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Discussion Starter #1
Close call this weekend.
Lost brakes coming down a 1.7 mile, 15% grade, 2300 ft descent mountain. I was also packing 600+lbs between driver, rider and gear.

I was alternating between brake pedal and engine braking when I felt my pedal getting soft. 10 minutes later I had zero brake pedal. After we got down (Casper Mountain, Sedona, AZ) I had brakes within 5 minutes of cooling down. Love that emergency brake!

** Here comes the questions....
-Would everyone agree that that is "normal" and acceptable performance?
-Has anyone considered running Dot4 or Dot5?
-Please weigh-in with your thoughts!

Thanks for your input!
-Mitch

2008 Ranger 700XP
Arizona
 

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As far as I know your brake system must be specifically set up for DOT 5 to use that type of brake fluid. I believe the DOT 3/4 are interchangeable but DOT 3 is not interchangeable with DOT 5. Putting DOT 5 in a DOT 3 system is supposed to cause problems with the seals.

I would think that the quality of brake pads and/or brake rotors would have a lot more to do with brake fade than would the type of brake fluid. That said, you may have cooked the brake fluid and a complete flush is in order. If your brake fluid was old then it could have absorbed a lot of water and that may have contributed to your problem.

For what it's worth, I flush the brake fluid in all my vehicles every two years.

What kind of pads/rotors are you running?
 

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Discussion Starter #3
Jim - I already planned to flush-flush and flush brake system this weekend. I did some more reading on DOT3/4 vs DOT5 and had similar findings. DOT3/4 has chemical properties that match its system seals, gaskets, boots.... DOT5 has a different chemical make-up that is known to eat everything rubber on DOT3/4 systems. My pads are stock Polaris with good meat still left. Rotors are factory also without glaze or wear streaking. Guess I don't brake too much....ha. Thanks for your thoughts!
 

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It's possible that your pads are glazed. I managed to do that on my truck when I sprayed wheel cleaner and got it on the rotors. I removed the pads and sanded off the glaze. That was a good 30,000 miles ago and they have been fine ever since.
 

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Discussion Starter #5
They're certainly glazed now! I ordered a full set pads which were due next year. Update...after bleeding brake lines, i discovered micro-size air bubbles at every wheel. Purged fluid and went with a high-temp DOT4. I'll keep a close eye on the system over the next few runs to make sure it's not the master cylinder introducing air into the system.
 
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