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How do you figure out the diameter of a bolt from the Service Manual?
Oh man I feel like I'm going to get flamed on this one. But how do you figure out the diameter of a bolt by looking at the Service Manual? I see it shows the length and pitch I believe but how do you decipher the diameter so you can grab the correct spanner or socket the first time (every time)?
Since I got a house last year with a garage I finally get to tinker and do my own repairs, but find myself having to grab 4-5 spanners or sockets for every single bolt since I can't figure out the size just by looking at it.
Would love to speed up my work flow, efficiency, accuracy and organization and feel this would be huge to understand.
Short answer, you can't. Thats not how bolts are specified.
Bolt specs for bolt diameter are for the shaft, where the threads are. Tool needed is irrelevant to specs. You use the tool that fits. Certainly Honda specifies this so they can make manufacturing simpler. But its not part of specs when you are sourcing your own fasteners, and its not stated in service manuals.
In a diy when someone says...then there are four 12 mm bolts... They are using a sort of shorthand. The bolts are NOT 12 mm (the bolt shaft is likely significantly smaller), but that is the tool you need to remove them, which is what is important to the reader. So we say it that way, when that is technically the wrong way to say it.
On our cars there are only a few sizes commonly used. 10, 12, 14, 17, 19 mm. There are a few 8 mm, and some larger than 19 (diff drain and fill bolts), but for most things you will do its those few.
You can usually guess between two sozes fairly easily. If its small, its either 10 or 12. If its large its 14 or 17. If its XL its 17 or 19. Usually you can get away with grabbing whichever two and you'll have the one needed. After a while you get real good at getting it spot on at a glance.
the manual specifies the torque and HEAD(socket) size
the item location chart in the manual list refers to the parts catalog section, reference the part number, the bolt size is listed in the listing name of the part number on any honda parts catalog site.
In addition to the service manual, I have a full parts catalog. I refer to the parts catalog if there is a question in my mind regarding M8 and M10 bolts because two pitch specifications are used for them. It it says that it is 0.8 pitch, I assume that it is M5 or M4. If a 1.0 pitch, then I default to M6. But, M8 are either 1.25 or 1.5 pitch while most M10 are 1.5. So, I either sort it out visually or refer to my parts manual.
If there is a question on my mind after a parts manual reference is obtained, I will go to one of the online vendors to find the bolt because they list them there by bolt diameter and length but without pitch.
Here's an example of the online designation of fasteners for the transmission case from my usual online vendor. If you look up the part reference number you will see that diameter and length.
Close to all the bolts on our cars use metric size threads, like M6 M8 M10 M12 M14.
So when you look at the manual or parts diagram above and it says 6x15 that is a M6 threaded bolt that is 15mm long.
The usual (there are very few exceptions) socket size on respective bolts are:
M6 10mm
M8 12mm
M10 14mm
M12 17mm
M14 19mm
Close to all the bolts on our cars use metric size threads, like M6 M8 M10 M12 M14.
So when you look at the manual or parts diagram above and it says 6x15 that is a M6 threaded bolt that is 15mm long.
The usual (there are very few exceptions) socket size on respective bolts are:
M6 10mm
M8 12mm
M10 14mm
M12 17mm
M14 19mm
You sir, are a genius! This is exactly what I'm looking for, and will put this on a post it and stick it to the wall in the garage. So I can go from looking in my manual, glance up to check the chart and reach the correct tool and then move on, this will help with my needs of : work flow, efficiency, accuracy and organization.
The other suggestions although helpful require too much computer cross checking work unless there are some unusual details about that part. Considering when in in the garage, with dirty hands, typing on a phone or laptop to find the bolt size will take longer then grabbing a handful of tools and just trying to figure it out.
You sir, are a genius! This is exactly what I'm looking for, and will put this on a post it and stick it to the wall in the garage. So I can go from looking in my manual, glance up to check the chart and reach the correct tool and then move on, this will help with my needs of : work flow, efficiency, accuracy and organization.
The other suggestions although helpful require too much computer cross checking work unless there are some unusual details about that part. Considering when in in the garage, with dirty hands, typing on a phone or laptop to find the bolt size will take longer then grabbing a handful of tools and just trying to figure it out.
Useful info indeed.
This only works for JIS bolts. Most metric bolts don't work on that relationship.
So as long as you are using factory (or JIS replacement) bolts of the same grade and head type, it will work.
This only works for JIS bolts. Most metric bolts don't work on that relationship.
So as long as you are using factory (or JIS replacement) bolts of the same grade and head type, it will work.
Lucky for me I only use OEM bolts and bits. And God bless you for knowing what JIS is. So many poor little rotor and MAP sensor screws would be saved if folks used a proper JIS impact and JIS standard screw driver set.
12-05-2018, 11:05 PM
How do you figure out the diameter of a bolt from the Service Manual?
