The brake fluid in the reservoir of my 89 Firebird tends to always be black. I had it flushed a year ago, and I noticed it got black. I had it flushed last week and two days of driving. I checked the fluid and it was black in the reservoir.

What is causing the brake fluid to turn black so fast?

 

time to change brake lines

 

So, bad brake hoses cause the fluid to turn black in the reservoir?

 

What rubber brake hoses are good? Autozone has Brakeware. And Advance has Tru Torque and mentions "Dorman - First Stop".

And I think Napa has their own brand for rubber hoses "Napa Ultra Premium Brake Parts".

Actually I just looked, and it looks like Napa is a limited lifetime. Where as Advance is one year. And Autozone doesn't say, but I'm guessing since it doesn't say then it probably is 90 days.

So for this, I'd probably go Napa just because of the warranty.

 

if you are going to do it, go with braided stainless steel since you are going to be down there anyway.

 

Nope, don't want to spend the extra money. And I've read of the stainless steel hoses braking on people.

They said those stainless steel brake hoses will brake. Where as the rubber will just get worse and worse, but still let you stop.

This is just a DD. No point in getting fancy like some recommend putting in Amsoil fluids or fancy spark plugs. I'm just keeping it OEM as it tends to be a no brainer.

 

Amsoil will last longer between flushes.

 

Bad seals in a master cylinder will also cause the fluid to turn black.

 

Had the same thing.

I suspect it was the master cylinder seals, so I bought a complete new master cylinder from Amazon for $50 (from memory). It's so cheap I'd do it to be safe.

I also put in a set of Goodridge stainless steel brake lines. These were great and a good upgrade.

 

Stainless steel braided brake hoses are far safer and superior to plain old rubber. whoever stated that SS hoses are a bad idea is very unacknowledged about the subject. I have had mine for at least five years with zero problems. They provide better braking by eliminating the expansion of rubber hoses and also have a much greater abrasion resistance, which has saved my but before.

 

Brake fluid has a life span and should be changed close to 25,000 miles or 3 years. The fluid brakes down and absorbs water/moisture in the air. All of the rubber parts of the brake system also disintegrate. If you don't know when the last time the master cylinder, brake fluid or brake hoses were, I would plan on changing it all. I polished a fourth gen master cylinder for my car, it seeped out blackish green fluid for for days. Every time I thought I had cleared it all, a few more drops would appear.

 

You should read this article. I don't think a difference of tenths of a millimeter in expansion will affect performance or pedal feel in any way.
http://autospeed.com/cms/title_Braid...9/article.html

 

Yeah, that article doesn't help your argument. Think about it in terms of volume as that article started to hit on. If we assume the inside diameter of the brake hose expands at the same rate as the outside diameter than for our formula we can plug in the od numbers in place of the id numbers. We know volume of a cylinder is equal pi times the radius squared times the height. We can assume the brake hose length is 6 inches or converted to mm is 152.4 10.76 initial is a radius of 5.38 and 11.02 is 5.51. The difference in the cylinders is 678 cubic mm. So what could have been the caliper piston expanding outward and extra amount is now eaten by your brake hoses.

 

Thanks for doing the math. You used the worst case hose from the article (an old worn out hose from a 1965 mustang and used the OD dimensions which would would yield an even greater final volume number) and still came up with only .68cc's difference. There is more variation than that between the under and over fill lines on the reservoir.

 

The level in the reservoir is irrelevant to the hydraulic system.

The point of non-expanding hose is that more of the effort applied to the pedal is used to put force on the piston instead of being wasted in ballooning the hose. The difference in pedal feel can be quite significant.