T-47 Torx Fastener

[swall]

The T-47 bit seems to be an oddball, as it is only about .012" smaller lobe to lobe than the T-50. It also does not seem to appear on many listings of Torx sizes. Anybody know what the deal is?

 

[TVP]

I am not aware of T47. It is not a standard on either the original Camcar (Acument) documents or in ISO 10664. T45 and T50 are standards. All of the original Torx information can be downloaded from the Acument website. The following is the specific document on driver bits:

http://www.acument.com/licensing/pdfs/standards/torx/drivers/metric/TMD-702.pdf

 

[CoryPad]

I think this is a special for GM. GM liked to skirt patent and licensing fees, so they sometimes did weird things. For example, they did special hexalobular designs that weren't quite Torx, and I think this is one of them.

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[Screwman]

Yep, Corey is right. This is not anything that was created by Camcar or any of the Torx licencees. I think this is a foolish part that GM came up with. He's right that it isn't a true Torx but a 'made up' shape that is similar to a Torx. In most cases you should be able to use a T-45 to work in these parts.

 

[CoryPad]

Yeah, if I remember right, it has the same radii for inner and outer lobes, whereas the original Torx has inner lobe radii that are twice as large as the outer lobe radii.

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.