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Metric, SAE, Tor-ex...why oh why?

splitz

splitz

NAXJA Forum User
Location
Nola
I am in the process of lifting my XJ, and have come to realize that there are a veriaty of bolt standards used on the vehicle. On the rear leafs it is 18mm, on the front LCA's it is 13/16", and the UCA's it is 15mm. Not to mention the different Tor-ex bolts located around the vehicle, seat belt (ok, that's pretty standard), front clip, sway bar links (which aren't even a real bolt...its wedged in there), and others I'm sure I'm going to come across.

Does anyone know why Metric and SAE are being used? Or am I just using the wrong socket for the job?

Oh, and what's with the Tor-ex thing! I hate Tor-ex. Chrysler seems to love using them, cuz they are all over my buddies' TJs & YJs!
 
Torx are used because robotic assembly line machines can grab them, hold them while moving and install them without dropping them. Thats the only reason.
 
Global Economy, the sub-components come from all over the world and we are the only one that still sticks by the old "Standard" measuring system, while the rest of the world is "Metric".

I never knew that about Torx and Robotic Assembly, why is a torx easier to grap by a robot than a hex head?

I've seen an increase in Torx Fasteners on all types and makes of vehicles, NOT just Jeep or Chrysler, but I'm NOT a mechanic, someone else may have a better informed opinion. The increase in Torx Fasteners because of Robotic Assembly makes perfect sense though, I'm just curious why Torx is better than others for a Robot.

We should have taken the Metric Plunge Long ago. Instead of phasing it in, just switch, sure people would be confused for a few months, but they'd learn.
 
Rick Anderson said:
I never knew that about Torx and Robotic Assembly, why is a torx easier to grap by a robot than a hex head?
Click to expand...

More surface area for grabbing and holding, ever watch a robotic arm, instant stops and starts, less prone to wobble and being thrown off.
 
RichP said:
...less prone to wobble and being thrown off.
Click to expand...
I'm getting the picture now, in fact, I've noticed Torx Head Bolts seat into the socket better and do NOT tilt, i.e. they perfectly line up in direction with the socket. A hex head can easily tilt at least a few degrees. Tough for a robot with one arm to insert a bolt if tilts and is NOT lined up with the robot arm.
 
I didn't know that 13/16 = 21mm or that Tor-ex is easier for robots...you learn something everyday :)
 
1" = 25.4mm

13/16" * 25.4mm per in = 20.6375 mm probably within tolerances, might be a tight fit over the bolt head.

3/4" * 25.4mm per in = 19.05 mm I have never had a problem interchanging 3/4" and 19mm sockets/bolts its so close both will work perfectly. 3/4" or 19mm is the size of the lug nuts on the XJ and most cars.
 
We strip them out all the time. That or it's impossible to keep the bits from wearing.
I'm not a fastener engineer, but it seems to me that torx are great for an occasional use type fastener, but not for something that you constantly take apart and put back together.
 
Its Torx not Tor-ex.

"By design, TORX head screws resist cam-out better than Phillips head or slot head screws. Where Phillips heads were designed to cause the driver to cam out, to prevent over-tightening, TORX heads were designed to prevent it. The reason for this was the development of better torque-limiting automatic screwdrivers for use in factories. Rather than relying on the tool slipping out of the screw head when a torque level is reached, and thereby risking damage to the driver tip, screw head and workpiece, the drivers were designed to consistently achieve a desired torque. Textron claims this can increase tool bit life by ten times or more." http://en.wikipedia.org/wiki/ISO_10664
 
They started to change over to metric in the late 70's, but rather than switch completely they made half the fasteners metric and half standard.
Must have been inspired by the tool manufactures cause now you have to have rwo complete sets of tools.
 
Including hammers? Where do I find a metric hammer?

I know what your saying, its frustrating that you have to double up on most of your tools, BUT its a little less than 2 complete sets.

You have to chuckle a bit, when you realize that METRIC socket sets come in 1/4", 3/8" and 1/2" drive sets. Lol
 
I've seen metric sockets in up to 1" drive - and they probably have larger.

I don't see socket drive nubs converting to 6m/m, 10m/m, 19m/m, ... anytime soon - although FACOM has a new-ish "cross-drive" that is supposed to support more torque, while still being able to work (somehow - haven't seen the info in a while, so it's just a memory tickle...) with conventional square drive sockets.

Of course, if they ever do, there will not only be a HUGE hue and cry from mechanics, but you can bet on huge tool shortages for a couple of years, and (if they're reasonably smart...) you should be able to swap in your old stuff for a discount on the new.

Be glad they managed to standardise the "foot" tho - it used to be the length of the foot of the sitting King (under English law) and property lines and standard measurements were subject to change every twenty to fifty years or so...
 
Another reason Torx is used, the drivers are universal there is not a metric or an imperial measurement standard. The head will be sized as T-10 T-20 etc. as a technician if every manufacturer used torx head fasteners we would only require one set of tools no matter the nation the device was made in. So torx tools could drive metric or imperial sized fasteners. The subassemblies can be built to any standard and we would all have the tools required.
 
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