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Author Topic: Zoöid Third Times a Charm CB175  (Read 54673 times)

Offline Texasstar

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Third Times a Charm CB175
« Reply #20 on: Jun 02, 2015, 18:44:50 »
We have been looking at some of CrazyPJ's work on hubs for inspiration and Zeke came up with this design. and I found something similar on Michael Moores Eurospares site


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« Last Edit: Jun 02, 2015, 18:48:53 by Texasstar »
It's an optimization exercise and not a maximization trip.-Teazer


And though she be but little, she is fierce - WS
http://zoomwithzeke.com/
Third Times a Charm cb175
http://www.dotheton.com/forum/index.php?topic=66169.0

Honda Cb175 Victoria!

www.dotheton.com/forum/index.php?topic=52299.0

Honda Cb200 Lucky!
http://www.dotheton.com/forum/index.php?topic=45872.0

Bultaco El Montadero 360

http://www.dotheton.com/forum/index.php?topic=64349.0

Offline teazer

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Re: Third Times a Charm CB175
« Reply #21 on: Jun 02, 2015, 20:12:02 »
Nice copy of a CB92 brake but not in magnesium.....

Offline Texasstar

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Re: Third Times a Charm CB175
« Reply #22 on: Jun 02, 2015, 20:28:44 »

Nice copy of a CB92 brake but not in magnesium.....
cool http://m.carandclassic.co.uk/car/C451649


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It's an optimization exercise and not a maximization trip.-Teazer


And though she be but little, she is fierce - WS
http://zoomwithzeke.com/
Third Times a Charm cb175
http://www.dotheton.com/forum/index.php?topic=66169.0

Honda Cb175 Victoria!

www.dotheton.com/forum/index.php?topic=52299.0

Honda Cb200 Lucky!
http://www.dotheton.com/forum/index.php?topic=45872.0

Bultaco El Montadero 360

http://www.dotheton.com/forum/index.php?topic=64349.0

Offline Texasstar

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Third Times a Charm CB175
« Reply #23 on: Jun 03, 2015, 06:59:48 »
Going OCB been researching how to make Vintage brakes better and ran across this article. http://www.klemmvintage.com/bighorntech.htm

It is a long read so I quoted it to give y'all a "brake".  So their claim is that they had to make a 150mm brake as good as a cb450 because of a rule change.  I love a good David and Goliath story.  I also have seen how sure footed "bighorn" sheep are up close and personal. ;)

"WHEELS
At bit of AHRMA Brake & Wheel “History” -   Every vintage motorcycle  rule set in North America (including AHRMA) permits upgrading machines to any “period correct” drum brake.  The biggest period-correct production front brakes are the 200mm DLS (double leading shoe) units found on the Honda CB/CL 450 & CB77, early Kawasaki H1, and the 4LS 200mm brakes of the early Suzuki 750 and 550 2-stroke triples.  Of all these 200mm brakes, the Honda brake offers the best mix of lightweight, great stopping power, and affordability.  With that, we bought a couple of CL450 front hubs on Ebay, and replaced our stock 21” rim/150mm single leading shoe brake with an 18”WM2 rim laced to our 200mm Honda DLS brake … it worked great.
   Then in winter ’09 AHRMA changed the wording of their Production brake rule to say that Ltwt bikes could no longer upgrade brakes. (supposedly due to skirmishes between CB400 four and CB 350 racers)  AHRMA’s poor choice of wording in this rule resulted in our Bighorns having to go back to the stock 150mm single leading shoe front brake (while a 180mm DLS brake is found on virtually every other bike in the class).  While we seriously questioned the wisdom (and safety aspects) of mandating worse brakes instead of “equal” brakes … the rules are the rules, no matter how dumb they appear to be.  With that we got to work refining our SLS 150mm brake (The details of or 150mm front brake improvement are below).  In the end, our modified and upgraded 150mm SLS brake stopped almost as good as the stock CB450 brake.  The truth is, all of our production road racing from’72-’75 was done with this same 150mm brake, and it was never a competitive problem then either.   
    In the winter of 2010, AHRMA once again altered the Production rules with wording that would require us to re-fit our old 21” front rim.  Since we were the soundly crushing the competition in our class, it was hard to see how this rule had any other purpose other than to disadvantage the Bighorns.  As of this writing, we have not yet decided whether to bother testing with a 21” front wheel.                                                                                   

Wheel Teardown -  Unless you have an absolutely “mint” rear hub, spokes, and rim, the rear wheel should be completely unlaced for preparation.   If your stock WM3 steel rear rim is in good condition with no visible dents, it can easily be used for any level build.
 
Fitting wheel bearings -  Installing new sealed wheel bearings is inexpensive and easy to do….we consider it mandatory.  However the Elite & GP builds require some added attention to detail.
   All Japanese wheels (of the period) have counter-bores in the hubs for the wheel bearing “ODs” to press up against, and an inner-hub steel-sleeve that spaces the two bearing “IDs” from one another.  However on virtually all Japanese hubs (of that era) that center spacer-sleeve is about 2+mm longer that the counter-bores in the hub are wide.  This means that at very high temperatures (and high turning loads) the hub can actually move slightly from left to right on the wheel bearing ODs.  To be sure this movement is not a lot …. But it only takes a small amount of wheel misalignment to induce high-speed wobbles and head shakes.
  To resolve this problem, the center sleeve spacer must be machined to “the exact” same dimension as the distance between the hub bearing counter-bores.   Klemm Vintage can do this modification for owners who don’t have the measuring and machining equipment to do so.
 
Vintage Brake Preparation -  Turning the brake drums and arcing the brake shoes of a drum brake are common mods done by many folks …. us included.  However there is an added detail that no one talks about…that makes a big difference in perfect brake performance.
  First a bit of history, it’s important to remember that 1970s Japanese motorcycles were made in an era when computer controlled machining did not exist.  On top of that, most Japanese motorcycles were mass produced to a meet price point, not a standard of mechanical excellence.   Mechanical perfection of the brakes on 60mph recreational bikes was not a big deal.  We learned these lessons while attempting to build our “perfect” stock 150mm front brake.
  In an effort to cover every possible variable, we laced our hubs to fresh rims, and planned to turn the drums with the wheels laced and trued.  We did this to cover the possibility that the spokes collective pressure may have the strength to slightly deflect the diameter of the brake drum.  We took our perfectly trued front wheel off the truing stand (that holds the hub by the outer edges of the two wheel bearings) and mounted in our lathe via the axle between the two wheel bearings.  Upon turning on the lathe, our perfectly trued rim “now” spun wildly out of round ….. it made no sense.  After taking considerable time for measurement and scrutinizing, we realized the problem was that the two wheel bearings in the hub were about .008” off center from each other in the hub itself.  If we had any hopes of this brake working perfectly, this problem had to be fixed.
  The short version of the fix is, we perfectly centered the (unlaced) hub in our lathe via the drum side wheel bearing and then cut the drum diameter, as well as two face and diameter locating surfaces.  This allowed us to mount the hub on a mill table to perfectly center the hub to check the concentricity of the other wheel bearing hole.  Doing this, we found both the front and rear hubs had the second bearing diameter .008”- .010” off center from the drum side bearing.  Instead of boring and resleeving the off center bearing hole to attain concentricity, we just bored the hub to fit a slightly larger double row bearing.  After pressing in the new double row bearing, our wheel (and brake drum surface) spun perfectly true on both the truing stand, and the lathe.  This hub was now perfectly true, and would offer full brake shoe contact with the brake lining.
  In addition to all this hub preparation, we also fit the brake shoes.  Fortunately, EBC still makes high-performance brake shoes for the stock 150mm brakes of the Bighorn.  While these shoes are made of a very good braking material, they are far from being a "optimum" shape.  With that, we mounted them on the backing plate a opened them to the hub diameter to give the the ideal "arc" contour for full contact with the liner diameter in the hub.  We offer this service for owner who do not have the equipment.

Brake Cooling -  No matter what front brake you are running, fading from heat can become a problem.  Many road racers fit a scoop of some kind on the backing plate to bring in cooling air, while others “swiss-cheese” the backing plate to get cooling air in.  Since our Bighorns would also be used for street use, we wanted to offer good cooling for the brake while minimizing the opportunity for large debris to find its way into the brake.  With that, we cut angled air inlet slots into the hub that would pull in air as the hub rotated.  We then drilled some air exit holes in an area of the backing plate that would not comprise the rigidity of the cam and pivot points.  After very little riding, there was a visible brake dust trail coming out of the air exit holes on the backing plate … and we got the cooling results we were looking for.

About Brake Cable Routing -  Multiple large radius bends in the front brake cable lead to a “mushy” feeling brake, and compromised brake effectiveness.  To minimize the number of these bends in the front brake cable, the front brake anchor should be made to a length that sets the cable parallel to the fork leg.  The cable can then be firmly secured to a cable holder at the top of the fork slider to further reduce cable movement.  The end result is a front brake cable that has only one 90’ radius as it mounts to the lever perch.  This single 90’ radius will net the least amount of cable movement, and significantly improve the positive feel of the front brake. (see photos above).
 
The Finished Race Prepped OEM Brake “On the Road” -  Like any fresh brake, it requires some “seating”.  Since our Bighorns were registered for street use, we took a an 80 mile road ride to help “seat in” the 150mm front brake of our bearing-aligned hub.  After this seating, we found the perfectly trued 150mm SLS brake to be within a hairs-breath as good as our old CB450 DLS brake.  The only downside was that it faded slightly if we did repeated high-speed to first-gear stops (that do not exist on any track).  At the very tight and technical Miller Motorsports track, our 220lb rider never experienced the feeling of “running out of brakes”.  The biggest difference was the increased use of the rear brake.  With our big 200mm DLS Honda brake, we used the rear brake only for trail-braking purposes.  With the upgraded stock SLS brake, the rear brake needed to be used as a true stopping force during high-speed to low-speed stops.  One unexpected advantage of the SLS front brake was safer braking into turns.  The old 200mm DLS brake was so “touchy”, that there was a risk of locking the front wheel if the brake was used heavily entering a high speed turn.  The less violent grip of the SLS brake allowed for full grip front braking deep into the turns with a nearly non-existent risk of locking the front wheel.  All in all, the AHRMA rule did not change the braking force of our Bighorn…. It just made that braking force much more expensive (in shop time) to achieve.  For those that do not have the equipment to do this front brake mod, Klemm Vintage offers this service."




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« Last Edit: Jun 03, 2015, 07:14:57 by Texasstar »
It's an optimization exercise and not a maximization trip.-Teazer


And though she be but little, she is fierce - WS
http://zoomwithzeke.com/
Third Times a Charm cb175
http://www.dotheton.com/forum/index.php?topic=66169.0

Honda Cb175 Victoria!

www.dotheton.com/forum/index.php?topic=52299.0

Honda Cb200 Lucky!
http://www.dotheton.com/forum/index.php?topic=45872.0

Bultaco El Montadero 360

http://www.dotheton.com/forum/index.php?topic=64349.0

Offline Texasstar

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Re: Third Times a Charm CB175
« Reply #24 on: Jun 03, 2015, 07:05:07 »
Their milled fins or louvers for a vintage brake look fascinating. 


Sent from my iPad using Tapatalk
It's an optimization exercise and not a maximization trip.-Teazer


And though she be but little, she is fierce - WS
http://zoomwithzeke.com/
Third Times a Charm cb175
http://www.dotheton.com/forum/index.php?topic=66169.0

Honda Cb175 Victoria!

www.dotheton.com/forum/index.php?topic=52299.0

Honda Cb200 Lucky!
http://www.dotheton.com/forum/index.php?topic=45872.0

Bultaco El Montadero 360

http://www.dotheton.com/forum/index.php?topic=64349.0

Offline teazer

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Re: Third Times a Charm CB175
« Reply #25 on: Jun 04, 2015, 10:15:35 »
Nice article but they are not correct about the bearing spacer.  Honda hubs have one bearing positively located and if the drum did expand, the other side bearing might move slightly but not by much and it's not as if the hub walks from side to side.

The spacer should be "slightly" longer than the gap for the OD so that the side thrusts are all on the centers.  How much longer?  probably 10 thou or so but a little more is not a problem.  If a wheel is made in a way that neither bearing is positively located it will take more effort to perfect it. Check the design. 

If they laced the wheel and trued it in a stand with an axle in it, the rim would still be concentric to the bearings and only the drum surface needs to be machined to get that right.  They are right that a well set up brake works much better than a stock brake and there is no reason for a brake to be grabby unless they used "green" linings.  Some combinations of drum material, brake geometry and brake compound are a bit touchy and on a light bike that can be problematic for sure.

Offline teazer

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Re: Third Times a Charm CB175
« Reply #26 on: Jun 04, 2015, 10:16:23 »
Their milled fins or louvers for a vintage brake look fascinating. 



Agreed.  That's interesting looking.


Offline Texasstar

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Re: Third Times a Charm CB175
« Reply #27 on: Jun 04, 2015, 10:31:34 »

Nice article but they are not correct about the bearing spacer.  Honda hubs have one bearing positively located and if the drum did expand, the other side bearing might move slightly but not by much and it's not as if the hub walks from side to side.

The spacer should be "slightly" longer than the gap for the OD so that the side thrusts are all on the centers.  How much longer?  probably 10 thou or so but a little more is not a problem.  If a wheel is made in a way that neither bearing is positively located it will take more effort to perfect it. Check the design. 

If they laced the wheel and trued it in a stand with an axle in it, the rim would still be concentric to the bearings and only the drum surface needs to be machined to get that right.  They are right that a well set up brake works much better than a stock brake and there is no reason for a brake to be grabby unless they used "green" linings.  Some combinations of drum material, brake geometry and brake compound are a bit touchy and on a light bike that can be problematic for sure.
whooo so glad we have Honda's. How would you check to make sure the bearing chases are concentric to each other and the hub?


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It's an optimization exercise and not a maximization trip.-Teazer


And though she be but little, she is fierce - WS
http://zoomwithzeke.com/
Third Times a Charm cb175
http://www.dotheton.com/forum/index.php?topic=66169.0

Honda Cb175 Victoria!

www.dotheton.com/forum/index.php?topic=52299.0

Honda Cb200 Lucky!
http://www.dotheton.com/forum/index.php?topic=45872.0

Bultaco El Montadero 360

http://www.dotheton.com/forum/index.php?topic=64349.0

Offline teazer

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Re: Third Times a Charm CB175
« Reply #28 on: Jun 04, 2015, 21:25:44 »
That's easy. 

Rule #1: Bearings are the baseline - the datum.  They are perfect wherever they are.  It's the drum that's potentially out of concentricity and needs to be turned. 

Rule #2: If the bearings are in the wrong place relative to the drum, see rule #1  :-)

How did they true a rim relative to the axle and it's out of round in a lathe?  Because either the rim wasn't true or they held the hub in the lathe not by the center (the bearings)

I may be missing something but I don't think so.  This stuff is not rocket science.

Offline Texasstar

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Re: Third Times a Charm CB175
« Reply #29 on: Jun 08, 2015, 07:24:12 »
Doing our layout for the trapezoids. Mom made us a template with drill guides. The plan is to drill the corners then cut it out with a jigsaw. We have scribed lower and upper radii for the top and bottom of the trapezoids.
It's an optimization exercise and not a maximization trip.-Teazer


And though she be but little, she is fierce - WS
http://zoomwithzeke.com/
Third Times a Charm cb175
http://www.dotheton.com/forum/index.php?topic=66169.0

Honda Cb175 Victoria!

www.dotheton.com/forum/index.php?topic=52299.0

Honda Cb200 Lucky!
http://www.dotheton.com/forum/index.php?topic=45872.0

Bultaco El Montadero 360

http://www.dotheton.com/forum/index.php?topic=64349.0