Brake Fluid Question

[britman]

I going to change the brake fluid on the R/3 shortly during my next maintenance interval. I see the book calls for DOT 4. It seems every bike I have ever owned with disk brakes calls for a different DOT fluid number. I know that DOT 3, 4, and 5.1 are glycol based and hygroscopic (wick water from the air) but what is the real difference between the ratings?

 

[Sidecar Flip]

I going to change the brake fluid on the R/3 shortly during my next maintenance interval. I see the book calls for DOT 4. It seems every bike I have ever owned with disk brakes calls for a different DOT fluid number. I know that DOT 3, 4, and 5.1 are glycol based and hygroscopic (wick water from the air) but what is the real difference between the ratings?

Geo:

The higher the DOT number, the higher the boiling point. That may seem inconsequential but it's important, especially during heavy braking when the calipers heat up. If the fluid boils, it looses it's incompressability and your brakes get spongy.

DOT 4 and 5 can either be Glycol based or silicone based with the silicone fluid having the highest boiling point but silicone fluid isn't compatible with glycol. If I were you and you are going to completely evacuate the system, I'd refill with synthetic silicone fluid. I'd also evacuate the system with a Silverline vacuum brake bleeder. Betcha Blob has one.

 

[HeR3tic]

Flipper, you NEVER cease to amaze me :bch: News you can use!

 

[HeR3tic]

The heat causing the water to vaporize into gas and it being the cause for the compression factor. Britman mentioned the hygroscopic nature of some fluids. The stock stuff no doubt needs a flush occasionally but stock (as recommended) refill fluid seems an easy enough regular maintenance. How much longer between flushings would a synthetic high grade fluid extend the change interval. My test: If I can't see my finger print under a dollop of fluid, whatever that be, then it's time to change. That doesn't mean I let the radiator fluid get so rusty brown that I can't see through it.

Speaking of coolant: I recently evacuated the radiator only, and refilled with a 1/2 blend (1/2 of recommended)Proline Water Wetter mixed with distilled water. It was thinner than the last change which got a small measure of anti-freeze. With this change, only draining the radiator, there was a very small measure of anti-freeze and a measure of Proline water wetter remaining in the engine coolant passages. The running temperature of the oil in the tank is 185 in 98 degree ambient air today. That is down nearly ten degrees. It is said that their product does cool better without any measure of anti-freeze. I'm convinced a seasonal change of coolant mixture is a plan.

 

[Sidecar Flip]

I'm good with physical aspects but my electronics suck. I wish the Rock had carbs. I look at that fuel rail and all the stuff under there and all the wires and sensors and just say to myself......I know how to do a 12 minute tune. Hopefully that will always suffice.

I read about the Tunperson stuff and the Power Commode and I'm amazed. I'm ****te scared if I tried to fiddle with the bike, it would turn into a toaster...one reason why it's completely stock and will stay that way.

That's one big reason why I bought the KLR. It's simple. Has a Kehin CVK carb, rock solid enscapulated transistorized ignition, 520 chain final drive, spoke aluminum wheels and single disc brakes. It's a lawnmower but it's a simple lawnmower.

 

[Sidecar Flip]

The heat causing the water to vaporize into gas and it being the cause for the compression factor. Britman mentioned the hygroscopic nature of some fluids. The stock stuff no doubt needs a flush occasionally but stock (as recommended) refill fluid seems an easy enough regular maintenance. How much longer between flushings would a synthetic high grade fluid extend the change interval.

Theoritically, indefinitely. Silicone fluid isn't hydroscopic. I have it DOT 5 synthetic silicone in my Bonnie/Sidecar. I did a complete flush and refill on the bike and the initial charge on the Performance Machine 4 piston disc on the sidecar was silicone. It gets ridden infrequently...once or twice a year and everytime I check the fluid it's just fine. My silicone fluid is purple by the way.