Brakes are SOOO spongey!

Both the front and the back. I just changed pads, and it is not much better. I also have a "mighty-vac" and I have bled the system by sucking, and by the standard method, niether making any substantial improvment.

I am thinking that I may have mixed some incompatible brake fluids. Would 5.1 not mix with 4?

Let's just say that I did mix some stuff that does not work together. What kind of fix is required? Bleeding the entire system, cleaning and re-filling the system, or, would I have to replace the rubber that holds the pistons?


Thank you!


if you are talking bout dot 5 fluid it does not mix or work in a dot 4 system.if you are refering to your front brakes i have had the same prop twice i have fond water entry to be the cause. brake fluid atracks water in an off road motor cycel i dont imagin there is any thing you can do any thing about it other than keeping the brakes bled. i just do it the old fashion way.

Change with new dot4 brake fluid from sealed container. Use Carbone Lorraine brake pads. Much-much better than stock!!!

You do not want Dot 5 fluid in your brake lines. :awww:

This is BAD, BAD, BAD. Can't remeber exactly why off the top of my head, but I know that it's not good. Something to due with silicone or something.

Like the other guy said, replace all of your fluid with Dot 4 and keep bleeding your brakes until they feel better. Sometimes the bleeding prodedure can take a while depending where the air is trapped in your brake lines.

Good Luck. :thumbsup:

The stuff was 5.1, which I was under the impression was compatible with EVERYTHING.

Maybe not! :awww:

Ok. I am going to bleed both systems, and ensure that I am running nothing but pure brake fluid, of only one sort!

Hopefully that will solve the issue.

Thanks! :lol::thumbsup:

5.1 is not silicone based like DOT 5.

5.1 is a higher temp than the DOT4, as far as I have seen it is compatible. But NOT needed by any means. DOT 4 or some Castrol LMA (which I would suggest) is all you need.

Flush the system with some cheap DOT3 you can get from the parts store. Be SURE that you tape the threads on the bleeder screws with teflon tape. otherwise with the vacuum method you will suck air from the threads at the bleeder screws.

DOT 5.1 is shouldn't cause a problem. But DOT 5 is silicone and will NOT mix! Check which you put in, if it's DOT5 you'll need to take everything apart and replace all the rubber parts....

Before you try anything drastic, first try pushing back the brake pads completely by carefully prying the pads away from the rotor with a large screwdriver and then pump up the brake lever. Repeat several times. This simple procedure often will backbleed pesky air bubbles up into the reservoir and firm up the brakes.

FWIW: Here's a tip I got from an old M/C mechanic for cleaning contaminated brake lines. Be carefull if you want to try this or you could trap some rubbing alcohol in the calipers (not good). Drain all the brake fluid from the system. Remove the hose from the caliper. Place the brake line over/in a jar or bucket to catch the fluid. Refill the master cylinder with rubbing alcohol to rinse out the water, contaminants and old brake fluid. pump it a few times until it drains the resorvior. Refill with clean alcohol and repeat until the alcohol coming out of the line is clean and clear. If you want to clean out the caliper you will have to disassemble it by removing the piston/s (PITA). After draining it leave the brake system open for about 30 minutes to allow the alcohol to evaporate. Reassemble, refill and bleed. :thumbsup:

The 5 was actually very good. It would be great if a person used brake fluid like we use gas or oil. The 5 does not mix with water. Moisture will not bother it. Great so far.

BUT, moisture eventually gets into the system. If you are using 5, the moisture settles to the bottom. In our case it is the caliper. I dont even know how to describe the rust looking stuff that the caliper turns into. My brakes on my 79 XS 1100 had to be discarded after using 5 for two years. It was very misleading. The fluid looked great, but the brakes became more and more mushy.

Years ago Motorcyclist magazine could not sing the praises enough of this fluid. They had everyone change over to it.

This was when I realized magazines were for entertainment only.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now