DOT 5 brake fluid

rumrumm · January 13, 2005, 05:11:21 PM

Anyone using this stuff? I have heard the only downside is that it boils as a lower temperature, but unless I am road racing, it should not be a problem, should it?

DRD57 · January 13, 2005, 06:37:09 PM

Quote from: "rumrumm"Anyone using this stuff? I have heard the only downside is that it boils as a lower temperature, but unless I am road racing, it should not be a problem, should it?

I've never used it because I heard that it make for a softre pedal. I like my pedal to be rock hard.

Jimmy Jay · January 14, 2005, 07:27:07 AM

I used it in the Vicky and never noticed any problems, even tho, as most, I like my pedal rock......

Jay

Inprimer · January 14, 2005, 08:07:53 AM

Quote from: "rumrumm"Anyone using this stuff? I have heard the only downside is that it boils as a lower temperature, but unless I am road racing, it should not be a problem, should it?

I have it in my car, been there for over 3 yrs. I don't have any problems,the reason I went to it is because I have a friend who worked as a Post office (Jeep) mech for over 40 yrs, he told me the PO used it exclusively ,and since I also worked for them I personally know that the don't waste their money on Snake oil . as I said no problems. The "boiling" issue has been adressed .I can't recall the problems but for street use I like it. It doesn't absorb moisture the main problem in contamination and rust in the system

Bob Paulin · January 14, 2005, 08:12:55 AM

Quote from: "rumrumm"Anyone using this stuff? I have heard the only downside is that it boils as a lower temperature, but unless I am road racing, it should not be a problem, should it?

Not sure where you are getting your numbers, but.........

Federal DOT brake fluid minimum boiling point (°F) standards are as follows.....

DOT class DRY WET

3 (glycol) 401° 284°

4 (glycol) 446° 311°

5 (silicone) 500° 356°

5.1 (glycol) 518° 375°

Downside to silicone in street cars is that it easily aerates and should not be used in conjunction with ABS.......

......and, since it does NOT absorb water, moisture in the system - and there IS moisture in EVERY brake system - collects at the lowest point - usually at the caliper and/or wheel cylinder - which creates a nearby puddle of water for braking heat to boil and turn to steam...resulting in a spongy pedal.

It is used in racing because it has a higher boiling point - not lower....

B.P.

DRD57 · January 14, 2005, 10:31:50 AM

Quote from: "Bob Paulin"
......and, since it does NOT absorb water, moisture in the system - and there IS moisture in EVERY brake system - collects at the lowest point - usually at the caliper and/or wheel cylinder - which creates a nearby puddle of water for braking heat to boil and turn to steam...resulting in a spongy pedal.
B.P.

Here in the southwest, where we have very low humidity, moisture in the brake fluid isn't a noticable problem. It's not uncommon to see cars 10 - 20 years old that have never had the fluid changed. I've never seen a car out here with rusty brake lines.

Another indication of how dry it is: The trunk lid for my 57 Cadillac has been sitting in my shop for over two years in bare metal. It looks the same as it did the day it was media blasted.

Inprimer · January 14, 2005, 03:23:06 PM

Quote from: "DRD57"
Quote from: "Bob Paulin"
......and, since it does NOT absorb water, moisture in the system - and there IS moisture in EVERY brake system - collects at the lowest point - usually at the caliper and/or wheel cylinder - which creates a nearby puddle of water for braking heat to boil and turn to steam...resulting in a spongy pedal.
B.P.

Here in the southwest, where we have very low humidity, moisture in the brake fluid isn't a noticable problem. It's not uncommon to see cars 10 - 20 years old that have never had the fluid changed. I've never seen a car out here with rusty brake lines.

Another indication of how dry it is: The trunk lid for my 57 Cadillac has been sitting in my shop for over two years in bare metal. It looks the same as it did the day it was media blasted.

thanks for the info

Crosley.In.AZ · January 14, 2005, 07:44:32 PM

go to the tech section here on this board..... read Bob's article on brake fluids.

very interesting information

tomslik · January 14, 2005, 08:20:13 PM

Quote from: "Crosley"go to the tech section here on this board..... read Bob's article on brake fluids.

very interesting information

might want to ask purp about pikes peak and silicone brake fluid.
i know he has some issues...

Skip · January 24, 2005, 09:20:19 PM

DOT 5 also lowers the durometer of rubber over time. If you don't use the brakes for a few months, the fluid seeps past the softened seals. A few winters of this and the seals are shot.

I have it in my Norton and I have to rebuild the master cylinder and caliper every few years.

It's in my '48 as well and I have to top it off every spring 'cause it's seeped past the seals in the master over the winter.

...and it's a b**ch to stop the car if you have to hit the brakes hard or more than once or twice in short span of time. One of these days I'll replace it.

I'll never put it in another vehicle.

rumrumm · January 25, 2005, 08:16:23 AM

Sounds like DOT 3 is the way to go. Thanks to all who responded.

Crosley.In.AZ · January 25, 2005, 09:29:16 AM

Quote from: "tomslik"

might want to ask purp about pikes peak and silicone brake fluid.
i know he has some issues...

yes ........ george does have some issues, but we still like him a bunch.

in fact , we like you tooo tom

purplepickup · January 25, 2005, 10:01:35 AM

Quote from: "Crosley"
Quote from: "tomslik"

might want to ask purp about pikes peak and silicone brake fluid.
i know he has some issues...

yes ........ george does have some issues, but we still like him a bunch.

I've even got some back issues I'll sell you

Tom is right. I run DOT 5 fluid in my pickup. I climbed Pikes Peak and when I got to the top I wanted to park my truck by the summit sign and take a picture. You're not supposed to do that so I thought I'd do it quick. The sign is real close to the edge where it drops off VERY sharply. I quickly pulled the truck down by the sign and had NO BRAKES! I threw the tranny into park and stopped but it scared the poop out of me. Trust me...it was very scary to start the trip back down without brakes. My sanity is often questioned. Low gear got quite a workout! About halfway down the brakes were almost normal again. When we got back down to Colorado Springs they worked good and have ever since. I was a little low on fluid but it only took about 1/4 pint when I filled it. I went on to Bonneville, over Wolf Creek Pass, and raced at the HAMB drags without any more problems.

I don't know what caused it. I'm sure it had something to do with the altitude but whether or not it was caused by silicone fluid, I don't know. I still haven't changed to DOT 3 but I probably will someday.