Most common SAE and Metric Thread Sizes for Automotive Work

[mike7]

A local wholesale store has some Hanson NOS taps and dies for cheap that I'm looking to pick up. Lacking a tap and die set, I usually purchase said tools on an individual as needed basis. But since this store has them for such a good price, I'm looking to stock up. My question to you is, what are the most common thread sizes, both SAE and Metric, for automotive work? Also, what are the most common thread sizes for bulk Grade 5 and Grade 8 hardware that you would find in Home Depot/Lowes/Tractor Supply?

 

[scissorman]

Most common SAE sizes would be 1/4"-20, 5/16"-18, 3/8"-16, 7/16"-14. For metric stuff the most commonly used is 6mm x 1.0, 8mm x 1.25, 10mm x 1.25

 

[2oolhound]

Here's the basic Irwin/Hanson set to about 1/2" in SAE and MM to compare to. This set averages about $300 around here.

http://www.irwin.com/tools/taps-dies-sets/76-pc-machine-screw-fractional-metric-tap-hex-die-set

The larger sizes from 1/2 to 1" are a lot more money so worth picking up if you're getting a deal.

My Irwin/Hanson set (MAC branded) are not HSS which is preferred but they are decent tools and preform well.

 

[theoldwizard1]

SAE fasteners have not been used on cars or light trucks in over 20 years.

 

[coralnut]

^ Don't tell that to my 99 Suburban. I thought all of the fasteners were metric until I tried replacing them and found that there were still a few SAE fasteners on it.

 

[K-Dog]

auto body by far 10mm leads the way.
Followed by 12mm 14mm and 8mm.

 

[coralnut]

Most common SAE sizes would be 1/4"-20, 5/16"-18, 3/8"-16, 7/16"-14. For metric stuff the most commonly used is 6mm x 1.0, 8mm x 1.25, 10mm x 1.25

It depends what you're working on. I'm restoring a 60s Olds and there are a lot of 3/8-24 fasteners where Chevy always used 3/8-16. In all of the diameters I've found lots of fine thread fasteners on Olds, and more coarse thread fasteners on Chevies. Go figure.

 

[jrobb316]

If you're working on new stuff, 6 x 1.00, 8 x 1.25, 10 x 1.25, 12 x 1.25, 12 x 1.50, 14 x 1.25, 14 x 1.5, 18 x 1.5

 

[CobraRed]

Necro bump

I seem to see a lot of standard pitch SAE and a mix of fine and standard Metric.

Anyone else?

 

[Dirty Diesels]

Most common SAE sizes would be 1/4"-20, 5/16"-18, 3/8"-16, 7/16"-14. For metric stuff the most commonly used is 6mm x 1.0, 8mm x 1.25, 10mm x 1.25

Plus metric 7mm x 1.0 inlet manifold bolts and 9mm x 1.25, for brake calipers! but these 2 sizes don't come in most sets and have to be purchased separately.

 

[CobraRed]

Are people seeing 12x1.25 or 12x1.5 more?

 

[AmishFury]

i see more 12x1.5 than 1.25

 

[leg17]

i see more 12x1.5 than 1.25

Wouldn't ignore these SAE fine threads in common sizes.
5/16-24, 3/8-24, 7/16-20, and 1/2-20.

The coarse threads are usually referred to as UNC.
SAE is the fine threads series.

 

[Jack84]

i see more 12x1.5 than 1.25

I see more M12x1.75 to be honest.

 

[bwringer]

M10X1.25 and M12X1.25 threads are common on Asian vehicles.

'Merkin and Euro generally use M10X1.5 and M12X1.75. (M12X1.5 pops up once in a while.)

Fortunately, M6X1.0 and M8X1.25 are standard the world over.

If you can, get an M10X1.0 "extra fine" -- it pops up once in a while for brake banjo bolts on Asian vehicles.



Inch **** rarely enters my world, but from what I understand you'll see it if you work on a lot of heavy equipment and farm machinery.

 

[Jack84]

M10X1.25 and M12X1.25 threads are common on Asian vehicles.

'Merkin and Euro generally use M10X1.5 and M12X1.75. (M12X1.5 pops up once in a while.)

Fortunately, M6X1.0 and M8X1.25 are standard the world over.

If you can, get an M10X1.0 "extra fine" -- it pops up once in a while for brake banjo bolts on Asian vehicles.



Inch **** rarely enters my world, but from what I understand you'll see it if you work on a lot of heavy equipment and farm machinery.

With the threads on Asian vehicles are you referring to the standard pitch according to JIS?

 

[CobraRed]

Anyone see M5x0.8's?

I came across one on an American car and was wondering if they are common now.

 

[T45]

M5 x 0.8 is a common fitment when using hex and torx bolts (4mm, t-25).

In standard hexagon, it's more on the rare side,

but a universal Iso/Jis/DIN fitment nevertheless (7mm wrench).

 

[Murphy4570]

Just buy one of everything, so you are covered. You will always have to work with the most oddball ****, I swear. Just yesterday I had to chase a motor mount nut, size 9/16-12 UNC. Not exactly a common size.

Most automotive fasteners are metric these days. Legacy stuff with old powertrains will have a bunch of standard fasteners.

 

[Astro_Pneumatic_Tools]

M5 x 0.8 is a common fitment when using hex and torx bolts (4mm, t-25).

In standard hexagon, it's more on the rare side,

but a universal Iso/Jis/DIN fitment nevertheless (7mm wrench).

DIN933 would call for a 8mm wrench on a hex with M5 threads if memory serves. 7mm wrench would be M4 threads.

 

[bwringer]

With the threads on Asian vehicles are you referring to the standard pitch according to JIS?

Yep. Specifically, Japanese and Korean cars and motorcycles generally use JIS standards.

 

[shootrj2003]

SAE fasteners have not been used on cars or light trucks in over 20 years.

Well for everything I work on I keep a set of metric and SAE taps dies AND wrenches AND sockets for,as well as Phillips,torx,slotted and every other tip available ,if I don’t have it,I will need it on the next job I start on. ( and I’m not a professional mech. By any means) oh and my gunsmith screwdrivers are about 85 different flat tips alone.Standardization was a great idea once,now it’s non existent. It’s good to be a blacksmith.

 

[bpwoodworking]

They seem to also very commonly use non-typical thread pitch. I assume the desire is propriety but it’s pretty frustrating at times.

 

[theoldwizard1]

SAE fasteners have not been used on cars or light trucks in over 20 years.

Well for everything I work on I keep a set of metric and SAE taps dies AND wrenches AND sockets for,as well as Phillips,torx,slotted and every other tip available ,if I don’t have it,I will need it on the next job I start on. ( and I’m not a professional mech.

I like messing around with old Briggs and Stratton engines. These are 100% SAE. I have full sets of SAE and Metric wrenches and sockets as well as taps and dies.

 

[WAID]

I like messing around with old Briggs and Stratton engines. These are 100% SAE. I have full sets of SAE and Metric wrenches and sockets as well as taps and dies.

That and the fact all of my vehicles are 20+ years old has me needing a good helping of both sae and metric.

 

[dchawk81]

It depends what you're working on. I'm restoring a 60s Olds and there are a lot of 3/8-24 fasteners where Chevy always used 3/8-16. In all of the diameters I've found lots of fine thread fasteners on Olds, and more coarse thread fasteners on Chevies. Go figure.

Oldsmobile is a finer product so it gets finer threads.

 

[VolvoRyan]

Plop onto Amazon and see what's in the basic Irwin-Hanson kits for metric and SAE. Stock up on those sizes. I've used all the metric sizes in mine.

-Ryan