Okay, before we begin, I did search and did not find what I was looking for just lots of post's about brake bleeding. Now that's out of the way, I read the manual but I just want to check with you all. I'm planning on changing out the clutch and brake fluid and if I read correctly it's DOT4 fluid in both clutch and brakes. Yes? If so, is one brand better than the other? I'm not trying to start a "what oil is better" thread. Just would like to know so when I do it in the next few weeks I'll be prepared. Doing the coolant also and going with Engine Ice, seems like a pretty simple process.

 

If you can find it, DOT 5.1.. thats five.One.. NOT DOT 5. is the best option, after that DOT 4 or 3 will work. Yes same fluid for clutch as brakes. Do a search on DOT5.1 fluid should find a write up or three telling you all you need on why it's a good choice.

 

Smack, I use a fully synthetic which meets and exceeds dot 4 & 5 specs and it works great! You can pick it up at any auto parts store.

 

DOT 3, polyglycol with a minimum boiling point of 401°F dry, 284°F wet. DOT 3 fluid will blend with DOT 4.
DOT 4, polyglycol with a minimum boiling point of 446°F dry, 311°F wet. DOT 4 will blend with DOT 3.
DOT 5, silicone with a minimum boiling point of 500°F dry, 356°F wet. DOT 5 will NOT blend with DOT 3 and DOT 4.
DOT 5.1, polyglycol with a minimum boiling point of 500°F dry, 356°F wet. DOT 5.1 will blend with DOT 3 and DOT 4.

 

SMACK.... Fully synthetic is NOT the way to go it will airrate under high heat and high pressures... its great for stored vehicles or show vehicles that get lite use..
Silicone, which is purple in color, is not hygroscopic and so causes virtually no rust or corrosion problems. It has a high boiling point and will not harm paint. However, it has a greater affinity for air than polyglycol. The air remains suspended in the fluid, making it more difficult to bleed the hydraulic circuit. When the Fully Synthetic first came out all of us racer types jumped all over it... but quickly found out its not the way to go... one good hot heat cycle the fluid airrated and the brakes got soft... 5.1 is the way to go at this time.

 

Thanks for the synthetic warning Ohio, but so far my fully synthetic fluid hasn't caused any softness in either my front or rear brakes and actually has provided a noticeably stronger front breaking feel

Have you had problems with it? I switched to it after my old Dot 4 fluid broke down...

 

Yes I have first hand experience with Fully Synthetic and yes it does feel great but there is the down side like I stated.. You stated "my old Dot 4 fluid broke down" what happened is your brake fluid reached its saturation point with moisture, being so standard brake fluid is hygroscopic... which is a good thing about standard fluid it holds the moisture in keeping the moisture from attacking the system, but once it gets to that point its time to flush it out.

 

That's good to know...Thanks Ohio! If I have any trouble with the synthetic I'll be switching back over to the 5.1

 

Just keep in mind fully synthetic has no protection against moisture so if you use it flush the system more often.. and it looks like your in FL and we all know there is no moisture down there...

 

We have a bit of moisture but it's not frozen

 

Smack Doogle sorry for hi-jacking you post...

 

thanks for the replies and no worries about the thread jack, this is educational!

 

You guys need to differentiate between "synthetic" and "DOT5". There are DOT3/4 fluids out there that are synthetic, Valvoline Synpower for example.

 

Valvoline Synpower is another option and it does meet the same specifications as DOT 4 but it is low-moisture so it would be a good to change it more often.

Valvoline SynPower® 502 degs. F 343 degs. F
DOT 3 401 degs. F 284 degs. F
DOT 4 446 degs. F 311 degs. F
DOT 5 500 degs. F 356 degs. F
DOT 5.1 518 degs. F 375 degs. F

 

Sorry Greg, the fluid I'm using is a 100% synthetic that claims to meet or exceed Dot3,4 & 5 specs. I picked it up at one of the discount parts stores and it works great! Don thinks I'll have problems with it, so I'll be watching it closely, but so far about 2K miles on it and it rocks

 

What is it and who makes it?

 

I finally had to chime in. ++1 with Greg on the Synpower (which is a "full synthetic I believe. I've used it for years with NO issues. Of course I flush my brakes & clutch at least once a year and often after riding in the rain for extended periods and/or days. Easy to do if you have a MityVac bleeder (the one with the vac guage and don't bother with their nipple attachments and just use the heavy wall smallest diameter tubing the provide in the kit).

See these links http://www.webbikeworld.com/Motorcyc...cle-brakes.htm and http://www.ibmwr.org/r-tech/oilheads/brakes.shtml

On the bleeder nipples I have used both the standard white teflon tape but the yellow "gas line" teflon tape is thicker and easier to handle (wrap counter-clock wise as you hold the outside end of the nipple in your hand and "chase" the tape into the threads with your fingernail or a dull knife). Grease does work but its messy and "Many machanics don't seal the nipple-hose connection with grease because air in the spent fluid does not affect the bleeding procedure, they do not mind seeing the air bubbles because the spent fluid will be disgarded and they do not check it for bubbles, and therefore they consider greasing the nipple as an unnecessary bother.".

OEMs and SpeedBleeder.com use a non-hardening thread sealant that Speed Bleeder sells (1/2 oz) for $10. I do not recommend Speedbleeders (which will not work with a MityVac) because squeezing the brake lever strokes the MC piston into the portion of the bore (cylinder) where corrosion lives which could/will tear up the piston seals.

 

So then normal (squeeze, open, close, release) bleeding can also tear up seals you say?? Also, I thought the master cylinder bore was aluminum (aluminium for you "other" guys ) so there would not be any corrosion to speak of.

Sorry to be the devil's advocate. Just trying to clarify.

 

I run 100% pure synthetic baby powder, it keeps the system dry, and does not irritate! best of all, can be stored after the bottle has been opened without going bad...

 

You are correct about the bore being (usually) aluminum but oxidation does "grow" there. As I'm sure you know, whereas aluminum does not oxidize or "rust" like steel (which produces hydroxides), it develops whitish/grey/brown deposits that can be removed mechanically or chemically (not easy to do in a MC) which WILL tear up the seals. Believe me, it happens. I have successfully removed oxidation from a MC bore but had to fill the pitting with 2-part epoxy and then carefully hone it smooth.

 

KC, thank you for your most valuable input. A savior, as usual.........

 

I am only glad that I can have a positive impact on this forum and this thread..I am certain that one day my vast knowledge on the subject will be recognized and sought after...

 

Please remind me to have you buy me a beer in July.

BTW,

 

Is the devil appeased?

 

I called Valvoline and asked which part of the formula was synthetic. The reply was that these glycols are not naturally occurring molecules, so they are synthetic. Emphasizing “synthetic” seems to be a marketing technique rather than unique chemistry,

Bottom line if change your brake fluid once at year you will be just fine for most riders..
I have tried many many different types of brake fluid over the years and the best to date is
Motul 5.1 in race conditions... When I say race conditions for me it means a 3 hour off road
Hare Scramble in tight woods were you are abusing the hell out of the brakes and the 5.1
is the best to date.. I flush the brakes after every race which most racers do... As for bleeding I use a vacuum bleeder.

 

Valvoline SynPower is what I'm using and it's working great and you can pick it up at Auto Zone for around 6 bucks

However, next change I'm going with KC's 100% synthetic baby powder

 

Does KC use 100% organic babies to create his synthetic baby powder?

 

Hehe, you just love to debate don't you?

To answer your question: No, not really. I took apart the 30 year old master cylinder on the XS750 not too long ago. No corrosion on the aluminum to speak of and the fluid was downright disgusting. I thought the hygroscopic nature of DOT3/4 minimized corrosion (but lowered boiling temps).

 

Go figure! Thanks for doing the legwork, Don!

 

No, I really do not like to debate but also am opinionated, so it goes with the territory.

My old 81 Kawi GPz550D1 (1st year of the GPzs with dual shocks, very nice steed) which I rode regularly but in those days maybe did not flush as often as you should developed significant bore oxidation (still have the old parts from the MC rebuild kit probably stashed away somewhere). Also, my 76 Yamaha RD400 MC needs bore care and a rebuild. I have fixed at least 3 other MCs with oxidation over the years so I guess you are just lucky or I'm not (if I did not have bad luck I would have no luck at all).

Check out my new thread for a Pit Bull group buy...