Clutch fluid??

[jwheat]

I asked this question in someone else's thread, but I haven't gotten an answer yet so I figured that I would start a new thread about it. I already know what fluids Cannondale and Magura say to use in the hydraulic clutches. My question is this....why can you not use DOT3 or DOT5 brake fluid in this system? DOT3 or better brake fluid is used in every clutch master/slave cylinder set-up that I have ever seen in automotive applications. Why is not usable in Cannondale clutch systems? I know that brake fluid will swell any rubber is not resistant to it...is it because the rubber seals in our systems are not resistant to brake fluid. I have had DOT5 brake fluid in my system for close to a year. Am I damaging my clutch master and/or slave cylinder?

[cannondale27]

Honestly I dont know.But welcome to R&D.How well does DOT5 work?Better feel?Worth changing often because it contaminates and loses its properties faster?If its a improvement I would consider giving it a try.

[Cdale_racer_669]

good question. isnt DOT 5 thinner than mineral oil or magura blood tho?

[jwheat]

C27...honestly...I can't tell a difference between the feel of my clutch and the feel of the clutches on the two Dales my friends own. I haven't changed my fluid in almost a year, so I will change the fluid out with some fresh DOT5 this weekend and let you know how it looks and if the feel of the clutch changes with fresh fluid. I say this because gradual changes over the last year may have gone unnoticed. To me..it has worked fine, but I wouldn't recommend it to anyone without a little further testing. I have two complete new clutch kits at my shop so I may get one of my buddies to try it in theirs and see how it does. If it messes something up then I have spares.

[cannondale27]

Great seems like you might be on to something here.Keep us informed.Want me to put this in R&D?

[jwheat]

That'll be fine C27. I keep everyone updated.

[cannondalerhino]

From what I understand the brakefluid is too corrosive!

[jwheat]

Ok...I agree with you that brake fluid is more corrosive, but it is in a sealed system. Is the piston or seals not up to resisting the brake fluid? I haven't seen it eat up anything in an automotive application (except paint and non-resistant rubber).

[wistech]

I was thinkinmg the same thing. I think the master is made out of zinc or magnesium. The other thing is most slave cyllinders use spring loaded seal cups for brake fluid. The magura uses an o ring of what im sure is buna n. You wouldnt want your o ring to swell and start slipping your clutch because of sticky cyllinders. Or worse what if it leaks past into the tranny . Lets make a phone call to magura and get the lowdown.

[jwheat]

I was kinda thinking the same thing Wistech....I'll try and find a number for them and give them a call first of the week. I'll let you know what they say.