Topic: Front Brake Adjustment Steps

[nccb]

So I just recently rebuilt my front caliper (cleaning really well, new seal, piston in good shape) and reassembled it.  I also installed a speed bleeder.  After bleeding the brake pads contract and retract on the rotor.  After that, I moved to adjusting the caliper so that pad b would have proper clearance.  My problem is that I cannot get the pad to have any clearance. 

I noticed that if I back the allen screws out just a bit the swing arm moves back a little and pad b clears and the adjustment arm can be moved back and forth a little bit.  When the caliper is tightened all the way like it should be its like it binds the arm and it won't adjust.  I don't know what to do with it and its pissing me off   Is there a certain procedure for adjusting everything or am I just missing something?

[mrrch]

 The swingarm should swivel freely on the bracket. Sounds like it may be sticking at the pivot.

[Irukandji]

You do know that the B pad is adjusted by the SPRING loaded screw........Right?

[MCRider]

So I just recently rebuilt my front caliper (cleaning really well, new seal, piston in good shape) and reassembled it.  I also installed a speed bleeder.  After bleeding the brake pads contract and retract on the rotor.  After that, I moved to adjusting the caliper so that pad b would have proper clearance.  My problem is that I cannot get the pad to have any clearance. 

I noticed that if I back the allen screws out just a bit the swing arm moves back a little and pad b clears and the adjustment arm can be moved back and forth a little bit.  When the caliper is tightened all the way like it should be its like it binds the arm and it won't adjust.  I don't know what to do with it and its pissing me off   Is there a certain procedure for adjusting everything or am I just missing something?

Push, or tap with a rubber hammer, the A side of the caliper to get the A pad to sink into its hole further than normal. That will give you operating room. When done the swingarm garden gate should swing freely, as mentioned.

Then adjust the B pad with the screw. Turn it counterclockwise to gain clearance. Clockwise to lose clearance. Use a feeler gauge for 5 to 6 thou of clearance. Lock the nut.

Then pump the brake to bring the A pad back into contact with the rotor. You should have a functioning brake. The A pad should glide on the rotor making the slightest of contact noises. The b pad should be free of the rotor by 5-6thou. Squeeze the brake again the A pad will draw the B pad into contact with the rotor. release and the A pad will withdraw so the B regains it's clearance.

If this is not happening then you've got a problem.

Has this been a functioning brake on this bike before?

PS: First step is to loosen or "back off" the adjuster screw (clockwise) so the rest of the instructions will work.

[TwoTired]

You are supposed to adjust the stationary pad clearance first, before having the piston press against rotor.
Piston retraction is aided by a bit of riding vibration.

Anyway, you now have to manually push the piston back slightly into its bore to adjust stationary pad clearance.
  The adjuster springs allows the stationary pad to move to the rotor.  The adjuster stop prevents the caliper from moving closer to the rotor, which you have to do to mash the rotor back into caliper bore.  So, you have to back off the adjuster to allow caliper to move closer to the rotor, thereby pushing the piston back into the caliper bore.

With the piston side brake puck out of the way, you can set stationary pad clearance and lock it down. Then the brake lever will push the caliper piston puck out to the rotor.  Don't expect total non-contact after release.  However, the wheel should turn freely after brake lever release.

All this assumes, you used the correct piston seal, used the proper lube for it, the caliper groove for the seal is pristinely cleaned to bare metal, and the piston isn't too pitted where the seal rides upon it, as the seal itself provides the retraction force to withdraw piston/puck from the rotor.
Also, the brake pad must not bind inside the caliper to restrict movement.  It is common to file new ones to properly fit.

cheers

[Dream750]

This procedure is taken directly from the 750 K4 owners manual: 

[MCRider]

This procedure is taken directly from the 750 K4 owners manual:

In the manual, they are using the tire side screwdriver slot. In that case, righty tighty, lefty loosey applies. This slot is tough (for me) to get to.

In my proc, I use the smaller outside facing in slot. This reverses the direction of turning the screw.

[nccb]

Ok thanks guys, maybe I did it backwards.  I pumped the pad a out to meet the rotor then adjusted pad b.  I will try it the other way around.  The brake wasn't functioning well before I rebuilt it, the brake wouldnt release the rotor.  I cleaned out the caliper very well, took a dental mirror and pick to the grove as well as a bristle brush on a dremel to clean the groove.  Replaced with a brand new seal and honda pads which fit in perfect and would also move freely in the caliper. 

First I'll depress pad A then inspect the caliper arm.  Then adjust pad B to proper clearance followed by contracting pad A closer to the caliper and hope this addresses the issue.  I tested to make sure pad A was contracting by sticking a feeler gauge in then pressing the brake to see if it closed (which it did) then release the lever to see if it open (which it did as well).

[70CB750]

I have special ground down screwdriver to adjust the bolt through the M6 hole, much better than messing with the other end, especially with dual disc setup.

[MCRider]

Ok thanks guys, maybe I did it backwards.  I pumped the pad a out to meet the rotor then adjusted pad b.  I will try it the other way around.  The brake wasn't functioning well before I rebuilt it, the brake wouldnt release the rotor.  I cleaned out the caliper very well, took a dental mirror and pick to the grove as well as a bristle brush on a dremel to clean the groove.  Replaced with a brand new seal and honda pads which fit in perfect and would also move freely in the caliper. 

First I'll depress pad A then inspect the caliper arm.  Then adjust pad B to proper clearance followed by contracting pad A closer to the caliper and hope this addresses the issue.  I tested to make sure pad A was contracting by sticking a feeler gauge in then pressing the brake to see if it closed (which it did) then release the lever to see if it open (which it did as well).

Ahh, a clue is uncovered. If before, the brake wouldn't release the rotor, you may still have that problem. More often than not, like 99% of the time such a condition is a problem with the master cylinder, not the caliper area.

The MC has 2 holes in the reservoir. The smaller of the 2 is the return hole. It allows fluid to retreat back into the MC when the lever is released and the pad A can then retrack. It is pulled away from the rotor by action of the flexing of the large ORing which you changed. But if the fluid has no place to go, the A pad will stay on the rotor with some force.

Clean the little hole with a very fine wire. Realize if this works, the debris isstillin there waiting to plug the hole again. Removal of the MC, cleaning and full flush of fluid is required. Where did the debris come from? The inside of the hose may be coming apart.

This has happened to many of us and it is a recurring thread.

Good luck!

[MCRider]

I have special ground down screwdriver to adjust the bolt through the M6 hole, much better than messing with the other end, especially with dual disc setup.

Yup. me too.

[nccb]

Ok thanks guys, maybe I did it backwards.  I pumped the pad a out to meet the rotor then adjusted pad b.  I will try it the other way around.  The brake wasn't functioning well before I rebuilt it, the brake wouldnt release the rotor.  I cleaned out the caliper very well, took a dental mirror and pick to the grove as well as a bristle brush on a dremel to clean the groove.  Replaced with a brand new seal and honda pads which fit in perfect and would also move freely in the caliper. 

First I'll depress pad A then inspect the caliper arm.  Then adjust pad B to proper clearance followed by contracting pad A closer to the caliper and hope this addresses the issue.  I tested to make sure pad A was contracting by sticking a feeler gauge in then pressing the brake to see if it closed (which it did) then release the lever to see if it open (which it did as well).

Ahh, a clue is uncovered. If before, the brake wouldn't release the rotor, you may still have that problem. More often than not, like 99% of the time such a condition is a problem with the master cylinder, not the caliper area.

The MC has 2 holes in the reservoir. The smaller of the 2 is the return hole. It allows fluid to retreat back into the MC when the lever is released and the pad A can then retrack. It is pulled away from the rotor by action of the flexing of the large ORing which you changed. But if the fluid has no place to go, the A pad will stay on the rotor with some force.

Clean the little hole with a very fine wire. Realize if this works, the debris isstillin there waiting to plug the hole again. Removal of the MC, cleaning and full flush of fluid is required. Where did the debris come from? The inside of the hose may be coming apart.

This has happened to many of us and it is a recurring thread.

Good luck!

Alright I'll take another look at the return hole.  I have visually inspected it and I can see the hole and it will squirt brake fluid out, which of course hits the only place i didn't cover on my tank.

[TwoTired]

I did experience a brake line that behaved as a one way valve.  Allowed pressure to reach the caliper, but not allow it to release.  'Twas a head scratcher until we cracked a hose attach fitting and got a gusher.  I can imagine a smaller degree of "one wayedness" or pressure hold before we got to it.

[lucky]

Get a manual and read it.

[nccb]

I have a manual, I have a shop manual, I also have the booklet that came with the bike.  I asked the question because the caliper adjustment arm wasn't adjusting.  This weekend I will redo the brake to see if the suggestions work.

[nccb]

Ok, so I tried redoing the caliper installation by first adjusting pad b to clearance with the adjustment arm.  Once that was set I locked the nut and began bleeding the brakes to get pad a in position.  Once again, it presses pad b to the rotor and the top of pad a remains on the rotor as well. I figured its the MC so i cleaned out the little hole with guitar string and tried it all over again with the same results.  I was pumping the brake fluid out of the MC and pressed my brake pad back in, as it was about to fall out, and as I was squeezing it in with my hand I noticed the MC was shooting a stream of brake fluid across my building from the return hole.

I have no taken the MC off and disconnected both brake lines.  I can blow air through the MC return hole so I take it that now it can't be the MC?  How do you test the lines?  I blew through the top line and air could travel through it.  I am assuming the brake fluid being shot through the MC means the return side of the line isn't clogged.  I am at a lose for what is going on.  I might redo the damn caliper again just to make sure but I had that thing spic and span and there was absolutely nothing in the groove.

[TwoTired]

Once again, it presses pad b to the rotor and the top of pad a remains on the rotor as well.

If you are looking for daylight between the pads, you will likely never be satisfied.

Did the wheel turn freely upon brake release?

The pads do swivel a bit in their sockets, as they have some "float" to them.
Do you have the nylon ring between the piston and bad?


To see if there is pressure remaining in the hydraulics after lever release, crack the line fitting at the caliper. A slow dribble is ok but but if there is a squirt when doing so, you have either a  line issue or an MC issue.
Are you certain the MC piston is free to fully retract to the snap ring stop?

[nccb]

To see if there is pressure remaining in the hydraulics after lever release, crack the line fitting at the caliper. A slow dribble is ok but but if there is a squirt when doing so, you have either a  line issue or an MC issue.
Are you certain the MC piston is free to fully retract to the snap ring stop?

Do you mean the line that connects to the banjo bolt at the three-way connector?  I am not certain the MC piston fully retracts as I didn't fully disassemble it, just took it off and blew air through the holes.  I was curious if the larger hole in the MC should close up all the way.  On mine I can still see a small gap, is that the piston that I am seeing? Would this cause the brakes to clamp?  Also, I didn't realize I didn't type it on my first post, my bike is a 750 k4 and doesn't have the nylon ring behind the brake pad.

[TwoTired]

Do you mean the line that connects to the banjo bolt at the three-way connector? 

No, the fitting AT the caliper.

I am not certain the MC piston fully retracts as I didn't fully disassemble it, just took it off and blew air through the holes. 

See if the caliper is holding pressure first with the above test.

I was curious if the larger hole in the MC should close up all the way.  On mine I can still see a small gap, is that the piston that I am seeing? Would this cause the brakes to clamp?

You would normally see two large holes at the reservoir bottom.  At first glance, the one closest to the line outlet would appear to be blind.  But, at the bottom of the bevel will be a tiny pin hole.  This is the hole that relieves pressure in the lines when the lever is released and the MC piston is retracted.  The pin hole must be clear, and the piston allowed to retract enough to clear that opening.

Also, I didn't realize I didn't type it on my first post, my bike is a 750 k4 and doesn't have the nylon ring behind the brake pad.

It should, according to the parts fiche.

http://www.westernhillshondayamaha.com/fiche_section_detail.asp?section=2560087&category=Motorcycles&make=Honda&year=1974&fveh=132838

Seat pad #17 is the nylon part I was referring to.  These are frequently "lost" or omitted as braking still occurs without the part.  But, it is there for a reason, which may or may not be the issue for you.

[nccb]

#$%* i remember that pad.  It was metal I think on mine.  When i took the caliper apart I set it in a place i would remember (failed) then i remember my son throwing something off of my deck but i didn't know what it was. . .that was it.  Its somewhere in my yard buried under leaves and rain 

[nccb]

 :'(just racked everywhere in the radius of a 2 year olds possible throwing strength, nothing.  God probably gave him the strength to clear the fence to spite my efforts in ever riding this damn bike again.

[nccb]

Found the pad seat that fits over the hollow of the piston, I had taken to my building and put it in my tool chest 

TwoTired, thanks for all of the help man, I imagine this is as frustrating to you as it is for me.  Regarding your test procedures:

1) I checked for pressure at the line fitting of the caliper by loosening it up a good 3 or 4 turns and no fluid.  Same goes with the bleeder screw, nothing comes out if they are just opened after the caliper and MC have been bled.

2) Regarding the return holes in the MC.  I have double checked that the tiny one is cleared by putting a small guitar string in it and also by taking it off and blowing air through it.  I even pressed the lever in with the string inserted and it bent the hell out of the string.  I am guessing that the piston is allowing enough clearance after that

After, reassembling the partially torn down MC and caliper (with the formerly lost pad seat) again these are my observations:  After adjusting pad b to the desired clearance ( .006") I then bled the brakes until no bubbles came out of the bleeder and the handle was firm.  I then lifted the front wheel  and checked that it spun, which at first it spun very little.  I put the slightest bit of pressure on the caliper and could feel the piston retract super easy.  Then it spun fantastically, pressed the brake, same issue but I kept spinning the wheel and it seemed to help out.  Is this normal?  People have mentioned that the rotation and vibration of the wheel is what helps the caliper retract the .012" back into place.  I haven't taken it on the road yet but am going to try today if I am able to.  I am beginning to suspect my lines, specifically the lower line.  I don't know if this is a good test or not but I was able to feel the slightest bit of air coming through the top line as I blew air through it but not so much on the lower line.

Sorry for the long post, lol