replace dot 4 with dot 5

I'm using Dot 5 in everything. Should not be a problem for you. Just do it.

I am kind of surprised to hear that from you PD. DOT5 was originally tried in hill climb cars. They liked it because the higher boiling point...They soon found it's limitation...Water.

Since DOT 5 is non-hygroscopic it did not absorb water which meant...it settled out of the system in the low spots which is the calipers. It was a short lived experiment as brake failures occurred in the people who tried it.

A hygroscopic fluid can take a teaspoon of water, spread it through the system and it will not have enough in the caliper to cause a problem. One drop of water in a non-hygroscopic system will eventually collect in the low spot; the caliper. There is almost always moisture in suspension of anything exposed to the atmosphere; which it is when you fill the system or open a bottle.

Brake fluid is suppose to be changed or flushed every 2 years or so. Who does? Very few of us do, and we know it is the truth, yet how often is it a problem? It is common to have a 30 year old car where the fluid has never been flushed and it is still performing. Not ideal but common.

Synthetic on the other hand is suppose to be flushed every year --and-- if you track it or drive it hard say in the mountains, it should be flushed before every event (if allowed).

I have read several articles in HOT ROD, Popular Hot Rodding, and even Street Rodder. They all suggest the DOT 5 only be used for cars rarely driven, show cars, non performance cars that never get their brakes hot. And even at that they suggest periodic checks of the calipers for early corrosion.

I can honestly tell you that I use it on all of my cars and have for 30 years.

In all that time I have had zero failures.

The moisture absorption into Dot 3 and Dot 4 brake fluid here in the NE is horrendous.

It contributes to the rust through on standard steel brake lines also. Most of my cars have been converted over to stainless hard lines though as well.

I personally think that it contributes to the pitting of the brake caliper pistons. Th Dot 5 does not.

I would think that if you are absorbing moisture into a completely sealed system, the system isn't completely sealed.

It isn't a bad idea to bleed your system every so often either.

From me you will hear nothing of the horror stories of using it.

By the same token, I have had nothing but bad luck with MSD ignition systems. Others have had the opposite.

I suppose in the universal balance of things this is necessary to protect the stability of the Universe? Equilibrium must be maintained? Ying and yang?

It seems to give a better pedal feel also.

So am I Ying or Yang?

Take your pick. I don't care which one I am.

No one's mentioned the fact that DOT 5 (silicone) brake fluid is more compressible than DOT 3, 4 and 5.1 brake fluids. You certainly wouldn't want to use it in your Pantera's hydraulic clutch system, where we need as much clutch release as possible. It will also attack natural rubber seals. Accordingly, Brembo, who's seals are made of natural rubber, simply state their calipers are incompatible with DOT 5 brake fluid. Wilwood sells DOT 5 fluid but suggests it only be used in Classic cars and Show cars; never in racing cars.

Works fine in the clutch. The safest way to set up a clutch is with a feeler gauge to verify that there is a minimum clearance at full travel.

Once set, the compress-ability of the fluid doesn't change.

Natural rubber is a disaster to use. There is no way to slow down the clock on it's natural deterioration.

Probably on a race car that is going to get torn down almost daily, Dot 4 is fine.

I'm thinking though that the real problem is that there are too many novice racers out there.

They are coming in with high HP engines and running the car too hard for the brakes.

I saw a vintage Mustang race coupe go through four sets of rotors in practice.

Do you know that the Ford GT40 Mk II's when they won at LeMans were limited to 6200 rpm in top gear?

The reason was of course longevity of the engine but also because the top speed of the cars coming down the Mulsanne straight had to be limited because the brakes had to last.

Seems a car capable of 228 mph (at 6200rpm) and weighing in at 2800 pounds has to be "pussy footed" to survive.

If you melt the brakes with Dot 4, then go to Dot 5 with a higher boiling temp and then boil that...you shouldn't be racing...you are too dangerous to everyone else on the track.

Here are a few references:

Wilwood Tech:

http://www.wilwood.com/TechTip/TechBrakeFluidTip.aspx

"Wilwood does not recommend using DOT 5 fluid in any racing applications. DOT 5 fluid is not hygroscopic, so as moisture enters the system, it is not absorbed by the fluid, and results in beads of moisture moving through the brake line, collecting in the calipers. It is not uncommon to have caliper temperatures exceed 200 degrees F, and at 212 degrees F, this collected moisture will boil causing vapor lock and system failure. Additionally, DOT 5 fluid is highly compressible due to aeration and foaming under normal braking conditions, providing a spongy brake feel."


"Street Rodder" Tech:

http://www.streetrodderweb.com...hanging_brake_fluid/

"Silicone fluid does not absorb moisture. As a result free water vapor within the system will be more corrosive and likely to cause oxidation of any ferrous components."

"Since silicone fluids do not absorb moisture, systems using silicone must be flushed and maintained at more frequent intervals than glycol-based fluids."



"HotRod" tech response to letter:

http://www.hotrod.com/pitstop/...ratings/viewall.html

"Bottom line: Leave the silicone fluid for the antique restoration guys or show car trailer queens who never really drive their cars anywhere."


I found that statement made in many articles about it I read; Trailer queens and show cars, slow poke cars, VW's, stock MG's...etc.

According to Ted Mitchell, Benditalia seals (OEM brake M/C, OEM clutch M/C and OEM clutch slave cylinder) are also incompatible with silicone brake fluid.

foaming under normal braking conditions, providing a spongy brake feel."

Not here...want a feel...of the pedal that is?



"Since silicone fluids do not absorb moisture, systems using silicone must be flushed and maintained at more frequent intervals than glycol-based fluids."

...and glycol fluids with moisture need to be removed.


I found that statement made in many articles about it I read; Trailer queens and show cars, slow poke cars, VW's, stock MG's...etc.

...and Doug and Doug's Pantera, and his two Shelbys, and his SHO and his SVT Contour and...get the point yet?

So are you Ying or is that me?

quote:

Originally posted by PanteraDoug:

So are you Ying or is that me?

I still have not figured that out yet.