1966/1967 clutch rod nuts - again......

[R N.]

Hello everyone,

I'm curious about the debate about the thick/thin clutch rod adjusting nuts for the '66/67 models - has this issue been settled or is the issue still open for debate? I found some good information from the post below, but still have questions.

https://www.forums.ncrs.org/showthre...=Clutch+swivel

My '66 (March build) and my '67 (December build) both have the thick nuts, so inquiring minds want to know if the current '66 TIM & JG is in error (as it says the thin nuts are correct) or is my car typical factory production?

The TIM & JG isn't clear on the finish of the nuts, but from what I have read, black phosphate appears to be correct - can someone confirm this for me?

My goal is to have my car as close to typical factory production as possible and not what the TIM & JG says, so I'm needing some guidance from the forum membership. Thank you in advance.

I've attached a photo of the clutch rod nuts from my '66 for reference.

[Kenneth F.]

Re: 1966/1967 clutch rod nuts - again......

Hi Kurt, My 1966, L-79, has nuts that are close to .320. The swivel has a straight indentation line at right angle to the threaded rod. The threads extend for 3.25 in. The unthreaded part of the rod is .520 in. and reduces to the threaded dia. in 2 steps. The VIN is 11,XXX. I do not have the knowledge to know what the finish is, but appears the same as the swivel. I have had the car since 1967.Ken

[Joe R.]

Re: 1966/1967 clutch rod nuts - again......

Kurt,

Maybe this photo will help you decide the finish and the size. The large black phosphate nut is just for reference. The 10 natural finish are for real and for clutch rods.

JRDSCN3988.jpg

[David L.]

Re: 1966/1967 clutch rod nuts - again......

Kurt,

The 1966 Corvette AIM (UPC 7, sheet C2) lists 124829 as the part # for the the clutch rod nuts. My 1966 Chevrolet Parts Catalog (Oct. 1965) lists GM # 124829 as 3/8"-16 Check Nuts (Lock Nuts, Jam Nuts) in Gr. 8.916 and described as Cadmium Plated.

Dave

[Timothy B.]

Re: 1966/1967 clutch rod nuts - again......

Here is a picture of the clutch adjustment assembly onmy 67 that was built Sept 66.

[Joe L.]

Re: 1966/1967 clutch rod nuts - again......

Hello everyone,

I'm curious about the debate about the thick/thin clutch rod adjusting nuts for the '66/67 models - has this issue been settled or is the issue still open for debate? I found some good information from the post below, but still have questions.

https://www.forums.ncrs.org/showthre...=Clutch+swivel

My '66 (March build) and my '67 (December build) both have the thick nuts, so inquiring minds want to know if the current '66 TIM & JG is in error (as it says the thin nuts are correct) or is my car typical factory production?

The TIM & JG isn't clear on the finish of the nuts, but from what I have read, black phosphate appears to be correct - can someone confirm this for me?

My goal is to have my car as close to typical factory production as possible and not what the TIM & JG says, so I'm needing some guidance from the forum membership. Thank you in advance.

I've attached a photo of the clutch rod nuts from my '66 for reference.

Kurt-------


GM says that nut GM #124829 was used for the clutch push rod application for all 1963-81 Corvettes. GM also says that nut is 3/8-16 thread size, 7/32" thick, and zinc plated.

I'm not so sure, though, that this nut was actually used for every car built during the 1963-81 period. Unfortunately, I MAY have changed the nuts on my 1969 so I can't say for sure. However, my recollection is that my car always had standard thickness nuts and not the 7/32" jamb nut style.

Any other 1963-81 original cars that can report. It's pretty easy to check this out.

[Edward J.]

Re: 1966/1967 clutch rod nuts - again......

Joe when i took my 63 apart I had a thin and thick nut. which appeared to be originals.

[Leif A.]

Re: 1966/1967 clutch rod nuts - again......

Kurt,Crystal clear picture!!! What are you using to take pics?

[Henry J.]

Re: 1966/1967 clutch rod nuts - again......

Kurt:My April-built 66 has the thick nuts. The finish appears to be black phosphate.

[R N.]

Re: 1966/1967 clutch rod nuts - again......

Kurt,Crystal clear picture!!! What are you using to take pics?

My iphone 5

[Michael H.]

Re: 1966/1967 clutch rod nuts - again......

Some time around 1975 or 76 in Downers Grove, IL when Buxbaum had a building full of incredible 63-67 Corvettes from California, I first noticed the different size nuts on the clutch rod of many different cars. At that time, most of his cars were low mileage unrestored originals so, for the most part, what the car had was most likely what it was born with.

His inventory was constantly changing so I always looked over the new cars that arrived.

I recorded a LOT of information (including VIN #'s) along with the style of the clutch rod nut.

It clearly showed that all 63-64's had two thin nuts.

Just about every 65 had one thin and one thick nut, the thick nut on the rear portion of the rod.

All 66-67's had two thick nuts.

When GM assembly instruction manuals became available in around 1976-77, I was a little surprised to see that the manuals for all five C2 cars called for the same 124829 thin nut. No mention of the thick nut that replaced it in production. It did though.

[David L.]

Re: 1966/1967 clutch rod nuts - again......

Some time around 1975 or 76 in Downers Grove, IL

I kept a lot of notes, photos, and sketches during my 15-year (Thanksgiving 1980 to May 1995) frame-up restoration of my 1966 convertible. During the latter part of the re-assembly process I was fortunate to have the 1966 AIM and a 1966 Chev. parts catalog. My old notes show that the clutch rod nuts were the thick type which did not match up with thin jam nuts (GM # 124829) as shown in my 1966 Chev. Parts Catalog. I just assumed that someone changed the nuts during the engine replacement that must have been done sometime between 1969 and 1979. The engine was from a 1969 Corvette but the 4-speed Muncie was original (stamped partial VIN matched with the car VIN). My 1966 currently has the jam nuts which are correct "according to the books" but actually may not be correct in the real world.

BTW, back in 1990-1991 I sold a "320" starter dated "6E31" and a NOS set of Trico RF-15 "dotted" wiper blade refills to a Downers Grove, IL, resident by the name of Pete who know resides in NM.

Dave

[Joe L.]

Re: 1966/1967 clutch rod nuts - again......

I kept a lot of notes, photos, and sketches during my 15-year (Thanksgiving 1980 to May 1995) frame-up restoration of my 1966 convertible. During the latter part of the re-assembly process I was fortunate to have the 1966 AIM and a 1966 Chev. parts catalog. My old notes show that the clutch rod nuts were the thick type which did not match up with thin jam nuts (GM # 124829) as shown in my 1966 Chev. Parts Catalog. I just assumed that someone changed the nuts during the engine replacement that must have been done sometime between 1969 and 1979. The engine was from a 1969 Corvette but the 4-speed Muncie was original (stamped partial VIN matched with the car VIN). My 1966 currently has the jam nuts which are correct "according to the books" but actually may not be correct in the real world.

BTW, back in 1990-1991 I sold a "320" starter dated "6E31" and a NOS set of Trico RF-15 "dotted" wiper blade refills to a Downers Grove, IL, resident by the name of Pete who know resides in NM.

Dave

Dave-----


A clue: when you find black/gray phosphate NUTS on a car, the chances are very great that they're original. Most hardware store fasteners, and especially nuts, have been zinc plated for many years. Once-upon-a-time, SAE grade 8 BOLTS sold in hardware stores were usually black phosphate but that ended quite some time ago and for years now are mostly zinc plated with chromate (gold) overplate.

When you find "natural" or "plain" finish fasteners, that's an almost CERTAIN sign that they're original. Hardware stores, auto parts stores, or GM dealers VERY rarely supplied so-finished fasteners.

Even when GM dealers supplied fasteners, most were not even GM supplied pieces and were zinc plated. Most of these were, at most, SAE grade 5 (even though some applications require grade 8). Generally, there was only one way to obtain a GMSPO supplied "standard part" from a GM dealer: give them the part number and ask them to order it for you. Of course, that's what I did for ALL parts.