Correct Mid-Year Clutch Cross-shaft??

[Joe R.]

Re: Looks like the '63-65 SB shaft

Hi Wayne:

One thing that's interesting about this is whether one of these configurations has any inherent advantage in terms of the mechanical advantage for pedal effort. Maybe the design had to be "de-optimized" when it was modified to accomodate the big block application.

I think I would have to see the complete installation in both configurations in order to evaluate any net difference in the mechanical advantage that the configurations implement. It seems too complicated to visualize by just looking at drawings.

[Tracy C.]

OK...lemme get this straight.

This is great discussion guys, except now I'm confident I have the wrong part for my 63. I have either the 65-66 Big Block or the 67 and later configuration.

From what I've gathered, the only difference between these two is an angular separaration difference of approximately 3 degrees.

Is this correct?

tc

[Tracy C.]

Re: OK...lemme get this straight.... addendum

How about the finish? My part looks to have a black oxide finish NOT zinc or cad.

tc

[Dwight P.]

Re: OK...lemme get this straight.... addendum

Tracy:
The 65 Judging Manual clearly states that all crossshafts (SB & BB) are zinc or cad plated. I have spent many hours searching ads and ebay for good used ones and never heard of a mid-year cross-shaft that had a black oxide finish.
Perhaps some of the other guys that have the 64,66, and 67 Judging Manuals will chime in.

DP

[John H.]

Re: Looks like the '63-65 SB shaft

Wayne -

On the 3888279 cross shaft, the measurement from the shaft centerline to the pushrod hole centerlines is 4-1/4" for the short arm and 4-3/4" for the long arm.

[Joe R.]

My attempt at a summary - please verify

Wayne, John, and Joe Lucia:

I just re-read this entire thread and I have attempted to summarize things as follows. Please correct me if anything looks wrong:

63-66 SB
part number 3832857
135 degree arm separation angle
4.65/4.0 inch arm lengths, center-to-center

65-66 BB
part number 3872962
155 degree arm separation angle
4.65/4.0 inch arm lengths, center-to-center

67-72 ALL
part number 3888279
155 degree arm separation angle
4.75/4.25 inch arm lengths, center-to-center

Based on reading the thread, the parameter that I am least certain about is the length of the arms. However, one thing I had been wondering about was the difference between the 65-66 BB and the 67+ designs. Perhaps the difference is in the length of the arms, since the angle seems to be the same.

The difference stated above is so slight that I think it would be very difficult to tell the two versions apart if you just picked one up at a swap meet and looked at it.

[Wayne M.]

Sounds good to me

was always wondering what the differences were. And the 3888279 had to have SOME difference because the identical angle (within measuring error) would not have required another design.

[John H.]

Re: My attempt at a summary - please verify

Joe -

Squares with my notes.

[Tracy C.]

Re: My attempt at a summary - please verify

Were all these finished with zink or cad or was the 67 and later part eventually changed to something else?

tc

[John H.]

Re: My attempt at a summary - please verify

Tracy -

The '67 shaft was zinc-plated; don't know about later years.

[Terry M.]

Re: My attempt at a summary - please verify

I know it is a little OT, but 1968-1973 was also zinc plated.