Brake fluid question

[canuck750]

Hopefully this is better than an oil or tire question ....

I have Brembo and Grimeca brake calliper and master cylinders that depending on the manuals I read call for either Dot 3 or Dot 4 fluids. Some confusion in the literature I found, especially for the Brembo components.

Can I substitute Dot 3 for Dot 4 or vice versa in a system without bleeding all the fluid out? Is Dot 4 'better' to use than Dot 3?

Thanks

Jim

[Antietam Classic Cycle]

DOT 4 has a higher boiling point than DOT 3. DOT 3 and 4 are compatible to mix.

[Markcarovilli]

 :1:

What Charlie said..

[canuck750]

DOT 4 has a higher boiling point than DOT 3. DOT 3 and 4 are compatible to mix.

Thanks !!

[Antietam Classic Cycle]

The brake fluid I've been using is "Valvoline DOT 3 & 4", pre-mixed! 

http://www.valvolinechemicals.com/sites/default/files/VALVOLINE%20Brake%20Fluid.pdf

[Old Jock]

Far as I'm aware the DOT classifications can be confusing, I've seen DOT 4 with higher boiling points than DOT 5.1 etc:

Unless you are going to the track any 3,4 or 5.1 and up will do, they are all Glycol based and can be mixed (like oil  )

Do NOT EVER USE DOT 5.0 or just DOT 5 it's Silicone based and is not compatible with normal brake systems

Only heresay but I've heard it can turn to jelly and attack normal seals etc: so stay well clear of DOT 5 and you will be good

[canuck750]

Thanks again, great information fellas!

[Two Checks]

DOT 5 is okay to use per Brembo. System must be flushed of all fluid. Best time to make the switch is when replacing components. I am fixin to replace everything.

[BMCMOTO]

The problem with DOT 5 silicone brake fluid is that it has a tendency to get air entrained in it that is difficult to bleed out. Never shake a bottle of silicone brake fluid, or at least let it settle for 24 hours if you do. I've used it in several applications. As someone else mentioned it sometimes leaves air voids where corrosion can occur.
 Technically all DOT fluids are compatible, thats the definition of the DOT specifications. I would not mix them regardless. If mixed the rating falls to the lowest of the mixed fluid. There are some European hydraulic brake systems that use a type of hydraulic oil, Citroen maybe?

Brian

[Roebling3]

Who wants an oil thread when you can have a brake fluid thread?

Synthetic brake fluid: Is it non-corrosive? Is it compatible with DOT 3 & 4? What about skin, eye, contact, ingestion. flammability?

Thank you all for being here.  R3~ 

[Psychopasta]

Especially when Charlie nailed the answer in the first reply 

[Lannis]

Especially when Charlie nailed the answer in the first reply 

A competent person giving the correct answer in the first reply never stopped ANY oil thread from going 5 pages in 2 days.   I don't know why a Brake Fluid thread would be any different.

First we've got to get through all of the "But I Can't Buy That At My Local Pep Boys, Can I Use Mazola Oil Instead" rap.   Then a few posts about how an oil of a different weight and spec is 2 cents a quart cheaper, and I've used it for 20,000 miles and my bike is still running, so all this 'recommendation' stuff is crap.   

Then some "Sez you!" and "So's your grandmother!" and then it's just getting started good ....

Lannis

[Roebling3]

SO. The suggestion is I should have known better? That being; All brake fluid has always been synthetic? But, it has only been evident (printed on the containers), in the last several years? Begging your collective thoughts.  R3~ 

[Lannis]

SO. The suggestion is I should have known better?   R3~

Not from me, since I was one of only two replies since your last post, in case it WAS me.  I was just joking around about "X threads" ....

Lannis

[Markcarovilli]

Lannis

Way to fan the flames.........

Mark

[Rough Edge racing]

 Years ago I had a 71 Datsun 510 that was seeping fluid from the clutch hydraulics....I used hydraulic jack fluid and it stopped leaking..

[Lannis]

Lannis

Way to fan the flames.........

Mark

I can see fanning the flames of an oil or tire or Harley or moly or ethanol thread .... but does a "brake fluid" thread really have enough flames to fan?   What's next, dielectric grease?   Wait, that's not a good example ....

Lannis

[Lannis]

SO. The suggestion is I should have known better? That being; All brake fluid has always been synthetic? But, it has only been evident (printed on the containers), in the last several years? Begging your collective thoughts.  R3~

The brake fluid we use now with a DOT rating is all synthetic, and is either glycol-based (3 and 4) or silicone-based (5).    I don't believe that mineral oil-based brake fluid has a DOT rating, and don't think it's used in automotive applications (any more).

Lannis

[Psychopasta]

Hey Roebling, I'm sorry if my comment caused any offense. I'm just being my usual silly self.

- Pasta

[normzone]

Many years ago my younger brother and a pal were riding around in the California desert and unknowingly tore a flex line to one of the rear wheel cylinders. They just kept bombing along pumping out brake fluid, until they had no brakes, then eventually rolled to a stop.

Once they figured out what happened, they rigged a patch with some fuel line and hose clamps. Having no other fluid available, they filled the system with Budweiser.

This worked well enough until the car went slower and slower and could not be convinced to move any more. The beer had foamed up and the brakes were all engaged.

So they bled foam from all the wheels and took off again. And then they had to repeat this exercise several times until they got back to roads and proper materials.

I think it would have made more sense to drink the beer and pee in the master cylinder, but I wasn't there, thank goodness.

[jacksonracingcomau]

DOT 4 has a higher boiling point than DOT 3. DOT 3 and 4 are compatible to mix.

Not always
I buy racing brake fluid expensive and higher boiling point than any generic
But it is marked dot 3, not for highway use
Not certain but maybe dot 4 is slightly less hydroscopic, hygroscopic ?
Google probably knows
Compatible yes but wise to flush through with new every change

[SED]

DOT 4 has a higher boiling point than DOT 3. DOT 3 and 4 are compatible to mix.

If this is correct then I have a question.  In the bad old days the rule was you did not use DOT3 in a DOT4 system because it would destroy the seals. My recollection is that DOT4 was designed for brake systems with natural rubber seals.  DOT3 fluid would cause those seals to soften and swell.  This was with old British sports cars.  Has this changed? 

My answer would have been that you could use DOT4 in a DOT 3 system, but not the other way around. 

[Rough Edge racing]

Not always
I buy racing brake fluid expensive and higher boiling point than any generic
But it is marked dot 3, not for highway use
Not certain but maybe dot 4 is slightly less hydroscopic, hygroscopic ?
Google probably knows
Compatible yes but wise to flush through with new every change

 Some DOT 4 fluid is labeled as less hydroscopic than DOT 3..........How many here ride hard enough on the street to boil DOT 3?

[Stevex]

The problem with DOT 5 silicone brake fluid is that it has a tendency to get air entrained in it that is difficult to bleed out. Never shake a bottle of silicone brake fluid, or at least let it settle for 24 hours if you do. I've used it in several applications. As someone else mentioned it sometimes leaves air voids where corrosion can occur.
 Technically all DOT fluids are compatible, thats the definition of the DOT specifications. I would not mix them regardless. If mixed the rating falls to the lowest of the mixed fluid. There are some European hydraulic brake systems that use a type of hydraulic oil, Citroen maybe?

Brian

I have to ask...why would you shake a bottle of any brake fluid?

[Lannis]

I have to ask...why would you shake a bottle of any brake fluid?

You overdid it at a big party the night before?   Otherwise ... ?

Lannis

[Sasquatch Jim]

  And you moderators gripe about click bate threads.  Maybe it is the word oil that causes all the trouble.
 Now for my vote.  Has anyone ever used sperm oil from whales as a brake fluid?  It was once used as transmission fluid in very expensive cars with good success.

 After research I find that until the endangered specie act, spermaceti oil was used as an additive in nearly all
American cars with automatic transmissions.  This was about 1971.

[Psychopasta]

Oh great. Now we have a sperm thread 

[Lannis]

Oh great. Now we have a sperm thread 

Oh come now.   That won't be so hard ....

[ejs]

No clue about whale sperm, but I do like whale meat.  . 

[Sasquatch Jim]

 The oil from a humpie or other whales isn't as good.  In its' day sperm oil was the highest quality available.
 And to be somewhat accurate, we can talk about it cause it is not really an oil.  It is a wax.  At least the stuff that comes out of the whales' head is.  The automotive industry used tons of it and never let on to the American public.
 They had 8 times as many tranny failures after they stopped using it until the wizards invented some high tech additives to replace it with.