Author Topic: Changed to steelbraided brakelines, can't get pressure on new brake lever/MC (Read 4861 times)

Shik · « **on:** July 24, 2012, 02:08:11 PM »

Hi guys,

I just installed a new (used) master cylinder and changed all brake lines and I'm trying to get pressure on the lever, but it seems that I'm getting nothing.
When I'm trying just to get the oil through with a transparent hose on the bleeder valve, it doesn't seem to get through. When I'm trying to bleed the lever does not get hard.

Any suggestions?

flybox1 · « **Reply #1 on:** July 24, 2012, 02:14:46 PM »

it may take some time to get all the tiny bubbles that cling to the inside of new brake line to work their way out.
keep at it. took me 3 days of off and on bleeding to get mine to firm up after new lines.
use a long hose on the end of the bleeder valve, and attach its other end up near your bars.
secure your MC lever to your right grip using a bungee or tape. turn your bars to the left and leave it overnight.
the bubbles will rise and be closer to the MC. bleed them again the next day, slowly. fast pulls break big bubbles into smaller ones....which take longer to rise and clear from the system.
repeat this for a day or 2, the more bubbles you get out, the closer you are to pressure.

Shik · « **Reply #2 on:** July 24, 2012, 02:20:39 PM »

Quote from: flybox1 on July 24, 2012, 02:14:46 PM

and attach its other end up near your bars.

the bubbles will rise and be closer to the MC.

Why is this important?

Thanks for suggestion.

flybox1 · « **Reply #3 on:** July 24, 2012, 02:23:36 PM »

i use this much as its what is handy, but you can use a shorter piece. you can also put the end down into a container for runoff....you just want a place for it to go as fluid will bleed out from the bleeder valve with the bubbles. you'll need to continue this until all bubbles from behind the piston are cleared. some times i've accumulated several inches of fluid into this tube. I dont want to have to stop and clear this until i'm done. DOT3 kills paint.

Shik · « **Reply #4 on:** July 24, 2012, 02:30:55 PM »

I use Dot 5.1...

So to sum up, I open the bleeder valve with the hose of course on, pump the brake slowly a couple of times, and leave it with the lever pulled overnight and then repeat?

aperry · « **Reply #5 on:** July 24, 2012, 02:35:58 PM »

There are a lot of threads here on how to bleed the MC. Is it a 750? If so, here are some things I learned:

I will never do this again without buying a Speed Bleeder. I got one ($7) for my rear caliper and it makes the bleeding process infinitely easier. But assuming you don't have time to wait for the Speed Bleeder to arrive....

There are a few ways to do this. My process was something like this:
a) Attach clear hose to bleeder, put other end in a drain bucket.
b) Get a wrench on the bleeder and be prepared to open/close it a lot.
c) Open bleeder, slowly depress brake lever only an inch or two, close bleeder, slowly allow lever to return to normal "up" position.
d) Repeat C until you see fluid emerge from bleeder into clear hose. Make sure the reservoir stays filled. Could take a while.
e) Now you need to keep doing this until you no longer see bubbles coming out of the line. Once you're content there are no more bubbles, you can close the bleeder and pump a few times and you should get pressure in the lever, but make sure you have the reservoir cap closed before "pumping".

Important note: On the 750 (maybe other models as well) depressing the brake lever all the way to the grip will cause brake fluid to drip from the brake lever. You'll see what I mean. It's only temporary, until the system is fully charged. That's assuming your MC is in good shape.

flybox1 · « **Reply #6 on:** July 24, 2012, 02:39:48 PM »

almost...
leave the bleeder valve closed.
pull your MC lever, and secure it to your handle grip
turn your bars to the left, and leave it overnight.
this position allows gravity to pull fluid down into your lines, and bubbles to rise.
every few hours or so, go out and tap each of the joints in the system to help release bubbles. add more fluid if needed. use something wood or rubber and tap the MC piston area. tap any banjo bolts, any elbows or connections, all the way down to your piston.

the next day...start your bleeding procedure again, just as aperry listed above....and do it slowly and carefully. any fast movement can suck in bubbles or break up bigger bubbles.
be patient.

use the setup i listed above for the next night...

Shik · « **Reply #7 on:** July 24, 2012, 02:44:19 PM »

Okay, this is a CB550.
Actually the bleeder valve is not in good condition, I mean the nut (where you put your wrench) is bad, but I can still turn it with a thing.

But I need to have this done pretty soon as my journey starts next thursday, and I'm not sure I can get a new one or speed bleeder that quick.

aperry · « **Reply #8 on:** July 24, 2012, 03:10:22 PM »

As long as the bleeder valve works the way it should and doesn't leak, then I think you can use it. Mine front caliper bleeder doesn't look great either.

I'll note that I didn't perform the overnight steps described by Shik. My front brake (the one without the Speed Bleeder) is rock hard and seems to work great. That said, I've read that some other people use the overnight method with mixed success. If you have the time to let your bike sit overnight for a night or two then it's probably a good safe way to ensure no air is left in the line.

Johnie · « **Reply #9 on:** July 24, 2012, 03:14:08 PM »

Never used a speed bleeder, but use a Mighty Vac on all my MC and caliper rebuilds. Without it I have had the same problem.

Psychonaut · « **Reply #10 on:** July 24, 2012, 03:23:32 PM »

Pulling the lever in over night won't get all the air out. Keeping the lever in keeps the port closed off. If you give quick short pumps, just enough to cross the port and back you will see bubbles come out. I tap the line with the plastic end of a screw driver to get the little PITA bubble to move up. If you go this rout tap the banjos too. Once you can get some firmness you can bleed out the bleeder or keep tapping and pumping the lever.

lone*X · « **Reply #11 on:** July 24, 2012, 04:02:26 PM »

There was a thread sometime last year about Honda Service Bulletins and I believe one of the items posted told the service people to not pull the brake lever all the way in when bleeding brakes. Seems like when there is no back pressure on the master cylinder the piston will travel past the return hole in the reservoir causing fluid to get into the area of the piston outside the seal causing corrosion and gunked up master cylinders. A recommendation was made to rubber band a small spacer to the grip to keep the lever from traveling all the way back to keep this from happening. I may not have explained it properly but it seemed like a revelation to a lot of folks when it showed up in the a fore mentioned thread. Something to keep in mind. You may want to search for that original thread unless someone has it saved and can share it.

OK, I found the thread. Check reply #18 for the brake bleeding SB.
http://forums.sohc4.net/index.php?topic=102388.0

Some other good items in this thread like the early chain problems caused by the routing of the battery overflow and such.

lucky · « **Reply #12 on:** July 24, 2012, 07:22:06 PM »

Used master cylinder huh!!! If the vent hole is plugged you will never be able to bleed your brake lines. no fluid will go into the piston of the master cylinder.

Stand in front of the bike looking aft. take the cover off of the master cylinder, look into the bottom, and the hole on the right has to be clear. Otherwise it is like putting you thumb over the end of a straw . No fluid will go down.

The hole is very small like a needle size.

Shik · « **Reply #13 on:** July 25, 2012, 11:26:52 AM »

So I bought this one today: http://www.thansen.dk/product.asp?c=5438100984&n=788922347&pn=-1013465728

This is used with compressed air, but I still do not get the fluid down the line and out of the bleeder valve.
Can anybody figure out where my problem could be?

flybox1 · « **Reply #14 on:** July 25, 2012, 11:34:03 AM »

stick the end of the bleeder valve tube up against your cheek, squeeze the brake lever, do you feel the air pushing through...if so, you still have lots of air in the system and need to continue bleeding. you will see your dot5 level decrease....keep filling it to the line in the cup.

if your DOT5 level is not decreasing as you bleed the system, then the fluid is not moving past the MC, and a teardown/rebuild is in order.

lucky · « **Reply #15 on:** July 25, 2012, 11:37:38 AM »

Quote from: Shik on July 25, 2012, 11:26:52 AM

So I bought this one today: http://www.thansen.dk/product.asp?c=5438100984&n=788922347&pn=-1013465728

This is used with compressed air, but I still do not get the fluid down the line and out of the bleeder valve.
Can anybody figure out where my problem could be?

Read reply #12 again.

lucky · « **Reply #16 on:** July 25, 2012, 11:40:36 AM »

If a #10 steel guitar string will not go through that air bleed hole then the system cannot fill with fluid.

I have seen that vent hole clogged up so hard I had to take a jewelers drill and drill through the dried up gunk. It is a very small hole the size of a sewing needle.
I will post a pic. Hold on.
This hole must be clear.

aperry · « **Reply #17 on:** July 25, 2012, 11:44:10 AM »

I don't know anything about that system that you bought, but I would agree with Lucky that it seems common for the return hole in the reservoir to get clogged. It's pretty tiny and it can be difficult to determine if it's actually clear. With everything disassembled, I remember checking this by blowing through the bore hole, putting one finger over the larger hole in the reservoir and feeling for air moving through the smaller return hole.

Traditional bleeding (slow shallow pumps with handle) can take a while too before fluid gets to the bleeder. But the reservoir level should drop slowly during bleeding if things are going well.

Don R · « **Reply #18 on:** July 25, 2012, 11:53:52 AM »

Lone*x was correct, read that thread. I'm surprised how some folks here insist some things wont work when they clearly do. BTW, if you hold the hose to your cheek don't shoot fluid in your eye. My work here is finished.

Psychonaut · « **Reply #19 on:** July 25, 2012, 03:39:16 PM »

Did you try a few quick blips of the lever after tapping the line?
Last week my friend bought a new MC to replace the one he thought was bad. In 5 minutes I got the lever firm without ever cracking the bleeder.

camelman · « **Reply #20 on:** July 25, 2012, 04:35:19 PM »

I'm with Psycho. Even with a completely dry system I usually don't need more than five minutes to have an operational brake with a firm lever. If the lever is soft, then I wiggle the lever a couple mm in each direction for five seconds and then do full squeezes until no more air bubbles come out. Back to wiggling, air squeezes, repeat... Once I get good resistance, I crack the caliper open a few times while squeezing the lever until no more air bubbles come out. Seriously, five minutes max. You might need to go through that procedure twice or three times, but it works.

I've never had to hold the lever in overnight, reverse fill the system, or any of those tricks. It is important to make sure the master cylinder holes are clear as lucky mentioned though.

Bodi · « **Reply #21 on:** July 25, 2012, 04:46:59 PM »

You may just have to prime the MC. Sorry if this was already explained, I haven't read every post.
With fluid in the reservoir, have the MC banjo off. Sueeze the lever in, and plug the banjo hole with a finger. Release lever. Repeat until you get fluid pumping out. If that doesn't work you can try applying vacuum to the banjo hole, using a large syringe works pretty nicely.
You need to get fluid into the MC cylinder. That takes a bit of vacuum, doing the lever pumping usually works.
You also need some vacuum to pull fuid from the reservoir instead of just sucking air back from a dry brakeline. I do a sort of reverse bleeding, I fill the caliper cylinder (with piston almost all the way out) with brake fluid (that syringe works pretty well again) then connect all hoses and then press the piston in with a C-clamp. That fills the brake lines from the bottom up.

Shik · « **Reply #22 on:** July 27, 2012, 11:52:05 AM »

Okay, I managed to solve this newbie problem by switching MC and using a vacuum "gun".
But my front brake was still a little sticky and the caliper house and disc was very hot after a short testrun.
I managed to get the piston out and the housing looked actually pretty good, no corrossion or gunk that needed sandpaper.
Now I'm putting back the piston in after using brake cleaner inside the house, but this seems to be pretty hard.

What is the procedure to get the piston back in?

Bodi · « **Reply #23 on:** July 27, 2012, 08:05:43 PM »

wet the seal and piston with brake fluid and rotate as you insert.
The vital bit to have really clean is the seal groove in the cylinder.

ncstatecamp · « **Reply #24 on:** July 30, 2012, 12:20:01 AM »

Quote from: lucky on July 24, 2012, 07:22:06 PM

Used master cylinder huh!!! If the vent hole is plugged you will never be able to bleed your brake lines. no fluid will go into the piston of the master cylinder.

Stand in front of the bike looking aft. take the cover off of the master cylinder, look into the bottom, and the hole on the right has to be clear. Otherwise it is like putting you thumb over the end of a straw . No fluid will go down.

The hole is very small like a needle size.

what about the other hole/dimple is that supposed to clear as well? because i couldnt get anything through it.

ncstatecamp · « **Reply #25 on:** July 30, 2012, 09:55:14 PM »

another option that i learned is as you are pumping, to help the air bubbles move, try vibrating or shaking the line. This seems to help any bubbles at any sharper curves get a move on.

News:

Author Topic: Changed to steelbraided brakelines, can't get pressure on new brake lever/MC (Read 4861 times)