Topic: Front wheel wont move!

[apostrophe28]

I recently replaced the seal on my front brake caliper, replaced the pads, and bled the system. Now my front wheel wont roll an inch even with the bleeder screw open  ...any thoughts?   K7 btw

[DJ_AX]

Did you adjust  properly for the new pads?

And double.triple check you put it back together correctly!

[apostrophe28]

Adjust what propperly for the new pads?
I took off the caliper, cleaned and replaced the seal, replaced and filled w fluid, bled.

[SohRon]

Adjust what propperly for the new pads?
I took off the caliper, cleaned and replaced the seal, replaced and filled w fluid, bled.

you likely need to set the gap between the fixed pad and rotor: .006" is what's recommended, and it needs to be set before you bleed. If this gap is too large or small, it will lock up the whole system. Also, did you properly lube the caliper piston before installing? The backs and sides of the pad "pucks" need lube as well.

[apostrophe28]

can you point me in the directions of instructions on how to set that gap?

[crazypj]

Loosen lock nut on fork leg, unscrew bolt through caliper arm (screw towards spokes)
 put six thou feeler between inside pad and disc, tighten screw 'til it just slides, lock locknut

[SohRon]

can you point me in the directions of instructions on how to set that gap?

http://forums.sohc4.net/index.php?topic=17788.0

[bollingball]

You don't have the service manual? You can not just through things like brakes back on with out knowing the spec. Do you have some sort of death wish?

Ken

[Don R]

I  downloaded the manual and whenever I am working on a particular area I print it out. someday I'll have the entire manual out in the shop as well as here.
 BTW, it's the bolt that goes through the spring and adjusts the swing on the caliper bracket.

[crazypj]

I  downloaded the manual and whenever I am working on a particular area I print it out. someday I'll have the entire manual out in the shop as well as here.
 BTW, it's the bolt that goes through the spring and adjusts the swing on the caliper bracket.

Yes it is

[Lil Red]

give the poor guy a break...i have manuals and am always porking things up...the first time i took the front wheel off i put hub nou on facing inwards... The front wheel had 3/4 inch of slop....my first tought ...surely HONDA...wouldnt design it like this...it took me like another hour to figure it out...

I'm lefty...i look at a manual and then in my head have to turn the bike over to fiure out what way to turn the sump pan bolt.

some of us just aint as gifted.

[apostrophe28]

FIXED: the plastic bushing between the piston and pad had fell and was binding up! bled and an easy fix!

new issues....extremely soft front brakes...have to clamp down 90% before i feel anything

[crazypj]

Spongy brake, bleed air out.
Air get trapped in M/C if it isn't level or slightly 'down' at hose fitting
Also, you don't pull lever all the way to bar, it's in service manual

[Randy]

The little hole in the calibar is plugged.. will not let the pressure back up to the cmaster

[apostrophe28]

when I release the brake it will squire brake fluid 2" out of the m/c...so I think the return circuit is fine

[LesterPiglet]

I had problems getting a hard brake on mine after lots of bleeding. I pumped the lever several times and then taped it to the bars overnight. Next morning it was a lot harder...still not perfect tho.

[trueblue]

I had problems getting a hard brake on mine after lots of bleeding. I pumped the lever several times and then taped it to the bars overnight. Next morning it was a lot harder...still not perfect tho.

+1 except I used a strip of rag, not tape to hold it nice and tight.

[crazypj]

Bungy lever to bar.
Put bike on side stand, turn forks full lock left , leave a couple of hours, turn full lock right and do the same. Tap brake lines with a screwdriver handle
When you remove bungy, hold lever and allow it to 'flick' out suddenly, it tends to pull air up and out of piston bore
You people are not shaking the bake fluid before using it? If you do you get 'micro-bubbles' in it which take at least 48 hrs to dissipate

[Rookster]

you likely need to set the gap between the fixed pad and rotor: .006" is what's recommended, and it needs to be set before you bleed. If this gap is too large or small, it will lock up the whole system.

Just to be clear on this.  If you are using the spring tensioner then you need to make sure the pad isn't dragging on the disk.  Other than that the pads will find their own gap based on the amount of fluid pushed into the caliper and the thickness of the disk.  That little spring isn't going to retract your pads any more than the amount of fluid that flows back into the master cylinder.  Many people (me included) don't even use the spring adjuster or screw.  The caliper finds its place over the disk based on the gap between the pads.  That gap is determined by the amount of brake fluid that acts on the piston.  My guess is Honda tried to minimize brake squel by attempting to fix the back pad a certain distance away from the disk.

Scott

[DaveBarbier]

I know this is kind of an old thread but I think I'm experiencing the same thing. My '78 550's brakes worked before I did some work (new pads and SS lines), but now the pad won't return.

So after I installed new pads (I had to use a clamp and push the piston back into the bore a bit to fit over the disk) then I put the new SS lines on and bled the system and THEN I set the gap. But now when I squeeze the lever the pad stays locked and doesn't return. What exactly makes the pad return anyway? The MC? I'm about to go out and see if the return hole is plugged up. I lubed the pad but it's still tough to get it to slide in the caliper. Caliper seems smooth and clean but it's just a really tight fit. Can I lube the piston (haven't done that yet) by pumping the lever and having it stick out a lot then lubing the exposed sides or does that need a complete disassemble?

Also, unrelated...my MC seems to be weeping at the lever joint. It's just moist, not dripping. That's bad, right?


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1978 Honda CB550K

[HotCarl73]

What exactly makes the pad return anyway? The MC?

The O-ring around the piston is square in cross section. When the piston is pushed out, it gets forced into a parallelogram shape. When pressure is released it goes back to square and pulls the piston back with it.

[LesterPiglet]

Most problems are with the little hole in the MC, make sure it is clean also. There are two holes in there.

[DaveBarbier]

Hm, ok thanks guys. I'll have to make sure both these things are free. But I'm replacing the MC anyway, but still want to see how it works.

Thanks


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1978 Honda CB550K

[trueblue]

If you pull the lever all the way back to the bar while bleeding you will get a little fluid bypassing the piston in the master and cause a slight leak .  Won't affect the master cylinder but it will affect your paint if it gets on it .

  If the pad is tight in the caliper that won't be helping the pad retract.  The other thing to do is remove the piston from the caliper and clean the oring groove.  They get a build up of crud and corrosion behind the oring and this causes the piston to bind.  

[DaveBarbier]

If you pull the lever all the way back to the bar while bleeding you will get a little fluid bypassing the piston in the master and cause a slight leak .  Won't affect the master cylinder but it will affect your paint if it gets on it .

  If the pad is tight in the caliper that won't be helping the pad retract.  The other thing to do is remove the piston from the caliper and clean the oring groove.  They get a build up of crud and corrosion behind the oring and this causes the piston to bind.

Interesting about the MC. I WAS bleeding for a bit and noticed the slight moistness right after. I wonder if my MC isn't leaking after all.

I lightly filed the pad and sanded it so the sides are super smooth. Added a little grease (I may have used too much before) and used a q-tip and lubed the piston after I pumped the brakes and had it almost falling out. Now the pad retracts somewhat. But I ordered a new seal for $9 that's coming tomorrow so I'll totally disassemble the caliper then. I have a feeling the caliper isn't terribly clean inside.

Just to be clear, when I let go of the brakes the wheel should spin completely free, right? A little drag isn't normal?


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1978 Honda CB550K

[trueblue]

The pads should drag just enough to just touch but not enough to slow the wheel if spun.  You may be able to hear them rubbing the disc, which isn't a concern. 

Don't put standard grease near the caliper piston, it will cause the seals to swell and compound your problem.  The piston gets all the lube it needs from the brake fluid inside the caliper. 

When reassembling the caliper after cleaning it out, use a little rubber grease on the rubbers to assist in putting it together.  It is castor oil based and doesn't affect the seals.  If you can't lay your hands on rubber grease you can use a little brake fluid to lube the seals.  If you do this though be careful around your paint .

[PeWe]

I had problem with braking front wheel when I steered 25-45 degrees or so. I had not tightened the nuts holding the wheel so it could move.

I knew that all bolts were not tightened. This was something I had planned to check before riding the bike. I hope I'll remember all

[DaveBarbier]

The pads should drag just enough to just touch but not enough to slow the wheel if spun.  You may be able to hear them rubbing the disc, which isn't a concern. 

Don't put standard grease near the caliper piston, it will cause the seals to swell and compound your problem.  The piston gets all the lube it needs from the brake fluid inside the caliper. 

When reassembling the caliper after cleaning it out, use a little rubber grease on the rubbers to assist in putting it together.  It is castor oil based and doesn't affect the seals.  If you can't lay your hands on rubber grease you can use a little brake fluid to lube the seals.  If you do this though be careful around your paint .

Ok, just checking that mine are still dragging way too much, haha. And maybe I should clarify; I used caliper slide grease for the pad and brake assembly lube for the piston.

Since then, I got my new seal and took apart my front caliper. My piston is garbage. Rusty and pitted. I emailed a member here for one of those phenolic pistons. I'm excited about that. My caliper seems to be alright. No scratches and very smooth to the touch but a lot of white gunk in the seal groove. Going to clean that out today with a brass wheel brush.

There's so much knowledge in this forum it blows my mind. So many questions have been answered.


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1978 Honda CB550K

[trueblue]

Ok, make sure you clean the groove in the caliper out good.  It should be a nice square shape.  Keep us posted on how you get on

[DaveBarbier]

I cleaned out the seal groove and it's super clean. They should change the saying to "This whistle is as clean as Dave's caliper seal groove." I'd say it has a better ring to it anyway.

I couldn't get a brass wheel. Instead I soaked a price of a shop towel in PB Blaster and let it sit in the ring for a couple hours. Then I, carefully...and with a small dental mirror, used a carbon steel brush on my Dremel. Piston will come in a couple weeks and I can re-assemble.


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1978 Honda CB550K

[Don R]

YOU GO! I mean er, stop.

[DaveBarbier]

Ok, just to have things documented...I got the new piston today. Phenolic for $44 from Godfrey, a user on this forum. It's so light and a honeymoon fit.

Installed new seal and piston with assembly lube and pad with high vacuum grease. Going to bleed with DOT4 tomorrow as the new Nissin MC I have calls for it. I'll have to flush out the DOT3 that's currently in the lines. After that, brakes will be all finished with new parts and my pad should (will?) retract as it should.

Any problem with doing the caliper rebuild without filling it with brake fluid? I think it should be fine but curious if I'll run into any bleeding problems.


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1978 Honda CB550K

[trueblue]

It'll fill up when you bleed it

[DaveBarbier]

Ok so got the brakes back together. Bled the system and it seems to be a lot better. I noticed that the phenolic piston is a little longer than the stock one and when I release the brake lever  the wheel still drags a little. Much less than before, though. I tried to adjust the arm but nothing made it completely free. Could the new piston be too long? Not giving the clearance needed to accommodate new, thick pads?

Any way to remedy this? Maybe sand down the pads a hair? Add a shim between the caliper sides?


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1978 Honda CB550K

[Don R]

The solid side of the piston is in and the pad fits in the hollow side right? Don't ask how I know that.

[DaveBarbier]

The solid side of the piston is in and the pad fits in the hollow side right? Don't ask how I know that.

Yup, hollow side out facing the pad.


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1978 Honda CB550K

[DaveBarbier]

Don't shim the caliper. If your wheel is still dragging after a full bleed, good lever pressure, etc. then you may have to lightly sand the pad face. BUT, before you do that, ride the bike about gently. It may be your rotor face is out of true.

I've found that until the system is fully bled, the caliper doesn't seem to want to pull the piston back, but after some use while riding, the pads seat in much better. But I repeat, ride gently and carefully!

If you're still encountering drag, check that the rotor is not binding in specific spots (bike on center, spin wheel by hand). If everything checks out, then use a sanding block with paper, and cross the pad at 45 degrees to avoid warping the pad. Gently, Grasshopper, very gently. 400 grit should be plenty to ease the pad face.

I've always used brake fluid to soak my seals in before assembly. It's all you need as the seal with impregnate with the fluid then live it's life immersed in it. Lube the backs of the pads with appropriate lube. Piston needs nothing but a smear of brake fluid to install through caliper seal.

As you put it earlier, your caliper inside can never be too clean!

Last bit: I always use anti-sieze when assembling the caliper (on the bolts ONLY) to  avoid tearing out the 10MM threads on the backside of the caliper. Especially if you are going to assemble/disassemble regularly. Just be sure not to use too much and wipe away any residue from the caliper housing before remounting it.

So I was told by Godfrey that the piston is suppose to be taller because it's supposed to render the nylon washer obsolete. So it's just the pad touching the phenolic piston. That should give me a few more millimeters in clearance and should be all I need. I wasn't aware that I don't need the nylon washer with this piston.

But if that doesn't work then I'll try the stuff you mentioned. Thanks Calj737, and good idea with the anti seize for the bolts. I'll totally do that.


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1978 Honda CB550K

[DaveBarbier]

Ok, just before my Thanksgiving dinner I removed the nylon washer and it's perfect. Wheel spins super free and the brakes are hard as a rock.

Thanks guys, happy Thanksgiving.


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1978 Honda CB550K