Brake Fluid Type?

Okay, the 73T is all restored and I want to pamper the thing. So, I am looking at using the best brake fluid, especially to hold me up in crazy Atlanta stop and go traffic. ATE Blue Racing is a bit more money then the Castrol DOT 3/4/5 brand but the blue certainly has the appeal for greater durability and is least to absorb water. Any comments on just what is the best fluid for these "S" calipers.

Thanks
BR
'73 "T"

Well, I don't know anything special, but I thought DOT 5 is silicon fluid. I'd heard this is not good for your system. Just heard it the other day again, from a performance car shop mechanic who had recently gone to brake school.

I am just about to put the fancy Ford stuff in my car. Five hundred and some degrees dry boiling point. Wet figures like the others (385 or something...). I'd be putting Blue in it, but I can't seem to find it around here when I go looking.

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'83 SC

DOT 5 brake fluid isn't necessarily silicon fluid (which I too have heard is no good).

I think there's something called ATE Super Blue DOT5 which is conventional brake fluid suited for Porsches.

Anyone with strong knowledge on this subject?

In a recent tech session, the mechanic told me to use only Dot 4 fluid. Dot 3 absorbs too much moisture. I don't remember the reason for not using Dot 5. But that's what he said.

DOT 5 brake fluid is silicon based. It is NOT compatable with systems that haven't been thoroughly cleaned of any trace of hydrophilic fluids. DOT 4 and 3 are glycol ether/ester based. The difference in 3 and 4 is the wet boiling point (higher on 4). Many racers use a DOT 4 brand from France called Motul. It runs about $8.50 a quart. The problem with silicon is that it is not compatible with water. Water WILL get into the system, and when it does it will pool and cause corosion. The only application I know of for DOT 5 is Harley Davidson Motorcycles, and we all know how reliable they are.

Thanks. I see ATE Super Blue Racing advertised in Automation as well as Automobile Atlanta. Their is also a ATE SL.
I am not sure if the ATE blue is a silicon based fluid and will find out. But if so, I believe the DOT 4, especially Castrol LMA (Low Moisture Activity) brand is the one I will go with.

BR

ATE blue is NOT silicon based and is fine to use in your car.
In fact, its quite popular with the P car crowd.

ATE blue is also available as ATE gold. The idea is that you alternate when changing the fluid ie if you have "blue" installed when it's time to flush the system you go to "gold" and that way you can tell when the fluid being bled out changes from blue to gold that you have all the old fluid out.

Charlie '87 Carrera

If you 'only' bleed the system by suctioning the rservoir, topping up , and bleeding, you are not changing the majority of the fluid in the calipers ... all you are doing is putting new fluid in the lines and master cylinder ... just think about the 'old' fluid sitting there in the caliper!

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Warren Hall
1973 911S Targa

Warren,

Then how do you get the old fluid out of the caliper? I thought that if you open up the bleeder screw and pump, was how to flush the fluid. Is there a different method?

Just my experience,
but I recently rebuilt the front calipers on my car. They had not been rebuilt in many years (if ever?), but I do regularly flush my fluid, using the standard "pump the pedal" method.
I didn't notice any problem with the fluid that came out of the caliper. It seemed pretty clean to me, it didn't appear that old fluid was building up in there.
Just my experience.

I remove the lines from the calipers with flare-nut wrenches, unbolt the caliper from the suspension, remove pads, remove bleeder nipple, and drain all of the old fluid out into a pan or bucket. After thoroughly cleaning the caliper with 'Brake-Kleen' or a similar solvent, reinstall caliper and pads, and proceed with the flush & bleed.

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Warren Hall
1973 911S Targa

How can you tell if your brake fluid is silicon or glycol based?

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Bill Krause
'79 911SC Euro

Well, if it 'smells' like a cross between ether and alcohol, it isn't silicone!

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Warren Hall
1973 911S Targa

This brings up the question of the best "bleeding method". I used to pump but now I feel that the vacuum type hand held units may be better because it forces more out at a faster rate; therefore, getting more paticulate or condensation out from the lines. How can that go wrong? But.....with the "S" caliper dual bleed lines which one do you do first? inner or outer?

BR
1973T

I too have graduated to the vacuum bleed method and I like it better, mostly because it requires no assistant. I have heard that the best method is where you pressurize the top of the MC reservoir, which pushes the fluid through. But again, the vacuum tool costs only about $25, works very well and can also be used for other purposes (testing vacuum-actuated devices like advance, retard, decel valves.....).

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'83 SC

I just bled the brakes using the vacuum bleeder MityVac. I was able to do it alone, but it was extremely tedious. I had to keep refilling the reservour over and over again. Took me 2 hours or so. Now I found out there's an inexpensive pressure bleeder available that should make the job a lot simpler. Check out http://www.motiveproducts.com

Boris
'87 911 Carrera 3.2

There is also something called the EZ Bleeder that uses the spare tire to pressure the system, a cap for the resevoir, and a quart plastic bottle. Imported from England and sold by a company in Florida. About $35 when I bought mine a couple of years ago. Works fabulously. Easy and quick, but you do have to remember to air the spare when done.
I will try to find phone number and web address. Search engine will find it also.
This does not address years of neglect and crud in the calipers. But flushing the fluid regularly is recommended for all brake systems.
David

Has anyone tried the new Valvoline SynPower synthetic brake fluid? It is supposed to exceed all DOT 3 and DOT 4 specs. It is also supposed to be compatible with all conventional brake fluids!

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Warren Hall
1973 911S Targa

[This message has been edited by Early_S_Man (edited 11-03-2000).]

i use the Valvoline Synpower synthetic in all my cars. recommended highly!

i also use the speed bleeders to bleed the brakes... i've got it down to 45 minutes for all 4 wheels with no outside help from anyone else.

obin