Author Topic: New (to me!) '77 CB400F - US model  (Read 38190 times)

Offline mattsz

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Re: New (to me!) '77 CB400F - US model
« Reply #255 on: July 19, 2019, 11:13:22 PM »
The "Opening Up" of the slot is a fairly common thing to see but with that and wear on the frame lug you get too much "slop" I have before now carefully straightened the stand for and put a shim washer under the bolt head to keep it tighter.

Thanks Bryan!  A shim between the bolt head and stand, or inside the slot next to the frame lug?  Not sure what a washer next to the bolt head would accomplish if the tangs (is this the correct word?) on the stand are straight and parallel.

I imagine a fair amount of heat would be required for straightening?  Would a propane torch be enough, or are we talking about something stronger, like acetylene?

Offline Bryanj

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Re: New (to me!) '77 CB400F - US model
« Reply #256 on: July 20, 2019, 08:55:22 AM »
Its been a few years since i did one but memory tells me the thread tightens up to a shoulder on the bolt so the bolt does not "squeeze" the fork tight. This means a shim between bolt head and outside of stand will stop it opening up again.
Propane should be hot enough.

Offline mattsz

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Re: New (to me!) '77 CB400F - US model
« Reply #257 on: July 20, 2019, 11:39:49 AM »
Its been a few years since i did one but memory tells me the thread tightens up to a shoulder on the bolt so the bolt does not "squeeze" the fork tight. This means a shim between bolt head and outside of stand will stop it opening up again.
Propane should be hot enough.

Ah-so, now I see what you're saying!  That makes sense.  What makes less sense to me is, when this bolt is installed, there's more threads sticking out the inner tang of the stand than are in contact with the tang itself.  Makes me wonder if it's the correct bolt after all..

EDIT: belay my last - I see now that there's missing nut to go along with that bolt...
« Last Edit: July 20, 2019, 11:44:40 AM by mattsz »

Offline mattsz

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Re: New (to me!) '77 CB400F - US model
« Reply #258 on: July 21, 2019, 08:17:56 PM »
The "Opening Up" of the slot is a fairly common thing to see but with that and wear on the frame lug you get too much "slop" I have before now carefully straightened the stand for and put a shim washer under the bolt head to keep it tighter.

In case you guys haven't figured this out by now, I'm new to this stuff.  I'm visualizing straightening the bent tang with a big hammer, or closing it in a vise, and imagining having it bend at the base where it joins the stand, rather than out near the end where it bent in the first place, so it's still bent outwards at the hole but won't fit back over the frame lug.  I was thinking that finding some kind of frame-tang-width spacer to insert in the gap while straightening the tang would save me from bending any part of it back too far - but then, I imagine that some spring-back would occur and a spacer would prevent getting it straight at all.

What's the best way to approach this?  Heat and a big hammer?  Heat and slow pressure in a vise?

Offline K2-K6

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Re: New (to me!) '77 CB400F - US model
« Reply #259 on: July 21, 2019, 09:23:49 PM »
Agree with Bryan assessment of spacing etc.

Also think your assessment of correction is bang on the money regarding how it's going to go back.

It looks like it's bent from the edge of the hole nearest the blind end of the fork outwards from there ,  but as you suspect,  I think just squeezed back with no support will result in bending at the root of the fork if not supported.

I'd go with a support internally from blind end to start of hole. Then heat the bolt head side directly,  and squeeze it inwards with "vice" grip type tool as you can set it to not pinch too far.

If not hot enough it will spring back,  you'll feel it yeald if temp is high enough and it'll stay put like that.

It's the pointed blue tip in a flame that's hottest,  get that point just touching the surface and it should get to traffic light red which will signal it's hot enough to yeald.

Offline mattsz

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Re: New (to me!) '77 CB400F - US model
« Reply #260 on: July 21, 2019, 09:38:15 PM »
Thanks for that advice, K2-K6!  I think I'll take it to work and rummage through our remarkable collection of random, odd-sized fasteners and find one with a non-threaded shank that's as close in diameter to the thickness of the frame lug that I can find.  Think something round that just fits in the gap at the root would do the job?

Offline K2-K6

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Re: New (to me!) '77 CB400F - US model
« Reply #261 on: July 21, 2019, 09:42:58 PM »
I think it should do,  it's just trying to stop the force all concentrating on that sharp internal corner where it naturally wants to go.

Offline mattsz

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Re: New (to me!) '77 CB400F - US model
« Reply #262 on: July 21, 2019, 09:45:18 PM »
I think it should do,  it's just trying to stop the force all concentrating on that sharp internal corner where it naturally wants to go.


Offline mattsz

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Re: New (to me!) '77 CB400F - US model
« Reply #263 on: July 23, 2019, 01:17:09 PM »
Just to give you guys an idea of where my head is with this project right now... I was about to ask a cam chain question that was already discussed awhile back on this very thread.  I just noticed that I've twice - on this very same page, even - brought to your attention my thought that the bike might have fallen or been in an accident.  Sorry... :-[

Offline taysidedragon

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Re: New (to me!) '77 CB400F - US model
« Reply #264 on: July 23, 2019, 07:35:02 PM »
Just to give you guys an idea of where my head is with this project right now... I was about to ask a cam chain question that was already discussed awhile back on this very thread.  I just noticed that I've twice - on this very same page, even - brought to your attention my thought that the bike might have fallen or been in an accident.  Sorry... :-[

No problem,  with a gear lever that shape there is no doubt!
Gareth

1977 CB400F
1965 T100SS

Offline mattsz

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Re: New (to me!) '77 CB400F - US model
« Reply #265 on: July 24, 2019, 01:15:58 AM »
Thanks taysidedragon - I'm mostly just embarrassed by how flaky I'm being about all this.  But it's been a crazy, stressful year and my moto interests have taken a distant back seat.

I'm not sure how I'd straighten that shift lever's twist - a replacement may just be a few dollars away...

https://4into1.com/gear-shift-lever-short-cb-cl-sl-xl100-125-200-250-350-500-cb500-550-650-750/


Offline taysidedragon

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Re: New (to me!) '77 CB400F - US model
« Reply #266 on: July 24, 2019, 11:17:26 AM »
If that lever is cheap I would buy it, otherwise fix the old one. A bit of heat and a vice should straighten it, fit a new rubber and it's done.  🔧👍
Gareth

1977 CB400F
1965 T100SS

Offline mattsz

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Re: New (to me!) '77 CB400F - US model
« Reply #267 on: July 24, 2019, 11:43:30 AM »
If that lever is cheap I would buy it, otherwise fix the old one. A bit of heat and a vice should straighten it, fit a new rubber and it's done.  🔧👍

It's "only" US$12 (plus shipping, but I was thinking of buying new brake hoses from them anyway).  But, as I'm already going to be working on the side stand with heat and a vise (and probably plenty of vice, too  ;) ), I might as well try the shift lever, too.  Worst case, I destroy it and I'm buying the new one anyway...
« Last Edit: July 24, 2019, 11:45:51 AM by mattsz »

Offline mattsz

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Re: New (to me!) '77 CB400F - US model
« Reply #268 on: July 27, 2019, 03:11:18 PM »
My ignorance rears its ugly head yet again: regarding using heat to straighten the bent steel side stand and shift lever - should I quench the heated area once I’m done working it to cool it quickly, or should I let it cool down in the air, in its own time?

Offline Moorey

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Re: New (to me!) '77 CB400F - US model
« Reply #269 on: July 27, 2019, 03:38:18 PM »
I wouldn't quench as it could make it brittle depending on the steel. The worst that will happen with normalizing is it will slowly bend again over time as it has done now..

 

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