Brake Fluid

[hope]

Have to replace all four wheel brake cylinders on my 40 Sedan, (new when installed years ago).
Because it sat so long the brake fluid Dot#3 absorbed enough moisture to rust the inside.


Did a search on search dept... (hunh) to get information about brake fluid use, and found so much difference of opinion on the use of Dot# 3,4,or5, that i still don't know witch way to go.


Leaning to go with#5 ?

[19Fordy]

Go with silicone #5. Been using it 30 years. No rust.

[alanwoodieman]

DOT 5 is what I have been using it since 87 when I had to get it at the honda motorcycle shop. I have been told by my counter man that synthetic dot 3/4 is not hydroscopic--???

[51 MERC-CT]

Check this thread out-- DOT5/Silicone favored by 52% over all the rest.
https://www.fordbarn.com/forum/showt...ht=brake+fluid

[hope]

Thanks everybody for the reply.

[Talkwrench]

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OR just use dot4 get some speed bleeders and life is easy, do it every two years or so. Shouldn't take you much more than 15 mins to do a flush.

[tubman]

Originally Posted by Talkwrench

OR just use dot4 get some speed bleeders and life is easy, do it every two years or so. Shouldn't take you much more than 15 mins to do a flush.

Good advice, but I have found from experience that it takes at least ten years for DOT 3/4 fluid to pick up enough moisture to even begin to be a problem. I have purchased a device that measures the moisture content of brake fluid in a vehicle. I test my vehicles yearly. The fluid in my 1951 Ford club coupe (which was restored in 1987) only began to approach the maximum allowable moisture content two years ago, so I flushed the system and replaced the fluid. I am also a firm believer in "Speed-Bleeders" and they made it a quick, one-person job. The fluid in my '67 Corvette (which was restored on 2007) is still well within allowable limits. When I did the brakes on my '68 Corvette about twenty years ago, I did use Dot 5 fluid. It worked fine, and lasted until I sold the car last fall, but it was very difficult to get bled properly. After that, I decided that while it worked well, it was not worth the effort required to bleed the system. I also wonder about the availability of DOT 5 in the future. It is NOT recommended for use with ABS systems, which are almost universally used these days, so I believe it's days may be numbered.

Just think of all the twenty year old "beaters" out there that have their original fluid. If there was a significant chance of brake failure because of deteriorated fluid, I'm sure there would be some very strict laws requiring regular periodic maintenance.

[19Fordy]

Tubman, thanks for the "tip" on future buying of DOT 5.

[philipswanson]

You really don't save time or work with speed bleeders. You still need a catch can either way. With stock bleeders you just submerge the end in fluid. No need to close screw until finished. Takes one person to pump brakes either way. Waste of $ IMHO.

[tubman]

Originally Posted by philipswanson

You really don't save time or work with speed bleeders. You still need a catch can either way. With stock bleeders you just submerge the end in fluid. No need to close screw until finished. Takes one person to pump brakes either way. Waste of $ IMHO.

One question : Have you actually ever used "Speed-Bleeders"? I have and much prefer them over the originals.

[philipswanson]

Originally Posted by tubman

One question : Have you actually ever used "Speed-Bleeders"? I have and much prefer them over the originals.

Yes, I bought a pair and was very disappointed in them not saving time. The process is the same except you don't need to submerge the end of the hose. It was an obvious waste of money for me. Never bought the other two.

[34PKUP]

Originally Posted by philipswanson

You really don't save time or work with speed bleeders. You still need a catch can either way. With stock bleeders you just submerge the end in fluid. No need to close screw until finished. Takes one person to pump brakes either way. Waste of $ IMHO.

Originally Posted by philipswanson

Yes, I bought a pair and was very disappointed in them not saving time. The process is the same except you don't need to submerge the end of the hose. It was an obvious waste of money for me. Never bought the other two.

Just because they are called "SPEED" bleeders does not mean that they will save time ( have never seen them advertised as 'saving time')
Stock bleeders can suck air past the threads, Speed bleeders are designed not to.

[philipswanson]

Originally Posted by 34PKUP

Just because they are called "SPEED" bleeders does not mean that they will save time ( have never seen them advertised as 'saving time')
Stock bleeders can suck air past the threads, Speed bleeders are designed not to.

Not true. The speed bleeders I bought, have the same pipe thread as the stock screws. They have to or they wouldn't fit into the wheel cylinders properly. You have to loosen them the same as stock ones so they will bleed. The only advantage I saw over the stock ones is you don't have to submerge the other end of the hose in fluid. If that's an advantage at all. Certainly not worth the money. That's why I never bought the other two.

[34PKUP]

Originally Posted by philipswanson

Not true. The speed bleeders I bought, have the same pipe thread as the stock screws. They have to or they wouldn't fit into the wheel cylinders properly. You have to loosen them the same as stock ones so they will bleed. The only advantage I saw over the stock ones is you don't have to submerge the other end of the hose in fluid. If that's an advantage at all. Certainly not worth the money. That's why I never bought the other two.

Obviously you are not aware that on the back stroke of the pedal the stock screws can leak air back into the system thru the threads.

The Speed bleeders have a flexible sealer applied to the threads to prevent
sucking air back into the system.

[philipswanson]

Originally Posted by 34PKUP

Obviously you are not aware that on the back stroke of the pedal the stock screws can leak air back into the system thru the threads.

The Speed bleeders have a flexible sealer applied to the threads to prevent
sucking air back into the system.

The two I bought had no special sealer on the threads.

[Drbrown]

I surprised this discussion hasn't raised the need to fully flush and clean of the entire brake system and its parts if converting from DOT 3/4 to DOT 5, and also the potential of DOT 5 to find leaks in the system where as DOT 3/4 would not. Or was that just a dream I had ?

The primary reason I install speed bleeders is to eliminate the need to have a second person pump the pedal while I open and close the stock type bleeder. The "hose in the jar" doesn't always work for me .... sometimes it behaved like a snake and had its own mind about twisting around.

[tubman]

Originally Posted by philipswanson

The two I bought had no special sealer on the threads.

It is starting to sound like you didn't actually have real "Speed-Bleeders" after all.

[Mart]

I have dabbled with dot 5 over the years but have settled on using dot 4.

[philipswanson]

Originally Posted by tubman

It is starting to sound like you didn't actually have real "Speed-Bleeders" after all.

Russell P/N 639590. Highly disappointed because I saw no big advantage over stock. If you want your stock ones to seal better, just wrap a little teflon tape on the threads.

[tubman]

Hmmmm. The ones you got must have been defective. The Russel 639590 that just about everybody sells obviously has the "flexible sealer" that "34PKUP" refers to in his post.

[philipswanson]

Teflon tape on the originals does the same thing. Cost = about 2 cents each. It's not rocket science.

[Mart]

You shouldn't need teflon tape on any brake fittings. If you do you have a problem. Do OE manufacturers use teflon tape? No of course they don't.

Mart.

[leon bee]

He was just talking about so it won't suck air around the threads while bleeding with a tube.

[Mart]

Ok good point. I put some red rubber grease around mine when using a vacuum bleeder. I think that helped.

[v8fordman]

Just put DOT 5 in a complete rebuild. Beware of brake light switch failure if you use an original switch. I would recommend using a mechanical switch.

[tubman]

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Originally Posted by v8fordman

Just put DOT 5 in a complete rebuild. Beware of brake light switch failure if you use an original switch. I would recommend using a mechanical switch.

Another reason for NOT using DOT-5.

[34PKUP]

Originally Posted by tubman

Another reason for NOT using DOT-5.

Please explain to those who would like to know, why DOT 5 causes the failure of brake light switches.
Every failed switch (using DOT 3) that I have cut apart to inspect shows that failure was due to arcing at the contact points causing a non conductive build up of material, thus , no continuity.
The contact points are not immersed in any brake fluid.

[v8fordman]

I would much rather have a mechanical switch and never change fluid or have the expense of new wheel and master cylinders. I personally have never had a switch failure, but only read what is stated here on the Barn. With that said, I can change a switch faster than anyone can change fluid or replace all of their brake components. My model A, Mustangs and others have had the same DOT 5 fluid in them for years with no problems. Plenty of moisture and corrosion problems with other cars using DOT 3

[51 MERC-CT]

Totally agree with the use of DOT 5 and a mechanical brake light switch.
The mechanical switch, not because of possible failure of a pressure switch but because a mechanical switch will allow the brake lights to activate as soon as the pedal is minutely moved and it does not depend on brake line pressure to activate.
How many would like to see their brake lights come on sooner than later??

[Pete]

"How many would like to see their brake lights come on sooner than later??"

I have a switch to turn mine off when running from rev'noooers.