Tool Talk
What's-It Forum => What's-It Forum => Topic started by: EVILDR235 on May 29, 2015, 03:40:55 PM
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I know about clutch head screwdrivers used on GM cars and trucks in the 40s and 50s. I have owned many old Chevies with them. Recently i have bought several screwdrivers that somebody called the new style clutch head screwdrivers. They are like a plain everyday driver except they have a straight blade with a round post in the middle. What is the story about them ?
EvilDr235
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If I under stand correctly your talking about a tamper resistant screw. Could that be it?
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Like this
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It has a blade like a straight tip screwdriver that one would use to drive wood screws, but in the middle of the blade it has a round section. i read that is the type of screwdriver that is made for clutch head screws. My grand daughter is not here right now or i would have her post a picture.
EvilDr235
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Like this
These are called tamper-resistant TORX.
Clutch type screws have a drive hole that looks sort of like an hourglass. These are the bits for them.
http://www.vintagetrailersupply.com/Clutch_Head_Screw_Bits_p/vts-578.htm
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There are two types of clutch head type A and type G. You sound like you are describing type A.
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They have the one-way clutch head used in many restrooms, & the clutch head types (like an hourglass)..
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bill300d has solved the puzzle. It is clutch head type A. I have several of the drivers, but have never seen one of the screws. maybe now i can sleep at night. Thank you bill300d for solving the puzzle.
EvilDr235
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I have a couple of type A drivers and have never had a need to use them. Then again I've never seen a fastener with a type A head on it that I can remember.
bill
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Some Mobile homes use clutch heads on the siding
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Wow guys you are pretty smart,
What I learn here never seizes to amaze me.
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After a lot of years I am firmly convinced there are more types of security screws than there are security screwdrivers. I have at least 3 "COMPLETE" according to the salesman, sets of security screwdrivers, and still find screws I don't have a driver for.
Hang in there Nola, I got a number of years on you and I still learn new tings almost every day.
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Yea If your not learning something new every day no matter what it is your your not paying attention.
bill
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Check this site out... everything you ever wanted to know about screw drive bits. I opened the page at the little known "Fearson" bit, not to be confused with Philips.
http://apexbits.com/apex-frearson-reed-and-prince-screwdriver-bits.aspx
Joe B
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There are two types of clutch head type A and type G. You sound like you are describing type A.
I found this old thread by doing a search on clutch head drivers. I’ve had this Apex driver for a long time and now I know a little more about it. Thanks, Bill!
-Don
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Shall be talk about Reed and Prince screwdrivers or JIS screwdrivers. Maybe we need a screwdriver forum ?
EvilDr235
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Here are some of the more common style of clutch head drivers. The upper Xcelite has a reversible shaft. Thanks for starting this thread back then.
-Don
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this style was popular for carmakers in the early 50's.
not sure why and they faded out by the mid fifties.
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If you ever go into a Thruway rest stop look at the bathroom toilet stalls. Most have the clutch style fasteners.
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GM was the auto maker who used clutch head screwdrivers. I guess they thought it would keep car / truck owners from working on their own vehicles. A person could use a regular slotted screwdriver on clutch head screws. I must own 20 clutch head screwdrivers and not a single screw that they fit. I was real sick 8 years ago and sold my 56 Chevy sedan that I had owned for 34 years and all the related parts.
EvilDr235
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I think the clutch heads were just an experiment by GM in seeking an alternative to the slotted screw. Post war was when lots of power equipment was starting to be used to assemble things and a slotted screw is not well suited to being power driven. Philips invented the Phillips screw form for use with automated drivers in the late 40's - the original patents expired about 65 or 66 and at that time a utility patent was 17 years.
I believe the use of clutch heads by GM was in part because a flat driver could be used in place of the special driver. The clutch head was designed to be power driven and to be compatible with a flat bladed screwdriver. Presumably the thinking was the factory could drive the screws with power equipment and mechanics/owners could use flat drivers they already owned. The type G was patented in the early 30's and is the form GM used by Joseph F Fieg to United Screw and Bolt Corp #1894034A on 1/10/33. Type A came along later (around 1940) under (I think) patent 2142185 also by Fieg to United Screw. A type A driver is designed to work with a type G screw as well as a type A screw. Feig described the type A as an improvement to the type G.
To me the question is not why GM used the clutch heads but why stopped with a folowup of why they migrated to the Phillips screw form. Phillips is designed to cam out when over torqued clutch head will not. Hard to find a lot of info on clutch heads though. The only thing I can think of is Phillips lends itself to a lot of low profile screw head designs like pan heads better than clutch.
In Canada Robertson is very popular as it here in the states with a lot of wood workers. For the same reasons Robertson is better than Phillips I believe clutch is also better than Phillips.
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What J.A.F.E. said about the factory being able to use power tools to drive clutch head screws and the home owner can still remove or install them with a regular screwdriver makes sense.
EvilDr235