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Help, brake bleeding.

11K views 85 replies 11 participants last post by  brock29609 
#1 ·
Installed a set of 4-pot calipers on the front using the SVRacing adapters and Galfer lines.
Added new Dot 4 to the system. A friend and I poured the fluid into the reservoir and sucked it out of the calipers using a vacuum bleeder. Did it until no air came out of both front calipers.
Front brake lever still really spongy. So we reversed the process and added the fluid into the calipers and drew it out of the new banjo bleeder I bought from SVRacing. Pulled a ton of fluid thru the system this opposite direction also. Still have a spongy front brake lever.
All I can think of is that there's still obviously an air bubble somewhere, but can't see how given what we did above. Maybe in the ABS pump, that the shop manual calls the HU/Hydraulic unit?
So I've zipped tied the front brake lever pulled in and will leave it there overnight. Maybe I'll get luck and whatever bubble is there isn't stuck in the HU and will migrate to the top where we can pull it out of the upper Banjo bleeder or hopefully it will just migrate into the master cylinder, who knows?

Any suggestions??!!

Thanks!!
 
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#2 · (Edited)
Try holding slight pressure on the brake lever as you slightly loosen the hose banjo bolt at the master cylinder--look for bubbles as the lever is pulled back. Be sure to tighten the banjo bolt before you release the brake lever. Repeat this process at the right caliper then the left caliper, and finally at the bleeder screws under pressure. Air likes to hide in the banjo bolt. This also applies to the rear brake circuit as well. With oem brake hoses I'd recommend using hose pinch-off pliers to isolate each branch of the hydraulic circuit, but I woudnt do that with your SS lines.
Does your brake lever "pump-up" if you pull and release rapidly? If so, look at the caliper pistons being pulled back in their bores(Ive seen that). I did have an issue like that years ago with a GSXR-750--it was a bleeder valve atop the front master cylinder under a rubber boot. Ive also had to loosen and tighten under pressure the pipes at the ABS unit while checking for bubbles. I have had to, but Ive read that sometimes the ABS unit needs to be actuated to remove air. Ive recently flushed brake fluids in my '14 DL1000 and a friend's 'DL650, but I made sure the reservois didnt run dry at any time.
 
#3 ·
I wonder if starting up the bike with it on the center stand, putting it into gear, and then stepping on and holding the rear brake pedal would continuously fool the ABS to thinking the rear wheel was locked up and make the ABS pump stay continuously activated thereby pushing out any trapped air. However if that worked, that might just push the air somewhere else into the system, requiring a full flush again just to work it out.
 
#5 ·
I figure that by doing it the normal way on the road, the ABS pump would only kick in during the period of time that the brakes are automatically released, whereas (maybe.......) doing it on the center stand would allow the ABS pump to continue cycling as long as your on the rear brake pedal, thinking that the wheel is still locked up.

Actually, I just went out to the garage and clipped the zip tie holding the front brake lever in and "gosh darn it" it feels fairly tight now. I think that by tying back the lever, any residual air that was somehow trapped in there even though I pushed 10 tons of fluid thru both directions, may have migrated upwards and dissolved into the air space in the master cylinder, which was my intent by tying back the lever and letting it sit for several hours. Going to push more fluid up from the calipers and thru my new master banjo tomorrow just to make sure, making sure I don't introduce any new air into the calipers.
 
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#7 ·
Did the ABS activation allow any trapped air to migrate into the MC, or did you have to bleed it off again?
 
#9 ·
WVS and Hatchi, I have to tell you...
In all the years Ive worked on bikes Ive never used the zip-tie method. Never had to.
I realize some service manuals show that, but for sure none of mine do, including my '14 DL1000 shop manual.
In WVS's case I think having the lever tied to the bar has the master cylinder piston closes off the compensating port in the master cylinder, so trapped air can't be released into the master cylinder reservoir, and stays in the hydraulic circuit.
I do know using zip ties during bleeding has been discussed in the past on this forum, maybe in relation to a clutch plate being pushed off its spline. I dont use a zip tie for servicing the clutch hydraulics either.
 
#10 ·
The instructions that came with the Galfer lines say to do it, but I think that's because they want you to pressurize the lines for a leak check.
Wouldn't zip tying the lever open up a path to the MC allowing air to escape?
 
#11 ·
No. There is compensating port in the bottom of the reservoir that is closed by the master cylinder piston seal when the lever(or pedal) is depressed. Sometimes you can rapidly repeatedly pull the lever and hold it for 3 seconds...then release it and see bubbles escape. By to this quickly youre not letting fluid back into the reservoir, so it build up behind the piston seal. When you finally release the lever it all comes back through the bottom of the reservoir. Also, look closely at the bottom of the reservoir, pull the lever, and slowly let up--sometimes you'll get bubbles out that way as well.
 
#12 ·
This is exactly the problem many have when converting to 4 pot calipers. I did too. I don't think the ABS module is the issue, but then again I know mine got better after some hard braking tests to bed the brakes and it might have been that I was allowing air out of the ABS module. I too agree that zip tying the lever down should be counter productive. What I done was leave the bike on the sidestand and the bars turned to the left. That makes the master cylinder the highest point. Then occasionally flick the brake lever about 1/4 way each time I walked by it. That allowed those pesky bubbles between the master cylinder piston and the rubber hose connection to the master cylinder to work out of the system through the fluid port. Which is indeed blocked when zip tied down.

Bear with it! Worth the trouble when you get it right. When you see owners report they were not impressed by the 4 pot conversion, I just know they didn't bleed it right.
 
#14 ·
I had no bleeding problems (other than the process taking MANY hold-open-releases) when I recently did the 2 pot Tokico to 4 pot Nissin conversion on my ABS-less '01 SV. It took a number of miles before the new pads were able to bed in but the results are quite noticeable upon hard braking. Normal braking did not produce noticeable gains. And who knows if the gains upon hard braking are attributable to the 4 pot calipers or the EBC sintered pads. But those gold colored Nissins are very pretty.:wink2:
 
#15 ·
Reverse bleed the braking system. In stead of the traditional method of trying to pull air down (vacuum) and out of the system you inject fluid into the system at the calipers and push the air up and out of the master cylinder. Air in fluid naturally wants to rise so why not help it do what it wants too.
 
#16 ·
I know reverse-bleeding works...but Ive never had to do that. I do use an air-powered vacuum tool, makes it quick,easy, and clean. But I do crack open the banjo bolts then the bleeder screws afterwards, never get a soft lever or pedal.
Whatever works, and whatever it takes.
 
#17 ·
I have an air powered vacuum bleeder tool too. They work good.

But I WILL learn how to do the reverse bleeding and buy the tools to do it. Sometimes things are made too complicated, and by every measure it makes more sense to push clean fluid in from the bottom! Maybe I have been doing it wrong all along!
 
#18 ·
RS, it isnt wrong if your method works.
Before I got my air bleeder I used MightyVacs, did the reverse-bleeding a few times. It worked. Took longer, more setup and care, used the different plastic attachments, all that. Not worth the extra time involved. But Ive tried both methods and came to my own conclusions.
One of the problems is that some owners will vacuum out until the reservoir runs dry and beyond. Then they spend an hour to purge air in the system that shouldnt have been allowed to enter in the 1st place. I vacuum at the bleeder screws until I have about 3mm fluid in the bottom of the reservoir--no lower. Refill, repeat until the clean fluid flows the old fluid out. Refill, lever or pedal under pressure and crack open each banjo bolt in sequence from the master to the caliper to purge the fittings. Finish with the bleeder screws and DONE. !0 minutes or less start to finish...and I'm not even on the clock at work!
At work we used a machine that pressurised the master cylinder reservoir while at the same time suctioned out the old fluid through the bleeder screw. The job paid 1 hour labor time, it could be done in 15 minutes.
Now I just do it for fun...and to make use of my tools.
 
#19 ·
Update:

Test rode the bike today. Despite a slightly still soft lever, the 4-pots are very strong. Absolutely noticeable. Hit the front brakes hard multiple times to activate the ABS, which I did feel kick in.
Going to let the bike sit overnight, then test ride again. If lever still soft, will bleed ONE MORE TIME from all three locations; both calipers and the MC bleeder I installed.
I'm also getting a noticeable rotational noise from the front, so I'm hoping that will disappear after more bedding in of the new sintered pads.
 
#20 ·
WVS, just asking...
When you apply the front brakes with the bike stationary, do the calipers move on their slides? Ive seen calipers stick and flex slightly on their mounts, and the 1st bit of lever application is used up in getting the calipers to stop then apply the pads. It gives a soft lever feeling.
 
#21 ·
Just keep bleeding, cussing it, bleeding, etc. It WILL eventually get to the point the lever feels really good.

The difference in initial bite is substantial! Yes, you can kick in the ABS now. Where before with the stock front brakes and good street tires I could pull the lever to the grip and not engage ABS on good concrete!

I do get a bit more "whirring" noise with these calipers when applying the brakes. That is the sound of the pads going over the holes in the rotor. Different size pads make it more noticeable.
 
#23 · (Edited)
Maybe that's the rotational noise I'm getting. The noise doesn't occur only on full rotation, but more often, so that would make sense. I'm guessing the sintered nature of the new pads is creating the sound as they're more abrasive?
Went back to the man cave for the third time last night. Bled all three bleed screws once again. Only one very small bubble out of the MC bleeder, but a bubble is a bubble. I also cracked the actual banjos and pumped a good amount of fluid through all three. Didn't see any air, however with that much fluid surging out around the banjo's it would be hard to tell.

The lever actually feels not too bad now. Going to test ride. If all well will post pictures of the project. What a friggin PIA. They only thing left if the test ride doesn't pan out is to remove the battery and battery box and crack the connections on the ABS pump/HU.
 
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#24 ·
Give it some time. When I did mine I left the bike on the side stand and brake lever tied down with a Velcro strap for several nights accompanied by repeated tapping on the lines and t connector. Mine had no ABS. Once the pads had seated properly to the discs the lever feel (and the brake intensity) was certainly crisper then early on. So I would just ride it for a while and then re-try bleeding if it remains softer than before the swap.
 
#35 ·
What do you gain by tying down the lever? I tried that, but the more I think about it, that would close off the passage to the MC, not open it which allows bubbles to hopefully migrate into it.
 
#25 ·
Might not apply, but when I rebuilt the calipers and went to bigger brakes on an E46 BMW I had a very hard time getting the pedal to feel firm. I eventually took it to a mechanic and he removed the calipers, slighty expanded the pistons, then put the caliper back on over the rotor tight. My pedal was rock hard after that and the brakes were fantastic.
 
#26 ·
@MAZ4ME, @realshelby

When you guys use the vacuum bleeders, how do you get a solid seal in the threads of the bleed valve?

Every time I've used a vacuum bleeder it continuously sucks tiny air bubbles from the threads of the barely loose bleed valve. Is there some "thread goo" you put on them to seal them up. Or does it not matter that it sucks air from the threads so long as vacuum is applied before unseating the bleed valve until after the bleed valve is re-seated? Might not allow air into the system, but sucks for monitoring the presence of air bubbles in the discharge.

I usually just default back to the pump it out with the master cylinder technique. Works OK, but requires 2 people. One to pull and hold the brake lever, and the other to release the pressure and re-seat the bleed valve. Then the lever guy resets and repeats.
 
#29 ·
Yes, you can get some tiny air bubbles when using a vacuum bleeding tool on the average nipple ( caliper part......you filthy....). Larger bubbles are air in the system. With the vacuum system all you need to do is just crack the bleeder a bit, not nearly as much as when you do the manual method. As long as you are pulling a vacuum, no air is going to get back in the caliper.
 
#30 ·
Grimmer, I never have a problem with bubbles around the bleeder screws. The vacuum applied to the bleeder will be pulling on the fluid through the bleeder, and maybe some air from outside the threads--but the, that air is pulled. out with the fluid from inside the caliper. It's quick, easy, clean, and effective.
 
#34 · (Edited)
I have a air vac also from Harbor Freight. What my buddy thought of and that worked great, was to pull the short tube from inside the reservoir off and replace it with a tube long enough to reach the bottom of the reservoir, then fill the reservoir with brake fluid.
Then by holding the palm of your hand over the exhaust port FIRMLY, you can turn the vacuum device into a device that pushes fluid into the calipers/lines, instead of out of them. While doing this hook another tube up to MC bleeder screw that you're going to buy from SV Racing (highly recommend), and have the fluid that you're pushing out of the system evacuated into a container from that bleeder screw. You can control the amount of fluid that you've poured into the your vacuum reservoir by modulating how much you depress the vacuum handle. This method is DEFINITELY a two-person job.

It worked great, and this way you're pushing the fluid in the direction the bubbles want to rise, not the opposite.
 
#32 · (Edited)
I use teflon tape. But in a prolonged bleeding job like me as the OP just ran into, you end up having to replace the tape a few times. Yes, the air will only be pulled into the tube going to your vacuum not the calipers or lines, however you won't be able to distinguish between what air is being pulled around the bleeder threads, and what nasty air is being pulled out of the brake lines. You only know you have evacuated air out of the brake lines when the tube shows solid fluid and NO air.

So moving on, the test ride was successful, but it took three prolonged bleeding sessions over three days to get there. As I said above, the only thing I haven't done is remove the battery box and crack the lines to the HU/ABS pump. This upgrade is absolutely worth it even with all this hassle. The stopping power on the front is markedly improved over OEM!

Here's some pics and descriptions of the Nissin 4-pot upgrade project. Due to the file limit I'll post the remaining on another post right after this one.

1. Old calipers. ( I put split conduit on my brake lines for protection.)

2. Dropped radiator (and shortened Shox Sox.). I really can't imagine doing this with the radiator in the way. I'm sure it can be done, but dropping the radiator, even without disconnecting the two hoses is very easy. Plus I combined this with my 8,000 mile service which included coolant, air filter, and spark plug changes. You have to pull the radiator forward to get to the most forward front cylinder plug.

3. Old brake lines disconnected from the junction boxes.

4. New Galfer lines on new calipers with crush washers.

5. New lines bolted to the junction box bracket before ABS lines connected.

Continued on next post.........
 

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#33 · (Edited)
Continued from previous post.......

6. ABS lines connected to the Galfer line blocks. Be very careful doing this. There are tiny little brass colored objects called Olive Inversers that are used instead of a typical O Ring connection. Due to the fact that you have to place these inverses in the Galfer females when they're horizontal, not vertical, put a VERY tiny amount of grease on the outside of the inverser to hold it in place while you carefully screw in the ABS line male. If you don't do this it could easily fall sideways and prevent the ABS line male fittings from seating properly causing a very bad leak. I cleared this idea by calling Galfer. They said that even if you did accidentally get a tiny amount of grease in the tiny hole that goes thru the inverser, the brake fluid is caustic enough that it will dissolve it. One way to make sure the Olive Inverser didn't drop on it's side is to count the threads remaining after tightening the ABS line male fitting down. You can see I have about 3 threads showing.
As an aside, IMHO, SV Racing and Galfer made the line from the junction box to the R side caliper way too long. There's altogether too much slack. Won't hurt anything, but not tidy.

7. New lines installed into bracket and bracket installed.

8. Caliper bracket adapter backplate

9. Adapter bolted onto Nissin caliper

10. Completed L side Nissin caliper installed.
 

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