On Sat, May 28, 2011 at 12:46 AM, John Miller <jem at milleredp.com> wrote:
>> You really have to pay attention because some of the metric sizes fit
>> pretty
>> well in imperial wrenches. B Generally the engine is imperial (I suppose
>> because of it's Buick history), and most of the rest is metric. B But
there
>> are
>> some exceptions that don't seem to make any sense. B For example, the rear
>> suspension links are 7/16" bolts, while the front uses 12mm. B Except for
>> the
>> ball joints, which are 1/2"....
>
> Yeah, this is pretty typical of a lot of vehicles of mixed parentage, or of
> UK or US build during the metric transition or in some cases where an
> off-the-shelf part is used that's been around since dinosaurs roamed the
> Earth.
>
> That engine was originally laid out around 1960, it would have been done
> with inch-measure fasteners at that time even if it'd been done in the UK.
> B Was that rear suspension link shared with something like the Rover SD1?
>
> I'm in the process of parting/scrapping my '91 Suburban. B This is a design
> that first entered production in 1973.
>
> Most of the chassis is still SAE. B The body is about 50/50 (oddly enough).
> B The 454 engine is all SAE but the 4L80E transmission is metric. B The
> steering box mounts with SAE bolts but the hose fittings are metric. B And
so
> on. B You get used to this after a while. B And yes, a lot of wrench sizes
> overlap (5/16 and 8mm are interchangeable, there are the rare 13mm capscrew
> heads that won't take a 1/2in socket, 19mm and 3/4in are pretty much always
> compatible, likewise 22mm and 7/8in, etc. and I think one automaker - Ford?
> - came up with an "11mm" head that'd accept a 7/16 wrench).
>
11 mm is 7 mm DIN, I believe. Standard bolt, not much used. There's
a 5.5mm head that shows up from time to time, which is really a 7/32".
My personal favorite insanity is where GM (and Ford and Chrysler,
though not as much) used a special bolt with SAE threads, and a metric
head, to, I've been told, meet contract requirements that jobs be done
with one toolkit. I don't know that's the resons, but the bolts
surely were there.
--
David Scheidt
dmscheidt at gmail.com
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