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Discussion Starter · #1 ·
Ok I'm not even sure I have a cb450 caliper or a 750 caliper. Having no knowledge if there is a difference between the two. The reason I say this is because I had an issue with a caliper and the piston was stuck in there, and after blowing it out with a compressor and trying to clean up the piston, it was definitely trash. I was given a cb750 piston and caliper, though still have the 450 backing plate. Long story short, I have both, and it's not working. Can I get it to work correctly on my cb450, or is the 450 piston and caliper completely different? The exact problem is they are tight right to the rotor and no amount of adjustment in the caliper swingarm is changing anything. Can anyone help?
 

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The return hole in the master is probably blocked/munged up......
 

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Do you have a photo of the assembly on the bike? They can be assembled incorrectly. Photos all ways help :D
 

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Discussion Starter · #4 ·
Sorry I don't. The bike is at my friends shop and I can only make it there to work on it on saturdays, so unfortunately I can't get a pic till then.

66, how do you mean?
 

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The 450 and 750 calipers are identical (although there are two types, the early finned ones and the smooth later)..... If the caliper looks like the one that was on there, it is the same.....
IF it is holding both pucks in constant contact with the rotor, one possibility is too much fluid "trapped" in the caliper....This is controlled by the return hole in the bottom of the master reservoir. There are two holes in the reservoir bottom, a large one (about 1/8" ) and the return pinhole (closer to the banjo).....
IF the whole caliper/arm assembly is improperly mounted on the fork leg the caliper can sit "tweeked" enough that both pads touch.... (fender brace on wrong side of the pivot clamp at the slider)
Either scenario can render the adjustment screw/spring useless....Pics will tell if the fender is the culprit.................
 

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Discussion Starter · #6 ·
I am not even running fluid or lines to the caliper yet though, just dry attaching, there is nothing within the caliper blocking...the piston is completely compressed.

I may be going to the shop on Wednesday, so I can take pics then.
 

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Discussion Starter · #7 ·
I didn't make it there today, so no pics yet, but I'm wondering...has anyone found aftermarket pads to be too thick? Another guy at the shop said his 750 pads seem thinner than my pads. Seeing as I haven't had my bike on the road in a year, which is when I last bought pads, I can't recall where I bought pads. I'm certain I bought cb450 pads (at least as how they were described, but don't know if they are an exact copy of the 750 pads.) If the case is that there is just too much material, there shouldn't be a problem with grinding them down I would imagine, or is that just playing with fire?

edit: also just to be sure, the setup looks like (from outside to inside) Caliper > brace > caliper correct? or is there spacer I'm missing? I just don't get how this doesn't fit with nothing blocking the pads from being seated all the way in. Thanks again guys, you've always been a great help!
 

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pawn said:
I didn't make it there today, so no pics yet, but I'm wondering...has anyone found aftermarket pads to be too thick? Another guy at the shop said his 750 pads seem thinner than my pads. Seeing as I haven't had my bike on the road in a year, which is when I last bought pads, I can't recall where I bought pads. I'm certain I bought cb450 pads (at least as how they were described, but don't know if they are an exact copy of the 750 pads.) If the case is that there is just too much material, there shouldn't be a problem with grinding them down I would imagine, or is that just playing with fire?

edit: also just to be sure, the setup looks like (from outside to inside) Caliper > brace > caliper correct? or is there spacer I'm missing? I just don't get how this doesn't fit with nothing blocking the pads from being seated all the way in. Thanks again guys, you've always been a great help!
Assuming you've got the right pads keep in mind that the piston has to be pushed back quite a bit before you can mount them. In my case, I installed the pad for the piston (make sure it seats on the piston properly) then use some pliers with (with a towel for protection) and squeeze the pad and outside of the caliper to compress the caliper piston. If the previous pads were worn quite a bit you might have to much fluid in the M/C now as well. In my case, I cracked the bleed valve on the caliper when I squeezed the piston in (using a towel around the bleed valve of course) to release the excess fluid.

Once it's squeezed and set, reassemble everything then re-bleed the brakes and you should be ok.

Let us know how it goes.
 

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Discussion Starter · #9 ·
i have no fluid in my master cylinder, and it's not even hooked up to the caliper yet, so that isn't the issue. I used a c-clamp to make sure the brake piston is all the way at the bottom so that also isn't the issue. This is driving me batty, only really because I haven't been near my bike to try and work it out, but I know it's not the issues you pointed out. The pads I have in there are the later style puck type and they fit within the caliper just fine, I'm just curious if their height is too much. I ordered a set of 450 pads last night just in case the previous ones are in fact incorrect, though they look just like the ones I ordered (but the height, again, may be the factor here.)
 

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Discussion Starter · #10 ·
i took some pics on my cell phone. I still don't know the problem really. Any help...hopefully the pics can tell any of you something to help me out with. Thanks again!





 

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Could be crystallized old fluid within the caliper....Did you clean that out before compressing the piston?
 

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Discussion Starter · #12 ·
yeah it's completely clear within the caliper...piston is completely seated, which is why I was wondering if the pads are too thick? They look like the right pads to me though, compared to other ones I've seen for the 750 (I don't have the opportunity to look at any 450's other than my own, which is why things are a guess to me, and this is my first foray into a 450 or any bike for that matter.)
 

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I spot one problem with your setup that probably has nothing to do with your current problems. Your fender is mounted outside of the caliper swing arm. It should go inside of the swing arm, otherwise the caliper grabs the disc in slightly the wrong angle making the front brake weaker.
[attachment=0:3t3om7sf]SSA51654-1024.jpg[/attachment:3t3om7sf]

I have a CB500 four (same caliper as CB750) and a CB450 K5. I will go outside and mesure them tomorrow (got a cold yesterday so I'm staying inside today) to see if I can find any differences. Was thinking maybe your setup is some kind of mixture of brake caliper parts if the 450 and 750 not are identical.
 

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Discussion Starter · #16 ·
i don't understand what you mean with the fender...I don't have a fender, just the fork brace and it's mounted in the only possible position it could be mounted in. Definitely let me know the measurements. Or if anyone could compress their caliper piston and let me know the pad depth, that would be awesome. I know for absolute sure the piston came from a 750...but I really thought the 450 and 750 were exactly the same calipers.
 

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Discussion Starter · #18 ·
i feel like I'm either blind or crazy because I have no idea what you are pointing out to me. I see no difference.
 

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Pawn..... The fender (or brace section) is in between the pivot and the fork in one pic, and interior (on top but closer to the wheel) to it in the other....
 

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Discussion Starter · #20 ·
ok so it was blindness in that case. I kept thinking to myself "is Znabb just messing with me?"

Thanks for pointing that out.

You're right about it not effecting my problem, however I will change that as soon as I get back to the shop.
 
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