Author Topic: Front Brake drag (and brake fluid debate) (Read 10476 times)

rg54669 · « **on:** April 27, 2007, 12:13:03 AM »

I saw a post about this but I can't find it now. I believe someone said to bleed the brakes, but I am not sure why.

I replaced my front brakes last week and did everything by the book(what book, I don't really have one). Now the brakes are rubbing against the disc quite a bit. Any ideas on what I need to do. The last set of pads had a tiny bit of air between them and the disc.

I checked Ron Ayers and those puppies are $234 each. I am not really in the mood to fork out the 5 benjis.

ZenMan · « **Reply #1 on:** April 27, 2007, 12:53:40 AM »

Sounds like your pistons may be binding in the calipers... usually because of a build-up of hard sludgy film or coating from the brake fluid heating up and baking on the insides of the calipers. When you replaced the pads you pushed the pistons into the cylinders farther than they were... thus getting into the dirt build-up.

Rebuild kits are cheap, and it's really not that hard to do it yourself. Then you can replace the fluid with fresh DOT 5 stuff that handles a lot more heat. Cleaning, replacing the seals and O-rings, and bleeding the system will give you factory-fresh brakes.

smooth operator · « **Reply #2 on:** April 27, 2007, 06:55:47 AM »

Yes, what Zen Man said. You may be able to free them up. Put them in a vise, using air to preasure them out(not all the way out,keep your prying devise between the pads) I use laquer thinner or brake cleaner will do to spray and clean. Be carfull not to gouge up your pads working them nice and easy back in. Untill it works freely. Dan

B6mick · « **Reply #3 on:** April 27, 2007, 10:07:22 AM »

And more likely a build up of brake dust and road gunk on the piston (outer side of the seal ) cleans off easy with a very gentle rub with a steelo soap pad. This 9 times outta 10 will have ya brakes returning to a no drag postion.

Red01 · « **Reply #4 on:** April 27, 2007, 02:58:17 PM »

Quote from: "ZenMan"

Then you can replace the fluid with fresh DOT 5 stuff that handles a lot more heat. Cleaning, replacing the seals and O-rings, and bleeding the system will give you factory-fresh brakes.

DO NOT use DOT 5 brake fluid in a DOT 3 or 4 system!!*[/list]
*Unless the DOT 5 container is very clear it is approved for DOT 3 & 4 systems.

DOT 5 brake fluid is silicone based and is not compatible with any polyethylene glycol based fluids, such as DOT 3, DOT 4 and DOT 5.1. DOT 3, 4 & 5.1 are hygroscopic, but DOT 5 is non-hygroscopic, meaning when water gets in DOT 5, it separates from the fluid instead of staying in suspension like the others. Since water is heavier than DOT 5 brake fluid, water will settle in the low spots and can cause corrosion. Also, when the brakes do get hot, the separated water will boil much sooner than the brake fluid and you can get air in the system. If you're looking for a brake fluid that meets a higher boiling point than the stock fluid, then use DOT 5.1 (it boils higher than DOT 5 anyway).

Boiling Point Ranges
Type: Dry/Wet Boiling Points

ZenMan · « **Reply #5 on:** April 27, 2007, 04:05:18 PM »

Quote from: "Red01"

Quote from: "ZenMan"
Then you can replace the fluid with fresh DOT 5 stuff that handles a lot more heat. Cleaning, replacing the seals and O-rings, and bleeding the system will give you factory-fresh brakes.

Whatever you do, DO NOT use DOT 5 brake fluid!!

DOT 5 brake fluid is silicone based and is not compatible with any polyethylene glycol based fluids, such as DOT 3, DOT 4 and DOT 5.1. DOT 3, 4 & 5.1 are hygroscopic, but DOT 5 is non-hygroscopic, meaning when water gets in DOT 5, it separates from the fluid instead of staying in suspension like the others. Since water is heavier than DOT 5 brake fluid, water will settle in the low spots and can cause corrosion. Also, when the brakes do get hot, the separated water will boil much sooner than the brake fluid and you can get air in the system. If you're looking for a brake fluid that meets a higher boiling point than the stock fluid, then use DOT 5.1 (it boils higher than DOT 5 anyway).

Boiling Point Ranges
Type: Dry/Wet Boiling Points
DOT 3: 205°C (401°F)/140°C (284°F)
DOT 4: 230°C (446°F)/155°C (311°F)
DOT 5: 260°C (500°F)/180°C (356°F)
DOT 5.1: 270°C (518°F)/191°C (375°F)

Ok, sounds like you know what your talking about... however;

Is modern Dot 5 different than 20 years ago? Because myself and everybody else use to use it at the track in our race bikes, and I used it in all my street bikes too. Of course we always used it as a complete replacement fluid in fresh, clean, newly rebuilt systems, and never mixed it with other DOT-rated fluids.

I can't remember anyone. including myself, that ever had a lick of trouble with DOT 5. The fact that it isn't water-soluble gives it a more positive hydraulic reaction, no sponginess and no fade at extreme temperatures.

Of course, you have to take the precaution of keeping water away from the stuff, but that just entails keeping the lid on and don't leave your reservior open to the air to absorb water. No big deal, it says that on the label.

I'm not saying you're wrong, Red, but isn't your big red warning sign above a little overly dramatic? I mean, like I said, I've never seen one problem over years of using it.

Red01 · « **Reply #6 on:** April 27, 2007, 04:20:27 PM »

Check you container. It's probably DOT 5.1. DOT 5 is actually difficult to find. It also needs rubber parts that are made for DOT 5. If you mix silicone and glycol based fluids, you're asking for seal trouble. Seals can swell or fail, either one with the same ultimate results - no brakes. Unless you TOTALLY cleaned out the brake system, you run the risk of old fluid being left behind.

DOT 5 was popular on the race scene when it first appeared, but was abandoned by most because of the water thing. It works good *IF* you can keep moisture out, but good luck with that.

Likewise, don't use some other kind of hydraulic fluid in your brakes either. Back when I was in A&P school, the old guy that worked in our tool room thought it would be a good idea to top of his car's master cylinder with some aircraft hydraulic fluid (MIL-H-5606 for you airplane folks). Afterall, if airplanes use it in their brakes, it must be good stuff, right? He discovered this wasn't such a bright idea when he got to the first stop sign and his brake pedal was so firm it wouldn't move. He rode a bus to school for the next few weeks while he replaced everything in his brake system but the drums & rotors.

So, no, I don't think the big red warning is overly dramatic. I don't want someone to go put DOT 5 in their bike and think it worth the emphasis.

ZenMan · « **Reply #7 on:** April 27, 2007, 04:45:07 PM »

I told you, it was 20 years ago. I don't have any now. It's been a long time since i did any racing or been around many racers.

It was Bel-Ray DOT 5 Silicone Racing Brake Fluid. White bottle, blue & black label. The fluid was blue in color.

It worked great and was a big improvement on the brakes at racing temperatures. Like I said, follow the instructions... don't mix it, keep it away from water, no problems.

But you're right, be on the safe side and use DOT 4 or the DOT 5.1. If the silicone stuff is that hard to find now then no worries. You don't need the racing stuff on the street anyway, it's nearly impossible to get your brakes that hot unless your going down 10 miles of steep mountain pass with a stuck-open throttle...

Red01 · « **Reply #8 on:** April 27, 2007, 05:35:58 PM »

I was just checking out Bel-Ray's site to see what they offer today. The only spot I found DOT 5 mentioned was on their V-Twin link, and when you click on it, it takes you to their Super DOT 4 stuff, which is what they list as the only brake fluid on any of the other pages, but when I put DOT 5 in their search engine, their DOT 5 silicone stuff does come up. Weird.

If you'd like to learn more details on brake fluid, check out:

StopTech's "Brake Fluid 1A" article

dgc · « **Reply #9 on:** May 08, 2007, 10:47:02 PM »

dammit red, you're on top of things!

ZenMan · « **Reply #10 on:** May 09, 2007, 01:19:58 AM »

Yep, he's like a vulture perched in a tree above you... close your eyes for a second and he's sitting on your chest ready to pull your tongue out.

ZenMan · « **Reply #11 on:** May 09, 2007, 01:34:28 AM »

BTW Red, you "forgot" to mention this from Bel-Ray's site:

Bel-Ray Silicone DOT 5 Brake Fluid
#97700
Bel-Ray Silicone DOT 5 Brake Fluid is for all applications specifying DOT 5 silicone type brake fluid. It exceeds FMVSS Sec. 571.116 specification. When maximum performance is needed, Bel-Ray Silicone DOT 5 provides superior fade-free brake performance under the most demanding high- and low temperature extremes.

http://www.belray.com/consumer/product_results.fsp?category=&q=dot+5

Red01 · « **Reply #12 on:** May 09, 2007, 12:10:20 PM »

I didn't "forget."

There was no need to mention it because the Bandit - like most non-HD bikes - does not specify DOT 5 silicone fluid.

ZenMan · « **Reply #13 on:** May 09, 2007, 12:19:49 PM »

Quote from: "Red01"

I didn't "forget."

There was no need to mention it because the Bandit - like most non-HD bikes - does not specify DOT 5 silicone fluid.

Ha ha! Great pic!

Alright already... I promise I'll never mention DOT 5 again, ok? Sheesh!

We did a lot of experimemntal stuff at the race tracks back then... the DOT 5 worked great. But I get your point!

H2RICK · « **Reply #14 on:** May 13, 2007, 08:48:10 PM »

Thanks for that, Paul. Your brake fluid "treatise" should be a sticky in the Tech section somewhere. Newbys need to know this stuff. Heck, we've all had guys ask us "What kinda oil should I use in my brakes ??", haven't we. I've actually made guys say "BRAKE FLUID" after they kept using the term "oil"
when discussing brakes.
Can you say "brake fluid", young Luke ???

Author Topic: Front Brake drag (and brake fluid debate) (Read 10476 times)

dgc