Northwest Nova

1962 - 79 Chevy II - Nova - Acadian
Parts & Accessories
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Clutch Fork Travel Problems???

January 19th, 2020  |  NWN  |  Transmission

Recently ran into this one. Gentleman got his new motor and trans in the car, and while buttoning things up, noticed the clutch fork appeared to have insufficient travel.  Basically, it did not have far to go before hitting the bellhousing. It appeared there would not be sufficient travel to properly engage the clutch bearing.  The correct Chevy II bellhousing, clutch fork and throw-out bearing were confirmed to be present. Everything looked to be the correct parts installed properly. So what gives???

GM used a few different clutch fork balls studs in the classic period and they vary in length. This is not terribly well known and suffers from the usual "they're all the same" ethos.  They are not supposed to interchange, having different pitched mounting stud threads, but that is according to the parts books.  We have seen instances of the wrong one installed, so who knows if that was actually applied in production.

The 1962 - 67 Nova clutch ball stud (#3790556) is somewhat unique at almost 2" in total length (certain Full Size and Corvette used it as well, but not many).  It is NOT the common one (#3729000) used by Chevelles, Camaros and just about everything else for decades.  A part you see for sale everywhere online, often erroneously advertised as fitting 1st and 2nd gen Chevy IIs.  In 1968 the bellhousing and clutch setup were one of the many items GM revised on the Nova, implementing the common "621" bellhousing.  This in turn uses the extremely common #3729000 clutch fork stud mentioned above; which happens to be ~1 1/2".

Going back to the gentleman's clutch travel issue and putting the pieces together, the common ~1 1/2" #3729000 clutch ball stud had made its way into a correct early Chevy II "309" bellhousing.  Remember they are all the same right? Everything went together without issue, but someone was paying attention and realized there was an issue with clutch fork travel; about 1/2" of an issue...  Out came the transmission and in went the correct 2" ball stud, remedying the problem.

And for the sake of conversation (and completeness), there are also the short stud #3725240 often found in trucks and #3769589 used with Corvairs.  Not terribly common, but good to be aware that those are floating around out there.  There are likely others we are overlooking, but this gets the point across and will give you something to watch out for if building a manual trans Chevy II.



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