dot 5 brake failures-fl models
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Stage II
Joined: Jun 2006
Posts: 2
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From:
dot 5 brake failures-fl models
While leading a group over Sonora Pass on a hot day, several of the late model FL series HDs experieinced rear brake and/or hydraulic clutch failures. Our research shows this failure to be based on the location of the rear brake master cylinder combined with the use of Dot-5 brake fluid. HD is ignoring our concerns and the potential safety proplem. This was not from over-use of the brakes, but due to the expansion of the air molecules in the Dot 5 fluid at high altitude and heat conditions.
If you have had a similar proplem, please post your concerns with NHTSA at www.nhtsa.gov, and let me on this forum.
If you have had a similar proplem, please post your concerns with NHTSA at www.nhtsa.gov, and let me on this forum.
Road Captain
Joined: May 2006
Posts: 554
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From: Citizen of the Republic of Texas, now in GA
RE: dot 5 brake failures-fl models
Mason, what's the deal here? Appears to be a questionable statement you made. In making that statement, you should have at least included a little of the reasoning behind it and perhaps a little investigative documentation. IMHO, your statement is unfounded and in all likelihood untrue.
You did not even introduce yourself to the forum before making the above post. Therefore, you have been rude, too.
You did not even introduce yourself to the forum before making the above post. Therefore, you have been rude, too.
Ultimate HDF Member
Joined: Nov 2005
Posts: 5,256
Likes: 5
From: Concord, CA
RE: dot 5 brake failures-fl models
I didn't see any bashing, just a statement of what he thought was an issue. He asked if anyone else has the problem, to send it to NHTSA. Sounds fair to me.
It may be true, it may only be true under the right conditions. I have heard many stories about DOT5 retaining/absorbing a lot of water. It's surely feasable that it can get hot and cause an issue if there is too much water in the line. How the water got there, I have no idea...
It may be true, it may only be true under the right conditions. I have heard many stories about DOT5 retaining/absorbing a lot of water. It's surely feasable that it can get hot and cause an issue if there is too much water in the line. How the water got there, I have no idea...
Road Captain
Joined: May 2006
Posts: 554
Likes: 0
From: Citizen of the Republic of Texas, now in GA
RE: dot 5 brake failures-fl models
Rhubarb
DOT 5 doesn't absorb water or mix with water so if water gets into the system from an outside source it flows to the bottom of the system. Because of this DOT 5 is much more reliable than DOT 4 when water has found its way into the system. This is also why you should and can purge any water occasionally by bleeding some through otherwise the water can oxidize lower reaches of the system. DOT 5 often feels spongy by nature. There are pros and cons to both DOT 4 and DOT 5.
Let's see some facts on the matter that Mason has posted to the attention of the users of this forum. I would like to see what Mason's investigation truly uncovered. Without documenting the statements, I cannot draw any information at all from the post. One question that I would like to know the answer to ... why did H-D switch to DOT 4? Can anyone answer me that one? Did it have anything to do with what Mason describes above? A note from a dealer the other day said that the change to DOT 4 essentially made no sense because DOT 5 was performing well. Additionally, DOT 5 does not remove or damage the beautiful finish on your beautiful bike.
Enquiring minds want to know.............
DOT 5 doesn't absorb water or mix with water so if water gets into the system from an outside source it flows to the bottom of the system. Because of this DOT 5 is much more reliable than DOT 4 when water has found its way into the system. This is also why you should and can purge any water occasionally by bleeding some through otherwise the water can oxidize lower reaches of the system. DOT 5 often feels spongy by nature. There are pros and cons to both DOT 4 and DOT 5.
Let's see some facts on the matter that Mason has posted to the attention of the users of this forum. I would like to see what Mason's investigation truly uncovered. Without documenting the statements, I cannot draw any information at all from the post. One question that I would like to know the answer to ... why did H-D switch to DOT 4? Can anyone answer me that one? Did it have anything to do with what Mason describes above? A note from a dealer the other day said that the change to DOT 4 essentially made no sense because DOT 5 was performing well. Additionally, DOT 5 does not remove or damage the beautiful finish on your beautiful bike.
Enquiring minds want to know.............
Banned
Joined: Feb 2006
Posts: 901
Likes: 1
From: Toms River, NJ
RE: dot 5 brake failures-fl models
hasnt the moco spec'd dot 4 for for the 06-07 models?
just read something about it in american iron, i'll find the article and post all i read
just read something about it in american iron, i'll find the article and post all i read
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Big Kahuna HDF Member
Joined: Feb 2006
Posts: 23,881
Likes: 34
From: USA
RE: dot 5 brake failures-fl models
Any time I see a 1 post with a serious safety warning my first thought is "troll". So please let's see some data here. 
BTW my dyna is spec. ed for DOT 4 part no. 99953-99a only.
BTW my dyna is spec. ed for DOT 4 part no. 99953-99a only.
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Ultimate HDF Member
Joined: Nov 2005
Posts: 5,256
Likes: 5
From: Concord, CA
RE: dot 5 brake failures-fl models
ORIGINAL: Longtimegone
Fair enough for me, too. Maybe I was the one that was rude. Damn, did it again...............
Fair enough for me, too. Maybe I was the one that was rude. Damn, did it again...............
It wasn't like he said "your frame will crack in half while riding 15MPH and put you in intensive care! Help me put HD out of business"
Thread Starter
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Stage II
Joined: Jun 2006
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From:
RE: dot 5 brake failures-fl models
I am new to forums, and do not know how to add attachments to my original post. I have a addtional research data on Dot 5 etc. and would be happy to forward it to anyone who wishes to see it. I may be e-mailed at dmason@hughes.net.
From what we have found, the proplem is air molecules in a silicone based Dot 5 brake fluid expanding at high altitude on hot days. Our group was at an elevation of over 8,000 ft and the temperature was in 85 degrees+. We had no problem with front brakes, we believe because the master is above the brakes.
When I followed HD's instructions to have my brakes bled at altitude, I was informed by the service department in Reno, NV. that this was a fairly well know proplem (although they won't admit that officially). That is why I am looking to see if others have had the same proplem. By the way, bleeding of the brakes at altitude is only a temporary solution. If the brakes are serviced at sea level, a return to high altitude on a hot day may result in a re-occurance of the proplem.
From what we have found, the proplem is air molecules in a silicone based Dot 5 brake fluid expanding at high altitude on hot days. Our group was at an elevation of over 8,000 ft and the temperature was in 85 degrees+. We had no problem with front brakes, we believe because the master is above the brakes.
When I followed HD's instructions to have my brakes bled at altitude, I was informed by the service department in Reno, NV. that this was a fairly well know proplem (although they won't admit that officially). That is why I am looking to see if others have had the same proplem. By the way, bleeding of the brakes at altitude is only a temporary solution. If the brakes are serviced at sea level, a return to high altitude on a hot day may result in a re-occurance of the proplem.