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Discussion Starter #1
Hi guys,
new to this forum but have been trying to get a new front caliper kit for my Honda Nighthawk cb450sc and have had no luck. The bike is in great condition but with the front caliper needing a service this is stopping me from partaking in rides with my mates and other collectors. I am in Australia so parts for this model a scarce.. Any help would be much appreciated in how I how get this machine back on the rd?? She is a survivor and to see her sitting there is not right for the journey of this bike...

any help please please please???
 

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Hey thanks for the info,
The problem is that the pistons don’t retract so therefore there is a high pitch scraping sound when the bike moves in neutral and also when in gear..
I was advised by a mechanic that I would need the kit to have the work done??
I’m not a mechanic so I’m only taking there word and advice, and because the bike is an import I can only find parts for this model through eBay etc...

I will look at the seals online and get the right parts and see if the mechanic can do the work needed and re -seal after the work is complete. I gues this is my option if unable to buy a complete kit..??
 

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The seal is a square cross section o-ring. The seal groove is angled to the piston bore. As the piston is pushed outward while braking, tension is built against the corners of the seal. As breaking pressure is released the seal wants to relax into its groove and takes the piston back in its bore in the process.

You need clean seal grooves, unpitted pistons and new seals.

And you don't need a mechanic to do this for you. Start a thread here in the appropriate section and help will be there. You can do this.
 

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There are 2 pads, one on the outside of the caliper and one on the inside.

How far from the disc is the one on the inside? look at it from the front of the bike. I adjust mine to be barely rubbing.

Edit: hmmm, I'll need to dig out the caliper to check if it's adjusting or not. If not, then you need to undo the 2 bolts holding the caliper and remove it. I pump the brakes to push the brake pad out and clean the piston. If it looks all crazy and messed up inside then clean and replace the seal. If no then you can try and use as is... it's simple enough to reassemble and disassemble once you have the replacement part. I use a c-clamp to push the pad and piston back into the caliper. Use sandpaper on the pads and disc if they're shiny. Brake cleaner spray to clean off and bolt back together and bleed the brakes. Maybe intimidating the first time, but difficult to break it or do permanent damage so no harm in trying.
 

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Pistons not retracting could be a clog at the master cylinder, but you want to get a look at the caliper first.

Do what Doode says, post photos and ask every question you can think of.
 

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You might give this a read. Front brakes seizing up / tight after several uses -... normally this occurs while riding that the brakes stay applied( pistons not retracting) but it could be your problem.
If the bleeder is opened/removed the pistons should retract using the C clamp method. If the seal aren't leaking and you get the pistons retracted then I'd leave it alone and watch for the parts to come up for sale. Other option is replace the caliper.
Your specific caliper fits these US models
Honda Motorcycle 1982 CB750K A - 750 FOUR K Front Brake Caliper 2
Honda Motorcycle 1982 CB650 A Front Brake Caliper 2
Honda Motorcycle 1982 CM450C A - CUSTOM Front Brake-Caliper
Honda Motorcycle 1982 CB450T A - HAWK Front Brake-Caliper
Honda Motorcycle 1982 CM450A A - HONDAMATIC Front Brake-Caliper
Honda Motorcycle 1982 CB450SC A - NIGHTHAWK 450 Front Brake-Caliper
The caliper mount fits these US models so a caliper from one of these would be a suitable replacement, just have to get the correct pads and make a note of it for the future.
Honda Motorcycle 1982 CB750K A - 750 FOUR K Front Brake Caliper 2
Honda Motorcycle 1982 CB650 A Front Brake Caliper 2
Honda Motorcycle 1983 CB450SC A - NIGHTHAWK 450 Front Brake-Caliper
Honda Motorcycle 1982 CM450C A - CUSTOM Front Brake-Caliper
Honda Motorcycle 1982 CB450T A - HAWK Front Brake-Caliper
Honda Motorcycle 1985 CB450SC AC - NIGHTHAWK 450 Front Brake-Caliper
Honda Motorcycle 1982 CM450A A - HONDAMATIC Front Brake-Caliper
Honda Motorcycle 1983 CM450A A - HONDAMATIC Front Brake-Caliper
Honda Motorcycle 1982 CB450SC A - NIGHTHAWK 450 Front Brake-Caliper
Honda Motorcycle 1985 CB450SC A - NIGHTHAWK 450 Front Brake-Caliper
Found a couple used caliper out of Japan
 

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Discussion Starter #14
You might give this a read. Front brakes seizing up / tight after several uses -... normally this occurs while riding that the brakes stay applied( pistons not retracting) but it could be your problem.
If the bleeder is opened/removed the pistons should retract using the C clamp method. If the seal aren't leaking and you get the pistons retracted then I'd leave it alone and watch for the parts to come up for sale. Other option is replace the caliper.
Your specific caliper fits these US models
Honda Motorcycle 1982 CB750K A - 750 FOUR K Front Brake Caliper 2
Honda Motorcycle 1982 CB650 A Front Brake Caliper 2
Honda Motorcycle 1982 CM450C A - CUSTOM Front Brake-Caliper
Honda Motorcycle 1982 CB450T A - HAWK Front Brake-Caliper
Honda Motorcycle 1982 CM450A A - HONDAMATIC Front Brake-Caliper
Honda Motorcycle 1982 CB450SC A - NIGHTHAWK 450 Front Brake-Caliper
The caliper mount fits these US models so a caliper from one of these would be a suitable replacement, just have to get the correct pads and make a note of it for the future.
Honda Motorcycle 1982 CB750K A - 750 FOUR K Front Brake Caliper 2
Honda Motorcycle 1982 CB650 A Front Brake Caliper 2
Honda Motorcycle 1983 CB450SC A - NIGHTHAWK 450 Front Brake-Caliper
Honda Motorcycle 1982 CM450C A - CUSTOM Front Brake-Caliper
Honda Motorcycle 1982 CB450T A - HAWK Front Brake-Caliper
Honda Motorcycle 1985 CB450SC AC - NIGHTHAWK 450 Front Brake-Caliper
Honda Motorcycle 1982 CM450A A - HONDAMATIC Front Brake-Caliper
Honda Motorcycle 1983 CM450A A - HONDAMATIC Front Brake-Caliper
Honda Motorcycle 1982 CB450SC A - NIGHTHAWK 450 Front Brake-Caliper
Honda Motorcycle 1985 CB450SC A - NIGHTHAWK 450 Front Brake-Caliper
Found a couple used caliper out of Japan
thanks for all this information, I have preferred new seals and pistons to start the work, and hope that they arrive soon:) I will try cleaning exsisting caliper first and then replace the pistons and seals of this all goes well then no need to replace caliper completely. I’m thinking it might be a better option to then look into replacing the caliper as parts are now becoming obsolete?
This has all been very informative and it’s probably best I start to do the work myself as the bike is going to need more attention as the years roll on.

what a great forum and can’t thank you all enough:)
Will let you know how it all goes..
NN
 

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thanks for all this information, I have preferred new seals and pistons to start the work, and hope that they arrive soon:) I will try cleaning exsisting caliper first and then replace the pistons and seals of this all goes well then no need to replace caliper completely. I’m thinking it might be a better option to then look into replacing the caliper as parts are now becoming obsolete?
Where did you end up getting the pistons from? I got a pair of the ones from Brakecrafters and it seems they're longer than the ones I pulled out...I started a thread here with my front brake caliper adventure. Thread isn't approved yet but it will be here: Confusion about front brake caliper piston and pad sizes...
 
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