silly brake fluid question

It ever hurts to flush extra fluid through the system. If I'm almost to the end of a bottle, I'll just bleed a bit more to use it up. If I have left over fluid that doesn't get used for a while, I'll use it as a pre flush on a vehicle with really nasty fluid.


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It may be apples and oranges, but how many of us change the fluid in our other vehicles (4 wheels)? I dont.

Yes - all my vehicles get fluid changed every other year - every three if I'm feeling lazy. Even at dealer rates, changing fluid is cheaper than changing components.

I guess changing the fluid is a nice touch and can make you feel better. My '03 Dodge just got its first flush when I recently did the front brakes for the first time. Fluid was a little dark but the brakes were functioning fine.
The brake system is, for the most part sealed, as is a partial container.

The service shops are liking this.....quite a bit I'd guess.

OM

PAS said:

It may be apples and oranges, but how many of us change the fluid in our other vehicles (4 wheels)? I dont.

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I have 4 bmw cars and an f250 truck. They all get fresh brake fluid yearly,. Except the two Bmw's that do track duty. They get fresh flush monthly in season.

Who uses a dealer for brake fluid changes? It is a simple diy process.

OK. Here we go....

I know BMW only recommends DOT4 fluid, but....

Recently I had a partial front brake seizure on my '99 R1100S ABS with 11k miles, on a day ride. I noticed the bike was extremely hard to push even a few feet on level concrete. On arrival back home and several hours of head scratching and wrenching, the problem was discovered in the small passages inside the left front Brembo caliper: there was substantial ground up, decomposing black rubber crud clogging the passage between halves of the caliper. This prevented the pistons there from retracting. Fortunately, it did not hold ALL the pressure, just enough to make the brake drag. The only place this rubber could have come from is decomposing OEM brake lines. Everything else in the system, seals, pistons, was pristine. I have pics of all this.

A retired motorcycle mechanic (Honda, Triumph, BSA) said this is a very common problem on most all bikes at 8-10 years. DOT4 is very aggressive chemically, eats paint, plastic, and stock brake lines are a synthetic rubber (plastic).

I learned a bunch.

Drop a quarter in each handlebar reservoir and leave it. This is the cheapest part you will ever "buy" for a BMW, and will prevent squirting brake fluid all over your bike. Ask me how I know.

I replaced ALL flexible lines on the bike with PTFE (teflon) lined AN3 braided lines (Spiegler), front and rear brakes, and clutch. They are all the same age and have been maintained well and used DOT4.

When you bleed or try to change the brake fluid in the brakes or clutch, you DO NOT get ALL the fluid in the system. Any fluid in the slave (caliper) cylinders is on a "dead end" in the system and will NOT be flushed no matter how much you pump thru there. This can be minimized by using a VACUUM system in stead of a "pressure", as in handle bar lever/master cylinder pumping action. You can push the new fluid thru, or pull it thru with a vacuum type device. With a vacuum device, you will be pulling all the caliper pistons into the fully retracted position and REMOVING as much of the old fluid as possible.

While doing this, you can visually verify that all pistons are FULLY retracting and operating properly by sighting along the surface of the disc at the pads with a small light.

DOT 5.1 is compatible (miscible) with DOT4, does not absorb atmospheric moisture, does not eat paint, plastic, rubber, PTFE, etc. In other words, you don't need to change it NEARLY as often, unless you just feel the need for ole times sake.

Some say that DOT 5.1 is compressible. A very good analysis is here:

http://www.buckeyetriumphs.org/technical/Brakes/Fluid/Fluid.htm

It says that yes, it is compressible, but not enough to make any difference. And the boiling point is higher.

Just MNSHO.

I think you are mixing up info on DOT 5 & 5.1 fluids. 5.1 can replace 4 and may have a higher boiling point, but is just as damaging to paint, etc.


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PAS said:

It may be apples and oranges, but how many of us change the fluid in our other vehicles (4 wheels)? I dont.

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I am a little less diligent with my car or truck. A caliper is less than $50. For my bike - ten (10) times that!!!!!

Mea Culpa, y'all!!

ONLY DOT5, not DOT5.1, is silicone based. DOT 3, 4, and 5.1 are glycol based. ONLY DOT5 is silicone based. Glycol is the stuff that eats paint, absorbs moisture from the air (desiccant), turns brown, needs to be changed frequently, etc.

Sorry for ADDING to the confusion.


Lowndes

I ran DOS3.2 in a Comador

lowndes said:

ONLY DOT5, not DOT5.1, is silicone based. ONLY DOT5 is silicone based.

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...and typically is not recommended for ABS-equipped vehicles due to its reduced lubricity which, I have had explained to me, impairs the functionality of the system.

GSAddict said:

An inexpensive tester

http://www.ebay.ca/itm/361587748261

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So for shlitz and giggles I got me me one of them there Brake Fluid testers and tested the half bottle of brake fluid which has been stored in my liquids cabinet for the past year.
I placed some brake fluid in the bottle cap, turned the tester "ON" and the picture shows the test results.
Would I discard the remaining brake fluid from this bottle?......I think not. Now I also tested another part bottle (almost empty) of brake fluid that I know is more than three years old, and it tested out with the green/yellow led lit up, which is less than 1% of water content in Brake Fluid. This bottle I will be discarding even though it could be used.
I personally change out the brake fluid in both F&R systems yearly during the bikes winter maintenance regime so I am not concerned with the damaging effects that moisture can have in the braking system since its not in there for a long period of time. I merely wished to make a point here that IMHO if the brake fluid is stored with a tightly fitted cap, that the amount of moisture that replaces the used amount of brake fluid will/should not affect the fluids integrity. Now with the newly acquired tester I can be sure of the moisture content before I use it.








INSTRUCTIONS (from the sellers website) for the tester are below

How To Check The Fluid Quality:

Press the button for power on, green LED will light up.
Insert the tester into reservoir for a second , then the results will be indicated correctly by LEDs.
Auto power off.

Indications:

Green: Battery OK, i.e.: No Water Contained in the Brake Fluid.
Green/Yellow: Less than 1% of Water Content in Brake Fluid.
Green/Yellow/Yellow: Approximately 2% of Water Content in Brake Fluid.
Green/Yellow/Yellow/Red: Approximately 3% of Water Content in Brake Fluid;The Brake Fluid Should be Changed.
Green/Yellow/Yellow/Red/Red: at least 4% of Water Content in Brake Fluid; The Brake Fluid Must be Changed Urgently, Extreme Danger.

snookers said:

So for shlitz and giggles I got me me one of them there Brake Fluid testers and tested the half bottle of brake fluid which has been stored in my liquids cabinet for the past year.
I placed some brake fluid in the bottle cap, turned the tester "ON" and the picture shows the test results.
Would I discard the remaining brake fluid from this bottle?......I think not. Now I also tested another part bottle (almost empty) of brake fluid that I know is more than three years old, and it tested out with the green/yellow led lit up, which is less than 1% of water content in Brake Fluid. This bottle I will be discarding even though it could be used.
I personally change out the brake fluid in both F&R systems yearly during the bikes winter maintenance regime so I am not concerned with the damaging effects that moisture can have in the braking system since its not in there for a long period of time. I merely wished to make a point here that IMHO if the brake fluid is stored with a tightly fitted cap, that the amount of moisture that replaces the used amount of brake fluid will/should not affect the fluids integrity. Now with the newly acquired tester I can be sure of the moisture content before I use it.


View attachment 57861





INSTRUCTIONS (from the sellers website) for the tester are below

How To Check The Fluid Quality:

Press the button for power on, green LED will light up.
Insert the tester into reservoir for a second , then the results will be indicated correctly by LEDs.
Auto power off.

Indications:

Green: Battery OK, i.e.: No Water Contained in the Brake Fluid.
Green/Yellow: Less than 1% of Water Content in Brake Fluid.
Green/Yellow/Yellow: Approximately 2% of Water Content in Brake Fluid.
Green/Yellow/Yellow/Red: Approximately 3% of Water Content in Brake Fluid;The Brake Fluid Should be Changed.
Green/Yellow/Yellow/Red/Red: at least 4% of Water Content in Brake Fluid; The Brake Fluid Must be Changed Urgently, Extreme Danger.

Click to expand...

I would agree with you in general.
It is however important to keep in mind where the plastic container is stored. In a high humidity environment the plastic container will absorb moisture.

GSAddict said:

It is however important to keep in mind where the plastic container is stored. In a high humidity environment the plastic container will absorb moisture.

Click to expand...

Absolutely

Brake fluid storage

Lee Valley tools (in Canada - probably similar outlets in USA) sell a product that dispenses 100% N2 - nitrogen gas. Since its heavier than air and contains no moisture, it displaces any air in a container to prevent drying or contamination of the contents. They sell it to preserve the integrity of leftover paint in a partially used can.
It also works to keep a part bottle of wine fresh once opened. I seldom have any left but it does work.
I'm guessing it would also work to preserve brake fluid in an opened container. Spray the nitrogen in the container - close the lid and there you go.

Nitrogen

The local paintball shop sells me 68 CI of 3,000 psi nitrogen for my PCP pellet rifle for $1. They don't want to charge me but I insist. It is dry, inexpensive, saves opened wine, and will send a .177 cal pellet thru a treated 2x4 and into a tree at 30 yds. Good stuff.

The air you are breathing is 78% nitrogen, but not 3,000 psi and not dry, but free.

DOT5 is good stuff, too, but BMW does not sell it. That may be why they don't "recommend" it. ??