Author Topic: CB750 K2 brake caliper pivot arm - is it stuck?  (Read 635 times)

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Offline KuangGradeMark11

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CB750 K2 brake caliper pivot arm - is it stuck?
« on: February 02, 2019, 06:27:44 pm »
Hi, so it turns out my K4 has a K2 front end.  Very confusing but this bike was sold in New Zealand and the frame number corresponds to K2 and the engine to K4 - sold in 1974.

It made ordering and sourcing some parts more difficult than it needed to be.

My question: should I be able to remove the pivot pin that attaches the swinging part of the brake caliper arm to the fixed part that bolts to the fork leg? It looks to me as if it should - there is a split pin to anchor it, and nothing obviously holding it, but it will not come out.  The arm now rotates (I have sprayed it with penetrating oil but the pin is turning with the lever arm and it WILL. NOT. SHIFT.  I have used progressively larger punches and hammers but am now giving it a rest before I get angry(er).  Anyway, assuming it should come apart, once i get it apart, do I just clean it up and use some grease?  Very frustrating.

Offline HondaMan

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Re: CB750 K2 brake caliper pivot arm - is it stuck?
« Reply #1 on: February 02, 2019, 07:19:32 pm »
Hi, so it turns out my K4 has a K2 front end.  Very confusing but this bike was sold in New Zealand and the frame number corresponds to K2 and the engine to K4 - sold in 1974.

It made ordering and sourcing some parts more difficult than it needed to be.

My question: should I be able to remove the pivot pin that attaches the swinging part of the brake caliper arm to the fixed part that bolts to the fork leg? It looks to me as if it should - there is a split pin to anchor it, and nothing obviously holding it, but it will not come out.  The arm now rotates (I have sprayed it with penetrating oil but the pin is turning with the lever arm and it WILL. NOT. SHIFT.  I have used progressively larger punches and hammers but am now giving it a rest before I get angry(er).  Anyway, assuming it should come apart, once i get it apart, do I just clean it up and use some grease?  Very frustrating.

It does come apart: it is held snugly by O-rings at the top and bottom of that long pivot pin. If they got wet, it could have corroded the aluminum (pot metal, really) that these are made from, and the corrosion grows the holes smaller a little bit. You can try heat: I use MAPP gas to heat the aluminum up and grow it a couple of thousandths around whatever bolt/pin/fitting I am trying to remove, usually helps a lot!
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Offline jaytee-nz

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Re: CB750 K2 brake caliper pivot arm - is it stuck?
« Reply #2 on: February 02, 2019, 10:18:52 pm »
Kuang - 1974 CB750's sold in NZ were in fact K2's as NZ never got the K4. I have the same mix of year and model. However, be careful as the odd part on them is K4 and not K2 so you need to check each time.
By the way - this section is NOT for asking questions as per the title.
Hondaman's advice is good (he is the unofficial guru on this site so knows all !).

Offline KuangGradeMark11

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Re: CB750 K2 brake caliper pivot arm - is it stuck?
« Reply #3 on: February 03, 2019, 07:07:33 pm »
Thanks, both of you.  Interesting about the NZ market being an afterthought.

I wasn't sure where to post my question - there doesn't seem to be a generic "Help, I've screwed this up" section. Would I have been better off in Tech > SOHC4Bikes?

The hilarity is that I now have a set of K4 fork tubes and a VGC front guard I paid too much money for that does not fit my forks. Still, what's another $700 odd if it gets the thing back on the road.

I've had the pivot soaking for 24 hours now so I will give it a smack tonight.  If that doesn't work I will buy a gas torch tomorrow (I dont own one...yet).
« Last Edit: February 03, 2019, 07:09:58 pm by KuangGradeMark11 »

Offline BenelliSEI

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Re: CB750 K2 brake caliper pivot arm - is it stuck?
« Reply #4 on: November 22, 2020, 06:33:02 pm »
Did one last week for another forum member. Find someone with a press....... slides out easily, but be careful to support the bracket (we used a deep, 6 point socket that worked perfectly).

Offline Stev-o

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Re: CB750 K2 brake caliper pivot arm - is it stuck?
« Reply #5 on: November 22, 2020, 06:36:23 pm »

I wasn't sure where to post my question - there doesn't seem to be a generic "Help, I've screwed this up" section. Would I have been better off in Tech > SOHC4Bikes?


Yes.  And if you want a quick answer, try the search feature.
'74 "Big Bang" Honda 750K [836].....'71 Honda 750K project.....'76 Honda 550F.....K3 Park Racer.....K5 Fiddy Dolla Special!......and a Bomber!............plus plus plus.........

Offline scottly

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Re: CB750 K2 brake caliper pivot arm - is it stuck?
« Reply #6 on: November 22, 2020, 06:42:43 pm »

I wasn't sure where to post my question - there doesn't seem to be a generic "Help, I've screwed this up" section. Would I have been better off in Tech > SOHC4Bikes?


Yes.  And if you want a quick answer, try the search feature.
Quick answer to an almost 2 year old question?? ;)
Don't fix it if it ain't broke!
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Offline Stev-o

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Re: CB750 K2 brake caliper pivot arm - is it stuck?
« Reply #7 on: November 22, 2020, 06:46:26 pm »

I wasn't sure where to post my question - there doesn't seem to be a generic "Help, I've screwed this up" section. Would I have been better off in Tech > SOHC4Bikes?


Yes.  And if you want a quick answer, try the search feature.
Quick answer to an almost 2 year old question?? ;)

Ha!  Yeah.....
'74 "Big Bang" Honda 750K [836].....'71 Honda 750K project.....'76 Honda 550F.....K3 Park Racer.....K5 Fiddy Dolla Special!......and a Bomber!............plus plus plus.........