Brake Fluid

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pretzladay
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Brake Fluid

Postby pretzladay » Sat Nov 07, 2009 12:02 pm

Read owner posting elsewhere that he had replaced brake fluid with DOT5 and had eliminated that annual chore. Good idea, or bad? Also, anybody have experience with Speed Bleeders? Good investment?
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The Meromorph
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Re: Brake Fluid

Postby The Meromorph » Sat Nov 07, 2009 5:06 pm

Speed Bleeders are excellent.

Using DOT5 fluid is a very bad idea...
First DOT5 and DOT4 should never be mixed, to the point where you have clean out the old DOT4 to the extent that there isn't any left. The crud they produce when mixed is nasty.
Second DOT5 is not hygroscopic, so the water in the atmosphere doesnt get absorbed into the brake fluid, but neither does it mix with the brake fluid. So the lesser amount of water that does get into the brake system, falls to the lowest point (that's your calipers!). Plain water boils at normal brake caliper temperatures, so when you do get a little water in there, you are likely to lose all braking suddenly! Far from avoiding the chore of bleeding the brakes, you should bleed them (a little) to get just the (little bit of) water out very frequently! (Every day would not be too often.) Or risk having no brakes when you need them...
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pretzladay
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Re: Brake Fluid

Postby pretzladay » Sat Nov 07, 2009 10:04 pm

Meromorph,
Thanks for the info, on both counts. Just bought an 04 R with 1800 miles, and I don't think the brake fluid has ever been changed, let alone bled. I'm 2.5 hours from the nearest BMW dealer, so you've been a big help. Thanks again
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The Meromorph
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Re: Brake Fluid

Postby The Meromorph » Mon Nov 09, 2009 12:56 am

With the DOT4 fluid (which you should continue to use), most times, bleeding the brakes exactly equals changing the brake fluid, because you bleed until only clean clear new fluid is coming out.
Occasionally (for example if you fail to tighten the bleed screw [DAMHIK :badgrin: ] ) you'll need to bleed only enough to get the little bit of air out.

Speed Bleeders work much better... :)
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OU812
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Re: Brake Fluid

Postby OU812 » Tue Feb 23, 2010 9:11 pm

So what is the difference between 3 and 4?
Just asking and thanks for your posts!
Steve
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The Meromorph
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Re: Brake Fluid

Postby The Meromorph » Thu Feb 25, 2010 10:13 pm

OU812 wrote:So what is the difference between 3 and 4?
Just asking and thanks for your posts!
Steve

DOT 4 is a significantly better formulation of the same basic technology.
You could use DOT 3 in an emergency, but it would get contaminated faster, and be more susceptible to boiling when it does. If I had to use DOT 3, I'd replace it with DOT 4 within 6 months. (Actually I'd replace it as soon as I could :) )
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Re: Brake Fluid

Postby OU812 » Thu Feb 25, 2010 10:21 pm

So I can flush DOT 3 out with 4?
Last edited by OU812 on Sun Feb 28, 2010 7:17 pm, edited 1 time in total.
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The Meromorph
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Re: Brake Fluid

Postby The Meromorph » Sun Feb 28, 2010 2:51 pm

Yes.
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Re: Brake Fluid

Postby OU812 » Wed Apr 28, 2010 12:29 am

Thanks for the info! Used DOT 4 on my 98' DR350 Off Road.
Image
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Re: Brake Fluid

Postby omg1010 » Thu Aug 12, 2010 6:01 am

DOT 4 and DOT 5 are not compatible. However DOT 4 and DOT 5.1 are. It is really confusing but the development was DOT 3 -> DOT 4 -> DOT 5.1. DOT 5 is a totally different stuff as this one is based on silicone and it is not compatible with the other DOTs because of the seals used in every brake system.

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OU812
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Re: Brake Fluid

Postby OU812 » Sat Feb 26, 2011 2:55 pm

Sounds like a computer update. :lol:
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Re: Brake Fluid

Postby cburgess594 » Thu Mar 29, 2012 2:29 am

If I haven't get into this thread. I have no idea about the break fluids "3 and 4." And there differences? Whew!! Made it here simply!

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Re: Brake Fluid

Postby def » Tue Aug 14, 2012 12:27 pm

Not to confuse the issue but some later model motorcycles use mineral oil for the hydraulic clutch systems....don't mix it up...know what grade fluid goes where on your motorcycle, auto, tractor or whatever.
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Re: Brake Fluid

Postby omg1010 » Wed Aug 15, 2012 1:30 am

Yep, the 1200 BMW models for example. If you use brake fluid to fill up the clutch circuit you'll ruin the entire circuit (seals).

Brgds
Oliver

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Re: Brake Fluid

Postby def » Sun Aug 26, 2012 7:36 pm

OU812 wrote:So what is the difference between 3 and 4?


Boiling point.
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def
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Re: Brake Fluid

Postby def » Sun Aug 26, 2012 7:43 pm

The Meromorph wrote: Far from avoiding the chore of bleeding the brakes, you should bleed them (a little) to get just the (little bit of) water out very frequently! (Every day would not be too often.) Or risk having no brakes when you need them...


Bleeding your brakes every day or more frequently than recommended is unnecessary and unwarranted.

Inspecting your brake equipment every time you take tire pressure readings (Not TPMs which IMO are useless) with a tire gauge is a good idea so you can monitor brake pads, brake calipers, brake dust, condition of wheels and tire tread depth.
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