higher dot brake fluid

[awesomeame]

since i'm removing my calipers in order to paint 'em, i'm gonna loose a bunch of brake fluid. so i was thinking...

why not get a higher "dot" brake fluid while i'm at it? GM calls for dot#3, but i was thinking about putting some dot#5 in instead. this would give me more responsive brakes, eh?

anyone see any problems with this idea???????

--matt

[hockeyman]

Dot 5 brake fluid can handle higher braking temps. We f-body owners really don't need it in our normal city/highway driving, but it couldn't hurt. If you do alot of autocross racing, then it would be wise to step up to it.

-Marc

[awesomeame]

ah, no autocrossing happening here. i was under the impression that dot#5 'compressed' less then dot#3. is that incorrect? or is the difference between dot#5 & dot#3 just temperature range? thanks!

--matt

[speedy-v6-camaro]

Temperature before it boils. Get some super blue if you can.

[V6Bob]

You DO NOT (yeah, I'm shouting) want to use DOT 5. It's silicone based and totally incompatible with what's in your system.

There's no difference in response with different DOT levels. I'd use what GM recommends.

[ December 29, 2003: Message edited by: V6Bob ]</p>

[awesomeame]

ok, thanks for the responses, guys! i'll stick with the dot 3 ;)

--matt

[Domestic Violence]

there are 4 types of brake fluid.

DOT 3
DOT 4
DOT 5
DOT 5.1

the a-hole mechanic put DOT 5 in my car at work. it ate the seals on everything. i had to have the brakes completely redone; over $2800.

GM recommends DOT 3, BUT you can use DOT 4 or DOT 5.1. DOT 5 is a purely synthetic silicon base. rather than mixing the water with the fluid, it separates and when the brakes get hot, the water boils out leaving the brake fluid alone. it is primarily made for RVs and vehicles that sit for long periods of time, not cars that run the brakes frequently; cars that would be more susceptible to moisture buildup in the brake lines.

DOT 4 and 5.1 are regular brake fluid, but have a higher boiling temperature. you can safely use DOT 4 or DOT 5.1, as commented by GM. (my city is suing the company that f'ed up the brakes on my car so i've become a brake expert.)

i know several 4th gen f-body road race guys who use MOTUL 5.1 and they're brakes work far better. you don't really need it unless you do road racing. i use 5.1 in my car at work and the fade isn't as bad as 3, but i probably use my brakes a little more than most.

[ December 30, 2003: Message edited by: Domestic Violence ]</p>

[imported_admin]

I'm going to reiterate what has already been posted:

DO NOT USE DOT-5 BRAKE FLUID IN YOUR F-BODY!!!

GM recommends DOT-3 and DOT-4. Valvoline makes an excellent DOT-4 brake fluid that can be bought at any auto parts store.

Here is an excerpt from the Modifications Encyclopedia:

<blockquote>quote:</font><hr>
Fluid
Just as not all other brake components are created equal, some brake fluids are clearly superior to others. This is another affordable first step in upgrading your brakes, along with braided lines. Brake fluid is the blood of your brake system, and without it working properly, you simply do not have brakes, on any wheel. It is worth taking a moment of thought.

As your brake fluid presses against the piston(s) of the caliper, tremendous heat is built up between the pad and the rotor. Most of this heat is dispersed through the air, but some of it travels through the pad, through the caliper piston, and into the fluid. Brake fluids generally have a very high boiling point, most high-performance ones being as high as 570 degrees Fahrenheit when "dry" (no water moisture present). However, water boils at 212 degrees, and from the moment you first opened the can of fluid and poured it into the system, it got attacked by contaminants and water moisture. DOT-3 and DOT-4 fluids, the most common, can absorb some water in the system. However, as water is mixed in with the fluid, the waters boiling point increases and the fluids boiling point decreases. The DOTs minimum boiling point for fluids is 284 degrees when "wet" (saturated with water). If you use a no-name generic fluid in your brake lines, chances are that the boiling point is pretty close to this minimum. The end result of all this is that during racing-style braking, some of your brake fluid will vaporize, expanding and causing the pressure within the lines to decrease dramatically. Your braking performance is then decreased.

The simple and best solution to this problem is to use high-quality fluid and change it regularly. This will have the effect of keeping the fluid relatively moisture-free and will give you maximum performance. If you road race you should ideally change your fluid before every race, and if you autocross you should change it every four races or so. For drag racers and street performance enthusiasts this is less of an issue, and changing it annually, using high-quality fluid, should suffice.

One final issue is that of the moisture mixing with the fluid in the system. If DOT-3 and DOT-4 fluids mix the water with the fluid, and mixing is a bad thing, why not use DOT-5 fluid? DOT-5 is silicon-based and will not mix with water. Thus, in a DOT-5 system, moisture will form small droplets inside the hoses. This is even worse than mixing it with the fluid, as the water droplets will retain their low 212 degree boiling point. Under heavy braking, this droplet will vaporize, expanding and transfering much kinetic energy to the nearby molecules of brake fluid. Continuing pressure on the brake pedal will thus re-compress this steam bubble, causing a slackness in the system. In the end, there is really no reason to use any DOT-5 brake system in any car, let alone a high performance one, and very few people do.<hr></blockquote>