Brake fluid upgrade?
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
Ahhh, they DO mix and work. Is it "ideal"? Of course not. Can it be done, safely on public roads? Of course it CAN. An example of what "can't" be done would be mixing of DOT 3 or 4, with DOT 5. That is a mix that can't be done.
I'm curious as to where/how you came up w/the 290* figure...actually all your boiling points. My experience has shown me that those figures depend greatly on the brand of fluid.
.
I'm curious as to where/how you came up w/the 290* figure...actually all your boiling points. My experience has shown me that those figures depend greatly on the brand of fluid.
.
Last edited by Tom400CFI; Jul 12, 2016 at 02:05 PM.
Instructor
Joined: Jan 2016
Posts: 148
Likes: 16
From: Verona KY
Ahhh, they DO mix and work. Is it "ideal"? Of course not. Can it be done, safely on public roads? Of course it CAN. An example of what "can't" be done would be mixing of DOT 3 or 4, with DOT 5. That is a mix that can't be done.
I'm curious as to where/how you came up w/the 290* figure...actually all your boiling points. My experience has shown me that those figures depend greatly on the brand of fluid.
.
I'm curious as to where/how you came up w/the 290* figure...actually all your boiling points. My experience has shown me that those figures depend greatly on the brand of fluid.
.
Burning Brakes
Joined: Nov 2014
Posts: 936
Likes: 51
From: Post Falls ID
Dot 3/4
Just to chime in because the thought crossed my slowing mind -- my 1984 Honda Sabre V65 required DOT4 in the cluthc and brakes. My 1986 Corvette, DOT3. It's not that they didn't know about it, just that it didn't matter. I think the Corvette could easily make temps higher than the Honda ever did.
*shrug* So I have DOT 3 and DOT 4 in my garage. Even though I don't have the bike any more.
*shrug* So I have DOT 3 and DOT 4 in my garage. Even though I don't have the bike any more.
Drifting
Joined: Sep 2014
Posts: 1,579
Likes: 59
From: Trieste Italy
While you can mix DOT3 and DOT4 fluids, it's not really a good idea to do so. The primary difference between the two fluids is the temperature where the fluid will boil in the system. Both DOT3 and DOT4 fluids by brand have temperature ranges for wet and dry boiling points that can vary as much as 50-100 degrees. DOT4 fluids will boil at a higher temperature compared to a DOT3 fluid. DOT4 fluids also tend to be more "hydroscopic" in that they can absorb moisture at a quicker rate.
I have been using ATE TYP200 DOT4 fluid in my autocross/track day car and it seems to work well (for me!!). This fluid has a wet boiling point of 392 degrees. By comparison, MOTUL 600 has a wet boiling point of 421 degrees (all values are Fahrenheit). A good DOT3 fluid like Castrol LMA has a wet boiling point of 311 degrees and the Ford HD Motorsports fluid has a 290 degree wet boiling point.
The factory fill for brake fluid in Corvettes has always been a DOT3 fluid. Which is fine for normal driving and even some "spirited" driving. But if the car gets aftermarket brake upgrades that will produce higher braking temps in the pads and rotors, or if the car sees a lot of autocross and track use, it's a very good idea to go with a DOT4 fluid. But that does mean a complete flush of the old DOT3 fluid and replace with a DOT4 fluid.
There are some cars that have DOT4 as a factory fill but they are typically very high performance cars like the "exotics".
I have been using ATE TYP200 DOT4 fluid in my autocross/track day car and it seems to work well (for me!!). This fluid has a wet boiling point of 392 degrees. By comparison, MOTUL 600 has a wet boiling point of 421 degrees (all values are Fahrenheit). A good DOT3 fluid like Castrol LMA has a wet boiling point of 311 degrees and the Ford HD Motorsports fluid has a 290 degree wet boiling point.
The factory fill for brake fluid in Corvettes has always been a DOT3 fluid. Which is fine for normal driving and even some "spirited" driving. But if the car gets aftermarket brake upgrades that will produce higher braking temps in the pads and rotors, or if the car sees a lot of autocross and track use, it's a very good idea to go with a DOT4 fluid. But that does mean a complete flush of the old DOT3 fluid and replace with a DOT4 fluid.
There are some cars that have DOT4 as a factory fill but they are typically very high performance cars like the "exotics".
Last edited by Christi@n; Jul 12, 2016 at 06:29 PM.
Melting Slicks
Joined: May 2013
Posts: 2,692
Likes: 349
From: Sacramento California
If you spend the time to change the master fluid, spend a little more time and just bleed the whole system properly. Small price for getting a long life from your components, and peace of mind that the job is done right 
I do mine once every 2 years, which is fine considering I don't really push the car hard very often. The fluid has a medium color after 2 years but not dark.All brake and clutch fluids in all my vehicles have been bled with Valvoline synthetic DOT4 brake fluid and I have never had any problems, regardless if there was DOT3 in there before. I will note here that it is extremely rare that I push my brake systems. I just bled the systems thoroughly with new synthetic DOT4 and called it a day. I can't see anything more than synthetic DOT4 would be needed unless you have a hardcore racing application, or just prefer to use exotic fluids in your street car.
Last edited by DGXR; Jul 12, 2016 at 06:49 PM.
Instructor
Joined: Jan 2016
Posts: 148
Likes: 16
From: Verona KY
Tom
The 401*F boiling point for DOT3 and the 446*F boiling point for DOT4 are the minimum dry boiling point temps in listed FMVSS 116.
There's an engineering term for the lowered boiling point when these fluids are mixed and I can't remember it.
Leland West Insurance Company (underwriters for enthusiasts) has a comprehensive brake fluid brand/type comparison chart on their website. www.lelandwest.com
Suzuki XS11 enthusiasts have a good bit of info on fluid types and usage listed their website also. www.xs11.com
Hope this helps a bit.
Jonathan.....
The 401*F boiling point for DOT3 and the 446*F boiling point for DOT4 are the minimum dry boiling point temps in listed FMVSS 116.
There's an engineering term for the lowered boiling point when these fluids are mixed and I can't remember it.
Leland West Insurance Company (underwriters for enthusiasts) has a comprehensive brake fluid brand/type comparison chart on their website. www.lelandwest.com
Suzuki XS11 enthusiasts have a good bit of info on fluid types and usage listed their website also. www.xs11.com
Hope this helps a bit.
Jonathan.....
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
Tom
The 401*F boiling point for DOT3 and the 446*F boiling point for DOT4 are the minimum dry boiling point temps in listed FMVSS 116.
There's an engineering term for the lowered boiling point when these fluids are mixed and I can't remember it.
Leland West Insurance Company (underwriters for enthusiasts) has a comprehensive brake fluid brand/type comparison chart on their website. www.lelandwest.com
Suzuki XS11 enthusiasts have a good bit of info on fluid types and usage listed their website also. www.xs11.com
Hope this helps a bit.
Jonathan.....
The 401*F boiling point for DOT3 and the 446*F boiling point for DOT4 are the minimum dry boiling point temps in listed FMVSS 116.
There's an engineering term for the lowered boiling point when these fluids are mixed and I can't remember it.
Leland West Insurance Company (underwriters for enthusiasts) has a comprehensive brake fluid brand/type comparison chart on their website. www.lelandwest.com
Suzuki XS11 enthusiasts have a good bit of info on fluid types and usage listed their website also. www.xs11.com
Hope this helps a bit.
Jonathan.....
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski