Jared's 1982 CM450C Cafe Project

Brent said:
Jared, with a degree in mechanical engineering I would have thought that the bikes ability to function safely, properly and better then stock would have been your goals. I don't see anything in your thread regarding the bikes geometry and I, like xb33bsa, have real doubts as to whether your mono shock/framing systems are safe. I just don't see the point in putting time and money into something that isn't usable in real world application, but it's not my bike or thread so I'll bow out.

Agreed Brent, thanks for the post. Safety was certainly one of my concerns and goals with this project. Admittedly not an easy or direct solution! I spent about 4 months researching suspension and frame dynamics (resources below) and the final revision of the rear suspension geometry is posted on page 2, from February 2014. Did you look through the whole thread? Here is another picture from my time doing all the research. The supporting calculations I had was enough to fill a file folder, so haven't posted any of that. It's can be nauseating for most people.

I have my safety concerns as well, mentioned above in my reply to XB33bsa. I did have a few other PE (professional) engineers review my designs in detail before executing anything. The main points of focus were the rear shock top mount (size of steel plate, thickness, location along curvature of frame, location width-wise across frame, punching forces into frame, size and length of welds, etc.), and the tubes for the swingarm outboard supports (size of steel tubing, wall thickness, etc.). My friend who has helped me problem solve and build much the bike is a mechanical & structural engineer who designs components for rockets that lauch satellites for Lockheed Martin, Ball Aerospace, etc.

I hope that answers your question(s). Feel free to post any other thoughts on here, I appreciate the discussion!

Suspension design resources:
Race Tech's Motorcycle Suspension Bible
http://www.sportrider.com/more-fun-geometry#ixzz2rvUGrpEB
http://blog.rectorsquid.com/linkage-mechanism-designer-and-simulator/
http://www.carbibles.com/suspension_bible_bikes.html
 

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The cross brace tubes are a nice triangulation touch and the top shock mount is fine in terms of placement etc. What we don't know is how thick the metal is that the brackets are attached to but I would be surprised if that was an issue. The real issue is that the frame has very little lateral rigidity. Some lateral flex is good - too little makes for a bike with no feedback and that's not good.

A more significant issue is the narrow rear pivot and those flattened tubes that are supposed to add stiffness. I am not a fan of flat tubes- they tend to flex and crack and tear. I can't see what the pivot looks like but it might benefit from locking it into the frame more stiffly. XB33 suggested a straight tie in to the steering head and that's always a good thing but not always practical. In this case a wide tube around the motor to the steering head might be the ticket and it would look super trick into the bargain.
 
This build is amazing man. Keep it up!

I have to agree about the welding - good idea to take it to a shop. I think the fact you've been able to do all the fit up yourself and tack everything in place is outstanding. Just that has saved the final welder a crap load of time. Now he'll just be able to run some nice clean (strong/relaible) beads where you want 'em!
 
Yes I read the bit on rear suspension geometry, it was the front I was questioning. Rake, trail, offset.

I think Teazer has touched on the concern expressed by XB and myself regarding flex in the box frame.
 
Brent said:
Yes I read the bit on rear suspension geometry, it was the front I was questioning. Rake, trail, offset.

I think Teazer has touched on the concern expressed by XB and myself regarding flex in the box frame.

Understood, I will have to go back into my research to find out how the front suspension changed. I do have all those numbers in a file somewhere. I'll check it out and get back to you guys.
 
Just picked up some new parts that I've been looking at online for forever...

MAC Exhaust, 2 into 1, black reverse cone
http://www.shop.macperformance.com/CM-HAWK-NIGHTHAWK-400-450_c139.htm;jsessionid=9DA546D000D5C73E436E7314511631CE.p3plqscsfapp006

SpeedMotoCo - headlight & brackets, tach and speedo gauges, Motogadget M-Blaze Pins for front signals, and flasher relays for front and back. Thanks Bryan!
http://www.speedmotoco.com/
 
I got the sub frame back from the welder last week...
 

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That is some pretty damn nice looking work...I think this is going to be a very special special. :D
 
JadusMotorcycleParts said:
Geeze I bet you're stoked! That looks mint. Worth every penny. Mind me asking what the welder charged?

No prob. The welder charged $470ish. I work for a crane, trucking, and machinery moving/installation company, and we haved moved all their big press breaks, CNCs, and other metal working machines for years. So he actually ended up giving me a couple hundred off. It probably would've been over $700 if I didn't know anyone. Alot more expensive that I would've thought, but was worth it for the peace of mind!

Been working on some final assembly and installing steering stem bearings, swinger pivot shaft bearings and seals, final bolts, etc. Glad to be able to sit on it and have it take some weight now.I'll be testing the spring rates, compression, travel, etc. under a variety of loads. Should give me some valuable info on overall suspension dynamics of the bike as a whole. Hope to validate the calculations I did over the last couple winters.
 

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Definitely got a nice robust look to it...is there much difference in the wheelbase?
 
goldy said:
Definitely got a nice robust look to it...is there much difference in the wheelbase?

I would have to look through my suspension geometry notes from a while back. But from what I remember, the new swing arm was only about 3/4" longer than the stock one. But also, the front forks were alot shorter, which shortened the wheelbase. Pretty soon I will be measuring all the as-built dimensions and comnapring them to my ideal/theoretical calculations from a couple years ago. I'll definitely do a full summery here for curious minds!

PS, the really tall guy next to the bike in that last picture is my friend... I am 5'8" and fit much better on this cafe bike than he would!

--
Jared
 
Finished resolving some conflicts with the right rearset, brake master cyclinder, etc., that has been a tough part of the bike. Then did some more body work and sanding on the fiberglass seat, and threw on the carbs and air pods for the picture. Starting to look like a real motorcycle!
 

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Here's some recent progress pictures on the CM450 cafe project... Took about 10-12 months to finalize the 7th or 8th revision of my gauge bracket, but turned out to be perfect. It's one of the reasons this bike has taken so long (4 years + now...), everything has to be perfect!!!
I also fabricated the switch housing for the headlights and blinkers (left handlebar), and worked on some of the wiring. I basically spent all of December writing, re-writing, revising, and double-checking the wiring diagrams. Was daunting at first... I hate electrical stuff. But pretty comfortable with it now. The only way through it, is through it! You might be able to make out the ignition button between the gauges
 

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POST-DATED TO June 7, 2018
I ended up figuring out some wiring issues... I had to scrap that dumb Ultima 'simple wiring module' and go with a standard starter relay. Makes things much more simple!! Was able to get 30amp to the starter motor pretty easily after that.

Since then finished all the miscellaneous wiring stuff, like cutting out, re-routing, and putting in new weather-tight connector plugs for the the CDI and voltage regulator underneath the seat. So here is pictures of all that, plus some painting I was doing yesterday. Painting prep sure is long and laborsome work!!! I put some knee indentions into the seide of the fuel tank, so feathering the body-filler in for that has been pretty difficult. Much more so that the huge dent in the front of the tank. The JB Weld "Steel Stik" is some amazing stuff!!
 

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Hi everyone... looks like I have not posted here in a long time. Been too busy finishing the project, having my first little baby boy, and the wife having a ACL knee surgery... At any rate, here are the last set of progress pictures and final pictures. Got the bike done a few days prior to the 2018 Distinguished Gentlemen's Ride, so that was actually it's maiden voyage. SOOOO MUCH FUN!!!

The paint I chose was "P36", which is from the Mitsubishi Eclipse. The logo was design by myself and a good friend. You you look at the background / border of the Honda wings, you can see my initials "JC" inconspicuously hidden :) The seat upholstry was done by Bitchin' Stitchin' (Lakewood, CO), and was only the second thing I didn't do myself. The other outsourced item being the subframe welding.
 

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