C2: 66 Z-bar/clutch cross shaft part number?

[Gary B.]

Can anyone tell me the difference between two part numbers that are supposed to correspond to the 66 small block Z-bar. One number is 3888279; the other is 3832857. Is one the production part number and the other a service replacement part number?

Thanks in advance,

Gary

[Joe L.]

Re: C2: 66 Z-bar/clutch cross shaft part number?

Gary------

No, both lever assemblies were used in PRODUCTION. The GM #3832857 was used for 1963 through early 1966 Corvettes with small block engines. The GM #3888279 was used for later 1966 with small block engines and ALL 1967-81 Corvettes with manual transmission.

The difference between the two? There is a very slight difference in the angular relationship between the two levers attached to the cross shaft. Why? I do not know. All of the cross shafts are GM-discontinued, but available in reproduction.

I SUSPECT that the several subtley different clutch cross shafts and linkages used over the 63-81 period had something to do with the problem with getting the finicky Corvette clutch adjusted properly. Beginning with the 67+ configuration, they just gave up, even though they still didn't have it exactly right.

[Gary B.]

Thanks Joe. *NM*

[Geoff C.]

Re: C2: 66 Z-bar/clutch cross shaft part number?

They are also available NOS

[Joe L.]

Re: C2: 66 Z-bar/clutch cross shaft part number?

Geoffrey-----

I should have known. I neglected to check my reference manual for that possibility.

[Gary B.]

Re: Joe, are the differences easily detectable?

Joe,

Are the differences between the 3832857 and 3888279 shafts easily detectable? Would I be able to tell which shaft I have on my car now based on some angle measurement? Since my car has a July 66 build date, it sounds like I should have the 3888279 version. Is that your understanding as well? Did the clutch work any better in your opinion with the latter version?

Thanks,

Gary

[Joe L.]

Re: Joe, are the differences easily detectable?

Gary-----

I don't think that you'd be able to tell them apart unless you had known-originals of either part number to compare them to. Like I say, the differences are rather subtle. I don't have the part specs so I can't otherwise tell you how to "quantify" the differences.

I feel very confident that your car was built with the 3888279 cross shaft assembly. Presumably, the 3888279 was an improvement over the earlier shaft and actuation "system". So, I would expect it to "work better", but I don't know anything more about it than that.

There is another factor, though, which might "indirectly" help identify the cross shaft and "indirectly" provide a clue as to what the configuration differences are between the 3832857 and the 3888279. In fact, due to the several different parts that were part of the "clutch actuation system" over the 63-81 period, I'll bet this factor has been the source of much "frustration" for folks trying to put togther clutch linkage systems, especially from "scratch".

Here's the factor: the clutch fork push rod for 64-66 Corvette small blocks using the 3832857 cross shaft assembly was a 10-9/16" overall length rod of GM #3844209. The clutch fork push rod for 66-81 small blocks, 65-66 big blocks, and 67-74 big blocks was an 8-37/64" overall length rod of GM #3872960. (Incidentally, 1965-66 big blocks used a different clutch cross shaft of GM #3872962. This cross shaft is only VERY, VERY slightly different than the 3888279).

The difference in the clutch fork push rod lengths between the rods would imply the difference in the angular relationship between the pedal lever and fork levers on the cross shaft. In fact, using some fancy geometry, it might even be calculable.

[Gary B.]

Joe: Thanks again. I''ll measure my push rod. *NM*