Brake Dilemma!!! does DOT 5.1 make big diff?

[Patan-DH]

Well I'm going to go race the Agentinian DH open next month and the course is really long and steep. (last panamerican course)

My hayes HFX-9 had a good solid contact feel and i like'em....but
They fade in long runs and i need to solve this.
So i researched here and found that maybe bleeding them with DOT 5.1 will help....

The question is: is anyone here running dot 5.1 in your hayes 9?

Does it eliminate the fading issue?

to continue the story today i went to every motorcycle store in buenos aires and couldn't find any better than dot 4.

Then i went to the main car autoparts shops av. and found a Racing cars shop who got some Racing fluid (AP-racing 600) but the seller told me than it was dot 6 or more and will kill the seals in brake system.

Then the last that i found is a national made DOT 5 that says "no Silicone" and in the back of the bottle says that is compatible and can be mixed with dot 3 and 4 fluids. this one only comes in liters and it cost about 11 dollars

I'm confused and don't know what to do.

1) get the DOT 5 and try. (it says non silicone)

2)get a 2 dollar dot 4 bottle, bleed them and sell'em after the race.
Then get a set of new 08 XT's and forget about DOT fluids that screw your paint and skin.... but i've tested the 08 xt's and thay fell a bit spoungy.....


Thanks in advance

[FrontRangeDH]

I have always used DOT 4 or 5, but never tried 5.1. Thought I heard somewhere that you shouldnt run it in Hayes, but I am not 100% sure, part of the problem may be the HFX 9, I always ran Mags and never had a problem

[Patan-DH]

I was afraid that it was a design error in the 9' master cilinder having no room to hold the fluid expansion given by heat......

So the mag is the only other brake with the feel of nines that not fade?

I've tested juicys, saints and i did not like em

[FrontRangeDH]

I really liked my Mags. I was on Codes last year and loved them! I am now on Saints and will be for a while. I like my Codes and Saints. It'll be a while before I am back on Hayes. They need a new DH brake. They just dont compare to the new stuff from everyone else. They are spending too much time developing XC/trail stuff IMO

[davep]

I have always used DOT 4 or 5, but never tried 5.1. Thought I heard somewhere that you shouldnt run it in Hayes, but I am not 100% sure, part of the problem may be the HFX 9, I always ran Mags and never had a problem

You are confusing numbers (I hope). DOT 3, 4, and 5.1 are all glycol based and are all compatible.

Dot 5 is silicone based, is NOT compatible with any other DOT fluids and has the potential to distroy all the seals in your brakes.

You most likely have a bit of moisture or air in the system leading to the fading (or the pads are overheating, and changing coefficient of friction), as the boiling point of brake fluid is quite high when dry.

All glycol fluids will absorb water out of the air over time, and as they do, the boiling point will become lower. Any new flluid will have a higher boiling point that old oil.

In general, 5.1 has a higher boiling point than 4 or 3, but that is not always the case. For example, motul rb 600 is a 'dot 4' but has the highest boiling point that I know of...

In the end, any new fluid (4 or 5.1) will be a benefit (if bled correctly)..check the wet and dry boiling points on the bottle...

[Udi]

http://www.ridemonkey.com/forums/showpost.php?p=2704763&postcount=21

Should be helpful, think I covered a few things there that some people don't realise about DOT3/4/5.1 fluid standards. For a short answer, I use and recommend the Motul DOT5.1 fluid, because it has a boiling point almost as high as the highest end DOT4 fluids, while having a considerably lower viscosity = easier bleeding and lighter lever action + faster response.

By the way, if your brakes are fading it's much more likely to be a pad/heat/glazing issue (ie. actual surface issues) rather than a fluid issue. If the levers are getting spongier/coming to the bar though then yeah I'd suspect the bleed or fluid.

[FrontRangeDH]

Yeah, I probably got those backwards, thanks for clearing that up, there are just too many fluids available.

The thing I always liked about my Hayes was that if they started feeling bad, a bleed was all that was required. There were times I would bleed them and the fluid would come out black. And once bled, they would be awesome again

[DirtyMike]

http://www.ridemonkey.com/forums/showpost.php?p=2704763&postcount=21

, I use and recommend the Motul DOT5.1 fluid,



YES, good stuff. And teh 5.1 will work better for long extended runs. But like others said you might just be due for a bleed out as it is anyways. I would go with the Motul 5.1 as well, thats what I am running in my juicy sevens, cant say ti really changed the overall feel, but def a difference on the long extended decents.

[Patan-DH]

YES, good stuff. And teh 5.1 will work better for long extended runs. But like others said you might just be due for a bleed out as it is anyways. I would go with the Motul 5.1 as well, thats what I am running in my juicy sevens, cant say ti really changed the overall feel, but def a difference on the long extended decents.

Yes, but I can't get Motul 5.1 in friken Argentina....... i guess is the price we got to pay to ride in silent and rider empty mountains.....

[Patan-DH]

http://www.ridemonkey.com/forums/showpost.php?p=2704763&postcount=21

Should be helpful, think I covered a few things there that some people don't realise about DOT3/4/5.1 fluid standards. For a short answer, I use and recommend the Motul DOT5.1 fluid, because it has a boiling point almost as high as the highest end DOT4 fluids, while having a considerably lower viscosity = easier bleeding and lighter lever action + faster response.

By the way, if your brakes are fading it's much more likely to be a pad/heat/glazing issue (ie. actual surface issues) rather than a fluid issue. If the levers are getting spongier/coming to the bar though then yeah I'd suspect the bleed or fluid.

Thanks for that information UDI. I guess I'll have to live with that 30° lower boiling point..... by now and until i Get to earn the money for a good brakeset.

[DirtyMike]

Yes, but I can't get Motul 5.1 in friken Argentina....... i guess is the price we got to pay to ride in silent and rider empty mountains.....

Motul is just one of my favorite brands, you can use any 5.1 though, valvoline makes a good product also that should be available at a local parts house. I have had good luck with that one as well

[ATOMICFIREBALL]

Dang this post reminded me it's time to bleed my Hayes HFX9's ! Nasty.:panic:

[norbar]

Udi you rock! It's the second time you improve my life. Grow tits and your perfect