Which brake fluid

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Oct 6, 2011 | 07:52 PM

hogster1961

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Cruiser

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Which brake fluid

I've just changed the bars on my bike and was set to bleed the front brake, then I noticed that the rear master cylinder cap says use Dot 5 the front M/C cap says use Dot 4?
I'm thinking the front master cylinder has been changed(I suspect the bike has been dropped by the P.O) so should it be Dot 5 all round? the manual I have doesn't even mention Dot 5.
The bike is a 2006 Fat Boy.
I know that 4 and 5 don't mix so if I go with Dot 5(which I would rather as I have a custom paint job) will I need to completely strip out the front calliper or is it enough just to flush it through with the new (Dot 5) fluid?
Thanks for any help/advice.

Oct 6, 2011 | 08:32 PM

sagebrush1976

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From: Peach Bottom, PA

I just changed the brake like on the front of my 06 FXST and it called for DOT4 also.

Oct 6, 2011 | 08:37 PM

scasey

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From: FLORIDA

My manual for an 06 says Dot4. I own a 2006 heritage. Can't help any further with the flushing out thing.

Oct 7, 2011 | 10:36 AM

oct1949

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From: 40 miles Northeast of Indy..

don't know bout Ur 06, my 07 says Dot 4 both front and rear.

Maybe one of them had the caps changed out

Oct 8, 2011 | 12:24 AM

Mr. Lucky

Stellar HDF Member

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From: Delaware

Pop the mc lid and see what's in there. DOT 4 comes in a variety of colors (I've seen blue, clear, and a variety of amber shades), but DOT 5 is always purple.

Oct 8, 2011 | 01:24 PM

Tom84FXST

Seasoned HDF Member

Joined: Nov 2009

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From: Farmington ,MS

Quote:

Originally Posted by Mr. Lucky

Pop the mc lid and see what's in there. DOT 4 comes in a variety of colors (I've seen blue, clear, and a variety of amber shades), but DOT 5 is always purple.

Dot 5 is always purple when you open a new sealed container...but once it is exposed to air, the purple goes away and it is amber. I always run dot 5 no matter what, because I am not getting dot 4 near nice paint. You can run dot 5 in any system, but I have never tried to flush out a system...I don't think you could get all the dot 4 out without disassembling the system...rebuild kits are cheap insurance.

Oct 8, 2011 | 06:33 PM

poppavein

Road Master

Joined: Sep 2009

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From: Pacific NorthWest Territory

DOT 5 fluid is highly compressible due to aeration and foaming under normal braking conditions, providing a spongy brake feel.

Harley switched to DOT4 when they started delivering ABS systems. DOT5 is not recommended for ABS systems due to this problem with aeration. Possibly the ABS unit itself can generate those bubbles when it is activated. (Which doesn't really make sense in a sealed system.)