Altitude issues.... Why?

[Craigatcsi]

We are on a trip thru Rapid City, SD the Coy, WY and Yellowstone, etc.... I have gone over the mountains in CO before and have had similar issues as today in the Mountains. When waaay up there my clutch doesn't want to disengage. It usually disengages very early, but when up there it is very near the bars before I feel any resistance in the handle, and it is difficult to shift. The same happened to my rear brake only, the front brake was not affected at all. At one point, I had NO rear brake until I pumped it a few times, then it was fine. My buddy was on his 08 HD and had no affects from the altitude.
Please understand that I know it is caused by the altitude and differing pressures in the air, but....

How does it / WHY does it do it to CLOSED hydrolic systems? (All of mine have been flushed / new within the last couple of years and are at the appropriate levels.)

Why aren't my buddy's HD hydrolic systems being affected - like my front brake?

[Ragtop69gs]

I can tell you from similar experience that your clutch &amp; brake fluids have excessive moisture in them and need to be changed. I had the same issue on a trip over Beartooth, flushing with new fluid solved the problem. &nbsp;Change the fluids every season, cheap, easy insurance.<br />
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We are on a trip thru Rapid City, SD the Coy, WY and Yellowstone, etc.... I have gone over the mountains in CO before and have had similar issues as today in the Mountains. When waaay up there my clutch doesn&#39;t want to disengage. It usually disengages very early, but when up there it is very near the bars before I feel any resistance in the handle, and it is difficult to shift. The same happened to my rear brake only, the front brake was not affected at all. At one point, I had NO rear brake until I pumped it a few times, then it was fine. My buddy was on his 08 HD and had no affects from the altitude. Please understand that I know it is caused by the altitude and differing pressures in the air, but.... How does it / WHY does it do it to CLOSED hydrolic systems? (All of mine have been flushed / new within the last couple of years and are at the appropriate levels.) Why aren&#39;t my buddy&#39;s HD hydrolic systems being affected - like my front brake?

[Lee H. Mann]

We are on a trip thru Rapid City, SD the Coy, WY and Yellowstone, etc.... I have gone over the mountains in CO before and have had similar issues as today in the Mountains. When waaay up there my clutch doesn't want to disengage. It usually disengages very early, but when up there it is very near the bars before I feel any resistance in the handle, and it is difficult to shift. The same happened to my rear brake only, the front brake was not affected at all. At one point, I had NO rear brake until I pumped it a few times, then it was fine. My buddy was on his 08 HD and had no affects from the altitude.
Please understand that I know it is caused by the altitude and differing pressures in the air, but....

How does it / WHY does it do it to CLOSED hydrolic systems? (All of mine have been flushed / new within the last couple of years and are at the appropriate levels.)

Why aren't my buddy's HD hydrolic systems being affected - like my front brake?

Decreased pressure on the outside increases pressure differential on the inside.
Make sure your clutch reservoir is not over-full.