So I go to change my front brake pads on my '01 FXST softail standard and I open the master cylinder...the fluid is yellowish in color. The H-D DOT 5 fluid is purple. I've read that the DOT 5 purple stuff will turn an amberish color over time.

How can I be sure that the yellow fluid in my master cylinder is DOT 5?

I've pulled some from the master cyl with a small syringe and put it in a shot glass and mixed in some of the purple DOT 5 stuff. They seem to mix together...they don't seperate. Neither one has an odor that i can identify as different???

Do you think that this stuff currently in the bike is DOT 5?

Any isight would be appreciated!!!

 

Not sure of any test that you can do but I know Dot 3 eats paint. find an old peice of metal and spray it with paint. when it's dry apply some fluid and see if it removes paint. If not you can eliminate Dot 3. you definately don't want to mix 3 and 5, you'll get a gel.

 

Thanks 48pan!

I've tested the stuff on a bunch of different painted surfaces and its not affecting the paint at all...I I wipe it around it just looks like a shiny siliconed surface....So I think I may be good.

The stuff I mixed up in the shot glass blended together as If it is the same stuff.

I'm thinking it has Dot 5 in it...I'm Hoping it has Dot 5 in it

 

How old is the fluid? since you have new dot 5, why not flush it!

 

DOT 3 fluid doesn't eat paint immediately. It takes a few days.

 

Question: How soon will the two form a gel?
Thanks
Jon

 

it will gel quick.
Which dot fluid does the master cylinder cover have printed on it?
If I did not know for sure which dot fluid I had, I would flush the brakes. It's really a simple job. Connect a piece of tubing to the bleeder on caliper, place tube in small container with the end submerged. (pour some fluid in the container so no air can enter caliper) open the master cylinder cover, pump brake lever/pedal, and as fluid is flushed out add to master cylinder.
That is one of a few ways to flush fluid. I used a vacuum canister w/air compressor hooked up to the caliper to flush mine.

If you do mix the fluid it will ruin the master cylinder, and the caliper, if the mixture makes it down the brake line to the caliper. They have rebuild kits for both.

Yes, the purple Dot 5 will turn the color of Dot 4.

 

Purple dot 5 turns yellow with age. An 01 SHOULD be dot 5. I've check a few old bikes by the mix method and you would notice right away as one floats on top of the other.

 

In my 06 manual I am suppose to drain and flush the brake system every 2 years. I would assume you have the same requirement. Myself, I would replace with DOT 5 fluid. Others will say DOT4, But I use DOT 5 because it is safer on paint, if I ever get a leak.
I think you have DOT 5 in it now.

 

Thanks for all the responses!

I determined that it was dot 5 that was in there.