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Why both metric and standard?

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#1 ·
I have an 83, and I am having a lot of frustrating moments in that there are several mix & matched bolts all about the car. Some are metric, some are standard, and some are just the wrong size (doesn't seem to fit any socket or wrench). I am curious if anyone knows if these bolts should all be either metric or standard, or if there is some sort of guide that tells what bolts are supposed to go where. As far as I know, the car was made in Canada, so that might explain the metric crap, but I would like to get the proper bolts in their places to aid in future assembly/disassembly. I am currently swapping the engine, and having to fart around with all sorts of different bolt heads is just wasting my time; not something I care to do again in the future.

Thanks for any info,
BW
 
#2 ·
pretty much every GM car made from the mid 70's to present has that same problem- if something has 2 bolts holding it on, it always seems like one is standard, and the other is metric. what were they thinking? part of the fun of working on those cars, i guess.

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1971 Nova(looks like 69 camaro from underneath!)
355sb, vortec heads, HOT cam,T-10 tranny, 3.70 gears 16X8" IROC wheels. 12" Corvette brakes on the way.
see pics here http://community.webshots.com/user/novaderrik

[This message has been edited by novaderrik (edited 08-01-2002).]
 
#3 ·
Crumbs... I wish they could have gotten their crap together, as working on all these mismatched bolt heads is less than fun. So I take it I am basically hooped, and that those odd bolt heads are actually supposed to be there. Bummer, since I was truely hoping that an imperial set of sockets and wrenches would do the job, but it looks like more of those "seemingly 5/16"; but ain't" heads will require that cheesy 8mm instead. I don't appreciate this metric intrusion, it only gets in may way! Either one or the other, GM, don't waste my time!

At any rate. thanks for the help my friends,
BW
 
#5 ·
In my experience, it seems that the major assemblies (like the engine itself) uses SAE, while the accessories use metric. To make matters even more fun, I recently discovered that my 92 Caprice wagon uses torx bolts to hold the alt on!! It was a big sucker too, something in the size 55 range. Of course I didn't discover it until after the parts store had closed, so out came the vise grips! I wasn't pretty, but it did the job in a pinch-had to get to work the next morning you know!

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Bret Copsey
'68 Camaro base coupe
'92 Caprice Wagon
'99 Venture Van
 
#6 ·
Even sadder is that it is not just the head of the bolt but the threads as well. When replacing a broken bolt you can no longer reach into that can holding similar sized bolts because they just won't work. Ever try to fit a 1/2 fender bolt into a metric J-clip or Tinnerman nut. No dice.
 
#7 ·
#9 ·
I was working on my brothers 91 Mustang last week. It uses metric bolts in the front spindle/brake assembly and then U.S. standard hose fittings. I spent an hour driving around looking for an 11mm flare wrench - no one makes one, they're all 10mm on one side and 12mm on the other. I finally tried my 7/16 flare wrench and it worked.
 
#10 ·
i guess this is why they invented the metwrench (did i spell that right?) and the gator grip. also, an old fashioned vise grip brand locking pliers works wonders, as previously stated.
what i always do on my cars is this- if it has a metric bolt that has a nut on the back, it gets replaced with a standard. if it is metric with a speed nut of some sort, it gets replaced with a standard nut and clip. if it is a metric blind tapped hole- it stays metric. i hate metric.
and, yeah, i never undrstood why metric sockets have the standard drive sizes. why don't they have their own drives- like a 10mm or so drive?

------------------
1971 Nova(looks like 69 camaro from underneath!)
355sb, vortec heads, HOT cam,T-10 tranny, 3.70 gears 16X8" IROC wheels. 12" Corvette brakes on the way.
see pics here http://community.webshots.com/user/novaderrik
 
#11 ·
It's not related to where the car was built; the industry was in the middle of converting from SAE to Metric during those years, and existing major components that were already tooled in SAE (like engines, transmissions, axles, etc.) were left SAE until they were replaced later with new designs and new major tooling. Other smaller new components that changed every year or so (bolt-on stuff, sheet metal, trim parts, etc.) were re-tooled to Metric as part of the regular annual model changes. It wasn't easy, especially in the assembly plants.

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JohnZ
CRG
'69 Z28 Fathom Green
 
#12 ·
Yes, I am finding mostly that it is the accessories and minor parts, like air snorkel, heater motor cover, fan shroud etc that use the metric. The rest seems standard, except for the alternator which has been mickey-moused and now sports 3 bolts all of different size. I come across the heads that don't seem to be either metric or standard (no socket really fits it well), but this no-name/no-size driver I have does the job. Most of these screws and bolts are just tapped right into the metal, so I figure I could buy a bunch of similar standard bolts and screws and just force them in. The whole dash and interior is full of different mix & matched screws too, which have obviously been put there by a previous owner, so I will likely replace those too.
 
#13 ·
Yeah......I'd like to meet the Bozo/s that made this "industry standard" decision......
Better yet, I'd like an adress to mail all My tool bills to
....I just think that domestic cars should have been left standard and import cars only should have been metric...
This is another reason I enjoy working on the old iron...
Grumble, grumble, whine, whine....it was another one of those "flat rate" days for Me today.....all better now tho
...
 
#14 ·
Cheer up, I was ripping the trans out of my astro yesterday and came across some fittings that weren't 11/16'ths (or 3/4), nor were they 17, 18 or 19mm.

Confused - I reached for my reversable metric crescent wrench which does the trick every time. That along with vice-grips(tm) a BFH, JB weld and Alabama chrome can fix anything.
 
#15 ·
by alabama chrome you mean duct tape?
They make a aluminum backed stuff now thats way tougher and stickier then duct tape, its also pretty shiny. (it will never see my car though).
I informed a school teacher of this last year while she was yelling at someone, and well to say the least she warned me that the next step was leaving the room (And not to get duct tape).
hehe the good old days (wait i'm only 17!)
 
#16 ·
Kurt6325:

That's a pretty interesting observation. Its
almost like driving on a parkway and parking
on a driveway, but that was a good one that I won't forget: Good man!!!

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