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What is “M” socket in service manuals’ M8,M10? Is it a torx?

21K views 34 replies 15 participants last post by  r0ckrat 
#1 ·
I am confused about what is “M8” or “M10”. In bike manual all sockets referred as “M”: M8,M10. Visually they have 6 sides like torx.
In the shop those with six sides are Torx and they dont even go down to 8 size.
And what is called “M” at hardware shop is having like 12 sides, not 6!

so confused. I got 3/8 wrench and socket set 8 to 19 mm. What do I need to buy to work on a bike?

 
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#2 ·
M6, M8, M10 etc are the thread sizes of metric bolts/screws. Often they are marked up as M8x20, or M8x30 or M8x40 etc. This is means it's a metric bolt 8mm thick with a 20/30/40 shank (length). If it has a smaller number associated with it this is the thread pitch. So a M10-1.25 x 50 is a fine thread metric 10mm bolt 50mm long. The head size is usually the width of the head of the bolt in mm, bolts are usually 6 sided. The drive size of the socket to fit these is given by the size of the square end of the ratchet spanner or torque wrench, it either 1/4" square or 3/8", 1/2" or 3/4" (which is way too big for a bike). Allen heads are measured by the width of the hole in the top of the bolt in mm. Torx tips have their own mysterious sizing but are star shaped and used throughout the BMW range. Hope this helps.
 
#3 ·
The M might be a size designation for the Torx “screwdriver” configuration. Since it isn’t SAE or metric (inch or mm), they just number them from 1 to .... (I think my largest is 45).

However, I thought it was T1 ... T45. So, maybe M means metric in mm? What kind of bolts are you working on that it uses a M designation?
 
#4 ·
Another thought. Without a picture to go by but only your words, it may be about Allen wrench size...which comes in SAE and metric. M6 could mean a 6mm Allen wrench. These tools come in individual sized and socket sets.
 
#7 ·
You need Torx (T) rather than spline (M) bits. M can also refer to the diameter of the threaded bolt shaft (M8 is 8 mm etc, as mjgt said).
In 3/8” drive you’ll need T40, T45 and T50.
You’ll also need a set of Torx keys (like Allen keys, but Torx rather hex).
I also frequently use 1/4” hex drive Torx bits with a Kincrome mini ratchet handle. Mainly T25, but sometimes T40.
Also a 13mm hex socket and (for the front axle, and adjusting the steering) a 12mm hex bit.
And usual non-specialist workshop tools.
 
#8 ·
Just to muddy the waters a bit more, the set of female TORX bits I have are labelled E (4 to 20).

108689



108690
 
#9 ·
@Kramer - 95% of all fasteners on the BMW are Torx. You don't need every size there is, but you do need basically all sizes, in increments of 5, from T20 through T50. They come as rachet driver bits, screwdrivers, and "keys" (like hex keys, but Torx shaped). You will want the larger sizes as rachet driver bits, and possibly some of the medium sizes as well. Medium and small, either as screwdriver or key, or both.

One way to tell what you will need the most is to walk around the bike, look at it, figure out the types of things you are going to be doing, and what type of tool will be the easiest to use on that location. You can always go back and buy additional tools as you need them...
 
#17 ·
Given the initial confusion over M (spline), I decided to muddy the waters ever further, with an international je ne sais quoi ;)

Where I live, the 'socket' is normally the cylindrical body, with a square drive hole (1/4", 3/8", ...) on one end for the handle, normally but not always a ratchet wrench, and something at the other end that will turn threaded things, whether nuts (hex, Torx, spline, ...) via a suitably shaped opening, or bolts or screws via an affixed 'bit' - Torx, Spline, Hex, ... To further confuse things, normal sockets used to remove hex nuts or hex-head cap screws are just called 'sockets'. I'm old enough to have been working on machines in the dark ages before the metric became a mandated thing, so I also have a fair collection of imperial sized wrenches and sockets. Rarely used these days, but every once in a while something shows up.

As I said, muddying the waters. Three drawers of my tool cabinet are allocated to the !&^@%&!@ things. I even have a few impact T-bit sockets in larger sizes that are all one piece; the 'bit' and the body are made of a single piece of chrom-moly steel. Take the mounting bolts out of your rear wheel in milli-seconds, NASCAR style. For when you absolutely positively need to get to Starbucks right now! Or because when you needed a specific larger size, impact was all that was available at the hardware store :)
 
#18 ·
I also have a fair collection of imperial sized wrenches and sockets. Rarely used these days, but every once in a while something shows up.
...impact was all that was available at the hardware store :)
Sometimes these coincide - I have a 1-1/4" impact socket as a 32mm anything was not available, and the bike was my only vehicle... The repair had to be done before EOD Sunday, and nothing else was available... (I think this was for the front sprocket nut.)
 
#20 ·
Being brought up on a steady diet of Japanese motorcycles, my 'normal' was the standard hexagonal bolt head, or on reasonably rare occasions, an Allen headed (hex) head bolt.

I used to look at the Torx fittings on BMWs etc with some trepidation and think they were 'a bit weird'. But now I am a total convert for these types of fasteners. Taking care to use the right Torx bit for the job, I've never yet munged one up trying to get it undone. Can't say the same for Allen head fasteners though... Until this thread, I wasn't consciously aware of the E(external) Torx headed bolts. As they say in the classics, 'every day's a school day'! Thank you for the enlightenment.
 
#28 ·
I'm not sure how serious a mechanic the OP is, or how many tools he already has. But if he is not planning to do any major repairs and maintenance on his BMW and doesn't already have a significant tool investment, I would start with a 1/4" drive socket set like this one:
Proxxon (23080) 36 Piece Socket Set with 1/4 inch Square Drive
Add a set of metric combination wrenches: Crescent 10 Pc. 12 Point Metric Combination Wrench Set - CCWS3
and a couple different kinds of pliers: AmazonBasics 3-Piece Pliers Set

You will be able to accomplish a lot of routine disassembly and repairs. You will probably add some individual specialized tools as time goes on - like a T50 wrench for the back wheel lugs: BMW T50 TORX REAR WHEEL WRENCH, and one for the front axle: 22-19MM HEX BMW AXLE ADAPTER TOOL - R1200 AND F800. Oil filter wrench and a couple of additional combination wrenches will round out your tool box.
 
#29 ·
@cpallenjr the only hex heads I've found on the bike are the mirrors (the under-seat tool kit has this covered), the brake bleed nipples (ditto for the front, but an 11mm is required for the rear, oddly) and the muffler clamp and brake caliper mounting bolts. Given a torque wrench is required for the caliper bolts, a 13mm socket is required and a 13 mm wrench for the muffler clamp (although a 13mm deep socket would cover both).

The front axle adapter you specify isn't actually needed for the LC – the axle is tightened using a 12mm hex shaft socket on the RHS and I've not found it necessary to grip the axle with a tool to stop it turning. My F800 axle unscrewed from the LHS using such a tool, so it was essential.

As a general point about how serious a mechanic the OP is, a Roadster is a pretty significant investment for most of us and whilst maintenance is fairly straight forward, I'd suggest it's not the bike to learn on unless you approach tasks meticulously, have a good mentor on hand, and read and understand every step in the maintenance manual before commencing any maintenance task. Haynes manuals have a lot of generic information in preliminary chapters (or is it at the end) which should be studied if one is a newbie. Just sayin ...
 
#30 ·
One lives and learns, T! The day one doesn't learn something new is the day one is dead. My understanding of the evolution of the TORX fastenings is that they were developed to make automatic insertion, torquing, etc., of such fastenings as the bike progresses along the production line more 'automatic' and with less damage - in other words, I guess, a productivity and quality gain.. Apparently the air-driven automatic tools engage better with TORX heads than with their predecessors. I like e'm, and have a good range of Torxs (if that's a word!).
 
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#31 ·
I am confused about what is “M8” or “M10”. In bike manual all sockets referred as “M”: M8,M10. Visually they have 6 sides like torx.
In the shop those with six sides are Torx and they dont even go down to 8 size.
And what is called “M” at hardware shop is having like 12 sides, not 6!

so confused. I got 3/8 wrench and socket set 8 to 19 mm. What do I need to buy to work on a bike?

You are not alone. I purchased some parts requiring a tool for a M8 bolt which translates to 13mm, but that does not help find the tool. The T-45 socket or T-handle wrench fits this torx shaped bolt. ( I had to take my part to Auto Zone to test fit. They Had one left thank goodness. My under seat tool kit only had a T40 90 degree wrench...so I bought the T-45 socket which fits my 3/8" socket wrench and it worked. for the M8.:) I see you have a Torx set that includes the T45.
 
#34 ·
Since I didn’t see this cleared up, the OP’s original post here in this thread shows a male spline drive socket in the RH photo. So, for clarity, these configurations exist. I have al of them in all drive sizes in my toolbox, not that they are all used on these bikes but all are found in vehicle applications.

-Torx (6 point star male) (T10-T60 is a common range)

-Torx-Tamper Resistant (male; identical to Torx but a recess at the tip to fit a fastener used in places where Antifa likes to steal stuff) (TR10-TR60 is a common range)

-E-Star (aka External Star, which refers to the fastener’s configuration) (6 point female; inverse of Torx) (E4-E20 is a common range)

-Spline drive
(12 point male-like a double torx configuration)
(12 point female-like a double E-Star configuration; atop a spline fastener, this has the distinction of also clearing any of the other fasteners here including square and 12-point; even acts to support removing a bolt that’s rounded off so a good easy-out alternative)
(4mm-20mm is a common range for both)

-Hex (aka Allen) (6 point hexagon male) (SAE sizes (e.g., 1/4”, 3/8”, etc) and Metric sizes (e.g., 6, 8, 10, etc)
 
#35 ·
-Torx-Tamper Resistant (male; identical to Torx but a recess at the tip to fit a fastener used in places where Antifa likes to steal stuff)
I am going to say this once, and will then forever keep my trap shut.

"Antifa" is short for "Anti-Fascist". I.e. against dictatorships and racism. For instance, the Nazi regime was a fascist regime, and all of the Allies (France, Great Britain, the United States, the Soviet Union, and, to a lesser extent, China) were antifa at the time.

Definition of fascism

1: often capitalized : a political philosophy, movement, or regime (such as that of the Fascisti) that exalts nation and often race above the individual and that stands for a centralized autocratic government headed by a dictatorial leader, severe economic and social regimentation, and forcible suppression of opposition.
2: a tendency toward or actual exercise of strong autocratic or dictatorial control - "early instances of army fascism and brutality" — J. W. Aldridge
 
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