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Author Topic: Jared's 1982 CM450C Cafe Project  (Read 24548 times)

Offline jaredc7

  • Posts: 60
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Re: Jared's 1982 CM450C Cafe Project
« Reply #40 on: Sep 04, 2015, 16:13:25 »
the frame has been welded and ground down on both side in 2 spots each side

near where you put the swingarm if those welds crystallized and or were ground down to much

then the frame is essentially been cut in half 

i would consider jack plating the sides of the frame if not making a wrap around stiffener

I have (3) stiffeners on each side going form the outside of the swing arm pivot to the engine mounts and the rear shock upper mount. They will all be welded to the 1/4" foot control brackets in the last picture above. Should trasfer the shear and torsion loads from the swing arm to all the appropriate strong points on the chassis and engine. I'll post pictures of that installation when we get to that point.
Jared

1982 Honda CM450 C

Offline DohcBikes

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Re: Jared's 1982 CM450C Cafe Project
« Reply #41 on: Sep 04, 2015, 16:23:13 »
Watching. Lots of ingenuity here. You are clearly not done with the frame so it makes no sense to critique that yet. I like it so far.

Are you going to try to match the VFR rear wheel? I love the five spokes, never have been a fan of three spokes.
« Last Edit: Sep 04, 2015, 16:25:12 by DohcBikes »
burning bridges sometimes light the most productive paths

Offline xb33bsa

  • Posts: 7726
Re: Jared's 1982 CM450C Cafe Project
« Reply #42 on: Sep 05, 2015, 08:10:14 »
yeah the frame aint done but you will need some perimeter structure some beams or a lattice work set of structural outer members tying in the outside of the swinger pivot,as well as the motor mounts of course up to the bacbone steering head area  .
longer swinger = much higher loads in the normal direction ie basically the lever of the swingarm is longer so the force trying to get the wheels out of line is a good bit more.the frame as stock had quite a bit of integrated structure to fight this force,the oem ugly ass rear frame that looped around so hideously and triangled into the upper rear backbone ,actually served a very  important  part of this duty,along with the cast alloy mounts.......compounding that issue is now the swinger pivot has huge forces in the more or less vertical plane wheras the stock twin shock lashup had very very little vertical loads at the swinger pivot.
basically if you could have layed the bike frame on its side supported at the contact patch area of the wheels and start stacking weight over the swinger pivot then you can see cleasrly that the frame wants to bend in the middle.same test with the ugly looping rear frame  removed ,or just cut loose from wher it ties in at the backbone, would be quite alarming a rubber band is what it would be like in comparison.
you can hopefully see that a longer swingarm would be resulting in more deflection in this "test"
having the overall frame centerarea weaker or more springy than it was originally is well a mistake.. but then you add in the constant up to well over  a thousand pounds of totally new vertical forces see sawing up and down at the pivot spindle (stock vertical loads were proly a cupl hundred pounds max if that),whilst it is trying to bend sideways at the same time and you might understand why you need more than just side plates
the single forward mounted shock,along with the longer lever  is the culprit directing highly multiplied suspension forces in a vertical plane where there was virtually none before,right smack dab in the middle of your modding

Offline jaredc7

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Re: Jared's 1982 CM450C Cafe Project
« Reply #43 on: Nov 02, 2015, 14:36:06 »
Watching. Lots of ingenuity here. You are clearly not done with the frame so it makes no sense to critique that yet. I like it so far.

Are you going to try to match the VFR rear wheel? I love the five spokes, never have been a fan of three spokes.

Thanks for the feedback DOHCBikes! I made more progress on the frame and chassis stiffeners this past weekend, so you'll at least know my direction. Let me know if you have any questions. Look fowrard to hearing your thoughts.

I'm probably going to keep the rear VFR wheel, I didn't really like how the 3-spoke NT650 Hawk wheel looked. The front wheel (2006 cbr600rr) should be fine, I'm probably not going to switch it out. I do like the 5-spokes much better, but it's not fitting into the budget so far. Plus I thin the front rotors should disguise the 3-spokes, or at least break up any obviousness from it.
Jared

1982 Honda CM450 C

Offline jaredc7

  • Posts: 60
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Re: Jared's 1982 CM450C Cafe Project
« Reply #44 on: Nov 02, 2015, 14:45:00 »
yeah the frame aint done but you will need some perimeter structure some beams or a lattice work set of structural outer members tying in the outside of the swinger pivot,as well as the motor mounts of course up to the bacbone steering head area  .
longer swinger = much higher loads in the normal direction ie basically the lever of the swingarm is longer so the force trying to get the wheels out of line is a good bit more.the frame as stock had quite a bit of integrated structure to fight this force,the oem ugly ass rear frame that looped around so hideously and triangled into the upper rear backbone ,actually served a very  important  part of this duty,along with the cast alloy mounts.......compounding that issue is now the swinger pivot has huge forces in the more or less vertical plane wheras the stock twin shock lashup had very very little vertical loads at the swinger pivot.
basically if you could have layed the bike frame on its side supported at the contact patch area of the wheels and start stacking weight over the swinger pivot then you can see cleasrly that the frame wants to bend in the middle.same test with the ugly looping rear frame  removed ,or just cut loose from wher it ties in at the backbone, would be quite alarming a rubber band is what it would be like in comparison.
you can hopefully see that a longer swingarm would be resulting in more deflection in this "test"
having the overall frame centerarea weaker or more springy than it was originally is well a mistake.. but then you add in the constant up to well over  a thousand pounds of totally new vertical forces see sawing up and down at the pivot spindle (stock vertical loads were proly a cupl hundred pounds max if that),whilst it is trying to bend sideways at the same time and you might understand why you need more than just side plates
the single forward mounted shock,along with the longer lever  is the culprit directing highly multiplied suspension forces in a vertical plane where there was virtually none before,right smack dab in the middle of your modding

Thanks for your feedback XB33BSA, all very good points. I did spend time last couple saturdays looking over the chassis and different ways to strengthen everything. It helps knowing that I won't be very hard on this bike, I have another motorcycle that I can go fast on and beat up.

There is a LOT of things going on around the swinger pivot that I'm trying to resolve. The right side has the rear break master cylinder and foot controls to deal with, and the left side has the chain to dodge with all those supports. Thats the main reason the underneath support on the left side was a chunk of steel flat stock (1/4" x 1") instead of 3/4" tubing like all the others. The left side also has a short tube going into the longer, more vertical tube next to it. Admitedly not the ideal situation, since you really want those forces directed to the centerline of the swinger pivot. But with the chain going right behind all of that, this was really the only option. Also added some stiffener plates on all along both sides the swinger pivot shaft housing.

Thanks again and looking forward to more feedback!
« Last Edit: Nov 02, 2015, 14:51:10 by jaredc7 »
Jared

1982 Honda CM450 C

Offline jaredc7

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Re: Jared's 1982 CM450C Cafe Project
« Reply #45 on: Dec 07, 2015, 20:46:08 »
Here some progress pictures of the subframe cross-bracing for the seat. It was pretty tricky with the coping and the fishmouths, but I got the hang of it after a few trys. I have the advantage of the local steel shops having a "minimum order", so I have about 20-30" feet of tubing left over!
Jared

1982 Honda CM450 C

Offline Letze

  • Posts: 35
Re: Jared's 1982 CM450C Cafe Project
« Reply #46 on: Dec 07, 2015, 23:48:31 »
The CM based builds are the ones surprising me the most lately. Really like the way you're going with this can't wait to see more!

Offline jaredc7

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Re: Jared's 1982 CM450C Cafe Project
« Reply #47 on: Aug 24, 2016, 18:41:58 »
I took another long break from the project this spring and summer, but here are a few progress pics of finishing up the subframe and getting the mold for the fiberglass seat. On the left side, the chain does have full clearance for the full swingarm travel. I had to do some special fabrication for the rear-set supports on that side, but figured it out after some trial and error. I'll get some pics showing the chain location relative to the rearset supports.
Jared

1982 Honda CM450 C

Offline johnu

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Re: Jared's 1982 CM450C Cafe Project
« Reply #48 on: Aug 24, 2016, 21:43:32 »
Jared, this is a great looking bike I love it you are doing awesome work but the seat hump doesn't suit the bike imho.  Not that it matters because as long as you like it that is all that matters.  It just seems like you are trying to utilize an old school cafe racer seat hump on a modern take on a cafe racer.  Please don't be offended that's just my opinion.

Offline jaredc7

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Re: Jared's 1982 CM450C Cafe Project
« Reply #49 on: Aug 25, 2016, 12:56:22 »
Jared, this is a great looking bike I love it you are doing awesome work but the seat hump doesn't suit the bike imho.  Not that it matters because as long as you like it that is all that matters.  It just seems like you are trying to utilize an old school cafe racer seat hump on a modern take on a cafe racer.  Please don't be offended that's just my opinion.


Not offended at all, I always appreciate feedback and the free-flow of thoughts, especially in this strange intersection of art and motorcycles! I was using the article from BIke Exif (http://www.bikeexif.com/build-cafe-racer) as a guide for the visual continuity of the bike as a whole, and specifically, the seat as it relates to the rest of the bike. So this classic cafe seat on the modern take of the cafe racer is actually what I was going for. But to be completely honest, this particular mold was destoyed when I made my first attempt at laying the fiberglass and epoxy resin. So I am actually in the process of re-doing the whole thing...  :o   >:(  :'(

So are you saying that a modernized cafe racer like this should have some type of modern, new, edgy seat style? Maybe you could send me a few picutres of examples over private message? I'm down to consider anything, as I know it will just help me to have the most conviction for the design I finally choose.
Jared

1982 Honda CM450 C