brake fluid in clutch

[cjack]

Interesting. How many other manuf use Brake fluid in the brakes and hyd fluid in the clutch systems? I've never seen anyone else that does. Seems like for simplicity you'd use the same fluid the other hydraulic system (brakes) uses.

BMW used Brake fluid in the clutch system until about 2005 or so. Depends a little on the model. A little later on the in line LT I think. Then they went to mineral oil.

[ANDYVH]

Because the R-bikes use a dry clutch it is unique compared to other bikes/brands with hydraulic operated clutches. A bike with a wet clutch, like 90% or more of the bikes on the market, is unaffected if the slave cylinder leaks oil. Won't harm the clutch but eventually the clutch won't work when there is no fluid in the system.

BMW, Ducati, Moto-Guzzi are the only common cycle brands to use a dry clutch. The BMW is also unique because the clutch is inline to the driveline, not 90 degrees to the driveline like a Ducati. Moto-Guzzi, I think, only uses a cable operated clutch. So BMW is unique to use a dry clutch along with a hydraulic operated clutch.

If other bike makers used dry clutch hydraulic systems its pretty likely they'd use non-brake fluid in the clutch system too.

[cjack]

Because the R-bikes use a dry clutch it is unique compared to other bikes/brands with hydraulic operated clutches. A bike with a wet clutch, like 90% or more of the bikes on the market, is unaffected if the slave cylinder leaks oil. Won't harm the clutch but eventually the clutch won't work when there is no fluid in the system.

BMW, Ducati, Moto-Guzzi are the only common cycle brands to use a dry clutch. The BMW is also unique because the clutch is inline to the driveline, not 90 degrees to the driveline like a Ducati. Moto-Guzzi, I think, only uses a cable operated clutch. So BMW is unique to use a dry clutch along with a hydraulic operated clutch.

If other bike makers used dry clutch hydraulic systems its pretty likely they'd use non-brake fluid in the clutch system too.

The new R bikes will have wet clutches as the new GS for 2013 has. The rest will follow. The K bikes already have wet clutches and as well the G and F bikes.

[marchyman]

Maybe they didn't need to use brake fluid in this application but in the interest of making things simpler and more idiot proof, I wish they would have. Is mineral oil any better than brake fluid in this application?

Yes, mineral oil is better in this application. Brake fluid absorbs moisture and needs changing every so often. Mineral oil doesn't. My bike has this embossed on the clutch reservoir cap:

WARNING
CLEAN FILLER
CAP BEFORE REMOVING
USE ONLY MINERAL OIL
SEE OWNER MANUAL

[jeepinbanditrider]

Because the R-bikes use a dry clutch it is unique compared to other bikes/brands with hydraulic operated clutches. A bike with a wet clutch, like 90% or more of the bikes on the market, is unaffected if the slave cylinder leaks oil. Won't harm the clutch but eventually the clutch won't work when there is no fluid in the system.

BMW, Ducati, Moto-Guzzi are the only common cycle brands to use a dry clutch. The BMW is also unique because the clutch is inline to the driveline, not 90 degrees to the driveline like a Ducati. Moto-Guzzi, I think, only uses a cable operated clutch. So BMW is unique to use a dry clutch along with a hydraulic operated clutch.

If other bike makers used dry clutch hydraulic systems its pretty likely they'd use non-brake fluid in the clutch system too.

I understand how the driveline is setup I used to have an 1150R. I'd honestly rather see just a plain ol clutch cable setup instead of a hydraulic system of somesort. At least on these bikes it seems like it might actually be a step up in reliablity

[pch123]

I understand how the driveline is setup I used to have an 1150R. I'd honestly rather see just a plain ol clutch cable setup instead of a hydraulic system of somesort. At least on these bikes it seems like it might actually be a step up in reliablity

Dont necessarily agree. If you use mineral oil I think the majority would find the hydraulic clutch actuation system is very reliable. More so than a cable. Also a lot easier to use. Clutch actuation issues on R's is pretty rare I believe.
regards
Paul

[PGlaves]

Maybe they didn't need to use brake fluid in this application but in the interest of making things simpler and more idiot proof, I wish they would have. Is mineral oil any better than brake fluid in this application? After I did this, I looked in my owners manual. It doesn't say anything about what fluid to use only to take it to a dealer if the fluid is low. On the cap it does say to only use mineral oil. It's my own fault for not making sure which fluid to use first.

The problem with brake fluid is that if it leaks at the slave cylinder, when it migrates along the clutch rod it doesn't just contaminate the clutch. It damages both the transmission input shaft seal and the engine output main seal. Then they both need to be replaced. Mineral oil is compatible with those seals so won't damage them. It also won't attract moisture and there really isn't any required change interval as there is for DOT 4.

All in all I consider it a big plus over the brake fluid.

[rguy]

there really isn't any required change interval as there is for DOT 4.

Correct. I asked my dealer if I could buy a pint of mineral oil to flush my clutch and they told me there was no regular recommendation to change it. They told me they could order me a quart if I really really really wanted. They did not keep any in stock except for what they kept for their shop.

[DROOT153718]

Mineral Oil (hydrualic) to operate the Hydraulic operated Clutch is fine with me.

The benefit is its self adjusting and smoother.

David

[racer7]

+1 for what Paul said

While I've got a bit of sympathy for someone who has made the mistake of using the wrong fluid just how much more do you think the manufacturer should do- the reservoir cap is clearly written with what is supposed to go in it!!! Maybe contrasting colors and flashing lights?
READ THE LABEL - pretty simple...

There might be some people who just don't know there is a difference between hydraulic fluid and DOT4 brake fluid. In such cases one has to wonder whether they are really competent to be messing with a $20K piece of machinery and ought to just take the thing to a competent mechanic- the good ones are always worth way more than you pay them. Even though I'm able to do my own work, I sometimes pay one of my competent friends in the business to do it- keeps my contact lines open, saves a little time, always gives me the chance to learn a few tricks from the good guys who turn wrenches every day - hey, I'm only a part timer at it and like anything else in life, there is always someone who knows something I don't.

[jdubick]

+1 for what Paul said

While I've got a bit of sympathy for someone who has made the mistake of using the wrong fluid just how much more do you think the manufacturer should do- the reservoir cap is clearly written with what is supposed to go in it!!! Maybe contrasting colors and flashing lights?
READ THE LABEL - pretty simple...

There might be some people who just don't know there is a difference between hydraulic fluid and DOT4 brake fluid. In such cases one has to wonder whether they are really competent to be messing with a $20K piece of machinery and ought to just take the thing to a competent mechanic- the good ones are always worth way more than you pay them. Even though I'm able to do my own work, I sometimes pay one of my competent friends in the business to do it- keeps my contact lines open, saves a little time, always gives me the chance to learn a few tricks from the good guys who turn wrenches every day - hey, I'm only a part timer at it and like anything else in life, there is always someone who knows something I don't.

I totally agree with you. I don't mind changing oil and simple tasks but these things are not like old airheads. I was at the National in MO last summer on my 2010 RT and a guy walked past me and pointed at my clutch reservoir with a disgusted look on his face and told me I needed to change the fluid before I ruined something. The bike only had about 5k miles on it at the time. When I got home and took it in to have the 6k service done I mentioned it to the expert mechanic who educated me.

[jbarneshb]

Does anyone else want to rub salt in my wounds? I know it was my fault. After doing it I did see the warning on cap saying to use mineral oil. I had only owned one bike before with a hydraulic clutch and it used brake fluid. In hind sight it would have been cheaper to have a dealer do it. My only experience with the BMW dealer was after buying the bike a few months ago. It had been 1400 miles and 2 years since it's 6K service and service light was on. I paid $375 to change fluids and turn light off. that didn't include brake flush which they wanted another $110 for. I would gladly pay $80/hr for actual time spent working on bike but that's not how it works. I will continue to do routine maitenance but will be more careful in future. Even with a couple of mistakes, I still think I'll be ahead moneywise and learn a little in the process.

[TinyTrains]

Hey, it happens. I decided to start cycling out the power steering fluid in my Mazda. So sucked out about an ounce and poured in an ounce of PS fluid, with plans to do this 32 times. After I did this twice, I discovered it uses ATF not PS fluid. Who would have thought!

Luckily, I only put in two ounces, and I continued my process with a quart of ATF. No problems with the car and only my own pride was damaged.

[pffog]

Does anyone else want to rub salt in my wounds? ...........

Live and learn, we all have done things like this.

[RoboRider]

I fix most anything myself. I'm WAY ahead on the money, and there's knowledge, independence, and satisfaction that goes with it. If I beat myself up over a little mistake once in a while I'd be quite unhappy. Write it off, move on, and be happy with the money you save in the longer term.