Topic: CB750KO - Caliper pin problem

[Johnie]

CB750KO - 18,000 miles - This past fall I noticed a rattle in the front.  Narrowed it down to the front caliper rattling at the point it attaches to the bracket by that long caliper holding pin. (#14 in the parts picture).  I can move the caliper up and down by hand easily and that is what is happening everytime I hit a bump.  Is there a chance item #14 could need replacing or is that movement common.  Or, is it just that adjustment nut for the disc that some like to take out would tighten things up?
Thanks 

[Raul CB750K1]

Do a search in the old threads, this has been discussed before. Long story short, got to the main page, where Glenn has put the Honda technical bulletins provided by our friend Bryan Jones (bryanj). There is one that deals with that "clunk", and the fix is to shim it with washers of different thickness as needed -the bulletin includes the washers' p/n)

[Bob Wessner]

I had the exact same problem and at just about the same mileage. Shimming took care of it. I also noticed enough of a gap had developed that one of the o-rings had slipped down further aggravating the situation.

[Johnie]

Thanks Raul and Bob.  I missed that one.  It will be nice to get that noise out of there.

[Bob Wessner]

Mine got to the point where I was trying to avoid rough pavement.

[Johnie]

I went to the tech bulletin and it says to use a 0.1mm or 0.2mm shim in there.  Heck, I can not even get a .05mm in mine.  The space is like paper thin.  Now I am thinking the pin or bracket is worn as there is no bushings there.  (Hard to believe with only 18,000 on it.)  With the bracket out of the caliper holder I can wiggle that pin back and forth on the top and bottom.  Can someone give me the width of a good caliper pin so I can compare it to mine.  Maybe all I need is a new pin.  Below is the pin in my dial. 

[kaysystems]

I went to the tech bulletin and it says to use a 0.1mm or 0.2mm shim in there.  Heck, I can not even get a .05mm in mine.  The space is like paper thin.  Now I am thinking the pin or bracket is worn as there is no bushings there.  (Hard to believe with only 18,000 on it.)  With the bracket out of the caliper holder I can wiggle that pin back and forth on the top and bottom.  Can someone give me the width of a good caliper pin so I can compare it to mine.  Maybe all I need is a new pin.  Below is the pin in my dial. 

Western Hills Honda may have new pins still.
One problem is that there is no way to get any grease in there. Those little seal 'O' rings always scrape it off. Also if you swing the caliper just a tiny bit you will notice that the pin moves too. The  'O' rings grip it. So the bracket is the bearing, not the caliper arm. The easy solution to this is to use a BIG split pin instead of the factory size. Make sure the split pin is a tight fit in the bracket & pivot pin. This forces the swing arm to move on the pin instead of the pin moving in the bracket, where there is water, dirt etc. If  the bracket wears, you will rattle.

Hope this makes sense.

David

[754]

This would be my fix, as vibration has egged out the holes.

Ream or bore the swing bracket and the alum bracket that bolts to the fork (may only have to do the top on that one. Adjustable Ream or bore till it cleans up ar atleast 85%.

Then machine a new pin out of stainless, and add a grease or oil hole near the top of the swing bracket or grease it once in a while.

 i bet some people WASH IT REALLY REALLY GOOD at the car wash or with a pressure washer.. cuase there was a bit of seepage there.. that will surely make the problem worse..

Added.. checked one today.. the swing bracket could be bored and bushed, if the pin has not worn in the bracket. The one I looked at the pin was sticking in the swing bracket and pivoting in the  c shaped bracket.

[Bob Wessner]

Make sure the upper and lower o-rings are present and in good shape.

[Johnie]

Yes, both rubber O rings were in place.  Still looking at 754's fix but never did something like this with a machine shop and am hesitant to take my OEM parts in there.  I was thinking of making some bushings to see if that would stop the rattle.  I wonder if some teflon tape would work? 

[Johnie]

754 was right the C shaped bracket bottom hole is egged out enough to make it wiggle.  I took some teflon tape as an experiment to see if I could take up the play at that point.  I was able to wrap 1 layer of teflon tape around that point and gently slide the pin in.  It is now snug.  I wonder how it would hold up?  Thoughts??? 

[754]

Use  brass shim stock , you can cut it with scissors. Or red loctite.. red will take up about .005 or more.

Because it is egged tho you will never take it all out with a shim. Could try JB Weld but you got to put the pin  or something in while it sets then get it out and run a drill through..

[754]

The pin is 10mm.

If you made a 11mm pin or 7/16., and carefully opened up the holes, this would clear up most of the slop. On the C part you could leave the lower hole or sligltly enlarge it and use a stepped pin.

[736cc]

  Don't forget to adjust side play; tighten adjuster until resistance felt then back off a turn

[754]

I stopped using those first time I did a dual disc in the 70,s. When I chromed the forks I removed the adjuster boss.

I really cannot see a need for them.

[merc2dogs]

 754 has the fix I'd go with, only difference is I'd most likely sleeve the now oversized hole to fit a stock sized pin.

 Maybe look into knurling the pin if it's not too awefully loose in the hole.

   I hate rattles from any source on a bike.

Ken.

[AshimotoK0]

Hi - My caliper pin is worn and both David Silver spares  and CMS list the part as discontinued
Honda P/N is 45116300030.
 
Does anyone know the best material to machine up a new one from please?

[754]

If  its only a few thou wear, you may be able to build up pin by plating.
 As far as making the pin, stainless is a bit more work, but needs no plating, otherwise shafting should be fine (will need plating).

[WHALEMAN]

I did the 754 method of machining out the bores and machining a new pin starting with a stainless steel bolt. Works great. Dan

[goon 1492]

That does sound like a good fix the 754 way, I also am interested in what you are talking about with the adjustable screw 754. So basicly I can take out the screw,spring and all and the caliper should be self adjusting and fully floating over the caliper, if I am understanding you right. It makes sense to me that way; but would there be any rubbing problems from the pads? common sense tells me that it won't and that with the adjusting screw it would eventually lead to a rubbing problem without constantly adjusting. I know Honda incorperated this into the design mostly for consumer friendly product functionablilty. Did I explain that right 754? I have been curious about it for several months since the last read that you talked about it.

[754]

Adjusting screws;
 Some swear by them.
 Some swear at them.

Personally, I think I had them on at first on a dual disc, after taking them  off (once) to get the wheel out for tire swap, I never used them again.

[Johnie]

That does sound like a good fix the 754 way, I also am interested in what you are talking about with the adjustable screw 754. So basicly I can take out the screw,spring and all and the caliper should be self adjusting and fully floating over the caliper, if I am understanding you right. It makes sense to me that way; but would there be any rubbing problems from the pads? common sense tells me that it won't and that with the adjusting screw it would eventually lead to a rubbing problem without constantly adjusting. I know Honda incorperated this into the design mostly for consumer friendly product functionablilty. Did I explain that right 754? I have been curious about it for several months since the last read that you talked about it.

I have found that if that adjusting screw is to loose it will allow that caliper to bounce around.  If the screw is properly adjusted with proper drag, it tightens it up and may help lessen or eliminate the noise over bumps.  But if you get that screw to tight you will heat up the pads to much.  If I get it to tight mine will squeal a bit.  Then I back it off a hair. 

[goon 1492]

Yeah that is kinda what I was talking about, and 754 is right it is a bit of a touchy subject for some  , I think I will give it a trial run when I get my duals back together, might just do away with them anyway, cause if the pin and or the bottom mount bracket(is that the c thing that ya'll are talking about? ) are in correct running condition there shouldn't be any slop in it, the adjusting screw should do one thing and thats keep the brake pad at bay until needed, it doesn't have any load bearing charistiscs just side adjustment.
Thanks for the comments.
also a nice steel bottom mount bracket with a brass bushing for a bearing would be a nice touch....     .....with a steel pin of course.

[AshimotoK0]

This would be my fix, as vibration has egged out the holes.

Ream or bore the swing bracket and the alum bracket that bolts to the fork (may only have to do the top on that one. Adjustable Ream or bore till it cleans up ar atleast 85%.

Then machine a new pin out of stainless, and add a grease or oil hole near the top of the swing bracket or grease it once in a while.

 i bet some people WASH IT REALLY REALLY GOOD at the car wash or with a pressure washer.. cuase there was a bit of seepage there.. that will surely make the problem worse..

Added.. checked one today.. the swing bracket could be bored and bushed, if the pin has not worn in the bracket. The one I looked at the pin was sticking in the swing bracket and pivoting in the  c shaped bracket.

Back on this subject - Is stainless steel hard enough to make a new pin from or should I have one machined in steel and then hardened?

[754]

It rides in aluminum, no need to be hardened..