919 Front brake troubles - Wrist Twisters
 
Thread Tools Display Modes
post #1 of 21 Old 06-09-2012, 10:03 AM Thread Starter
Woodward Ave
 
Bryan's Avatar
 
Join Date: Mar 2012
Location: Metro Detroit
Posts: 130
Rep Power: 1
 
919 Front brake troubles

I took my front brakes calipers apart looking for something obvious that would cause them to stick. They've been sticking for a couple weeks now, getting progressively worst. I thought it was my brake lever causing causing it because when i adjusted them or loosened it up and snugged it back it would not stick so much temporarily. Once I got the caliper off I realized the pin that the pads ride on had a some corrosion and was dry as a bone. I took them out cleaned them up with some low grit sand paper and put some anti-seize on the pin so it would allow the pads to moved in and out easier. I has having issues making clearance around the rotor with the pads back in the caliper. So I took them back out and tried to push the pistons back in to make more room. That wasn't working out all that well so I made an unwise decision and pushed 3 of the pistons all the way in, which forced the 4th one to pop out of the cylinder. Brake fluid spilled out and I put the piston back in the cylinder right away. After that my brake lever was mush. I'm pretty sure I introduced a whole bunch of air into the system. Doing a bit of research in the forum I found the thread about a homemade brake bleeding suction system out of a mason jar and a couple pipe fittings. I put it together this morning. It seemed to work good at first but then realized that the compressor I have is way too weak to create a good suction. My compressor is a very old portable one with an electric motor. It barely holds 60 lbs of pressure in the tank. The suction system is very functional though. Big thanks to marylandmike for writing that up. So now I am considering either going over my parent's house and using my stepdad's adult size compressor or taking it to the dealership. The Honda dealership is my last resort.. Is there any other options here other than bleeding the brakes for hours on end? Is there any common places to look for leaks in the system?

Bryan is offline  
Sponsored Links
Advertisement
 
post #2 of 21 Old 06-09-2012, 10:10 AM
rmb
Let's go!
 
rmb's Avatar
 
Join Date: Aug 2009
Location: Sussex Couty NJ
Posts: 7,655
Rep Power: 1
 

Awards Showcase
Wrist Twisters Event Attendance Wrist Twisters Event Attendance Wrist Twisters Event Attendance Wrist Twisters Event Attendance 
Total Awards: 9

You didn't touch the brake lines so I wouldn't look there. I would just start pumping and bleeding until you get all new fluid coming out of the calipers, make sure you use DOT 4 and don't let the master go dry, keep watching it and refill when needed. Also, keep watching the caliper for leaks where the piston came out. And for future reference, whenever you're going to push the pistons back into the caliper, car or bike, always crack the bleeder to let the fluid out instead of pushing the old fluid back into the master, if you don't, this can cause big problems especially on an ABS equipped vehicle.

rmb is offline  
post #3 of 21 Old 06-09-2012, 10:22 AM
Serial Monogamist
 
ST-DocLizard1's Avatar
 
Join Date: Dec 2007
Location: Hampton, NJ
Posts: 1,509
Rep Power: 1
 

Awards Showcase
Wrist Twisters Event Attendance Wrist Twisters Event Attendance Wrist Twisters Event Attendance Wrist Twisters Event Attendance 
Total Awards: 21

Anytime you need to push the pistons back in the caliper, you should take the time to clean them with a toothbrush and brake cleaner. If there are areas where you can't get to, take a pair of soft jawed pliers and rotate the piston/s in their bore. Nylon stocking material is great for "shoe shining" these. When they are spotless, you can retract them.
You probably introduced some air into the system, but don't disregard the fact that you may have screwed up the dust or hydraulic seal on the caliper on the one that popped out.
There are many different tricks to bleed the system: top down, bottom up, vacuum, "push backs", loosen the fittings, etc.

Doc



"FRIENDS DON'T LET FRIENDS EARLY APEX."
ST-DocLizard1 is offline  
 
post #4 of 21 Old 06-09-2012, 11:26 AM Thread Starter
Woodward Ave
 
Bryan's Avatar
 
Join Date: Mar 2012
Location: Metro Detroit
Posts: 130
Rep Power: 1
 
If the seal was screwed up there would there be brake fluid dripping from the bottom of the caliper while we are bleeding? I could take that caliper back apart and slide the piston out the right way this time. We bled these brakes for a little over an hour using this method- pump up, hold lever, open bleeder, hope for fluid to come out, close bleeder, release brake lever, repeat. Had a lot more fluid come out after we took the brake lever off and used a screwdriver to push on the little rubber button on the master cylinder. We started to get a lot of air bubbles out of caliper that the piston came out of. Hopefully we can get this squared away by tonight. This job got a lot bigger when that piston hit the ground. It's okay though. It's all a learning experience. Thanks for the info, guys.

Bryan is offline  
post #5 of 21 Old 06-09-2012, 11:30 AM
rmb
Let's go!
 
rmb's Avatar
 
Join Date: Aug 2009
Location: Sussex Couty NJ
Posts: 7,655
Rep Power: 1
 

Awards Showcase
Wrist Twisters Event Attendance Wrist Twisters Event Attendance Wrist Twisters Event Attendance Wrist Twisters Event Attendance 
Total Awards: 9

If you don't see fluid dripping from the caliper the piston fell out of I think you're good. Keep pumping!...

rmb is offline  
post #6 of 21 Old 06-09-2012, 11:37 AM
Curmudgeon
 
semi_gray's Avatar
 
Join Date: Oct 2006
Location: Chicagoland
Posts: 899
Rep Power: 1
 

Awards Showcase
Donation Donation Veteran 
Total Awards: 3

Quote:
Originally Posted by rmb View Post
And for future reference, whenever you're going to push the pistons back into the caliper, car or bike, always crack the bleeder to let the fluid out instead of pushing the old fluid back into the master, if you don't, this can cause big problems especially on an ABS equipped vehicle.
I didn't know this, thanks!

I plan to die young, as late as possible.
semi_gray is offline  
post #7 of 21 Old 06-09-2012, 12:20 PM
rmb
Let's go!
 
rmb's Avatar
 
Join Date: Aug 2009
Location: Sussex Couty NJ
Posts: 7,655
Rep Power: 1
 

Awards Showcase
Wrist Twisters Event Attendance Wrist Twisters Event Attendance Wrist Twisters Event Attendance Wrist Twisters Event Attendance 
Total Awards: 9

Quote:
Originally Posted by semi_gray View Post
I didn't know this, thanks!
Welcome, I found out the hard way on our CR-V, killed the ABS pump... Got it covered under warranty luckily.

rmb is offline  
post #8 of 21 Old 06-09-2012, 03:16 PM
Old, Bold rider
 
robtharalson's Avatar
 
Join Date: Jan 2007
Location: Aurora, Colorado
Posts: 2,377
Rep Power: 1
 
Garage

Awards Showcase
Donation Veteran Community Leadership 
Total Awards: 3

Let's go back to the original complaint and break it down.
Dragging brakes.

You may ask, "Why are my disc brakes dragging?" A more important question to ask is "Why don't disc brakes normally drag?"

The why is relatively simple. When the brakes are applied the pads bear against the discs. Releasing the lever creates a low pressure in the system, helping the square section piston seals that deform when the pistons are pushed toward the discs to relax, pulling the pistons away from the discs by an average of 0.13mm (.005"). This requires a passage for the displaced fluid to return to the reservoir. Therein probably lies your problem. Read on.

When the brake lever is fully out the primary piston seal uncovers a small drilling in the master cylinder wall, called the compensating port, which connects to the reservoir. Retracting the caliper pistons pushes the fluid back up the lines to the master cylinder compensating port to the reservoir. This assumes the port is not blocked either by debris, or the brake lever. The clue you gave about feeling better :
Quote:
I thought it was my brake lever causing causing it because when i adjusted them or loosened it up and snugged it back it would not stick so much temporarily.
may point us in the right direction.

Loosening the lever allowed it to move back sufficiently to allow the piston to finally clear the port and allow the fluid a path back to the reservoir. The caliper pistons retract and all is good until the lever is tightened down, and the symptom returns.

The Holmesian conclusion is the brake lever is either an inaccurately made aftermarket unit that is holding the piston too far in, or the stock lever has a bit of debris trapped between the brake light switch and the paddle that actuates it, again closing the port and causing your problem.

I think.

Rob

If it has already been done, it is safe to assume it is possible to do it.
On the other hand, if it has not been done never assume it is impossible to do it.
------- Rob --------
robtharalson is online now  
post #9 of 21 Old 06-09-2012, 03:27 PM
(-(-(-(-(- -)-)-)-)-)
 
andrewebay1's Avatar
 
Join Date: May 2009
Location: Seattle, WA
Posts: 6,883
Rep Power: 1
 
Crystal clear as always Rob. Great input!

My classified(s):
Nothing at the moment

----------------
------------
---------
------
---
- '96 Race-retired GSXR 750 (Sold)
- '01 RC51 SP1 (Sold)
- '03 919

"Security is mostly a superstition, it does not exist in nature: avoiding danger in the long run is no safer than outright being exposed. Life is either a daring adventure or nothing."-Helen Keller
andrewebay1 is offline  
post #10 of 21 Old 06-09-2012, 04:06 PM
blur
 
drewvir's Avatar
 
Join Date: Feb 2009
Location: Deptford,NJ
Posts: 1,372
Rep Power: 1
 

Awards Showcase
Donation 
Total Awards: 1

and our resident genius speaks and the room falls silent. thanks rob!

'04 Honda 919, Candy apple red met., 17/44t sprockets,f-16 windscreen,delkevic ss exhaust,Tharbars,givi engine bars, billet alum. led turns w/ running lights,red adj.levers from china, bar end mirrors,grip heaters,adj. foot peg brackets,adj. bar risers,dunlop Q2(that are better than your pp 2ct,lol)bike wired for gps and phone charger
drewvir is offline  
post #11 of 21 Old 06-09-2012, 04:49 PM
Le So Cal Troll
 
nd4spdbh's Avatar
 
Join Date: Sep 2009
Location: So Cal
Posts: 5,766
Rep Power: 1
 
god hath spoken!!!!

nd4spdbh is offline  
post #12 of 21 Old 06-09-2012, 07:59 PM Thread Starter
Woodward Ave
 
Bryan's Avatar
 
Join Date: Mar 2012
Location: Metro Detroit
Posts: 130
Rep Power: 1
 
Quote:
Originally Posted by robtharalson View Post
Let's go back to the original complaint and break it down.
Dragging brakes.

You may ask, "Why are my disc brakes dragging?" A more important question to ask is "Why don't disc brakes normally drag?"

The why is relatively simple. When the brakes are applied the pads bear against the discs. Releasing the lever creates a low pressure in the system, helping the square section piston seals that deform when the pistons are pushed toward the discs to relax, pulling the pistons away from the discs by an average of 0.13mm (.005"). This requires a passage for the displaced fluid to return to the reservoir. Therein probably lies your problem. Read on.

When the brake lever is fully out the primary piston seal uncovers a small drilling in the master cylinder wall, called the compensating port, which connects to the reservoir. Retracting the caliper pistons pushes the fluid back up the lines to the master cylinder compensating port to the reservoir. This assumes the port is not blocked either by debris, or the brake lever. The clue you gave about feeling better : may point us in the right direction.

Loosening the lever allowed it to move back sufficiently to allow the piston to finally clear the port and allow the fluid a path back to the reservoir. The caliper pistons retract and all is good until the lever is tightened down, and the symptom returns.

The Holmesian conclusion is the brake lever is either an inaccurately made aftermarket unit that is holding the piston too far in, or the stock lever has a bit of debris trapped between the brake light switch and the paddle that actuates it, again closing the port and causing your problem.

I think.

Rob
Spot on, sir. It is a crap aftermarket brake lever that will be replaced with oem asap. I did do a slight modification to the lever to make it usable for the time being. I ground part of the lever where it touches the master cylinder with a file. The lever is adjusted all the way in right now so the brake feels sloppy, but it does work! It allows the cylinder to decompress completely. The suction system worked like a charm once I got a hold of a good air compressor. The only think that worries me is how different the fluids came out on each side. The left side (the side that the piston came out) let out a decent amount of fluid, then stopped. I can crack the screw and it lets out a inch of fluid into the tube but the suction won't pull it out anymore. Won't pull air or fluid into the canister. The other side is the opposite. It will pull bubbles out like crazy with a little fluid. I would expect them both to act the same, but this is not the case. It did have a lot of fluid come out at first, but now bubbles. The master cylinder is full, but it won't draw anymore fluid through on that side. Both sides drew out pretty much the same until half way through, then they started acting different. We added brake fluid whenever it dropped to the low side in the sight. The brakes are working great right now, though! Thanks for the thorough explanation, Rob!.

Bryan is offline  
post #13 of 21 Old 06-09-2012, 08:22 PM
Cornicen
 
undercover919's Avatar
 
Join Date: Apr 2011
Location: Iowa
Posts: 566
Rep Power: 1
 
I hate to steal this thread but we are still on subject.

My 919 has had some drag issues as well that past week or two. I noticed one day after aggressive (not really aggressive) braking and I thought I could hear the slight whirring of the rotors like I was still braking with the front brakes. It takes a little while to go away and seems to have been getting slightly worse. Stock levers, haven't replaced pads recently but I feel that I have a blockage as Rob mentioned. How do I go about trying to clear it? Your help is greatly appreciated!

2003 Honda Shadow 750 ACE (Sold)
2003 Honda 919
undercover919 is offline  
post #14 of 21 Old 06-10-2012, 04:15 AM
rmb
Let's go!
 
rmb's Avatar
 
Join Date: Aug 2009
Location: Sussex Couty NJ
Posts: 7,655
Rep Power: 1
 

Awards Showcase
Wrist Twisters Event Attendance Wrist Twisters Event Attendance Wrist Twisters Event Attendance Wrist Twisters Event Attendance 
Total Awards: 9

Quote:
Originally Posted by undercover919 View Post
I hate to steal this thread but we are still on subject.

My 919 has had some drag issues as well that past week or two. I noticed one day after aggressive (not really aggressive) braking and I thought I could hear the slight whirring of the rotors like I was still braking with the front brakes. It takes a little while to go away and seems to have been getting slightly worse. Stock levers, haven't replaced pads recently but I feel that I have a blockage as Rob mentioned. How do I go about trying to clear it? Your help is greatly appreciated!
Start by replacing the fluid, completely bleed the systems. When's the last time you replaced fluid?

rmb is offline  
post #15 of 21 Old 06-10-2012, 10:20 AM
Cornicen
 
undercover919's Avatar
 
Join Date: Apr 2011
Location: Iowa
Posts: 566
Rep Power: 1
 
Have not replaced fluid since I got it last year.. would speed bleeders and adding fluid (DOT 4) top down until it comes clean be sufficient?

2003 Honda Shadow 750 ACE (Sold)
2003 Honda 919
undercover919 is offline  
post #16 of 21 Old 06-10-2012, 11:48 AM
rmb
Let's go!
 
rmb's Avatar
 
Join Date: Aug 2009
Location: Sussex Couty NJ
Posts: 7,655
Rep Power: 1
 

Awards Showcase
Wrist Twisters Event Attendance Wrist Twisters Event Attendance Wrist Twisters Event Attendance Wrist Twisters Event Attendance 
Total Awards: 9

Speed bleeders would be fine, just make sure you get all of the old fluid out.

rmb is offline  
post #17 of 21 Old 06-11-2012, 07:16 PM
Cornicen
 
undercover919's Avatar
 
Join Date: Apr 2011
Location: Iowa
Posts: 566
Rep Power: 1
 
Just changed fluid and it didn't look that bad, but wow it sure has made my front brakes noticeably nicer. Before they seemed to have "stops" that made the brake lever less fluid when actuated. It made it so after you passed a "stop" it would go in much further and grab much harder. It now actuates in one nice fluid motion and I feel 100x more confident at how the front responds now.

My only gripe is that the primary reason I flushed the fluid (besides knowing that it needed to be done anyway) was that the brakes seemed to drag for a while after using them, mainly when used more aggressive. Since the auto chain oiler I installed helps keep the chain lubed regularly and nice and quiet I can still hear what sounds like the front pads dragging slightly. I don't hear the obvious whirring for a while after I brake like before, but are the pads supposed to drag slightly or should I flush again?

2003 Honda Shadow 750 ACE (Sold)
2003 Honda 919
undercover919 is offline  
post #18 of 21 Old 06-11-2012, 09:10 PM
Tirone
 
Join Date: Jul 2011
Location: Los Angeles, ex Brisbane
Posts: 61
Rep Power: 1
 
When I bleed my brakes, I put the end of the hose from the bleeder into a semi filled bottle of old fluid. This way I don't have to open,down,lock,up, sequence. I just keep pumping, checking on the level in the master cylinder. Much better wuith new fluid.

nalla is offline  
post #19 of 21 Old 06-12-2012, 11:05 AM
Old, Bold rider
 
robtharalson's Avatar
 
Join Date: Jan 2007
Location: Aurora, Colorado
Posts: 2,377
Rep Power: 1
 
Garage

Awards Showcase
Donation Veteran Community Leadership 
Total Awards: 3

Quote:
Originally Posted by undercover919 View Post
Just changed fluid and it didn't look that bad, but wow it sure has made my front brakes noticeably nicer. Before they seemed to have "stops" that made the brake lever less fluid when actuated. It made it so after you passed a "stop" it would go in much further and grab much harder. It now actuates in one nice fluid motion and I feel 100x more confident at how the front responds now.
The stops you are feeling are only peripherally due to the old fluid -- the primary cause is the cam end of the lever that pushes against the end of the piston is dry or contaminated, and since the cam slides against the piston when applied it is sticking / releasing and cocking the piston in the bore. The lubricity of brake fluid decreases with age, so when the piston cocks it drags against the bore, eventually scoring the surface and causing leaks. When the fluid was flushed it "cured" the problem by masking the symptom.

The actual cure is to remove the lever, thoroughly clean off all grease and dirt including from the end of the piston and the brake light switch area, and apply a generous amount of general purpose grease to the pivot and cam. Once it's reassembled wipe away any excess grease to prevent collecting too much dirt. It is also possible that this cleaning will allow the piston slightly more rearward travel, promoting more effective caliper piston retraction and less drag.

Rob

If it has already been done, it is safe to assume it is possible to do it.
On the other hand, if it has not been done never assume it is impossible to do it.
------- Rob --------
robtharalson is online now  
post #20 of 21 Old 06-14-2013, 07:37 PM
Tirone
 
Join Date: Aug 2007
Location: Florida
Posts: 13
Rep Power: 1
 
HMMM...same problem on my 2003 919 so Sunday it's getting a brake fluid change and lever look over!

129CBRider is offline  
post #21 of 21 Old 06-15-2013, 07:37 PM
Tesserarius
 
morgstang's Avatar
 
Join Date: Feb 2013
Location: brenham
Posts: 610
Rep Power: 1
 
2 words... mityvac..oops thats 1

morgstang is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Wrist Twisters forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

 
For the best viewing experience please update your browser to Google Chrome