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Brake Fluid Question

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  #1  
Old 06-29-2010, 08:32 AM
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Default Brake Fluid Question

Ok to start off I know I can look this up in the service manual, but I am at work and want to buy this stuff on the way home and forgot to look it up last night.

What brake fluid do the 2008 and later Touring bike Brembo brakes take? Which DOT is it?
What Brake fluid is used in the 2009 FLSTC brakes?

Reason for these questions is I am going to swap my FLSTC front brake out for a Touring Brembo one. And need to get brake fluid. Just not sure if they both have the same kind of different kind.

I will be using the same brake lines, do I have to do something special if I am changing fluids? or just let the old fluid run out and then replace with new? (even if DOT is different?)

Any recommendation on brand of brake fluid?

and any recommendation on brand of brake cleaner?

thanks
 
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Old 06-29-2010, 08:36 AM
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Found this:
Harley sells DOT 5 Brake Fluid with the following disclaimer: "Fits all models (except '05-later Touring models, '06-later VRSC™, DynaŽ, SoftailŽ and '07 SportsterŽ models)."

Harley sells DOT 4 with this disclaimer: "Fits '05-later Touring and '06-later VRSC™, DynaŽ and SoftailŽ and '07 SportsterŽ models."

Here's an interesting read on the fluids.

D.O.T. 5 Brake Fluid

DOT 4, like DOT 3 and DOT 5.1, is a polyethylene glycol-based fluid (contrasted with DOT 5 which is silicone-based). Fluids such as DOT 4 are hygroscopic and will absorb water from the atmosphere. This degrades the fluid's performance by drastically reducing its boiling point. In a passenger car this is not much of an issue, but can be of serious concerns in racecars or motorcycles.

from which I take that I need DOT 4, which is the same as the 2009 FLSTC already has. IS this correct?
Is there any reason to switch to DOT 5.1?
 
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Old 06-29-2010, 01:53 PM
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Lol where are the brake fluid experts when you need them:P
 
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Old 06-29-2010, 04:54 PM
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I became an expert on Brake fluids after I changed the fluid on my '02 Softail and realised that I'd used the wrong fluid....DOT 5 is silicon based and has the advantage that it doesn't attract water. This is a good thing, as water in Brake fluid reduces its effectiveness and can cause corrosion. Also, DOT 5 doesn't attack paintwork. It is however quite expensive and in the UK harder to find than the others. DOT3, DOT 4 and (confusingly) DOT 5.1 are not silicon based so will attract water and ruin paintwork. They can be mixed with each other, but NOT with DOT 5 as the result is a gel which will clog up the system. The brake system components will handle either type of fluid.
So the simple answer is, if you alter brake components (Cylinders, hoses etc) just continue to use the same fluid as before.
 
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Old 06-29-2010, 04:57 PM
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Find a touring bike and look on the Master Cylinder. It will say. No baggers where I am right now, but it seems like it would be DOT4. Post in the touring section and you will have an answer in a minute I'll bet.

Drew
 
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Old 06-29-2010, 04:58 PM
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Oh and DOT 5.1 is a higher spec than DOT3 or DOT 4, so I'd use that in preference to the other two.
 
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Old 06-29-2010, 05:51 PM
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I understand dot5 has higher boiling point also, and used in performance / race conditions where the brakes are constantly operating at the maximum limit, so I'm guessing a complete waste of time on a road bike.
 
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Old 06-29-2010, 06:33 PM
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Yes I'd agree that DOT5 is probably a higher than necessary specification for a road bike - and HD have gone back to DOT 4 for 06 onwards models. But if you've already got DOT5 in the system, may as well stick with it to avoid any problems.
 
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Old 06-29-2010, 07:22 PM
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Have a friend with a Jeep Wrangler and when he went to get the oil changed at a quick lube place they added the wrong fluid to his master cylinder. You could step on the brakes five or six times and they'd work like normal but on the next time the pedal would drop to the floor. The biggest problem with it was it was discovered after the accident.

Use the correct fluid.
 
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Old 06-29-2010, 10:58 PM
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Dot 5 will give overall better braking performance and is not as corrosive as Dot 4. I'd say make the switch to Dot 5, but make sure you clean your brake system of all the Dot 4. Your master cylinder/hose and caliper will thank you in the long run. Not to mention your seals.
 


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