chassis differences - early to late CMF?

[OhioTed]

Could anyone comment on the chassis differences between early 70's CMF bikes ("standard-mount" shocks), and late-CMF (74.5/75, lay-down shocks)?

From memories of my '75 Hare Scrambler, I am familiar with the beef-ed frame rail, where the upper shock mounts are.  How about the rest of the frame?  

Would it be a direct "swap-out" to apply early-CMF engine/suspension/tank/airbox/etc to a later, lay-down-shock frame?

[Paul Danik]

Ted,

     I think the correct answer is, yes and no... Would most everything bolt on, pretty much yes, but there are a few different components on the later machine. I am assuming that you just want to build a bike that would be a little better rider than the earlier model. If you are just doing a swap out for a better rider, the area that would concern me most is the suspension. You would most likely want to use the longer 35mm forks and the shocks would need some consideration. The more I think about this I am also curious about the airbox?

   Do you have both the later model frame and swingarm?

Check out these two machines from the 40/10 event.
http://www.pentonusa.org/GalleryServerPro/default.aspx?moid=1829&hr=1

When I get the other lane plowed out I will take a closer look and see if I notice any other issues, maybe Randy can chime in, he has his fine example at a number of POG events.  I think his is one of the ones in the picture.

Hope this helps.
Paul

[Gary Roach]

Ted,

Are you talking about frames with Sachs motors or KTM motors?

On the the later model frames with KTM motors, they do have a different airbox. On the later model airbox, everything above the chain is cut off. The reason why is, the later model frame has longer rear wheel travel, so the airbox had to be redesigned for more chain clearance.


Gary

[marsattacks]

nd Ted might not be including CMF non-hi breathers, but they are CMF too and there are sidestand, brake and gas tank differences for them, no?  So what I'm suggesting is at least three? eras of CMF frame development from 72 to 75/76.

[OhioTed]

Thank you for the responses, guys.  Paul's suggestion is correct - I am looking to update an early CMF/KTM-engined Penton for improved riding performance.  

However, considering that in addition to the frame itself, shocks, forks, triple clamps and airbox would all have to be changed as well, looks like a long way around.

[Paul Danik]

Ted,

   I was thinking you were using a Sachs powered donor machine and swapping into one of the 74 1/2 frames with angled shocks that was set up for the Sachs engine. Judy always says I hear what I want and not what I am told[8D]

Paul