Is Motul RBF-600 okay for clutch fluid?
08-02-2007, 11:09 PM
#1
Is Motul RBF-600 okay for clutch fluid?
I'm having my crawford headers installed next week, and doug at crawford suggests putting high-temp clutch fluid in to ensure that it doesn't boil due to the heat from the headers.
From what I understand, for clutch fluid, you just use brake fluid. So I bought some Motul RBF-600 brake fluid that I plan to use, which has a boiling point of 600 degrees. I know it may be a bit overkill (or maybe not), but nevertheless, will this work for my clutch fluid? If not, what high-temp fluid do you guys recommend for this situation? I do drive the car on the track, if it matters. thanks
From what I understand, for clutch fluid, you just use brake fluid. So I bought some Motul RBF-600 brake fluid that I plan to use, which has a boiling point of 600 degrees. I know it may be a bit overkill (or maybe not), but nevertheless, will this work for my clutch fluid? If not, what high-temp fluid do you guys recommend for this situation? I do drive the car on the track, if it matters. thanks
08-03-2007, 05:04 PM
#3
I don't think it would matter, but the RBF was used in the Formula SAE car we had and it absorbed water very quickly compared to some other fluids. I use it on my own car for track days, but I bleed the whole system every year as a precaution. We couldn't leave it in for six months of hard use before we noticed a change. It seems very hygroscopic. Since the clutch fluid isn't somehting you bleed very often, I wouldn't use it. But, how hot can the fluid get unless it's running by a turbo downpipe? So, even the wet boiling point will probably be more than high enough for clutch duty. just my .02 on the hygroscopic issue,
Will
Will
08-03-2007, 08:44 PM
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I'll second Resolute's recommendation of not using the Mutol RBF600 or most high performance brake fluid.
Motul RBF600 and the likes will work superbly as extreme temperautre hydraulic fluid, but they are simply too hygroscopic as a long term solution. So unless you plan on this for a short term basis and willing to flush the clutch fluid routinely (no more than 6 months is also my recommendation here), it's best you choose something less prone to sucking the water molecules out of the air.
Your first line of defense should be to add addition heat insulation to the clutch line that runs dangerously close to the Crawford headers.
If you must, you could always go with the Castrol SRF brake fluid, which is LESS-hygroscopic. But be prepared to empty the wallet for them. 1-liter is ~$75
Resolute,
Former Formula SAE alum. here too!
Motul RBF600 and the likes will work superbly as extreme temperautre hydraulic fluid, but they are simply too hygroscopic as a long term solution. So unless you plan on this for a short term basis and willing to flush the clutch fluid routinely (no more than 6 months is also my recommendation here), it's best you choose something less prone to sucking the water molecules out of the air.
Your first line of defense should be to add addition heat insulation to the clutch line that runs dangerously close to the Crawford headers.
If you must, you could always go with the Castrol SRF brake fluid, which is LESS-hygroscopic. But be prepared to empty the wallet for them. 1-liter is ~$75
Resolute,
Former Formula SAE alum. here too!
Last edited by THX723; 08-03-2007 at 09:33 PM. Reason: typo
08-03-2007, 09:19 PM
#6
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Originally Posted by THX723
I'll second Resolute's recommendation of not using the Mutol RBF600 or most high performance brake fluid.
Motul RBF600 and the likes will work superbly as extreme temperautre hydraulic fluid, but they are simply too hygroscopic as a long term solution. So unless you plan on this for a short term basis and willing to flushing the clutch fluid routinely (no more than 6 months is also my recommendation here), it's best you choose something less prone to sucking the water molecules out of the air.
Your first line of defense should be to add addition heat insulation to the clutch line that runs dangerously close to the Crawford headers.
If you must, you could always go with the Castrol SRF brake fluid, which is NON-hygroscopic. But be prepared to empty the wallet for them. 1-liter is ~$75
Resolute,
Former Formula SAE alum. here too!
Motul RBF600 and the likes will work superbly as extreme temperautre hydraulic fluid, but they are simply too hygroscopic as a long term solution. So unless you plan on this for a short term basis and willing to flushing the clutch fluid routinely (no more than 6 months is also my recommendation here), it's best you choose something less prone to sucking the water molecules out of the air.
Your first line of defense should be to add addition heat insulation to the clutch line that runs dangerously close to the Crawford headers.
If you must, you could always go with the Castrol SRF brake fluid, which is NON-hygroscopic. But be prepared to empty the wallet for them. 1-liter is ~$75
Resolute,
Former Formula SAE alum. here too!
ALL brake fluid needs to be changed routinely - its probably the one thing people never touch, but should. If you do alot of track days, 1 x per year is more than fine. If you never track the car, once ever couple of years will suffice for all practical purposes.
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08-04-2007, 06:06 AM
#8
You guys bring up a good point. Since we track our cars a couple times a month, we changing out brake fluid, like most people change their underwear. 
It's a superb track fluid.
We regularly use RF600 for the street, and have not experienced any issues. But IMHO, regardless of fluid, I would be flushing/changing it at least once a year for street usage.
It's a superb track fluid.We regularly use RF600 for the street, and have not experienced any issues. But IMHO, regardless of fluid, I would be flushing/changing it at least once a year for street usage.
08-05-2007, 04:36 PM
#9
Originally Posted by THX723
I'll second Resolute's recommendation of not using the Mutol RBF600 or most high performance brake fluid.
Motul RBF600 and the likes will work superbly as extreme temperautre hydraulic fluid, but they are simply too hygroscopic as a long term solution. So unless you plan on this for a short term basis and willing to flush the clutch fluid routinely (no more than 6 months is also my recommendation here), it's best you choose something less prone to sucking the water molecules out of the air.
Your first line of defense should be to add addition heat insulation to the clutch line that runs dangerously close to the Crawford headers.
Motul RBF600 and the likes will work superbly as extreme temperautre hydraulic fluid, but they are simply too hygroscopic as a long term solution. So unless you plan on this for a short term basis and willing to flush the clutch fluid routinely (no more than 6 months is also my recommendation here), it's best you choose something less prone to sucking the water molecules out of the air.
Your first line of defense should be to add addition heat insulation to the clutch line that runs dangerously close to the Crawford headers.
I have a 500-ml bottle of Motul "DOT 5.1" brake fluid sitting around unopened, that I'll probably never use for my brakes -- would this be a bit longer-lasting (less hygroscopic)? The boiling points according to the bottle are: dry 522 F, and wet 365F, should be plenty for the clutch.
Also - how much fluid will the clutch take for a drain and refill -- will one 500-ml (1 US pint) be enough? thanks again
08-06-2007, 01:32 PM
#11
Originally Posted by mthreat
Thank you everyone for your feedback -- this is exactly why I posted, I knew I'd get some good responses! I'll save the RBF-600 for the brakes, and instead use something a little less extreme, which hopefully won't need to be replaced as often.
I have a 500-ml bottle of Motul "DOT 5.1" brake fluid sitting around unopened, that I'll probably never use for my brakes -- would this be a bit longer-lasting (less hygroscopic)? The boiling points according to the bottle are: dry 522 F, and wet 365F, should be plenty for the clutch.
Also - how much fluid will the clutch take for a drain and refill -- will one 500-ml (1 US pint) be enough? thanks again
I have a 500-ml bottle of Motul "DOT 5.1" brake fluid sitting around unopened, that I'll probably never use for my brakes -- would this be a bit longer-lasting (less hygroscopic)? The boiling points according to the bottle are: dry 522 F, and wet 365F, should be plenty for the clutch.
Also - how much fluid will the clutch take for a drain and refill -- will one 500-ml (1 US pint) be enough? thanks again
If I were you, I'd just throw in some Valvoline SynPower and be done with it. It doesn't have the high boiling point of the racing fluids, but why would you need it? It will last a long damn time without needing to be changed, and that seems more suited for a clutch line's needs than a caliper that sees track time.
Will
08-06-2007, 10:16 PM
#13
Originally Posted by Resolute
I could be wrong, but I thought the Motul 5.1 was a silicone base fluid? If that's the case, then I'd stay away from it. Maybe one of the Motul vendors will know, because I don't feel like looking it up.
If I were you, I'd just throw in some Valvoline SynPower and be done with it. It doesn't have the high boiling point of the racing fluids, but why would you need it? It will last a long damn time without needing to be changed, and that seems more suited for a clutch line's needs than a caliper that sees track time.
Will
If I were you, I'd just throw in some Valvoline SynPower and be done with it. It doesn't have the high boiling point of the racing fluids, but why would you need it? It will last a long damn time without needing to be changed, and that seems more suited for a clutch line's needs than a caliper that sees track time.
Will
08-07-2007, 06:19 AM
#14
Originally Posted by mthreat
I just checked the bottle and it says "non-silicone base". I just need some high-temp clutch fluid because of the crawford headers, but maybe the motul is overkill. thanks for the feedback.
08-07-2007, 06:38 AM
#15
Originally Posted by Sharif@Forged
RBF600 is not a DOT 5 fluid...it is a Dot4 racing fluid. it is compatible with OEM fluids, and is not as touchy as a pure Dot5.
Will
08-07-2007, 06:47 AM
#16
Originally Posted by Resolute
The RBF600 is, but what about the 5.1 he has? I thought that was a silicone fluid. I've seen a few bottles of it around, but never really looked at it. I don't know of anyone actually using the 5.1, but if they make it it must have some purpose.
Will
Will
I was just curious if the claims of Motul being more hydro than other brands, were refering to the Dot 5.1 instead of the RBF600, which is DOT 4.
08-07-2007, 07:11 AM
#17
Originally Posted by Sharif@Forged
The 5.1 is a pure racing fluid. I havent sold it before, since most people drive their cars on the street, rather than full race only cars.
I was just curious if the claims of Motul being more hydro than other brands, were refering to the Dot 5.1 instead of the RBF600, which is DOT 4.
I was just curious if the claims of Motul being more hydro than other brands, were refering to the Dot 5.1 instead of the RBF600, which is DOT 4.
Will
08-07-2007, 08:53 PM
#18
Originally Posted by Resolute
The 5.1 designation seems confusing then, but I think they were trying to coney that it is a fully synthetic fluid like DOT5 fluids, but better than a pure silicone fluid, so they called it 5.1... those crazy french guys. Anyhow, Motul bills it as a long life fluid for cars with ABS systems and for clutch lines and is less hygroscopic than their racing fluid, so I say it's a good bet for your clutch if you've already got a bottle of it.
Will
Will
I just went to stoptech's web site and read their brake fluid article here:
http://www.stoptech.com/tech_info/wp...fluid_1a.shtml
They explain DOT 5.1 fluid:
Historically, DOT 5-level performance (specifically boiling points and viscosity) could only be achieved with silicone-based fluids. However, modern compounding has created glycol ether-based fluids which now meet DOT 5 bogeys in these key areas. Consequently, the DOT 5.1 moniker was created to differentiate between these two very different chemistries which both meet DOT 5 performance requirements.
In so many words, DOT 5.1 fluids are simply DOT 4-type fluids which meet DOT 5 performance requirements. Because of this, they typically can be mixed with DOT 3 or DOT 4 fluids without concern. In some circles, they are even referred to as ‘DOT 4 Plus’ or ‘Super DOT 4’ fluids because they are more similar to a conventional DOT 4 fluid by chemistry than they are to a conventional DOT 5 fluid. In fact, DOT 5.1 is essentially comprised of Borate Esters.
While it may not be obvious, the big advantage of the DOT 5.1 fluids is that they contain all of the nifty water-absorbing characteristics of the DOT 3 and DOT 4 fluids while simultaneously providing for very high boiling points and relatively stable viscosity over a wide range of temperatures. The best of all worlds, you could say. ...
09-12-2007, 11:08 AM
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Originally Posted by mthreat
While it may not be obvious, the big advantage of the DOT 5.1 fluids is that they contain all of the nifty water-absorbing characteristics of the DOT 3 and DOT 4 fluids while simultaneously providing for very high boiling points and relatively stable viscosity over a wide range of temperatures. The best of all worlds, you could say. ...