master cylinder reservoir, then pull at the bleeders until fresh fluid shows at the hose. No mess, no fuss. Periodically empty the used fluid (when the there is not enough vacuum in the container), and recharge the vacuum. We can get 5-10 vehicles from one vacuum charge, depending an how careful the students are to shut off the tank. We use an AC vacuum pump to pull down the containers, but one could hook the hose to your intake manifold to draw the vacuum on the used refrigerant bottle also. We use clear plastic hose from the hardware store, but it loses its flexibility after a while. Inexpensive to change.
Terry

[ December 06, 2003, 03:46 AM: Message edited by: 9c1 ]

 

[DPMiller]

It's common practice in Europe (and probably the rest of the world) the replace brake fluid on a regular basis. Manufacturers service schedules call for it...

 

[wtd]

I flush new brake fluid through all of my brake lines every time I change pads which is roughly every two years. The fluid that I flush out is usually pretty dirty and it makes me feel better to have new fluid in there.

Wayne