Brake fluid for racing

Tim M

Tim M

PRESIDENT, Member # 015
GCC Member
Location
St. Charles
First Name
Tim
Last Name
Mauldin
This has been mentioned before, but thought it worth repeating. In case you are thinking of track time this year, it would be a good idea to know your brake fluid. I have learned a lot, over the past two years because I had to learn from the installation of my electric brake system. See the attached links for detailed explanations of each type of fluid:

http://www.superchevy.com/technical/chassis/brakes/0509sc_fluid/index.html
http://members.rennlist.com/911pcars/brakefluid.htm
http://www.timskelton.com/lightning/race_prep/brakes/brake_fluid.htm
http://www.afcoracing.com/tech_pages/fluid.shtml
http://www.trackpedia.com/wiki/Brake_Fluid#Referenced_material

There are many cons to using Silicon brake fluid, however, this is what was suggested for me to use in my system. I have, and since I have sealed all the leaks, I do not experience brake fade, spongy pedal or other issues mentioned in the articles above. However, I would not suggest you use it in your standard systems. Some of the experts and track guys may want to chime in here, if I were taking my car to the track (road courses) I would be changing my brake fluid EACH time BEFORE I went. Don't go to Wal-Mart or Autozone and buy the cheap stuff either. Old Dog's and other race shops sell a Willwood that is very good, high boil point but is rather expensive. If I do a lot of track time, I will be switching to this. For those just driving on the street, change your fluid once a season I would think. Remember, the DOT 3 and 4 fluids you have in your system draws moisture. This could become a problem even on our spirited cruises.

Just some food for thought as the driving season is fast approaching.
 
OK -this will be year #3 for me. So, I guess I'll have the system flushed. I can go to Old Dogs and get the Wilwood stuff. How much should I buy?
 
4 bottles if you're going to do a complete system flush, but, if you have someone do it for you, they will be able to get it as part of the flush.

Wait until maybe Dean, Kerry or Tom weigh in though.
 
Willwood 600 EXP is the stuff you need. You could probably get by with Willwood 570, which is about half the price. I always make sure there is fresh fluid in the caliper before event track day. The other component here are your brake pads. Fluid can only do so much. I would suggest trying the fluid and if you have fade late in the session meaning that you have good pedal pressure but just don't stop as well, then you need a more aggressive pad. I usually switch from street pads to race pads and back again for daily driving. Race pads are always dusty but they will work when they get hot. They don't work well when they are cold so not appropriate for street driving. You can probably get by just fine with just switching the front pads first.
 
your local ford dealer should have dot 4 ( alot less $ then some others and just as good ) - the destroyer of fluid is moisture - fords dot 4 was requirement in svt cobra's - brake flushing is a good idea and really was never done to much until ABS came about and many learned the hard way that moisture can be deadly on valves in these systems. If you have been running dot 3 or 4 I would not switch to silicone - have heard some leaks may result
 
DOT 4 can cost as little as $3 bucks a quart to $50 a pint. It is all about the wet boiling point. It really needs to be pretty close to 600 degrees. I don't think the Ford dealer sells this type of fluid. It will cost you almost $20 a pint for what you need. If it is under $15 a pint, you aren't helping the problem. The exception might be, as I mentioned, the Willwood 570. It is a little cheaper than the other race fluid but it should be good enough for a track day.
 
The dot 4 that ford has has a very high boiling point ( blue in color ) what lowers the boiling point on old fluid is moisture - if your system is up to snuff dot 4 should be plenty good - we sold many cobra's and 4 GT's and had to have this in stock to service them. I am very famillar with wilwood fluid 600 stand for 600 degree dry boiling point and does exceed that fords came in around 580. All the pro-stock nhra cars that gateway race cars built only ever had 1 brake problem - due to 1 knuckle head had to have a chrome master cylinder and created problem where pistons in master cylinder did not come back all the way back and clear ports - his 1st clue was very hard to bleed - second was when he staged car and looked at presure guage everything was fine, made a pass and bingo - guage showing presure with no foot on brake after a run due to brake drag . I would say no to some of the off the shelf fluids out there - you get what you pay for. 1 other guy switched to silicone fluid after having reg fluid and had lamb calipers seeping - we flushed system and replace seals ( square in shape ) on front pistons and put back in dot 4. I have seen rotors glowing red after a run and no brake presure problems - so if you want to spend the $20 a bottle stuff and you really think you need it go for it - but remember brake fluid of any brand attracts moisture and that what lowers the boiling point. tim what you will feel is lose of peddle when this happens ( fluid boiling and presure down due to the bubbles )- fade is when you have peddle and you have to stand on them due to pads not grabbing rotor surface. Another misconception brakes will grab better on a freshly machined surface this is not the case, better on smooth worn surface due to the pad contacting more material. And when you have your calipers off make sure the slides are not sticking. If they are clean and put back with high temp anti-seize lube.
 
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Thanks for the info. I wasn't aware of that fluid from Ford. That is a pretty high wet boiling point. I totally agree with you, that should be good enough for any of us. I just prefer Willwood or Motul. The cool thing about the different colors is that you can see when your new fluid arrives at the caliper! I can say that if you can have problems with brakes, I have had them.

I would say that it is the boiling that causes a soft pedal. Fluid boils becuase of the increased moisture which lowers the wet boiling point. I would rather spend $20 on brake fluid to get something I trust than to run the risk of a soft pedal which could make my very precious day at the track less enjoyable. Yeah $20 bucks is high but it is cheap insurance to never have brake pedal issues.
 
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WOW this is a great thread. You guys are WAY over my head. It sure is nice to have this kind of knowledge in the club & especially from the great people we have in this club. MODERATOR if you deem this post off topic feel free to delete.
 
All of the above true. My experience with Silicone. I used DOT 3/4 and had no leaks and no issues UNTIL the pump motor stopped. The reason it stopped, the DOT 3/4 had carried some dirt and moisture in to the motor. Since the motor has a couple of small ball bearings to pump the fluid, they seized, giving me true manual brakes. When I called them about the motor seizing, they asked if I was using DOT 3/4 and suggested I switch to DOT 5, which I have. I did have leaks once I switched to the DOT 5, but have gotten than fixed. Also, the DOT 5 doesn't eat paint. I found the DOT 3/4 will eat the powder coat off the frame :( The DOT 5 has no Wet boiling point as it does not attract moisture. I have not noticed either condition of brake fade or grabbing and have only good things to say so far about the DOT 5 fluid. I now have an inline filter on the return of the brake fluid back to the motor and wonder if I could now use DOT 3 or 4.
 
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Dean you refer to it as wet boiling points - never heard that always rated as dry boiling point. 1 of the best tools you can own to see if by chance you have a dragging brake is one of those infred temp guns - make hard run and stop then check side to side, shoot caliper and you will see not even close to 600 degree you might see 400 - just checked my normal fluid I use for pass cars and its rated at 510 and spec made for abs brakes has some sort of drying agent additive in it for protection
 
I changed to EBC "red stuff" pads last year along with Willwood fluid on Dean's recommendation. There was a HUGE difference! After doing this I would say the first place to upgrade for the track is brakes not HP. Also on Dean's suggestion I bought cheap, clean fluid to flush the lines before I added the Wildwood, just fyi.
 
That is true, however, good to know the WBP because, as you said, DOT 3/4 will attract moisture. For instance, in the link I referenced, look at the DBP on the Performance Friction Z-Rated - 550 degrees - really good, but, look at the WBP - 284. Which tells me, if this brake fluid had moisture in it, or if the lines had moisture in them, the results on the track wouldn't be so good, would it?
 
You're right, however, what happens when you take the lid off your master cylinder? You have now opened your system. I realize not much get's in this way, but it can happen if you forget to put it back on. Don't ask me how I know :rolleyes: I think the point here SHOULD be:

1) Buy a high quality fluid, especially if you're going to be on the track - drag or otherwise
2) Whatever the DOT rating (excluding 5 here) make sure the boil temp is high enough to handle the temps, my opinion is get one that holds up both dry and wet.
3) If you've never put in a high temp 'racing' fluid and you plan to get on the track, please do so before you get on one (road course/autocross).

Just wanted to make sure us newbies had the info necessary to get on the track safely. Expect some input from Paul, Tom, Dean, and Kerry :)
 
I can't say what the industry standard is but I have 1000's of miles on the track. Here is what I believe to be true. Real racers want a high dry boiling point. Why? because they change their fluid after every drive and never have the fluid in the car long enough to draw moisture. Street cars need to focus on wet boiling points due to the fact that most street cars very rarely change their fluid. Wet boiling point is measured with 3% water in the system. Most passenger cars will have some nominal moisture. Even given that, it really doesn't matter because most street cars are not driven hard enough to ever really test the fluids capacity to perform.

Here's where that leaves us. In a performance street car that might see an occasional track day you are going to need both a high wet and dry boiling point for optimum performance. I am not willing to bet that I have all the air out of my reservoir or that my fluid is brand new out of a fresh can. In most cases the techs will open your reservoir to check your fluid anyway. It is easier and cheaper for a manufacturer to engineer a high boiling point with less concern about how rapidly it will attract moisture or in other words the wet boiling point. The higher the ratio between a wet and dry boiling point, the lower the likely hood you will boil the fluid, creating an air pocket and a soft pedal. (assuming you start with a high dry boiling point.)

http://www.afcoracing.com/tech_pages/fluid.shtml

I am a student of the game so if this isn't correct, I am would like to know.
 
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