Let the debate begin!

There seems to be a number of posts lately that talk about calipers, lines, MC and other parts that leak but no one discusses the fluid.

It's my understanding that we're supposed to flush our sytems yearly. Does anyone do this?

Further, i understand that DOT-5 fluid (silicone brake fluid) should eliminate the need for flushing and eliminate brake line corosion. Anyone refute this?

It seems to me that, other than higher cost, I've never heard a reason not to switch to DOT-5. Does anyone know of any?

Last, where does DOT-4 fit in. I see it listed as "Heavy Duty." What's the diff? Higher boiling point? Does this matter?

As I said at the start, let the debate begin!

 

DOT 5 does not eliminate corrosion, even though it's not hygroscopic if water gets into it it will sink to the lowest point, your calipers and will cause rusting. Also, the pedal feel is reduced with DOT5. DOT4 has a higher dry & wet boiling point (so vapors will only be formed at higher temps > better brake pedal feel) than DOT3. Wet BP is the BP when contaminated with water. I prefer DOT 5.1, 'highest dry & wet boiling points but expensive and can be hard to find.

To sum it up the advantages to silicone fluid (DOT5) is it doesn't attack paint & it is not hydroscopic (doesn't absorb water)

Disadvantages:
compressible at high loads (near BP)
water puddles in system
can be a PITA to bleed
expensive

 

Oh and there used to be problems with the sealing of o rings w/ DOT 5, there were problems with the swelling agents, I'm not sure but most likely this has been cured by now.
Some good fluids are:
FORD HD
Castrol SRF
Motul RBF 600
Motul Racing 600
AP Super 600
NEO synthetics Super DOT 610

 

As always, thanks for your input TT. It never occured to me that being hydrophobic could cause issues. If the system is closed though, how could water or condensation enter? I would expect some accumulation with a hydrophilic liquid but not a hyrophobic one.

 

I'm in the planning stage right now for a winter replacement of my braking system. I had planned on switching over to DOT 5 for maintainence reasons. Now it sounds like that may not be the best solution...

Suppose I want a good compromise fluid (lowered flush frequency, average feel, average temp tolerance, etc.)...what would be a good choice for the lazy enthusiast?

 

As said above:


Disadvantages:
compressible at high loads (near BP)
water puddles in system
can be a PITA to bleed
expensive

compressible: not that great for racing use... (how are you driving your car??)

water puddles: have not heard of this, cannot comment..

bleeding - I did not have any problems

expensive - well, it's probably good for three years, so what ? $40 vs $10 every three years ?

It does not eat paint, that's a very good thing !!

I use it only for a few months myself, a friend of mine uses it for 10 years with the same set of calipers and as far as he can remember he never even flushed it... he drives his Vette only 1000 miles/year and never had a break problem since he installed the brakes and changed to silicone fluid ten years ago. It was his experience/advise that made me use it. If my breaks also last ten years then I'm happy...

 

Redvetracer said something awhile back that made an impression on me. He said something to the effect of "look at what professional drivers use." Although DOT5 may work well in a lot of applications, I want the best performing system I can have, even if it involves a little bit more maintenance. For me, DOT3/4 makes the most sense because it's much cheaper and all my family's other cars use it too.

DOT3 and DOT4 will mix fine, DOT4 being the better of the two. I like using DOT4 because it makes me feel better, even if the gain is marginal. (Cost difference between 3 and 4 where I am is about $.20/quart) DOT5 must be used separatly, and I think many recommend replacing the entire system with new components to switch.

EDIT: I was just thinking, why does DOT5 not necessitate flushing as often? I would think that the same contaminants that get into a DOT3/4 system would just as easily get into a DOT5 system?

 

Found this info (I modified the chart a bit for easier understanding....I hope ):

[From Hackney:] The "Estimated BP After 6-months" column is estimated based on a page I found that says brake fluid gains about 3.5% moisture per year, which is where the wet boiling point is measured.

Assuming linear degradation this column is where you'd be. The last two columns may be confusing. They're the price per ounce, divided by the degrees F the fluid exceeds the dry or wet DOT spec; sort of a price for performance number where lower is better. Yeah, I'm an engineer.

FWIW: My conclusion: ATE Type 200 and Super Blue are not only the cheapest of the performance brake fluids, they are also the cheapest per degree of boil protection, and have a very high 6-month BP estimate. In addition you can alternate with each change and the color difference will tell you when you're done. [Note that ATE Blue is not DOT-approved because of the color.] ATE and some of the higher-performance fluids are available from ogracing.com. Valvoline and Castrol are commonly found in mass merchandisers.

Conversions: F = (C x 1.8) + 32
C = (F - 32) x .5555




Fluid 1)Dry BP
2)Wet BP
3)Est. BP after 6 months
4)US $/oz
5)US $/oz per °F > DOT4 (#5 has the a and b)

----------------(1)..(2)..(3)............(4).......(5a) Dry..(5b)Wet
Castrol SRF.......590 518 554........$2.076....$.0144.....$.0100
NEO Super DOT..585 421 503.........0.983.....,0071.......,0089
Motul Racing......600 585 421 503...0.712.....,0051.......,0065
Motul DOT 5.1....509 365 437.........0.675.....,0107.......,0125
ATE Type 200/ATE
Super Blue.........536 392 464.........0.295.....,0033.......,0036
Valvoline High
Perf Synpower....513 333 423.........0.16.......,0023.......,0073
ATE SL..............500 329 415
Castrol LMA........450 311 381.........0.219.....,0547.........n/a
DOT 5 Spec........500 346 423.........n/a.........n/a...........n/a
DOT 4 Spec........446 311 379.........n/a.........n/a...........n/a
DOT 3 Spec........401 284 343.........n/a.........n/a...........n/a

 

Read this too:

http://www.babcox.com/editorial/bf/bf40142.htm

 

Ihave used silicone Dot-5 on everything from a Boss 302, Harley Davidson, Ford Ranchero to a half dozen Corvettes over the last 20 years. All I can say is that it has been absolutely trouble free to include 3 years of autocrossing a 1973 Corvette.

I have never had any significant, if any at all, trouble bleeding the brakes. If you have power brakes, you will probably not notice any difference at all in the pedal. With manual brakes it may not be as hard as good as high-performance hydraulic fluid, but again I've not experienced any problems. The Boos even sat for more than a year a number of times, the 1973 for three years once and always had a good pedal with no leaks.

I primarily switched to reduce maintenance on my brake systems on vehicles I don't drive every day. It has met all my expectations.

Having said all that, I would not use it on a serious racing vehicle because it will expand if the brakes get really hot and due to the closed system increase pressure and begin to apply brake pressure. This is the primary reason that it is not recommended or used in racing vehicles.

I have found the best procedures for using it is to flush the system well; I use isopropyl alcohol, and then flush until clean silicone fluid comes out. Then bleed normally. Silicone does aerate easily, so I pump slowly when bleeding. I bleed them again a day or two later and the results have always been satisfactory. Most important of all, I've never had a compatibility problem or a corrosion problem with any of the vehicles.

Bottom line is it has worked for me for more than 20 years and I will continue to use it whenever it makes sense to me to do so.

GUSTO

 

Valvoline SynPower DOT 4. A synthetic DOT 4 brake fluid available at AutoZone. Cheap and effective. Higher boiling point and lower moisture absorption. Perhaps a good compromise.

http://www.valvoline.com/pages/produ...asp?product=51

 

Sorry but, I'll just stick with Ford brake fluid, the same stuff that won LeMans in the GT40 and MKIV "wondercars" of the 1960's (210+MPH down the Mullsane Straightaway for 24HRS without failing.) Henry Ford II spent a lot of Ford's money on the LeMans project and I'll gladly pay the $3-4 for a can of his "trick" brake fluid. Ford fluid is the BEST even though it's only a DOT3 rating, due to it's poor Wet boiling point number BUT fresh and "dry" without water in it it will go to 575 degrees "dry" boiling point and if you flush it out every 2-3 years it will be in a "dry" condition. We used Ford Fluid in our J-56 equipped 180MPH Trans Am Vette and it worked well. Wilwood and Performance Friction actually buy the Ford brake fluid in a re-packaged can and sell it for between $6-9 a can (all you have to do is look at the wet/dry boiling point ratings on the re-packaged fluid and see for yourself that it is the same a the Ford fluid, the same container even!) Go ahead and buy the Motul, Castrol, (whatever) fluid, I'll buy a better set of tires with the money I saved and beat you with them!

 

i like the castrol dot 4 LMA formula

 

They don't sell the Ford HD fluid here, I'm stuck with Catrol SRF but what the hell, t's only a few $ a can.

 

The point about Ford brake fluid is pretty well know around the racing community here in the Detroit area. I've heard it for years and know a ton of people who use (yes, in their Chevy's) it and swear by it.

Old Henry put a ton of cash into the GT40 program. No stone was left un-turned to win that race.

 

Do yall have a part number for the ford stuff?

 

My understanding was that the Ford fluid absorbs water much more easily than other performance fluids. So it is excellent for racing where you change the fluid all the time, but not as good for regular use.

 

C6AZ-19542-AB and described as "High Performance DOT3 Motor Vehicle Brake Fluid" on my can. BE SURE the can lists the dry boiling point at 550 degrees. My stock is old (but it is very well sealed) I bought a crate of it from a dealer auction of a failed Lincon Mercury dealership about 8-9 years ago (paid $2 a con for it!) 3 cans should fill a "dry" brake system with new dry calipers, master cylinder, hard lines and hoses.

 

VBP sells it, too.

 

So if I am reading this right, if I have been using DOT 3 and want to move to DOT 4 it would be ok?