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How much brake fluid is needed to flush the system?

IdahoMtnSpyder

Active member
The 2014 RT service manual shows the brake system capacity to be about 18 oz of fluid. The procedure for replacing the brake fluid calls for 1.75 qts of fluid to do the job. For those who have replaced brake fluid how much more than the system capacity did you use to make sure the system is cleanly flushed? I bought 24 oz of fluid. Do I really need to go buy another quart to make sure I have enough to do the job?
 
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I used a Harbor Freight hand vacuum pump. Hook it to the right front caliper first and pump out the old fluid until it changes color. The new clear fluid will show up after several pumps. Replace the fluid in the reservoir as you go. DON'T allow the reservoir to go dry! Do the same on the left caliper and then the rear caliper. Don't refill the two reservoirs to the brim. Leave a little room about 1/4" below the top of the neck. Don't fill to the top of the threads. Go ride and make a couple of good hard stops and then recheck fluid levels. Lacker thinner will cut the brake fluid if you spill any and need to clean it up. There are a number of posts on this subject explaining different procedures. Almost any of them will help you get the job done. Good luck & have fun. 1 qt. is 32 oz.
 
There are a number of posts on this subject explaining different procedures. Almost any of them will help you get the job done.
But I don't remember anyone saying how much fluid they used up in the process. The service manual procedure calling for 1.75 qts (56 oz) when the system capacity is 18 oz seems like a lot of extra fluid to have available to do a good clean flush. I guess I could go buy 3 more 12 oz bottles and return any full bottles I don't use.

You said you did right front brake first. The service manual says to do left front, right front, rear, and ABS, in that order.
 
But I don't remember anyone saying how much fluid they used up in the process. The service manual procedure calling for 1.75 qts (56 oz) when the system capacity is 18 oz seems like a lot of extra fluid to have available to do a good clean flush. I guess I could go buy 3 more 12 oz bottles and return any full bottles I don't use.

You said you did right front brake first. The service manual says to do left front, right front, rear, and ABS, in that order.

I expect that your procedure is similar to mine. My manual calls for 1.85 qts. The fluid replacement procedure directs you to do the full system bleeding procedure. And that procedure runs you through everything twice. Once by doing manual bleeding and once by doing the BUDS bleeding procedure. That's why it calls for so much fluid. Nobody that I heard of is going through all of that.

Unless you think you have an air problem, all you really need to do is flush out of each caliper until the fluid runs clear. When you stop is up to you. Just keep filling the reservoir and don't turn the key on until you're done - or you'll have that pesky low pressure switch code. And unless you have an air problem, you can skip bleeding out of the ABS unit - unless you really want to contort yourself into a new yoga position. Flushing both front and rear circuits will adequately flush the ABS body. All in all, I used just under 2 bottles and had a third in standby.

I've used a vacuum unit and Speed Bleeders. I'll never go back to a vacuum unit.
 
I concur with the opinion about vacuum bleeders. I've tried many times to use my MityVac to bleed brakes and it almost always results
in sub-optimum bleeding. The bleeder screws just leak too much around the threads. If they sealed then it would be a very useful tool,
but they rarely seal, and using teflon tape to seal the threads is not such a good idea due to pieces of the tape making their way into
the system. SpeedBleeders are much more reliable, a bit more work than a vacuum bleeder, if the vacuum bleeder worked as well as one
would hope it would...but it rarely does.
 
I expect that your procedure is similar to mine. My manual calls for 1.85 qts. The fluid replacement procedure directs you to do the full system bleeding procedure. And that procedure runs you through everything twice. Once by doing manual bleeding and once by doing the BUDS bleeding procedure. That's why it calls for so much fluid. Nobody that I heard of is going through all of that.

Unless you think you have an air problem, all you really need to do is flush out of each caliper until the fluid runs clear. .
Thanks. I'll probably do the ABS bleed part since I have the BUDS s/w. PowerSports Diagnostics had it on a sale price at the end of last year and I couldn't resist!
 
Got the flushing completed today. First off I gotta say Speed Bleeders are the cat's meow! They make the bleeding process almost fool proof!

Well, I figured out that the service manual has it almost right! By the time I was finished I had used almost all of the three 12 oz bottles of fluid I bought. What surprised me was how much fluid it took to completely flush the system thru the left front brake. It took about 14 oz to get to the clear fluid stage. The fact I added fluid to the reservoir before I pumped it down much probably made it so it took more fluid to flush it all out. In other words, the more old fluid in the reservoir when I added the new fluid the more mixing of old and new took place. But I sure wasn't going to take any chances of letting the reservoir get empty and suck air in the line! Here are a couple of pics of the left front bleeding results. How much the dark color of the old fluid in the jar is due to age, and how much is the color of the fluid BRP uses, I have no idea. The lighter fluid in the paper cup is new fluid from the bottle, and the other paper cup is new fluid bled from the brake. In the first pic you can see the new flushed fluid is almost new fluid clean. In the second pic the fluid from the brake is almost as clear as the new bottle fluid. That is the point I said good enough!

Left front almost done.jpg

Left front done.jpg

The right front didn't take near as much fluid to flush the system clean. This pic is after maybe 4 oz were pumped through. The rear brake took a little more to come clean, but nothing like the left front.

Right front done.jpg

Flushing the VCM took only about 4 oz to come clean. I did the BUDs bleeding process in the same sequence as the manual flush.. BUDS tells you when you have pumped enough fluid through each of the four units. That part of the process used up maybe 4 oz total for all four. So in the end I used about 34 oz.
 
"You said you did right front brake first. The service manual says to do left front, right front, rear, and ABS, in that order."

Nice job and nice post. From looking at the schematic of the brake lines it appears the left and right front lines could be an even split so line length may not be as critical an issue as we thought. However, the left front first would be the obvious choice. https://www.cheapcycleparts.com/oemparts/a/cam/602170a287a8660f147ed044/hydraulic-brake
 
So using the speed bleeder, I assume you move one bleeder to the wheel you are doing and then onto the next. With that said, does the same bleeder work on front, rear and the ABS unit? Guessing they are different between models as well.
 
So using the speed bleeder, I assume you move one bleeder to the wheel you are doing and then onto the next. With that said, does the same bleeder work on front, rear and the ABS unit? Guessing they are different between models as well.
I installed one on each brake and ABS. For the price I wouldn't mess with using one only. If you do the BUDS procedure you have to bleed each one a second time. The three brakes are 6mm thread and the ABS is 10mm thread.
 
So using the speed bleeder, I assume you move one bleeder to the wheel you are doing and then onto the next. With that said, does the same bleeder work on front, rear and the ABS unit? Guessing they are different between models as well.

On mine the back bleeder was a different size!
 
On mine the back bleeder was a different size!
Was it 2013 or 2014 when BRP switched to the Brembo brakes? The bleeders on the Brembos are the same size for all three. There was confusion a few years ago about what the sizes should be until the Speedbleeder folks got it figured out that MY made a difference.
 
Mine is a 2013 STS and has Brembos. I usually use a hand pressure pump doing brakes but will look into the speed bleeders. I’ve seen them for years used on cars but have never tried them. I’ll have to look up sizes.
 
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