[John V.]

Things that make me go crazy!

Found a group of '64 Tempest parts cars. Pulled off the skirt to frame bolts and special washers from one car and saw that one of the bolts was a coarse thread bolt.

I assumed that bolt was "wrong" so I pulled a bolt from the adjacent 2nd car and took home (2) bolts and 2 special washers, both bolts were fine thread, with the special thread cutting point.

After cleaning them up I saw that the 2 bolt heads had different manufacturer's marks. Had an opportunity to revisit the cars and decided to see if I couldn't find a bolt to get a matching pair of head markings. Just me being anal.

Pulled the remaining bolt off the 2nd car and was stunned to see that it was a coarse thread bolt.

So now I decided to pull the pair of bolts off the remaining 3rd car.

Lo and behold, it also had a coarse thread bolt and a thread cutting fine thread bolt.

In all 3 cases, the coarse thread bolt was installed on the driver side, the fine thread on the passenger side.

All 3 cars were Pontiac Plant builds. I only checked the Time Built on the one, it was a June build.

I can't say that the Pontiac Plant always did it this way in '64. But since all 3 in this yard used this combination of hardware, seems like that might be the typical usage for a Pontiac Plant build at least around the time these 3 were built.

I have 2-1/2 sets now. I looked around for the coarse thread bolt & washer that I left behind 2 weeks earlier. I had left it on a decklid, owner said the cars hadn't been touched since I was there but I didn't see it, else I would have 3 sets.

I won't know if my Fremont car used a coarse thread bolt or used the fine thread on both sides until I visit it in a couple weeks.

The pix are the set from the 3rd car but aside from head markings, no visible differences between cars. Notice the thread difference but also the difference in bolt length.

The coarse thread bolt I measure at 1-3/16" long, the fine thread is 3/4" long.

If anybody knows why the driver side bolt should be coarse thread and longer vs. the fine thread passenger side bolt, please enlighten me!

BTW, p/n 535114 was a PMD issued p/n, this part numbering was used prior to the introduction of the 7 digit 977xxxx series that began in '62.

535xxx numbers were issued circa 1959 intended for first use for the '60 Pontiacs. Not uncommon for early p/ns to have remained in use for '64 Pontiacs or beyond. After about 545xxx, PMD engineering switched to the 977xxxx series although for inexplicable reasons, some previously unissued 545xxx and 546xxx p/ns were issued in 1969 or so, some for the RAIV components, just prior to PMD switching to a new series of p/ns, this time 6 digits that began around 477xxx. This series lasted until about '77 at which time there seemed to be some overlap with the earlier 6 digit series such that some 525xxx p/ns may have been duplicates of p/ns from the early '50s. I believe that after that time, a new p/n format was introduced that was used throughout GM, eliminating the Div. specific p/n formats.

Circa 1964, Olds p/n were 6 digit but began with a 3 in those days. Buick was using a 7 digit numbering system that began with a 1. Chevy used a 7 digit system that began with a 3. All to the best of my knowledge.