brake sludge that floats in the resevoir

[Jace009]

Being the young and dumb in the same day alows for oneself to fully experience his/her mental readiness :lol:  yaaa

My question:
The brake fluid in my bike is probably orginal [91 model ] so I'm going to attempt to change out the fluid by pouring in DOT 3 new green fluid in to resevoir and open up the bleader valve on the claiper and wait for the old gooup to "bleed" out. Theoriticaly the old fluid is clear and the new DOT3 is green so when it bleeds green were good to go right? Is this a correct method?, having a limited ability from an auto mechanic performing this on a car's disk brake....AND is the front resevoir under the black cover on the right side of the handle bar..how easy is the access?

[dgyver]

If you think the fluid in there is original then I would drain it completely and then add new. Might as well use DOT4, higher boiling point and fully compatible with DOT3.

[The Buddha]

I'd use dot 5 ... bluish in color and very resistant to water... BTW 2 year use limit on dot 4, 5 year on dot 5. Dot 5 also has indefinite shelf life... being non petro based... and no wont eat up the rubber parts.
Cool.
Srinath.

[dgyver]

DOT5 is silicone based NOT compatible with any other brake fluids.

[Rema1000]

A full change-out is best.  But I'm always afraid that I'll get air in the master cylinder and need to rent a vacuum pump.

I'd try to suck-out the crud, and some of the fluid from the reservoir, using a syringe (ask for a big syringe, with no needle, at the Walgreens pharmacy window).  Remove fluid until the reservoir is low, but not empty.  Then top-up with new stuff, and suck it back out again using the syringe.

Then top-up again, and pump it out the lower brake nipple until the reservoir is low;  and top-up and pump-out; then top-up, and call it good.

This wastes fluid, but you're going to have to dispose of the whole bottle of fluid anyways.  If you replace most of the fluid once per year (in the spring), then the amount of old fluid becomes pretty small.

[Jace009]

A full change-out is best.  But I'm always afraid that I'll get air in the master cylinder and need to rent a vacuum pump.
.

This is what I'm afraid of......I will look into DOT 4 & 5.


Sorry about the misleading title...I don't have sludge in it but I know the fluid is very old since it's a 91 model that has 6k miles and sat in storage for a while..[my only logical guess].

[Rema1000]

DOT 3/4/5.1 mixed with DOT5 = jelly.
DOT5 is only recommended for use in a new brake system, or after system rebuild.

[Shadowhawk]

There is a dot5.1 fluid that is compatible with dot 3&4 without the "sludge issue".  I'll look in my fluid box as soon as I get a chance and pass the specifics on.  I've used it in a couple of cars with great results, in my GS450LD without problems, but I couldn't find it when I was working on the brakes on my GS500.  As soon as I find the bottle, I will be putting it in my 4X4 and my GS500(once I get in on the road again), and buy a bottle or two to keep around.

Don
Shadowhawk
'92 GS500
'83 GS450LD

[The Buddha]

OK dot 5 doesn't screw up anyhitng if mixed with dot 4 ... probably have the properties of dot 4 mostly ... hence you wasting expensive fluid ... I have mixed them... no problem.
Then - air in the system... once again not an issue... it will automatically get bled out, suck/pump out the whole system till its dry, then fill with dot 5 and bleed/pump. I have in cases taken the calipers off and inverted them with the line still connected and the bleed screws out to get fluid out, and it has filled back up fine and worked good after a bleed. Air tends to go to the top anyway... so a ride down a bumpy road will effectively get all the air into the reservoir. Then for extra saftey hit brakes and crack and tighten every bleed point in the system. No more air... Oh BTW make sure you push the pistons back in all the way when swapping fluid ...
Cool.
Srinath.