Why did AMC make different chaincases?

[mdt-son]

Hi all,

AMC produced various alloy chaincases, and for the alternator twins and singles, both back half and front half covers differed.

For instance, for the back half, the 1960 G12 has p/n 025019 while G3/G80 has p/n 024152. Yes, different fixing at the engine and maybe a stud in a different position.
They could have changed the engine castings to make them identical, couldn't they?

However, the front half differs as well! The 1960 G12 has p/n 025021 while the G3/G80/G80CS has p/n 024012. Why are they different? At the outset one could think the chaincase for singles would have a shortert shaft-to-shaft distance due to the bigger flywheels, but this appears not to be so. Member Jean-Paul claims that both engine types have an identical shaft-to-shaft distance of 230 mm or 9.00".

While there is a rationale for differing inner chaincases, what's the rationale for differing outer chaincases? I am pondering ... someone out there has an answer, I am sure.

-Knut

[Rob Harknett]

Changes are made with everything.

[1608]

Sophocles couldn't have put it better Rob

[mdt-son]

Rob: WRONG! This wasn't a change but rather a variant running in parallel. The fact that chaincases differ is evident, but where is the illumination content?

1608: It isn't a tragedy that there a variants - unless the company goes bust because they don't know what they are doing. Interesting attempt at bringing greek playhouse dramas into the discussion, but hardly funny.

[Rob Harknett]

I have few bikes with alloy chain cases, so can only guess, any change would need to be made , to improve, or allow other component changes to fit. Even the old tin chain case patanted in 1933 had changes made, sealing rubber and alloy band increased in width at he end of the prewar era, removable clutch cover domes. Also some fitting changes were made. Perhaps some one could mention some of the alloy case changes to look for.