Is it Metric or SAE guessing game

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Today I have an 84 Chevy G-30 Van with a 350 in for a Water Pump and Thermostat. Pretty easy job really. Except that this era of GM cars and trucks had a hodge podge of Fastners. Some are 3/8 threads with a 9/16 head. Others are a 3/8 thread but with a 15mm head and others are pure metric. Those of you that were not around when these were popular do not know what you are missing.
 
Originally Posted by Chris142
Others are a 3/8 thread but with a 15mm head.....


Why ??? Who 'designed' that and for what reason ? Honestly though, when you're working on something and primarily removing and replacing fasteners, you don't really get concerned with the threads themself.
 
Originally Posted by hallstevenson
Originally Posted by Chris142
Others are a 3/8 thread but with a 15mm head.....


Why ??? Who 'designed' that and for what reason ? Honestly though, when you're working on something and primarily removing and replacing fasteners, you don't really get concerned with the threads themself.

Someone @ GM.. Most of the bolts that hold brackets and such on are 15mm heads. The engine block and heads were still sae. I can't explain more lol
 
Early 80's had some weird mixes, i guess from different suppliers. Engine bolts that were sae, and body and accessory bolts that were metric.
 
Originally Posted by Chris142
Today I have an 84 Chevy G-30 Van with a 350 in for a Water Pump and Thermostat. Pretty easy job really. Except that this era of GM cars and trucks had a hodge podge of Fastners. Some are 3/8 threads with a 9/16 head. Others are a 3/8 thread but with a 15mm head and others are pure metric. Those of you that were not around when these were popular do not know what you are missing.

I can relate, my 83 Silverado with the 305 has the same mismash of sizes, nothing more frustrating than going thru my socket drawer looking for that [censored] metric socket. now i have separate drawers in my tool box for sae and metric tools.
cheers3.gif
 
I changed out the master cylinder in a Mercury Sable back in the 90s. There were 4 bolts on it. All 4 were different sizes. 10mm, 12mm, 3/8, and 1/2. Looked like any of the 4 would be sufficient for the job.
 
Same issue on my 94 Camaro. Made even worse with all the modifications I have on it.

Although my 89 Camaro is almost entirely SAE. There are only a couple things that are metric on that car.
 
Didn't many GM automatic transmissions like the 700R4... go metric in the 80's and have METRIC stamped on the pan?
 
My buddy's late 80s Buick sedan came from the factory with 'METRIC ' stamped into the oil pan in 2 inch high letters so that you'd see it when it was up on a lift.
 
My folks '83 Monte Carlo with the Buick V6 was a mix.
Only things besides services were the original radiator (too small) and 1 window regulator.

Not a bad car actually.
 
Our '89 Olds 98 Touring Sedan was a mix. That was my first experience with metric and SAE in one vehicle. Now I get to deal with stupidly light metric nuts and bolts mixed with random inside-out Torx and spline drive things that BMW and Audi ownership brings to the table.
 
Originally Posted by Imp4
My buddy's late 80s Buick sedan came from the factory with 'METRIC ' stamped into the oil pan in 2 inch high letters so that you'd see it when it was up on a lift.


I'm pretty sure Ford did the same thing.
 
Just SAE and metric ? That's pretty easy. When I started my apprenticeship in 1970 we still worked on mainly British cars. Some of them changed from Whitworth to SAE in the early '50's, some didn't, and some changed much later. So you didn't know if the Morris Minor you were working on was Whitworth or SAE, and was probably a mixture of both. And then came Metric, and it was JIS for Japanese cars, and ISO for the European cars. I could tell at a glance what I needed.
 
We still have a late 70s GM paper catalog for light trucks at work with a page that warns that the vehicle may have a mix of standard and metric fasteners.
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