ooops..

lsolon · 08-23-2001, 05:24 PM

First off, hope I didn't offend anyone with my last post on people on this board being nuts. Just having fun! Everyone needs hobbies and, yes I agree w\what s_man said.

Now the oops part. Decided to bleed the brakes before I fired up "to blu for you". Just a little heads up to people-READ DIRECTIONS!!! I added dot 5 fluid to dot 3. It's like adding water to oil. Oh well, guess its as good a time as any to drain the whole system.
She runs great though after 8 months of sitting. Got to love the ol prosche.

Clark Griswald · Clark Griswald's Garage

You gotta be nuts to use DOT 5 brake fluid.

Seriously, you don't want that stuff in your car. It absorbs air and becomes compressible.

lsolon · 08-23-2001, 05:42 PM

Really, why the hell did the guy reccomend it? Why is it sold in stores? So what should it be, dot 3 or 4? What is dot 5 for?
Cool color though, blue. Matches my car. No, that's not why i bought it.
Thank god i didn't drain the whole system and put that stuff in it.
Thanks for the info

feelyx · 08-23-2001, 07:36 PM

I think the color is purple, made of silicone, and doesn't the stuff boil at high altitude?
I could be wrong but I thought I read that somewhere.

Tim in Sac

RarlyL8 · RarlyL8's Garage

Dot 5 brake fluid is silicon based.
It is NOT compatible with water or other brake fluids. You sould not use it in any application where the fluid is not changed very regularly. Water that collect in the system will pool in the low spots (your calipers) and rust them rather quickly.

Oh yes, the application. It is used for racing. Silicon can handle a LOT of heat.

[This message has been edited by RarlyL8 (edited 08-23-2001).]

rvanderpyl · rvanderpyl's Garage

Actually Dot 5 doesn't have to be silicone based, it's just that for years that was the only product that could meet the DOT 5 spec's. There are non silicone brake fluids that meet the DOT 5 standards and are compatible with DOT 3 and 4 fluids, these referred to as DOT 5.1 One of these is MOTUL 600 racing a French manufactured fluid. It's colour is Amber. (From up fix-in der porsche volume 11)

Robert

Early_S_Man · 08-24-2001, 10:17 AM

Regarding PROPER INSTALLATION OF DOT 5 silicone brake fluid:

If you drain all of the old fluid, then fill the system with 91& isopropyl or methyl alcohol ... let it sit for a half-day or so and drain that out, followed by removal of master cylinder, calipers, and any proportioning valve, then blowout the lines with dry compressed air ... followed by a rebuild of master cylinder and calipers, you won't have any problems with DOT 5 silicone brake fluid, assuming that you fill the system very slowly by gravity. It is perfect for older cars that don't see much road use! It lubricates all of the rubber parts, minimizing wear, and doesn't absorb moisture, so corrosion of iron, steel, and aluminum parts isn't a problem, either!

------------------
Warren Hall
1973 911S Targa
1992 Dodge Dakota 5.2 4X4 parts hauler

911pcars · 08-24-2001, 10:47 AM

I concur with Robert (rvanderpyl). DOT 5 is just one of the specs for minimum wet and dry boiling points (DOT 3, 4 are the others).

Silicone fluid just happens to meet DOT 5 specs. This is suggested for cars that don't see a lot of miles (collector cars, classics, etc.). Silicone fluid isn't hygroscopic (affinity for moisture), thus internal parts will last longer. In an active vehicle, silicone tends to retain air bubbles; not good for decelerating as needed. Moisture will also tend to collect in pools and cause corrosion instead of being absorbed.

The latest HD fluid is a new product sold by Wilwood, EXP600+ (no affiliation). They claim higher dry boiling point than Castrol SRF.

Here's a link for a summary of HD brake fluids:
http://members.rennlist.org/911pcars

Sherwood Lee

lsolon · 08-24-2001, 01:18 PM

Thanks all for the info. Not really sure i need dot 5. Going to drain system and go back to dot 4.

patalive · 08-24-2001, 01:55 PM

Years ago, my PO changed over to DOT 5 Silicon brake fluid but I'm guessing he did not follow S-Man's procedures. My brakes became very spongy - Unfortunately, when I changed back to DOT 4, my shop again did not clean out the system of all the DOT 5. I had brake problems, off and on for the next 6 months - a build up of white crust, like calcium deposits, inside the lines, pistons and MC. Cost a bundle, but finally got the system cleaned out and parts replaced. Beware!
Chuck
83SC