Some guidance on changing brake fluid

FloydV

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It's cold out, and my brakes have a little give when I grab them, so I thought I'd change the fluid. Standard DOT4.
You guys correct me if I get it wrong.

The only drain nipple I see is on the left fork. There is a hose that connects the two calipers together. The nipple is on the left one. I would connect a drain hose to it and open it. I would also loosen the the front brake lever and rotate it so that the reservoir would be level.

Then I would connect the hose to the nipple, loosen the nipple, and start using my vacuum pump to pull fluid out until the system seems empty. Following that, I would add new fluid and keep pumping until fresh fluid with no bubbles comes out of the nipple into the vacuum pump container while making sure the brake fluid reservoir stays full by adding fluid as necessary.

Then I would close the nipple and make sure the brake fluid reservoir is full. Then replace the cover, and I should be finished.

The same for the rear brake.

Am I very close to right? I forgot. What size is the nut on the nipple?

Thanks,

Floyd
 
do you already have a service manual? Service manuals for Suzuki GSX-R Motorcycles, free download of service manuals for your GSXR bikes

P.S. Go to p 500 of the manual (Gen II) for the START of the procedure. When I switched pads/lines on my old 08, I used this:

31mmGbKI2TL._SL500_AA300_.jpg
 
I always suck the resevior out first, then fill it with the new fluid.Then bleed the lines and calipers thru the bleeder screws making sure to keep the resevoir full untill the new fluid comes thru the screws.I use a vacuum pump and never have an issue.
 
Wait, let Tuf comment. I just did this last weekend when I changed my pads; he had a bunch of 'tips' that made this a lot easier.

P.S. If your brakes are already charged, you won't need a pump to do this if you do it right!!
 
one tip to help burp any trapped air: pull lever in, zip tie and leave overnight
 
Ok, since Tuf hasn't posted yet, let's see if I can remember it all:

- If you were going to change pads too, do all the flushing/bleeding first so you don't get any fluid on the new pads.
- Open the top filler cup, take some paper towels and soak up all the fluid in the cup. There is only about a tablespoon of fluid actually in the lines, and this way all you have to do is bleed enough old fluid out to get to the new fluid.
- fill the fluid cup about half full with new fluid.
- take a t-shirt and tie it around the cup so that if any leaks it doesn't fall all over your nice purty plastics (brake fluid will eat the paint up quickly.
- put the rubber plug back on the cup and the cap with a half-turn (just enough to cover it.
- take a piece of clear rubber tubing and a cup (I get a red drinking cup and tape it to the fork so I don't have to hold it). Slip one end of the tube over the bleeder nipple, and the other into the cup. P.S. There should be a nipple on each caliper, and one on the brake master cylinder

- Now, here's where it gets interesting. Apply pressure to the brake lever, and WHILE HOLDING THE PRESSURE, loosen the bleeder valve (8 mm open end wrench) just enough so that the fluid, under pressure from the applying the brakes, will come out of the valve into the tube/cup. DO NOT LET UP ON THE BRAKE LEVER! Ride the lever down the the handle bar, and BEFORE LETTING OFF OF THE LEVER, tighten back up the valve. Pump the brake lever back up to full pressure (if you need to) and repeat. Every couple of times you do this, take a look into the cup and see what level your fluid is, as fluid will travel out of the cup, and down the lines. When you need to, stop and put some fluid in the cup between bleeding cycles. Once you've put about a half cup thru the lines, you have flushed the old fluid out. As long as you do not let up on the brake while the valve is open, air will not come up into the valve, and as long as you keep fluid in the cup, no air will get into the master cylinder.

- Air: IF you have air in your lines (and as long as you follow the above, you will introduce no air into the system), there may be tiny bubbles in your fluid as it comes thru the bleeder valve, but with a few repititions it will be gone. Once you are satisfied, tighen up the bleeder valves, then go top off the cup with fluid, put back on the cap and tighen.

- If you want, put a bungee cord or something on the brake lever overnight and in the morning see if it's gone down any; if so, bleed it once or twice more using same instructions above (I've never had to).

- What is CRITICAL is NOT to induce air into the system by either a) letting the cup get completely empty and pumping air into the master cylinder, or b) Letting up on the brake lever BEFORE tightening the valve back up and sucking air up into the caliper from the bottom.

- If you do get some fluid on the brakes, clean them with some spray brake cleaner and a rag to remove.

- Ask TwoBrothers about the first time he needed to bleed/charge his brakes at Barber. I had just done it myself the first time, and we pumped and pumped and couldn't get his brakes to come up - it was because we wern't closing the bleeder valve before letting go of the brake...

- If you do it this way, you won't need a pump, and you won't take the chance of sucking air into the system from the top. If you do get air in the system, you will need to bleed the master cylinder back up to pressure before working on the calipers/lines.

If you ever want to change brake pads, then the above is one step in that process before you replace the pads.

Take your time and enjoy, wrenching on your own bike is very entertaining!
 
That is a very thorough breakdown of how to do it. This is similar to bleeding brakes on a car, except it takes two people because you can't keep pressure on the pedal and be at the bleeder valve at the same time.

Thanks,

Floyd
 
Good Job Keith!

I'll add that you should always use clear tubing on the bleeder valve so you can watch the fluid as it escapes for signs of bubbles.

Another little trick that race guys use is to zip tie the brake lever to the clipon when you haul your bike to the track. This shaking and bouncing will get the tinny little bubbles that may be trapped in a crack or crevis some place to turn loose and find their way to the top. I use this little trick often.

If you use your bike at the track often, change your brake fluid AT LEAST once a year and more often if the track provider knows you by name.

DOT 4 brake fluid is what the factory recommends and I agree. I use the Motul 600 that Kromedome pictured above. It's more expensive than most but its really good stuff with a very high boiling point. If you never attend a track day the boiling point is not an issue and using high end fluid is not as important.

Bleed your brakes thoroughly and often. Your brake lever is the second most important thing in your life to have firm on demand! :beerchug:

There is a bleeder valve available called a "Free Bleeder" that makes the job a bit easier. The Free Bleeder has a check valve internally that allows you to simply pump the lever while the valve is open without fear of ingesting air back into the system when the lever is released. They work quite well.
 
Very cool SteveO; I thought I specified clear tubing but thx for clarifying. So why haven't u told me about those valves before?

P.S. I have some Amsoil DOT 4 fluid with a 10% higher boiling point than Motul :)
 
Those "Free Bleeders" are for people with "MONEY" not a cheap bastid like YOU! :laugh:

Are you sure the Amsoil has 10% higher or 10 degrees higher boiling point. Is that wet boiling point or dry boiling point. I'd be interested to know?

For a hillbilly pig farmer in Murfreesburo, Tennessee,,,,,,,,,,,,,,,,,,,, you did a very good job on your brake bleeding post! :bowdown:

Now, put on your rubber boots, go feed dem pigs and leave the sheep alone, woodga? :whistle:


Very cool SteveO; I thought I specified clear tubing but thx for clarifying. So why haven't u told me about those valves before?

P.S. I have some Amsoil DOT 4 fluid with a 10% higher boiling point than Motul :)
 
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