Author Topic: Front wheel does not spin after reinstalling brake caliper. (Read 4676 times)

jcupit01 · « **on:** March 13, 2012, 05:09:33 PM »

Hey all,

I have a 75 CB550k1 that I have been rebuilding over the winter. One of the first things I did was rebuild the master cylinder and replace the pads. I thought everything was together fine and it sat while I did the top end rebuild. Taking it out for a test run I noticed it was struggling to get going, turns out the front wheel spins very little, there is active resistance. I loosened the caliper bolts and it spun great, so obviously the brakes are screwy.

It does not matter what the caliper adjuster screw is doing or where it is set, as soon as I tighten the two caliper bolts the wheel locks up again. I bled the lines to zero bubble and I inspected the pads and all looked normal. The only thing I can think of is that the aftermarket pads I got are too thick or the caliper is not retracting correctly and maintaining a grip on the rotor. Any thoughts appreciated.

Thanks

cmonSTART · « **Reply #1 on:** March 13, 2012, 05:25:02 PM »

I've found too-thick pads before, but rarely.

The caliper should be free to slide on a couple shoulder bolts I think. These might be gunked up a bit. Or, the caliper itself might need rebuilding.

OpTiCz · « **Reply #2 on:** March 13, 2012, 05:26:33 PM »

I had the same issue.
For me, the white ring behind the pad had come off center. Can you post a pic of the pads currently seated?

Sent from my SGH-T989 using Tapatalk

camelman · « **Reply #3 on:** March 13, 2012, 09:19:20 PM »

I concur with the nylon ring issue. It needs to rest around the raised bump on the back of the active pad.

SohRon · « **Reply #4 on:** March 13, 2012, 09:22:06 PM »

Did you open up the fluid return hole in the MC? That will cause the brake to freeze up. And check that nylon ring (you did install it, right?). One way to test the fluid return is to apply the brake, then release it. Immedietly open the bleeder on the caliper and if you get a stream of fluid, your return hole is blocked.

Push the moving pad back into the caliper, so that the pad face is even with or below the caliper face, then adjust the gap between the fixed pad and rotor to .006"; that will at least get you started out right at the caliper end, and hopefully you can trace it from there.

scottly · « **Reply #5 on:** March 13, 2012, 09:28:28 PM »

Make sure the caliper arm pivots freely on the pin.

ekpent · « **Reply #6 on:** March 13, 2012, 09:31:12 PM »

Piston or pad is sticking in the caliper. Whack it with a rubber mallet and see if it free's up till you hit the brakes again.

phil71 · « **Reply #7 on:** March 13, 2012, 09:34:56 PM »

isn't there a drag adjust, that would possibly be way out of spec once new pads are installed?

ADW · « **Reply #8 on:** March 14, 2012, 08:47:24 AM »

Quote from: SohRon on March 13, 2012, 09:22:06 PM

Did you open up the fluid return hole in the MC? That will cause the brake to freeze up. One way to test the fluid return is to apply the brake, then release it. Immedietly open the bleeder on the caliper and if you get a stream of fluid, your return hole is blocked.

DING DING DING! We have a winner! At least in my case...72 CB350F did exactly the same thing after my complete winter redo on it. Was fine for the first couple rides then front was super tough to turn. Ended up using a wire brush wire (stiff, yet small) to poke through the MC fluid return hole and that fixed it.

SohRon...when you say "open up the fluid return hole..." is there a known procedure/recommended size or something? I've had this happen a couple of times now so if there's a piece of "tribal knowledge" that many agree on as to how to open up that hole a touch without screwing anything up I'd love to hear it!

SohRon · « **Reply #9 on:** March 14, 2012, 08:59:07 PM »

There is no "accepted" procedure for clearing the return port hole; people use guitar strings, dental pics, random stray wire, etc, when it gets plugged. It definitely requires attention whenever the MC is rebuilt or otherwise renewed, and I would suggest that, if it does clog, it's a good indication that a system flush and MC rebuild is in order.

ADW · « **Reply #10 on:** March 15, 2012, 04:15:30 AM »

Quote from: SohRon on March 14, 2012, 08:59:07 PM

There is no "accepted" procedure for clearing the return port hole; people use guitar strings, dental pics, random stray wire, etc, when it gets plugged. It definitely requires attention whenever the MC is rebuilt or otherwise renewed, and I would suggest that, if it does clog, it's a good indication that a system flush and MC rebuild is in order.

OK, I thought maybe when you said "open" the return hole you meant people were enlarging it a touch so that it didn't plug so easily.

SohRon · « **Reply #11 on:** March 15, 2012, 05:36:37 AM »

Quote

OK, I thought maybe when you said "open" the return hole you meant people were enlarging it a touch so that it didn't plug so easily.

No, not at all. That hole is as small as it is for a reason. so we don't want to mess with it. Cleanliness is the word of the day!

bollingball · « **Reply #12 on:** March 15, 2012, 05:44:19 AM »

Quote from: ADW on March 15, 2012, 04:15:30 AM

Quote from: SohRon on March 14, 2012, 08:59:07 PM
There is no "accepted" procedure for clearing the return port hole; people use guitar strings, dental pics, random stray wire, etc, when it gets plugged. It definitely requires attention whenever the MC is rebuilt or otherwise renewed, and I would suggest that, if it does clog, it's a good indication that a system flush and MC rebuild is in order.

Just for grins if you open your house door do you make a bigger hole or turn the door knob to get in?

OK, I thought maybe when you said "open" the return hole you meant people were enlarging it a touch so that it didn't plug so easily.

jcupit01 · « **Reply #13 on:** March 17, 2012, 08:40:32 AM »

Some excellent suggestions here. I will address the MC return hole today, will try the little test. I took apart the caliper last night and verified correct assembly. My manual, stated that the piston should be able to be pushed back in "by hand". Well this definitely was not the case as I had to crank on a "C" clamp to get it back, it was not going easy for sure.

THanks for the help!

crazypj · « **Reply #14 on:** March 17, 2012, 08:53:38 AM »

Caliper needs a re-build.
The seal grove has corrosion in ity and is pushing seal onto piston too tight
It needs doing every couple of years

jcupit01 · « **Reply #15 on:** March 17, 2012, 11:02:46 AM »

A rebuild normally entails replacing seal and not the piston right? I have not torn it apart yet so I cannot speak for the condition of the piston in it's entire length. I do know a new piston is about $90 new and would rather just get a new seal. When I drained this caliper last fall, the gunk that came out of it was a brown sludge like I have never seen before. Obviously this Caliper was ignored for pretty much the entire life of bike.

Also the bleeder valve seems to be broken, at least the nipple is busted. Will replace that as well.

LesterPiglet · « **Reply #16 on:** March 17, 2012, 11:04:27 AM »

Be gentle with that nipple. Don't want that snapping off.

jcupit01 · « **Reply #17 on:** March 17, 2012, 11:13:06 AM »

Lol, it is already snapped off. I got the bike with it like that.

crazypj · « **Reply #18 on:** March 17, 2012, 08:23:14 PM »

Quote from: jcupit01 on March 17, 2012, 11:02:46 AM

A rebuild normally entails replacing seal and not the piston right? When I drained this caliper last fall, the gunk that came out of it was a brown sludge like I have never seen before.

Your probably going to need a new piston. There will be a ring of pitting where the seal touches it.
Don't buy stock Honda, get either the stainless steel one or the phenolic (on e-bay) about $50.00

RAFster122s · « **Reply #19 on:** March 17, 2012, 10:25:50 PM »

There is a member here on sohc4 forums out of texas who has phenolic pistons available to members at a price better than 50. Dont recall his name, he's in the services section of the site. He modifies the lincoln ls pistons to fit our bikes...

jcupit01 · « **Reply #20 on:** March 18, 2012, 06:14:12 AM »

Okay, I am not sure how to remove this piston from the caliper. I fully extended the piston and gently tried to pull it out but no good. Ideas or can you point me to a thread that covers this? I did a search with no good results on this topic.

70CB750 · « **Reply #21 on:** March 18, 2012, 06:32:28 AM »

Grease gun to the bleader, plug the brake line and pump it out.

RAFster122s · « **Reply #22 on:** March 18, 2012, 07:22:52 AM »

You can thread the grease gun in partway at the brake hose/line connection by hand and then pump it out. Works well for me. Since you dont force it it wont messup the threads.

ekpent · « **Reply #23 on:** March 18, 2012, 07:43:18 AM »

You can se an air compressor also if you don't want to make a mess or don't have a grease gun Handy.
But a word of WARNING-Secure the piston with a loosely fit c-clamp,wrap in a good rag and wear good gloves. When the piston lets go it can shoot out like a bullit

cmonSTART · « **Reply #24 on:** March 18, 2012, 08:34:57 AM »

Quote from: ekpent on March 18, 2012, 07:43:18 AM

You can se an air compressor also if you don't want to make a mess or don't have a grease gun Handy.
But a word of WARNING-Secure the piston with a loosely fit c-clamp,wrap in a good rag and wear good gloves. When the piston lets go it can shoot out like a bullit

I cover the whole works up with an old towel or anything handy to keep the piston from flying away. It makes an nice little pop, too!

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Author Topic: Front wheel does not spin after reinstalling brake caliper. (Read 4676 times)

bollingball