Honda CB750 Sandcast

Sandcast Frame differences vs. K0 Frame

Joe K · 9 · 5748

Joe K

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Does anyone know any noted differences between the sandcast and K0 frames? Other than some having the left mounted horn.


kp

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The only difference I know of is this gusset fitted to the early sandcast frames. What it's for is anyone's guess  ;) KP

Yabba Dabba KP


Steve Swan

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I've compared the early sandcast steering heads to the later sand cast heads as well as post-7414 frames and there are differences, but i cannot remember them, there is a difference in the divots and recesses as i recall.

I have not had the good fortune to have these different types of bare frames all lined up in a row to be able to go back and forth to make first hand comparison observations.

If Chris Rushton sees this post, i am sure he will know steering head differences, he pretty much has a memory like a steel trap.

Just looking at the picture you provided, KP, i cannot say what specific differences there are between early, middle and late steering heads, but obviously you have a picture of an early LH horn mount steering head with the steering damper gussets and like i noted in my most recent post, there are LH horn mount frames without this steering damper gusseting.

I do know these early and later frames have differences in their steering head's gussets, divots and recesses.

As far as other frame differences, I do know and I will say the gussets on the rear section of the frame for the posts of the upper shock mounts, this gusseting is shorter on the sandcast frames than on vin frames somewhere after 7414. Also, the weld beads are not as heavy nor as smooth as later frames.

And I will say the welded seams of early sandcast frames on the two stamped halves of the rear frame to engine mounts (in the swing arm area) are not as tall as later sandcast frames.

The swedged/spot welded sections of the frame where the front down tubes fit into the steering head are less finished, more pronounced, than later sandcast frames.

Overall, the welds on the early sandcast frames are not as clean as welds on later sandcast frames.

I have never had the opportunity of having these different bare frames sitting side by side to account for the differences, this is the only way one could be sure of the differences is to have the frames sitting side by side for comparison.

Seems there are 3 different types of sandcast frames.

1. Early LH horn mount with steering damper gussets.
2. Later LH horn mount *without* steering damper gussets.
3. RH horn mount w/o steering head gussets.



hondasan

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Other than the gusset under the steering head, and Lh / RH horn mounts, the other areas of difference that I am aware of are:
- the way that the frame downtubes are attached to the corresponding "sockets" that come down from the steering head changes in appearance during the sandcast run - I believe that there is more weld used on the earlier sandcast frames frames.
- The profile of the flattened section of frame at the rear of the
airbox changes between early and late sandcast frames.
- The frame gussets at the rear shock mounts were extended in length to address the problem of the rear seat loop section of frame snapping off (a particular problem with overloaded carriers fitted, or overweight passengers!). I believe this change occurred fairly late in the K0 run though.

And no doubt variations in pressing shape and weld detail as production evolved as commented by Steve Swan.

Another subject that pictures would help with, but no room inside for that, and too cold outside in the middle of a UK winter  :-[ :-[
 

Hope you all have agreat New Year - Chris R.
Chris R.
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Joe K

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I am curious to know if the sandcast or K0 frames have the metal clip helmet holders on them. My sandcast frame does not show them so I don't know if they were cut off or never part of the original. Please let me know if you have them or not.

Thank you,
Joe


cb7504

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Joe:
The helmet holder bracket started on the CB750 K2. Marty K


Joe K

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OK, thank you, Marty. Then that explains why my frames don't have them. I wasn't sure if they cut them off or not.


tomcourtney

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Bob and i were comparing my sandcast frame beside a late K0 and noticed the Triangular reinforcing on the top rails behind the coils is much thicker on the early frame TC
I sold my first Sandcast and regretted it till I bought it back 6958/7149, its taken a few years to get a couple more 6946/7169, and 6970/E6956