Spark Plug Socket Drive Size

[_brian_]

Most of my spark plug sockets are 3/8 drive. I have 2, the 5/8 and 13/16 sizes, that I also have a 1/2 drive for. I have never used the 1/2 drive ones, I guess I just never found the need or reason to use them. My question is ... what and why do others use the 1/2 drive spark plug sockets for?

I understand that years back there was no 3/8 and it was 1/4, 1/2 and 3/4. In that scope, the 1/2 drive makes total sense. Given the fact that spark plugs are somewhat fragile, the only reason I can think to use a 1/2 drive socket is user preference. I wonder if there is a functional reason for the 1/2 drive.

 

[Badger 13]

Back in the mid 60's / early 70's, I would use my 1/2" drive on plugs. There was more room, and easier access then. Is was certainly easier breaking the plugs loose with the 1/2".

 

[BrandoJames]

Most of my spark plug sockets are 3/8 drive…I wonder if there is a functional reason for the 1/2 drive.

Given that most spark plugs have a torque range in “inch/pounds" instead of “foot/pounds”, It would be quite risky to use a 1/2” ratchet on spark plugs. Your chances of breaking that plug off in the block goes way up.

But it’s really no different with socket sets, where you see a 1/2” set going all the way down to small sizes like 10mm. No one in their right mind would use a 1/2” drive with a 10mm. But I’m sure there are rudimentary DIYers out there who only own one ratchet, so they want all their sockets in one drive size.

 

[sberry]

There is nothing wrong with using 1/2 on tight plugs. How is it more likely to break one with a larger drive? There are some things really backwards here. It's so much easier to use the larger drives especially on tight fittings vs trying to shove 3/8 guts in to a 1/4 ratchet. That is about as amateur idea as I have heard, .
I had helper a while back, fart 45 minutes with a 3/8 drive, 3 ft away is 1/2 that take 20 seconds to get and 15 to use withoutbending the handle and reefing the guts out of the small tools. I try to use the largest practical tool, not the smallest.

 

[KnurledNut]

Your chances of breaking that plug off in the block goes way up.

Head?

 

[BrandoJames]

There is nothing wrong with using 1/2 on tight plugs. How is it more likely to break one with a larger drive? There are some things really backwards here. It's so much easier to use the larger drives especially on tight fittings vs trying to shove 3/8 guts in to a 1/4 ratchet. That is about as amateur idea as I have heard, .
I had helper a while back, fart 45 minutes with a 3/8 drive, 3 ft away is 1/2 that take 20 seconds to get and 15 to use withoutbending the handle and reefing the guts out of the small tools. I try to use the largest practical tool, not the smallest.

So why not use a 3/4" AirCat on that spark plug, lol. "Largest practical tool" is really subjective, and spark plugs have a tendency to break. I think most guys here would start off using a 3/8" drive on spark plugs. But given your scenario, where one tool isn't doing the job--then it does make sense to move up to a stronger tool.

 

[BrandoJames]

Head?

Yes, thank you.

 

[DFB]

I've never even owned a 1/2" drive spark plug socket.

Mine are only 3/8" drive


Though I can understand the loosening leverage that can provided with a larger drive/bigger handle on a tight plug.

Ya that's what an adapter is for

 

[mr.lemons]

I don't understand how you are more likely to damage the plugs with 1/2 over 3/8. I think you have more control over torque with the longer handles on 1/2.

 

[tdkkart]

I don't understand how you are more likely to damage the plugs with 1/2 over 3/8. I think you have more control over torque with the longer handles on 1/2.

Because apparently if you're using a 1/2" drive ratchet you'll automatically try apply 200ft/lbs of torque to the spark plug?

How about using the longer 1/2" drive ratchet to get your hands out of the tight space and not chew all the skin off your knuckles?

 

[Nineeightyone]

I've been using 3/8" drive to remove spark plugs, and then for installation 1/4" drive since that was the only size I could get the recommended torque range in an inexpensive torque wrench. Normally I'll just get them snug, but working on a car I still owe money on, I've become a big fan of trying to do everything the right way.

Unfortunately finding a 1/4" drive spark plug socket hasn't been easy, so I'm still stuck using an adapter -- but given that there's a range of 8-10 ft-lbs, I set to 9 and hope that it's close enough. Can't be perfect everywhere, but I can sure as hell try.

 

[snapmom]

a snap on metric 1/2 dr plug socket

 

[sberry]

Sears tool sets used to come with 1/2 drive sockets.

 

[Mechanical Noise]

It usually takes more force to pull off a 1/2" drive socket as compared to a 3/8" drive socket. So, there was less chance of leaving the socket on the plug when pulling on the extension bar.

Now we have locking extension bars.

 

[Mechanical Noise]

Given that most spark plugs have a torque range in “inch/pounds" instead of “foot/pounds”, It would be quite risky to use a 1/2” ratchet on spark plugs. Your chances of breaking that plug off in the block goes way up.

The torque to remove a plug is much higher than the installation torque. I never heard of anyone breaking a plug off in the head while installing it. Removing it, sure. Installing it, never.

I've broken a few plugs but that was because I let the plug socket get cocked and I broke the insulator.

But it’s really no different with socket sets, where you see a 1/2” set going all the way down to small sizes like 10mm. No one in their right mind would use a 1/2” drive with a 10mm. But I’m sure there are rudimentary DIYers out there who only own one ratchet, so they want all their sockets in one drive size.

I used to use my 1/2" drive 10mm all the time. I didn't like to bring out extra socket trays if I didn't need them and I had a wide spread of 1/2" drive sockets. It wasn't crazy at all. Things are more cramped nowadays, so I'm using smaller tools.

 

[BrandoJames]

I used to use my 1/2" drive 10mm all the time. I didn't like to bring out extra socket trays if I didn't need them and I had a wide spread of 1/2" drive sockets. It wasn't crazy at all. Things are more cramped nowadays, so I'm using smaller tools.

On one of the tools sites (it may have been GJ), there was a "rule of thumb" posted regarding ratchet drive size: try to match the diameter of the fastener to the drive size. So that ratio would look something like this:

Under 10mm = 1/4" drive
10mm--14mm = 3/8" drive
15mm or over = 1/2" drive

The above makes sense to me. No one is going to send the tool police to your garage if you ignore it. For me, the main goal is to lower the risk of stripping a fastener.

 

[unslow1]

I have them on ratchets in the trunks of my vehicles for lug wrenches. They were never getting used anyway so I have a decent setup for changing tires. Unfortunately they got a lot of use this year.

 

[2ndGearRubber]

Given that most spark plugs have a torque range in “inch/pounds" instead of “foot/pounds”, It would be quite risky to use a 1/2” ratchet on spark plugs. Your chances of breaking that plug off in the block goes way up.

But it’s really no different with socket sets, where you see a 1/2” set going all the way down to small sizes like 10mm. No one in their right mind would use a 1/2” drive with a 10mm. But I’m sure there are rudimentary DIYers out there who only own one ratchet, so they want all their sockets in one drive size.

If you are talking about automotive plugs for cars/trucks, this is objectively false. Most range from 14-20 ft/lbs.

 

[rijndael]

There's a nice chart of plug torque here:
https://ngksparkplugs.com/en/resources/spark-plug-installation

 

[Mr Ratchet]

I have them in both 3/8" and 1/2" drive and use both. I mostly use the 3/8" drive but, it's nice to have options.

 

[Mechanical Noise]

On one of the tools sites (it may have been GJ), there was a "rule of thumb" posted regarding ratchet drive size: try to match the diameter of the fastener to the drive size. So that ratio would look something like this:

Under 10mm = 1/4" drive
10mm--14mm = 3/8" drive
15mm or over = 1/2" drive

The above makes sense to me. No one is going to send the tool police to your garage if you ignore it. For me, the main goal is to lower the risk of stripping a fastener.

Torque is proportional to force applied and handle length. A 3/8" drive ratchet with a 12" handle is going to give twice the torque with the same force as a 1/2" drive ratchet with a 6" handle. Drive size is irrelevant.

Yes, I do have ratchets which more or less meet those descriptions.

 

[Wrench97]

The torque to remove a plug is much higher than the installation torque. I never heard of anyone breaking a plug off in the head while installing it. Removing it, sure. Installing it, never.

I've broken a few plugs but that was because I let the plug socket get cocked and I broke the insulator.



I used to use my 1/2" drive 10mm all the time. I didn't like to bring out extra socket trays if I didn't need them and I had a wide spread of 1/2" drive sockets. It wasn't crazy at all. Things are more cramped nowadays, so I'm using smaller tools.

Just so you can't say that any more..............I had a new hire fresh out of tech school break a new plug off in a Nissan H20 forklift engine about 20 years ago. He denied it but there was a 1/2" impact gun on the lift when I got there..........................................

 

[jgromada]

i could imagine a scenario where you have an old plug and its really, really stuck. Generally speaking the 1/2 drive comes with large ratchets and you can get more torque to remove.

But putting one on, i would never use anything other than a 3/8 in

 

[M6erfan]

On one of the tools sites (it may have been GJ), there was a "rule of thumb" posted regarding ratchet drive size: try to match the diameter of the fastener to the drive size. So that ratio would look something like this:

Under 10mm = 1/4" drive
10mm--14mm = 3/8" drive
15mm or over = 1/2" drive

The above makes sense to me. No one is going to send the tool police to your garage if you ignore it. For me, the main goal is to lower the risk of stripping a fastener.

Unless I'm misunderstanding something, according to the list above, 3/8" drive is good for all of 5 socket sizes???

 

[davethorik]

Unless I'm misunderstanding something, according to the list above, 3/8" drive is good for all of 5 socket sizes???

In a theoretical world where you don't know what you're talking about, where spark plugs go into blocks, yes. 5 sizes. Maybe less.

 

[BiggityBen]

On one of the tools sites (it may have been GJ), there was a "rule of thumb" posted regarding ratchet drive size: try to match the diameter of the fastener to the drive size. So that ratio would look something like this:

Under 10mm = 1/4" drive
10mm--14mm = 3/8" drive
15mm or over = 1/2" drive

The above makes sense to me. No one is going to send the tool police to your garage if you ignore it. For me, the main goal is to lower the risk of stripping a fastener.

lolwhut

 

[M6erfan]

In a theoretical world where you don't know what you're talking about, where spark plugs go into blocks, yes. 5 sizes. Maybe less.

I freely admit that I may not know what I'm talking about, but in my world it's more like this...

<15mm = 1/4"
10-24mm = 3/8"
14-32mm = 1/2"

Now keep in mind that I work a lot with vintage motorcycles and aluminum threads so I run into relatively large fastener heads that are fairly low torque.

Anyway, I've never owned a 1/2" drive SP socket. But then again, I don't work on Ford Tritons either...

Edit: Almost forgot, I recently added a 26mm socket to my 3/8" drive arsenal.

 

[BrandoJames]

I'll try to make a few friendly replies below:

1. Typically spark plugs have a relatively low torque spec and are often published as inch/pound. That doesn't mean every spark plug spec is in inch/pound. The Chilton & Haynes repair manuals I'm familiar with usually list spark plug torque spec in inch/pounds. I'm sure it depends on the vehicle & whatever publication you're using.

2. Ratchet drive size isn't irrelevant just because you're using a longer handle on a smaller drive size. That's cherry-picking. One needs to compare like-to-like: Use the same size handle on both a 1/2" drive and a 3/8" drive. It's not just the handle generating torque (twisting force). The larger 1/2" anvil is also turning.

3. The 10mm--14mm range for a 3/8" ratchet covers the most widely used fasteners in my experience. The range is arbitrary of course, a "rule of thumb" as stated earlier. The 1/2" range for hand ratchets is fairly limited--anything above 17mm usually means impact for me. Not sure why people are getting upset--you can use your 3/8" ratchet on lug nuts if you want.

 

[az45]

I've never broken a spark plug when the when the socket was on straight, only when its at an angle and I'm not paying attention. I usually grab a 3/8 rig with a swivel..if all I had was 1/2 I think could make it work.

Its user error if you f up using to big or too small of a tool...hand tools usually don't break many things without assistance.

The exception of course is that if the tools are anything but Snap-on, they shouldnt be trusted

 

[M6erfan]

I'll try to make a few friendly replies below:
...
Not sure why people are getting upset--you can use your 3/8" ratchet on lug nuts if you want.

Who's upset?

Anyway, when talking fastener head size, are you referencing JIS, DIN, ANSI? It can make a difference. For instance an M10 bolt, the head size can be 14mm, 16mm, or 17mm. Would you use 3/8" drive on a JIS 14mm M10 and go up to 1/2" for the DIN 17mm M10? Of course not, the important part is that it's an M10. What about "small head" JIS fasteners? Pretty common with motorcycle hardware.

I try to use common sense and typically use the rule of 2x the drive size. Which would be 1/4" (6.35mm) drive up to 13mm, 3/8" (9.5mm) drive up to 19mm, 1/2" (12.7mm) drive up to 27mm.

Of course none of this matters as far as stripping threads. I can strip threads on an M10 easily with any of the 3 drive sizes.

 

[joel63]

I freely admit that I may not know what I'm talking about, but in my world it's more like this...

<15mm = 1/4"
10-24mm = 3/8"
14-32mm = 1/2"

Now keep in mind that I work a lot with vintage motorcycles and aluminum threads so I run into relatively large fastener heads that are fairly low torque.

Anyway, I've never owned a 1/2" drive SP socket. But then again, I don't work on Ford Tritons either...

Edit: Almost forgot, I recently added a 26mm socket to my 3/8" drive arsenal.

What use did you find for a 26mm? Just wondering.

 

[_brian_]

[/COLOR]

What use did you find for a 26mm? Just wondering.

inner tie rod end on Envoys/Trailblazers is what I hear.

 

[Mechanical Noise]

Just so you can't say that any more..............I had a new hire fresh out of tech school break a new plug off in a Nissan H20 forklift engine about 20 years ago. He denied it but there was a 1/2" impact gun on the lift when I got there..........................................

Well, now I've heard it all! At least for the time being.

 

[Mechanical Noise]

2. Ratchet drive size isn't irrelevant just because you're using a longer handle on a smaller drive size. That's cherry-picking. One needs to compare like-to-like: Use the same size handle on both a 1/2" drive and a 3/8" drive. It's not just the handle generating torque (twisting force). The larger 1/2" anvil is also turning.

Torque is force times distance to the pivot point. It's the bolt that pivots on it's centerline. The centerline is going to be the same regardless of the size of the drive.

 

[M6erfan]

[/COLOR]

What use did you find for a 26mm? Just wondering.

Front sprocket holding nut (motorcycle). Torque value is 60 lb-ft. I have a 1/2" 26mm but I wanted a 3/8" drive to cut down on the tools I bring to the track. And my 3/8" torque wrench goes to 100 lb-ft.

 

[Two Speed]

I may get roasted , but taper seat plugs; +1/8 turn after touch down. gasket seat plugs +1/2 turn. Who cares what the drive size is.

 

[DGersic]

I have both 3/8” and 1/2” drive spark plug sockets. I don’t know why. I don’t remember getting the 1/2” drive sockets, and can’t recall ever actually using them.

A 3/8” ratchet or breaker bar, a half dozen extensions, and a u joint, and I can reach any spark plug I’ve needed to.



Sent from my iPad using The Garage Journal mobile app

 

[joel63]

Front sprocket holding nut (motorcycle). Torque value is 60 lb-ft. I have a 1/2" 26mm but I wanted a 3/8" drive to cut down on the tools I bring to the track. And my 3/8" torque wrench goes to 100 lb-ft.

Thanks.

 

[Semi-hole mechanic]

Growing up we never had 3/8 drive sockets and I still have the 13/16 in a 1/2 drive even though all my others are 3/8

 

[Semi-hole mechanic]

Forgot to mention that Ive only ever broke one spark plug and it was with a 3/8 drive ratchet in a 3.8L V6 in a Taurus.