SAE or metric

[Alowes2837]

This may seem odd, bit late, stupid or something that will lead to an oh dear along the line. As posted before I am in the process (a long one) of moving to the US as I am now under contract buying an auto repair garage. I am currently a tech here in the UK. Any way on to the point, most if not all of the vehicles I work on here have metric size fastners, I understand that the euro and asian vehicles there will be the same but what bout the majority of US cars and light truck etc.

 

[48548]

Stuff made after a certain age is mostly metric, but there are some exceptions... Not sure what the date range is, but I would say most 90's and newer are all metric.

 

[alamerang]

Mostly everything now is metric due to the fact that most companies are becoming more global. You might want to get a decent set of SAE wrenches and sockets but for the most part (and I know everyone is going to kill me for this) most metric tools work on SAE fasteners. If I go buy tools now I usually buy metric unless there is some specific SAE size I need.

 

[Alowes2837]

Thanks for that guys, that is what I thought considering the majority of manufacturers all share parts and engines. I have both obviously more metric but do have some good imperial stuff.

 

[Diesel_Crawler]

First off screw the metric system!

Why not both? its the only thing it is good for is getting to have 2 sets of everything!

 

[tonydanzah]

Get metric very few sae nut and bolts and +1 on metric working on standard

 

[mn_commander]

From what I've seen, 'bout only thing that uses SAE is aftermarket accesories for trucks, vans, and some cars

 

[byrd]

the major problem i have with the automotive industry using metric fasteners is most of the tool specials on the truck are geared this way. i work on euipment and most of it is made in the US so that means SAE fasteners. there are never any package or special deals on SAE tools!

 

[wantedabiggergarage]

From what I've seen, 'bout only thing that uses SAE is aftermarket accesories for trucks, vans, and some cars

I would also add, lots of flare nuts (brake and full lines) are still SAE. I think the late 80's there were still a lot of cars with metric engines, and SAE bodies.

 

[StupidHippie]

Any way on to the point, most if not all of the vehicles I work on here have metric size fastners,.

Both of my British cars are SAE!

Pick up a basic set of SAE tools....you'll need them eventually.

Rob
Triumph TR6
'65 MGB

 

[Miter Wrench]

I use SAE all over the house for non-automotive repairs (plumbing, assembling stuff, lag bolts etc.)

 

[wreckercologist]

I would also add, lots of flare nuts (brake and full lines) are still SAE. I think the late 80's there were still a lot of cars with metric engines, and SAE bodies.

I've been running into flare nuts on Mopar and GM stuff lately that neither metric or SAE will fit properly.

It wouldn't be a bad idea to have a basic SAE set of tools around for aftermarket accessories as well as doing maintainence or repairs on the shop equipement (air compressor/lift/jacks/ect).

Nothing wrong with buying more tools.......I thought about buying an old English motorcycle so I could justify owning Whitworth tools!

 

[RbrtAWhyt]

Seems like everything I work on has a mixture of both...

 

[Jaralaccs]

the cross over was all the way back in the early 80's for american cars (which aren't even on the road anymore)
everything is metric on cars now

 

[matthew]

Nothing wrong with buying more tools.......I thought about buying an old English motorcycle so I could justify owning Whitworth tools!

And I thought I was the only one so tempted (although I wanted a Jag or Healy, not a motorcycle, but I'll probably start with collecting the Whitworth tools).


As much metric as there is on cars nowadays, it is still possible to find SAE - I almost mistook the lugnuts on my car (a 2006) as metric, until I noticed the manual said the studs were 1/2"...

 

[tyndall]

the cross over was all the way back in the early 80's for american cars (which aren't even on the road anymore)
everything is metric on cars now

LOL, the only American vehicles I have are early 80's and older. It seems as though the more SAE fasteners on an American vehicle, the more reliable it is.


For a garage you'll need the basics in SAE. As a customer, I'd be pissed if a supposedly professional mechanic rounded off a bolt because he didn't have something a simple as a 1/2" wrench.

 

[MrMark]

The late model GM car I have worked on is a mix of SAE and Metric. There is no real rhyme or reason, you literally have to try each fastener to be sure.

There are a FEW metric and SAE sizes that are close and 3/4 - 19 mm are virtually identical, but the notion of using metric on imperial fasteners reveals one to be a total hack. No two ways about it. Use the proper tool for the proper fastener. If I saw a guy using a metric wrench on an imperial fastener I would be out the door fast.

 

[aar0s]

My late 80's mustang has both, and no rhyme or reason to whats where on the car. drives me nuts sometimes. Most of whats on the engine is SAE.

 

[MrMark]

I think most GM engines are SAE and the bodies metric; the reverse of what someone said earlier.

I could have this wrong, but it is my recollection.

 

[alamerang]

The late model GM car I have worked on is a mix of SAE and Metric. There is no real rhyme or reason, you literally have to try each fastener to be sure.

There are a FEW metric and SAE sizes that are close and 3/4 - 19 mm are virtually identical, but the notion of using metric on imperial fasteners reveals one to be a total hack. No two ways about it. Use the proper tool for the proper fastener. If I saw a guy using a metric wrench on an imperial fastener I would be out the door fast.

So I take it you have never in your life used a 14mm on a 9/16 or vise verse? Or a 13 on a 1/2"? Seriously, 99% of the time it works fine. I know a lot of mechanics do it all the time with no problems. I agree that yes the right tool for the job but a few thousandths of an inch difference will not immediately equal a rounded off bolt.

 

[MrMark]

So I take it you have never in your life used a 14mm on a 9/16 or vise verse? Or a 13 on a 1/2"? Seriously, 99% of the time it works fine. I know a lot of mechanics do it all the time with no problems. I agree that yes the right tool for the job but a few thousandths of an inch difference will not immediately equal a rounded off bolt.

NEVER. No. NEVER EVER EVER. The thought of doing something like that would not even cross my mind unless I was stranded and had no choice because I had no tools. 13 and 1/2 is not even close in my book.

 

[alamerang]

NEVER. No. NEVER EVER EVER. The thought of doing something like that would not even cross my mind unless I was stranded and had no choice because I had no tools. 13 and 1/2 is not even close in my book.

Well different strokes for different folks, but I don't always have time to bust out the calipers and measure every bolt head I'm working with. I must bow to your superior standards sir...

 

[scottmlew]

I suspect that most, if not all, of us have, at one point, inadvertently used a metric tool on an SAE fastener, or vice versa. Sometimes the fit is very close; to this day I am not 100% sure whether the lug nuts on one of my vehicles are SAE or metric, and sometimes the "error" in the actual size of a fastener, or damage to the fastener, causes the "wrong" tool to fit better than the "right" one.

 

[MrMark]

13 and 1/2 has 12 thousands difference. Same with other example you gave.

5/8 and 16 is 5 thousands. 5/16 - 8 and 3/4 - 19 are the close ones at 2 - 2.5 thousands. Anything over 5 thousands is too much in my book.

I bring out both sets of tools and try each if there is any doubt. I imagine if I worked at this for a living I would learn which bolts were which from repetition and experience. I don't have the luxury of experience. When I do something it has to be done right, the first time. So I take my time, and I make sure I have the correct tools, even if it means stopping the job to get the tool I am missing. It does happen.

 

[MrMark]

19 and 3/4 are common for lug nuts. They are only 2 thousands different w/o taking into account manufacturing tolerances. If it's german its a 19, if it's a GM it's probably a 3/4 but I always use whichever fits better on the GM because you never know with them.

 

[alamerang]

So the width of a human hair is the difference between a 13 and 1/2 and a 14 and 9/16. This you can completely eyeball? Got it! Seems to be so close its not gonna matter. Even the tolerances from the bolt factory aren't that close.

I am not saying this rule of thumb always works but seriously in some cases you can even tell. Just seems like we're splitting hairs....

 

[MrMark]

So the width of a human hair is the difference between a 13 and 1/2 and a 14 and 9/16. This you can completely eyeball? Got it! Seems to be so close its not gonna matter. Even the tolerances from the bolt factory aren't that close.

I am not saying this rule of thumb always works but seriously in some cases you can even tell. Just seems like we're splitting hairs....

I'm not saying I can eyeball it; I can't. I just have to try and see how the fit is.

Here's what would happen: on a GM car I would start work on the engine and I would start with the belief that the engine was SAE and go from there. If something didn't fit right, usually too much slop I would break out the metric and try that. I would curse GM and go back and forth when a sloppy one came up and try to see if any patterns on GM could be learned.

This is why I would much rather work on a MB.

A 13 on a 1/2 will be easy to tell. It will be real loose. 12 thousands is a lot on a bolt fit.

 

[alamerang]

I'm not saying I can eyeball it; I can't. I just have to try and see how the fit is.

Here's what would happen: on a GM car I would start work on the engine and I would start with the belief that the engine was SAE and go from there. If something didn't fit right, usually too much slop I would break out the metric and try that. I would curse GM and go back and forth when a sloppy one came up and try to see if any patterns on GM could be learned.

This is why I would much rather work on a MB.

Well that's what I have been saying. If its too loose then yes get the right tool but 99% of the time someone wouldn't know the difference if they were using a 13 on a 1/2" or a 14 on a 9/16". On a lot of metric and SAE tools the differences are so close you might not even notice it.

13mm on a 1/2" never let me down...

 

[devilphrog]

The End All Answer to our debate!

 

[MrMark]

I'm real particular about what I do when it comes to tools and mechanical work. I have never really come across anyone that would consider using metric on SAE fasteners. Might be a regional thing.

 

[alamerang]

I'm real particular about what I do when it comes to tools and mechanical work. I have never really come across anyone that would consider using metric on SAE fasteners. Might be a regional thing.

Might be since all us Texans are light years behind all of ya'll there in the great state of California. Now if you'll excuse me I needa feed my horse so I can get to work drivin cattle tomorra...

 

[scottmlew]

19 and 3/4 are common for lug nuts. They are only 2 thousands different w/o taking into account manufacturing tolerances. If it's german its a 19, if it's a GM it's probably a 3/4 but I always use whichever fits better on the GM because you never know with them.

Yep, that's the specific set of sizes I was thinking of regarding my vehicle!

 

[jsaw]

Mostly everything now is metric due to the fact that most companies are becoming more global. You might want to get a decent set of SAE wrenches and sockets but for the most part (and I know everyone is going to kill me for this) most metric tools work on SAE fasteners. If I go buy tools now I usually buy metric unless there is some specific SAE size I need.

My thoughts exactly