corvettedave383

i have wilwood alloy master cylinder, wilwood alloy 6 pot calipers front and rear, using steel brake lines, do some track days aswell, whats the best grade to use, dot 4, dot 5 etc??

REELAV8R

Dot 3 originally. There is a dot 3/4 that will work as well and I use.

If you want plenty of info on dot 5 and 3/4/5.1 compatibility read here;

http://www.buckeyetriumphs.org/techn...luid/Fluid.htm

Much more info than most want but it does answer some questions.

corvettedave383

ahh thanks , great info

GUSTO14

Here's a pretty accurate chart that shows the major differences in brake fluids regarding boiling points, a critical factor particularly in vehicles that will see track time. A major factor affecting boiling point is how much moisture is contained in the fluid. It's critical enough that many DOT 3, 5 and 5.1 fluids have a disclaimer on the container warning against using it from a previously opened container. (A warning that is routinely ignored I might add.)



DOT 3, 4 and 5.1 are glycol (mineral) based fluids. They have an affinity for moisture which means they absorb it quickly when exposed to it including moisture in the air. DOT 5 is a silicone based fluid and has no affinity for moisture and will not absorb it from the atmosphere. It is recommended that glycol based fluids and silicone fluids not intentionally be mixed.

My personal preference is to use DOT 5 (silicone) fluid in my non-ABS vehicles, and DOT4, racing fluid for my ABS equipped vehicles.

Good luck... GUSTO

0Todd TCE

Here's a link to the most comprehensive fluid list I know of.

BRAKE FLUID FOR DUMMIES

gkull

I use Ap Racing 617. I used to use motul

gkull

I think wilwood has a 600

0Todd TCE

One thing I failed to mention: there's often confusion regarding fluid and what makes it 'better'. The better is about temperature, not function.

One brand or grade will NOT make your car stop any better. It's simply how durable it remains at extreme uses or neglect from contamination....

"If you don't boil what you use now...you don't need higher boiling point fluid" Still true today.

fishslayer143

DOT 5 is not compatible with any other fluid or OEM rubber lines

gkull

Just go get something around 600 degree and as part of your race prep pull all 4 tires and bleed each caliper until the fluid is clear

Even with my aluminum hat rotors it transmits lots of heat to the wheel bearings. I use hi temperature disk brake wheel bearing grease. Right now it is the 500 degree drop temp kind

ddawson

If you want to switch to DOT5 how do you clean the system enough to make the change?

GUSTO14

Daniel, I've always done this when installing new calipers or wheel cylinders and most of the time a new master cylinder. This simplifies the process significantly, and I utilize Corning manufactured DOT5 (silicone) fluid.

I start by removing the old calipers and leaving the lines open. If not using a new master cylinder, I begin by flushing the old one with isopropyl alcohol, blowing that out and finally flush it with DOT5 fluid. I also disconnect the lines when possible from the master and blow them out with low pressure air, followed by reconnecting and flushing them with DOT5 as well. Connect the new calipers and or wheel cylinders and bleed the brakes normally. Once I've bled the brakes to my satisfaction, I will come back a day or two later and bleed them once more.

When bleeding brakes with DOT5, bleed slowly to avoid aerating the fluid as it takes longer for air bubbles to dissolve in DOT5 than glycol based fluids. This is the primary reason I re-bleed them a day or two later.

In order to gain the most benefit from switching to DOT5, it is important to remove as much of the glycol fluid as possible from the entire system. Any old residual glycol will contain moisture which can lead to corrosion and compromise the main benefit of switching to DOT5, which is to avoid corrosion. Having said that, this method has worked for me every time I have done the switch. I have never had any subsequent issues with moisture related corrosion or incompatibility issues of DOT5 that may have come in contact with residual glycol fluid. Then again, I may just be darn lucky.

If you are unable to start with new calipers (or wheel cylinders) you will need to disassemble and clean them thoroughly of any glycol fluid. Since you will more than likely find evidence of moisture related corrosion, having some rebuild kits on hand is very helpful.

Good luck... GUSTO

USAFVeteran

I run DOT 3 in my diesel truck that pulls a 15,000lb toy hauler, in my 69 Corvette, my wife's car, in the sand car, and in the motorhome. I've never had an issue in any of these

cagotzmann

Save yourself the trouble of going DOT5 (silicon based). I don't think there are any extra benefits vs Dot 4 or other fluids (higher temp ratings) in glycol based fluids. As for the moisture absorption issues with these fluids most tracks for track days may have rules that your brake fluid needs to be flushed within a 6 month period prior to the event. This should be part of your track prep tasks anyway.

jimvette999

"DOT5
DOT5 brake fluid is also known as "silicone" brake fluid.

Advantages:
DOT5 doesn’t eat paint.
DOT5 does not absorb water and may be useful where water absorption is a problem.
DOT5 is compatible with all rubber formulations. (See more on this under disadvantages, below.)

Disadvantages:
DOT5 does NOT mix with DOT3 or DOT4. Most reported problems with DOT5 are probably due to some degree of mixing with other fluid types. The best way to convert to DOT5 is to totally rebuild the hydraulic system.
Reports of DOT5 causing premature failure of rubber brake parts were more common with early DOT5 formulations. This is thought to be due to improper addition of swelling agents and has been fixed in recent formulations.
Since DOT5 does not absorb water, any moisture in the hydraulic system will "puddle" in one place. This can cause localized corrosion in the hydraulics.
Careful bleeding is required to get all of the air out of the system. Small bubbles can form in the fluid that will form large bubbles over time. It may be necessary to do a series of bleeds.
DOT5 is slightly compressible (giving a very slightly soft pedal), and has a lower boiling point than DOT4. DOT5 is about twice as expensive as DOT4 fluid. It is also difficult to find, generally only available at selected auto parts stores.
https://oldihc.wordpress.com/2012/11...t-brake-fluid/

As GUSTO14 stated should be quite adequate and was how I did it...
fwiw...I use DOT 5 in my vette for the past 25 years and my Vmax motorcycle for the past 18 years without 1 problem. I'd use it in my other rides but they're anti-lock....in those I siphon and refill the reservoirs once every couple of years to get rid/reduce the water that's been absorbed.
Jim

corvettedave383

thanks guys, great info

C3 4ME

Just bought DOT 5 at today at my local Napa, for $25 for a quart. I've been running DOT 5 in my Corvette for the 11 years I've owned the car and wouldn't change it. Nice firm brake pedal and no chance of ruining paint when I've got brake lines open as I did today.