Why Torx?
 

Why in the name of all that is sweet and holy, did they decide to use Torx over allen heads on rotor bolts? I have wondered this forever, and anyone who has ever owned a Chrysler can understand why Torx absolutely sucks. Any good reason for this?

Good question..

The torx is the evolution of the allen style. I prefer it, altho it is annoying to have two styles of almost the same wrench.

This is the third time I typed this. The backspace function, as it relates to a webpage is far more annoying than any silly bolt/nut/capscrew design.

its a consprisy with brake makers and torx bolt makers to take over the world

They will need to get in line, i think the cell phone guys have the jump.

I think Torx are fine as long as you have the proper tool for it. Otherwise, I curse like a sailor...and then some.

They are so horrible though... if you look at them cross-eyed, the head strips. The bits wear out after a few uses sometimes (one of my friends is a custom 4x4 fabricator and goes through extremely high grade Torx sets like nothing working on Jeeps). Actually my first exposure to Torx was in the 4x4 world, and if you ask any Jeep owner about Torx, guaranteed you get an eye roll and groan. Its a painful subject for most. I absolutely cannot see how Torx improves on any way from an allen key. The heads on the screws for most rotors are so shallow that you wind up slipping the bit a few times in the torquing process. Can you tell I HATE Torx? Thanks to Chrysler, I have 4 Torx bolts on my Mitsubishi, and hey, guess what? They are all stripped out! Once the bolt rusts, if it has a Torx head, its gone... the bit will just tear the head apart.

Rant over. For now.

you need the exact torx size bit, or your completely ****ed

Thanks for speaking out. I always wonder the same thing since frist time I saw those but afraid to ask because there is some good reason that I don't know. I'm glad to know I wasn't the only one. Hex wrench works for me. I'll avoid torx as much as I can.

Raiyn, I have found the exact opposite of all 3 of those points to be true... I just don't get it.

Hey Rev

Did you notice Jon Stewart was absolutely LOSING it?

Its not just Chrysler that is crazy about Torx; many cars are peppered with these fasteners these days. I have been told they are favored because they are suited to robotic assembly techniques. Can't see that being a big factor for bike, except for some low-end mass produced models.

Joe

Anyone who worked on military aircraft instruments back in the day would remember screws that had "hex spline" heads. These were basically a six sided spoked kind of pattern. They were commonly used on the little knobs that adjusted (whatever) on the gauges. The big problem with these was that the tools would strip with just a thought at times. Torx ended up as a kind of cross between hex spline (there were 4_spline and 5_spline, too) and what's commonly called an Allen hex head. The big advantage to Torx (over hex Allen) is that there is substantially more surface contact between the tool and the fastener (as Raiyn alluded to). It's the same as when you hear "the distance between Oregon and Mexico is 400 miles, but the California coastline is actually 2500 miles long". I'm just guessing at those numbers, but we've all hear those kind of stats and said "huh?".

If Torx fasteners are not overtorqued when installed, you should never have a problem with stripping the heads. Yet one more reason that most people should use a torque wrench. The two major causes of fasteners getting stuck are overtorquing and not lubricating the threads. You see it hammered home almost daily on this forum. You need to grease (or use anti-seize paste) just about every fastener and mating surface on a bike. If you don't, expect problems down the road.

Another thing that a lot of people seem to miss is that if you Loctite something and it gives you a difficult time coming out, take the time to heat it up for a couple of minutes with a hair dryer or heat gun. Alternatively, there are release agents available for threadlockers, but they are nasty chemicals and heat works just as well. This will save you a lot of stripped tools and fastener heads. For people that don't have a lot of experience with using Loctite, it's very important that you match the strength of the Loctite to the size of the fastener. If you put 270 on a 4/40 or 2mm screw, that is no good. If you did not understand that last sentence, then you need to either seek advice when using threadlockers or spend the time to learn what threadlockers match what fasteners and applications. It's ain't rocket science, but you have to take the time to learn the correct matches and applications for this stuff. If you get it wrong, plan on plenty of stripped fastener heads and tool bits (and the accompanying frustrations).

Sorry about the tangents, but alot of this stuff is related. Experience mechanics can often get away without the torque tools, but a good example of why you should use them is stated in Gerd Schraner's book. He states that after years of building wheels with no tensiometer, he was surprised at how inconsistent his own work was when later checked with a calibrated tool. Anyone who does not use torque tools, and starts to, will find out the same thing.

One thing that I will absolutely guarantee you about Chrysler, or any other big manufacturer, is that they are using torque-limited drivers to install these fasteners. All of this is motivated by TQC (total quality control) or some other form of statistical quality analysis, and, the ergonomics of repetitive motion for the assembler.

True, The torx is a metric only size, it is the evolution of the phillips tip and allen head.
I threw all my slotted screws away a long time ago.

TORX screws are available in standard sizes also, not just metric.

I believe there is only one set of actual driver tools though, that's what I meant, not thread sizes.

On paper, it makes sense, but in the real world, they suck.

If you guys have touble with Torx, I'd hate to see what you do with conventional phillips! Actually, a Flat Blade, Phillips, and Allen will all fit a Torx head.

I don't know what torx are, but I'm guessing theyre the star shaped bits, like the ones that hold my disc rotor in?

exactly

This also holds true for allen head bolts!

If this is true, this would be the biggest advantage by far. I don't know much about Torx because I have never used it. It maybe worth looking into.

From the Newman Tools website:

Get The Wiha TORX Advantage.

TORX requires no insertion pressure for driving and no cam out forces are generated.
TORX has axial power transmission areas, Tools don't slip. Reduces possibility of distorted screws.
Wiha TORX has 6 large torque transmission surface areas that allow for higher sustained torque forces.
Wiha TORX has 15 degree efficient drive angle Tools and screws won't become distorted. better screw to tool contact.
Wiha TORX profile is precision machined for an exact fit and long tool life.
Smooth rounded edged reduces possibility of damage to parts or assemblies