Topic: CB400F how to remove caliper

[Mr.Moose]

My front brake is sticking, wheel only freely spins 1 rev, and I'm trying to remove the caliper to clean it. Clymer manual says to remove front wheel to do this, and the repair manual on this site says to remove the fender. My problem:

1: When removing the wheel I can not get the solid brake line off of the caliper. Is this supposed to come off easily? Is there a trick to get a stuck line off? The wrench is slipping on the nut, and I'm afraid I've ruined it.



2: How to I get the fender off without removing the brake line? It is really stuck in the hook it sits in on the fender.



Any help is appreciated

[kfleschner]

I wound up not taking the caliper assembly off the mounts because I had a similar issue as you. In my case the nut was 40 years old and frozen to the caliper body. I had to pound a smaller wrench into the nut and take a hammer to the lever side of the wench to get it off. Once this comes off you can take the fender off if you want. I never did.

[MoMo]

PB blaster or something similar, let it soak and try again. If the 10mm head is too buggered use a very good pair of vise grips.  Also, break loose the bleeder valve while the caliper is still mounted.   PB will also help in removal of the rubber grommet that is stuck in the clip. 

[Bodi]

The hardline connector will come out. Try heating the area with a propane torch - not super hot but at least sizzle hot. Shoot penetrating oil or brake fluid around the base of the threads, it will get sucked in as the thing cools. The aluminum caliper housing heat expands more than the steel "bolt" so it should be looser when hot. Use visegrips if the hex is rounded off. Also get the bleeder bolt out, if it breaks off (not unusual) you have more fun work in store.
Then remove the two large caliper bolts and take the caliper inner and outer parts off.
The grommet is probably rather hardened. If you can work the hardline into the grommet, it comes out much more easily.
The pivot for the swinging arm is a problem area. Disassemble, clean, lube, reassemble. It should swing freely but have almost no free play otherwise.

[jonda500]

A pipe wrench is the best spanner for that nut, I'd crack it and the bleeder loose - use vice grips if you have to but just crack them loose and then do them back up as you will be wanting to pump the piston out with the brake lever to clean all the sticky crud out of the caliper bore. You don't need to remove the wheel or fender, just the 2 caliper bolts - you don't even really have to disconnect the pipe from the caliper but it does make it easier to clean - make sure to clean the seal groove thoroughly! John

[Don R]

Do you have a tubing wrench? Almost a box end with a slot for the line to pass through? I put tension on it and tap lightly on the caliper near the threads, heat, penetrating oil, etc also helps.
 The rubber is hard on the line bracket, shoot some silicone lube on it and get after it.

[Powderman]

Next time use the proper "line wrench" that grabs 5 sides of the nut

[Mr.Moose]

Thank you all! Will be buying new wrenches and propane tomorrow and report back:)

[Mr.Moose]

The line wrenches i bought was crap (even tho it was expensive) but the combination of vice grips, heat and penetrating oil worked perfectly. Didn't heat it much at all, but it didn't come off without heating. Oil was rather thick and filled with gunk. Now parts are clean and ready to be assembled, the swing arm swings freely, and the piston looks nice and whole. Hopefully problem solved.

[Scott S]

 Do you have a new piston seal? I wouldn't waste my time putting it back together without one.

[Mr.Moose]

Have a new seal and it's in, and brake is now releasing.... but.... I did a proper beginner mistake. Got brake fluid on the disc, didn't realize until I had spun the wheel, tested that the brake released, with new pads installed. Is there any way to fix this? Google it now and some sources say "new disc and pads"....

Any input?

[Scott S]

 Dawn dish washing detergent a d super hot water on the pads. Just let the spigot run on them until the water is super hot. They'll air dry quickly when done.

 Brake cleaner on the disc. You can follow up with a good scuffing with some 800 grit.

[MoMo]

nice work, clean with brake cleaner and you should be good to go.  I'd scuff the pads...Larry

[Mr.Moose]

Okay. I am definitley doing something worng.

Cleaned rotor, but managed to get copper paste on another new set of pads. Hopefully I can still use them.

But: Brake lever is more spongy than it was, can be pulled all the way to the handle bar, and the piston is now not retracting properly again and brakes stick. Bleed the brakes with 2 cans of fluid, bleeding normally like the manual says (open, squeeze, close, letgo....*100), and with a no return valve on the end of a hose on the bleeder niple. Still, very soft brakes. Anybody got any idea what I am doing wrong here?

Is it worth buying a compressor and a bleeding tool? Can put it in a shop of course, but I want to do this myself and in Norway the cheapest garage here in my city charges $110 an hour plus plus, so I can buy a compressor for what he charges to bleed my brakes.

[MoMo]

a compressor to bleed brakes?  Your master cylinder may need to be rebuilt...larry

[Mr.Moose]

a compressor to bleed brakes? 

Yeah, I see they sell those vacuum driven bleeders (both for motorcycles and cars) that is run by an air compressor.

Your master cylinder may need to be rebuilt...larry

Any signs that this is needed? Brake fluid bowl looks very clean, brake lever can't be pushed all they way in (anymore, left a strap on the lever for a few hours, read about that trick, and it is a little better), and it gives a proper squirt from the return when pulling the lever.

Thank you for replying!

[MoMo]

Bleed the master cylinder first--pump, squeeze, then crack the banjo bolt until air  stops releasing, then work on
down the path by bleeding at the union on the lower triple, bleed the caliper last.  I've never used any method other than that.  The vacuum bleeder is one tool I do not have...Larry

[Bodi]

That sounds like you MC is OK.
Piston pullback (for no drag) is partly from the caliper seal - crud in its groove screws that up. Also from the MC piston pullback before it uncovers the tiny hole. Air in the system messes that up as well as giving spongy feel.
The caliper and the switch tee are rather excellent bubble traps. Repeated bleeding might eliminate all air. If you can take the caliper and tee off and tie the caliper up to the ceiling then bleeding from the MC works better as bubbles love to go up. The alternative is to pressure bleed from the caliper. Many cars require pressure bleeding now with all the ABS stuff. Tapping and twisting around the switch tee while pressure bleeding helps get the bubbles in there free. The MC reservoir will squirt and overflow during pressure bleeding, be super careful with brake fluid and anything painted!
I've tried vacuum bleeding with an el cheapo kit and it was a PITA plus didn't solve an air problem. I don't think there's enough flow to carry bubbles down the lines.
You can do McGuyver pressure bleeding with the caliper: undo the caliper bolts so the piston side is free. Pump the piston out with the brake lever as far as you dare (not to fall out, not to empty reservoir). Slowly push the piston back in (C-clamp) with the caliper pipe inlet highest, tap the caliper while doing this to dislodge bubbles. Do it again while tapping the switch tee with its inlet highest. This should get the system 99.9% air free, you're pushing the bubbles UP the way they want to float. This has worked for me and succeeded where many repeats of standard bleeding failed to give a mush free lever feel.

[Mr.Moose]

Bleed the master cylinder first--pump, squeeze, then crack the banjo bolt until air  stops releasing, then work on
down the path by bleeding at the union on the lower triple, bleed the caliper last.  I've never used any method other than that.  The vacuum bleeder is one tool I do not have...Larry

My english and motorcycle terminology is not perfect, so... "crack the banjo bolt", doed that mean tap it? Or open it? I don't really get how you can bleed one part of the system at a time like you describe here.

You can do McGuyver pressure bleeding with the caliper: undo the caliper bolts so the piston side is free. Pump the piston out with the brake lever as far as you dare (not to fall out, not to empty reservoir). Slowly push the piston back in (C-clamp) with the caliper pipe inlet highest, tap the caliper while doing this to dislodge bubbles. Do it again while tapping the switch tee with its inlet highest. This should get the system 99.9% air free, you're pushing the bubbles UP the way they want to float. This has worked for me and succeeded where many repeats of standard bleeding failed to give a mush free lever feel.

Will give this method a try, thank you!

This morning the brake felt firmer after being left with the lever pushed in over night. But the pads were still sticking on a little. I bought a proper clamp and was able to push the piston all the way in, it takes quite a lot of pressure! As soon as I release it, it slowly comes back out about 1,5mm, enought to grab the disc. This is with no pressure on the lever at all, so what is pushing the brake piston back out? If this was trapped air, should't the pressure just release in the fluid bowl on the master cylinder? I had no idea figuring out a brake system could be this difficult!

[Mr.Moose]

Nobody has an idea what would be pushing the bake piston back out without any pressure on the lever?

Think I'll take the caliper apart again, install an OEM gasket, and try bleeding yet again...