sae vs metric

[tdm571]

While working on my 97SE and others in the junkyard, it has become quite irritating how some bolts are SAE and others are metric. This makes the conversion tables in the manuals indispensable. Are the 04+ GP's any better or just as big a crap shoot?

[TheOtherNick]

Pretty much everything on a 3800 is metric besides the valve cover bolts.

[Scottydoggs]

new cars for the last 15 years or so have all been built with metric bolts, for the most part, that's all makes and models, metric is so much easier to use anyways.

[JoRoW99]

Correct me if im wrong but I think the front bolts of the downpipe are metric and the rear ones are SAE... wtf

[tdm571]

Pretty much everything on a 3800 is metric besides the valve cover bolts.

That's not been my experience. Yeah, you could use a 13mm on some bolts, but there is a little play and a 1/2" fits perfectly. Like the dog bones or the fender braces. I don't remember off the top of my head, but I know there were some SAE bolts when I taking the heads off in the junkyard for a top swap. I think they were 7/16.

[TheOtherNick]

dog bone=15mm
fender brace=13mm
supercharger=10mm, one 13mm
tb=10mm, 2 8mm on the support bracket for n/a cars
egr=13mm
valve cover=3/8
alt bolts and nut= 15mm
map bolts=10mm
water pump pulley=8mm
front cover and water pump 10mm and 13mm
crank bolt=15/16
rear cover=3/8
oil pan 3/8
head bolt= 5/8IIRC
head stud nut= 1/2" 12 or 6 point
x over nuts= 13mm
starter bolt=15mm
starter batter pos nut=13mm 14mm on some after market
starter relay wire=10mm
p/s pump=13mm
tensioner pulley=15mm or t55 torx
icm bracket=15mm
cam bolt= 1 1/16" or 24mm IIRC
torque converter bolts=18mm
transmission bell-housing bolts=18mm
rear engine to trans bracket bolts=13mm
axle nut 32-36mm depending on year and axle manufacturer
strut to knuckle bolts=21mm
ball joint nut=18mm 19mm on some aftermarket
strut top nuts 15mm
front sway bar bushing clamp bolts=15mm links 13mm-15mm depending on manufacturer
rear sway bar link nuts=18mm, 15mm on back to hold the ball
manifold bolts 13mm
02 sensor= 7/8"
icm harness bolt=7mm
Lim bolts=3/8"
hub bolts=1/2"
blower motor/blower resistor 7/32"
small dash bolts=7mm larger ones 13-18mm
Seat bolts=T60 torx IIRC

[sseilmnop]

I figure the engine internals are English because the engine was designed back when everything was English. They wouldn't change to metric unless completely redesigning such as a new engine.

[matt5112]

but they kinda did with the series II.

[QUICKSILVER462]

It all depends on the cheapest bolt supplier.

[sseilmnop]

The blocks are milled on cnc mills already set up for drilling and tapping English. To drill some holes English and some holes metric would require adding more tooling. I would guess every tapped hole in the block, crank and heads are English. The rest of the car and engine brackets are probable metric.

[BillBoost37]

didn't see these in a quick skim.
LIM bolts 3/8"
Wheel hub bolts 1/2"

[tdm571]

Thanks for the list Nick. That should come in handy for a lot of jobs. If I hadn't started this as a rant, that would be an awesome sticky. It does prove my point that GM was inconsistent though. Are those sizes accurate for the 04+ vehicles?

[16MustangVet]

I hate to say it and I'll put the flame suite on for it. EVERYTHING should be metric!! I fvckin hate SAE! Lets see if a 10mm is too small grab a 11mm done! None of this fraction crap. At the very least build the whole damn vehicle with one or the other! Not half and half. Bi-polar assembled cars are like dealing with my wife!! LMFAO and trust me thats enough!!

[BillBoost37]

On 99% of stuff you are fine grabbing the next up or down. But at the 10mm/3/8 size with the rounded edge bolts that GM used, yeah. It's kinda necessary.

[tdm571]

The 13mm and 1/2" sizes are real close too. I checked a lot of the 13mm's Nick posted above. They all have a little play and are dead on for the 1/2". The funny thing is, they have the metric strength markings.

[ZR1Vette09]

My dad (engineer) hates the metric system, and for a legitimate reason: if you're a decimal place off by multiplying by a wrong power of 10, it's much harder to spot than just a plain wrong number you can find in standard English. I'm indifferent.