To use DOT 4 or 5.1 brake fluid?

I've searched many of the brake threads and understand the why I should use ONLY these types of brake fluids and how to flush the brake system before switching fluids. However I want to know how each one of these fluid types will effect performance? IE: faster brake response?, slower reaction time for the pad to pull away from the rotor?

I've used the Avid 5.1 fluid that came with the brake bleed kit but I'm now out and I can't find 5.1 at any of my local shops. I know that I can p/u DOT 4 at any auto supply store but how will each perform pros and cons?

BTW: I have Avid Juicy Ultimates

 

I doubt you'll notice a difference between the two. You're right, don't mix them though. Most moto stores sell the 5.1

 

According to Avid advertising, DOT 5.1 has a higher boiling point than DOT 4

 

5.1 = higher boiling point.. I.E. less brake fade

^^^..what he said8-[

 

I run 5.1 fluid from Napa Auto Parts.

 

5.1 also has a higher viscosity, youll find that if you drop to the 4, youll find your rebleeding more often, and the lever isnt going to feel right. The orfices are different sizes in the systems avide made that used factory DoT4 and DoT5.1

 

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Yet another Avid thumbs down?

Fair enough Lee, in my experience the thinner stuff is snappier and the thicker a little slower to rebound but it's all good. Use a sealed container then toss the excess, avoid mixing types or brands since just like motor oil they will not typically mix.

 

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I'll take your word for it, but Hope says "don't mix them".

 

I can tell you that the only difference on a street bike I felt between dot 4 and dot 5 was the price.

 

get 5.1 at a motorcycle shop like motocross.

 

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I hate to be pedantic... ok, not really... I live for this...

BUT, a DOT 5.1 brake fluid doesn't necessarily have a higher boiling point than a DOT 4 brake fluid. There are other qualities such as viscosity at low temperatures.

Compressibility is going to be nearly identical, as is the viscosity at temperatures you will ever encounter in San Clemente.

My worthless opinion: get some DOT 4 from Summitracing.com and bleed your brakes often. You'll be better off bleeding frequently with DOT 4 than bleeding infrequently with DOT 5.1. If DOT 5.1 makes you happier, by all means get it, but don't forget to bleed frequently.

 

Ok so whats the difference between DOT 5.1 at a motorcycle shop and brake fluid at say pep boys that says exceeds DOT 5.1 standards?

 

Name brand vs. generic? Name brand of course, whether you get it from Pep Boys or else where. That'll be the difference. We all know how much they cut back on quality when it comes to generic or store brands.

 

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XC=DOT4 & DH=DOT5.1 ..keepin it simple

When brake fluid boils it becomes a gas.. a gas is compressible. THIS WILL CAUSE BRAKE FADE ..you'll get what you pay for here: 5.1 FTW :bang:

 

This thread is great! I recently bled my Avid brakes I used DOT 5 (silicon) from the local Kragen.

I did a complete fluid swap on 2 brakes and filled it with the DOT 5.

However, on another brake I only pumped some of this DOT 5 into the system to bleed out air bubbles. Hence, I have a mixture of the new DOT 5 with the original Avid DOT 5.1. According to the above discussions, this is a no-no!

So what adverse effects are there for mixing? Do I need to flush out the old fluid ASAP to avoid damage?

Rode the Fullerton Loop tonight with it and it performed fine.

Will the DOT 5 cause problems for the Avids?