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Author Topic: 75 CB360 - bad omen "yatagarasu" build  (Read 39022 times)

Offline MiniatureNinja

  • Posts: 521
Re: 75 CB360 - bad omen "yatagarasu" build
« Reply #120 on: Mar 19, 2018, 18:09:34 »
cut down the instrument mounts off the top triple clamp. probably will finish this a little nicer - but I would eventually like to get a Ripple Rock dropped triple kit just not liking the $700 price tag right now

I am undecided about shaving down the bar mount holes as well - not that I will use them for anything. just more work

« Last Edit: Mar 19, 2018, 19:06:06 by MiniatureNinja »
'75 Honda CB360 - thread

Offline crazypj

  • Posts: 13446
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Re: 75 CB360 - bad omen "yatagarasu" build
« Reply #121 on: Mar 20, 2018, 20:55:47 »
Almost forgot, remember to soak the friction plates in the engine oil your going to use for 24 hrs or so. I used to 'wet' them and then put the set in a freezer bag (uses less oil plus keeps the dust off)
That's really nice yoke set but $700.00 is way too much for me (seems pretty expensive  anyway) Of course, you have to start with some very large (expensive) chunks of alloy to be able to whittle down to correct size and shape. Haven't priced 2" thick 6061 for years, it put me off making them though. I've seen a few CB550 and 750's where the holes were plugged and welded then carved down to give a 'factory race shop' look but never on 350/360
« Last Edit: Mar 20, 2018, 20:57:22 by crazypj »
'you can take my word for it or argue until you find out I'm right'
Best thing I ever overheard
"yep, PJ's my boss, he taught me everything I know, just didn't teach me everything he knows"
Brian Morgan, 1982

CB360's,  http://www.dotheton.com/forum/index.php?topic=11736.0
XS650,  http://www.dotheton.com/forum/index.php?topic=11922.0

Offline MiniatureNinja

  • Posts: 521
Re: 75 CB360 - bad omen "yatagarasu" build
« Reply #122 on: Mar 23, 2018, 00:14:17 »
Almost forgot, remember to soak the friction plates in the engine oil your going to use for 24 hrs or so. I used to 'wet' them and then put the set in a freezer bag (uses less oil plus keeps the dust off)
That's really nice yoke set but $700.00 is way too much for me (seems pretty expensive  anyway) Of course, you have to start with some very large (expensive) chunks of alloy to be able to whittle down to correct size and shape. Haven't priced 2" thick 6061 for years, it put me off making them though. I've seen a few CB550 and 750's where the holes were plugged and welded then carved down to give a 'factory race shop' look but never on 350/360

it will be almost a month before I'm ready for the assembly phase. I remember from the manual that the plates should be soaked for a minimum 1 hour. but I figured overnight wouldn't hurt it

now, I worked late into the night welding, and I'm not very good at it but I am proud of what I have accomplished


The bracket for the under seat electronics and battery tray, still needs holes drilled - spacers made of carbon fiber will have the tray sitting about 10mm below the frame


here is the tab for the front brake cable. Master cylinder will bolt onto a bracket utilizing the original coil mount holes - non-standard coils will be mounted lower probably where the keyswitch/horn mount holes are - again, hole needs drilled and tapped for cable adjuster


and the pièce de résistance: shock mount tabs and frame hoop FINALLY all welded up and square. this was much more difficult than I thought it would be but in the end it turned out great and I don't recommend anyone do it. it was probably completely unnecessary and a pain in the ass - shock mount slugs still need to be welded, once swing arm is done and mounted so I can figure out how long they need to be
'75 Honda CB360 - thread

Offline crazypj

  • Posts: 13446
  • Split personality, I fake being smart
Re: 75 CB360 - bad omen "yatagarasu" build
« Reply #123 on: Mar 23, 2018, 11:00:43 »
Rear shock mounts are really bad.
You should not have the corner welded it creates a stress point. (I tried to point it out earlier) You may be able to drill a hole in corner to 'convert' it to a buttress? All ther stress is now going into centre of tube.
Find Tony Foals book on chassis design, the relevant pages are available online and maybe on his site? (may also be on, Euro Spares Michael Moore's site?)
I looked it up
http://www.eurospares.com/frame.htm
'you can take my word for it or argue until you find out I'm right'
Best thing I ever overheard
"yep, PJ's my boss, he taught me everything I know, just didn't teach me everything he knows"
Brian Morgan, 1982

CB360's,  http://www.dotheton.com/forum/index.php?topic=11736.0
XS650,  http://www.dotheton.com/forum/index.php?topic=11922.0

Offline MiniatureNinja

  • Posts: 521
Re: 75 CB360 - bad omen "yatagarasu" build
« Reply #124 on: Mar 23, 2018, 14:51:37 »
Rear shock mounts are really bad.
You should not have the corner welded it creates a stress point. (I tried to point it out earlier) You may be able to drill a hole in corner to 'convert' it to a buttress? All ther stress is now going into centre of tube.
Find Tony Foals book on chassis design, the relevant pages are available online and maybe on his site? (may also be on, Euro Spares Michael Moore's site?)
I looked it up
http://www.eurospares.com/frame.htm

I won't argue with you - you've been doing this much longer. I will have to look further into it.

I did read through Toney Foals frame mods page and it covered folded gussets and a way to stiffen the frame and basically said that triangle gussets as mounts have very little effect - I brought your point up to a fab shop (they don't do motorcycles, but they build offroad buggies and race trucks) and they said that amount of flex there will be near non-existent because anything behind that triangle bears no load, none - not even a tail lamp will be there

I pulled some inspiration from a DCC build, and This Build which both seam to have done the same thing I have
« Last Edit: Mar 23, 2018, 15:36:05 by MiniatureNinja »
'75 Honda CB360 - thread

Offline crazypj

  • Posts: 13446
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Re: 75 CB360 - bad omen "yatagarasu" build
« Reply #125 on: Mar 23, 2018, 18:47:17 »
If you really look close at the 'Sausage' (trust me, the original 'Savage' badge didn't look like 'savage')
Anyway, if you look close you can see the triangle is on the outside centre line of tube plus looks a lot like the original. You buggy builders are doing whats cheap rather than right. Any suspension mount is a high load area, you also have torque twisting the plate and 'flexing' weld as it's going to be offset. Correct thing to do would be make 4 plates total, weld them on the outside center of tube then have a bar to mount shock.Moving the mount inwards about 1" will also put them at an angle they won't like, the rubbers will be at or above maximum flex (unless you move lower mounts inwards or use Heim joints both ends of shock body to compensate for the angle)
 I think Husqvarnan MX/Enduro bikes used that type of mount to narrow seating area, probably around 1980?
 It will work as is but is highly likely to fail in use.
More bad news,
Diaphragm is damaged, looks like a screwdriver mark where someone tried to pry top off carb or something?
third pic is of JBM diaphragm, still trying to get a new one under guarantee. I've never had one break before but looks like the 'guarantee' is 'your SOL buy another one' so I'm no longer recommending them
« Last Edit: Mar 23, 2018, 21:27:02 by crazypj »
'you can take my word for it or argue until you find out I'm right'
Best thing I ever overheard
"yep, PJ's my boss, he taught me everything I know, just didn't teach me everything he knows"
Brian Morgan, 1982

CB360's,  http://www.dotheton.com/forum/index.php?topic=11736.0
XS650,  http://www.dotheton.com/forum/index.php?topic=11922.0

Offline MiniatureNinja

  • Posts: 521
Re: 75 CB360 - bad omen "yatagarasu" build
« Reply #126 on: Mar 23, 2018, 18:59:28 »
I have some turned mounts for the shocks, that stick out about 18mm, the shocks won't be at an angle - they will be straight as they are supposed to. Also, the mounts are not on the center of the tube, they are about 3/4 the way to the outside on the top tube, and cross the center line for the down tubes (since they are at a weird angle)

I brought this up in my post while mocking it up, that I was considering using 4 plates on the outside of the frame how you describe, but decided against it as I saw 10 builds the way I have done it, and only 1 the way you described. TC bros, Dime City Cycles, Cognito Moto all have "kits" that do it this way, and i called Cognito, they assured me it was plenty strong for a bike shock mount. if it were indeed a gusset on a frame for strength or a car - things would be different


I very much appretiate your input and I am not dissagreing or discounting it. We've talked about "experts" before that steer people in the wrong direction and I know you're not one of them. i just feel confident in what i've done so far. If it turns out to be a problem (and it will be monitored) then I can always redo it... it's just metal
« Last Edit: Mar 23, 2018, 19:03:08 by MiniatureNinja »
'75 Honda CB360 - thread

Online irk miller

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Re: 75 CB360 - bad omen "yatagarasu" build
« Reply #127 on: Mar 23, 2018, 19:20:59 »
You buggy builders are doing whats cheap rather than right.

I'm not arguing whether his bracket is right, but those guys are building rigs that go through a helluva lot more intense abuse than what we will ever throw at these motorcycles.  And they cost into 6 digits.  I trust those guys.

Offline MiniatureNinja

  • Posts: 521
Re: 75 CB360 - bad omen "yatagarasu" build
« Reply #128 on: Mar 23, 2018, 19:32:02 »
I'm not arguing whether his bracket is right, but those guys are building rigs that go through a helluva lot more intense abuse than what we will ever throw at these motorcycles.  And they cost into 6 digits.  I trust those guys.

I was doubting what I did - and I brought my frame into them, wasn't just a phone call too.

still doubting it when someone is so adamant about it.  :-[
'75 Honda CB360 - thread

Offline crazypj

  • Posts: 13446
  • Split personality, I fake being smart
Re: 75 CB360 - bad omen "yatagarasu" build
« Reply #129 on: Mar 23, 2018, 21:36:58 »
I use CAD, (cardboard aided design ;D )
I'll draw a picture as it's way faster than trying to explain and quicker than a computer 'drawing' .
What thickness plate did you use? (1/8", 1/4"?)
Here's a very basic pic of what you have and what you sould have. The right side (IIRC) is about 4 times stronger but requires more welding plus is a little more than half the weight of a single 1/8" plate but lighter and stronger than 1/4" plate. Frame tubes share the stress on each side instead of all the stress on the centerline one side. (the extra lines are to represent the  down tube, left it out on right side drawing)  It's a quick sketch so I didn't label all the 'movement' arrows


I'm not arguing whether his bracket is right, but those guys are building rigs that go through a helluva lot more intense abuse than what we will ever throw at these motorcycles.  And they cost into 6 digits.  I trust those guys.
I would like to see some pictures of what they actually build, 1/4" wall thickness pipe would be lot stronger than the 0.080" frame tube Honda use. Lot of people will tell you one thing but actually do something completely different.  If they don't have a structural engineer or at least copy design that has been through 'the math' they could be just jumping on a band-waggon with no real idea what they are doing.
The welds themselves don't look too hot for a 'professional' welder.
 I've seen better from people with zero welding experience after a 3 hr course (yea, I was certified MIG at one time, many  many years ago)
« Last Edit: Mar 23, 2018, 22:47:33 by crazypj »
'you can take my word for it or argue until you find out I'm right'
Best thing I ever overheard
"yep, PJ's my boss, he taught me everything I know, just didn't teach me everything he knows"
Brian Morgan, 1982

CB360's,  http://www.dotheton.com/forum/index.php?topic=11736.0
XS650,  http://www.dotheton.com/forum/index.php?topic=11922.0