a small bolt cutter works good....
Never thought of that! I'm not sure the Knipex compact Cobolt cutters would be ideal since they appear to be a bit bulky looking at the head. It has to be a one-handed operation as I need my other hand free. Thanks for the suggestion though.

The next time I go to Japan (was supposed to go in April), I'd like to compare the Japanese and European mini bolt cutters side by side. The Japanese ones appear to be more compact at the head.
I converted my 911 to wheel studs from lug bolts. I went with a style of stud that has a 22mm bullet nose. The stud, coupled with the design of my wheel I'm running (CCW Corsair C14), requires something deep enough to fit over the bullet nose, and provide enough length so a torque wrench isn't going to touch the fenders. Below is what I'm working with:
I will need to turn the center bore of the socket. Unfortunately, the catalog didn't list the diameter of the thru hole running through the socket, but there is plenty of material there for me to open it up to 5/8". I went with the Tone over the Koken due to the fact it's longer, and has a thicker diameter. Don't ask me why I can't just use an extension on a normal socket. That would be too easy
Nice wheels. I hope the turning of the bore goes well.
New from KTC. Short handle adjustable wrenches. Contacts a hex fastener in three places rather than the usual two. Not sure if it's a new idea but thought it was interesting.
https://ktc.jp/catalog/index-category/category-list/wms-24__46
Straight up LOBSTER
I emailed Koken UK about the 2137 bit holder not holding bits securely and got this reply.
'Thanks for your feedback,
2137 & 3137 are not made to locate in the indent in the bits.
For your application please see attached 12139 .
12139 has a small internal ring that locates into the indent all around the bit, this will solve your problem.'
I made it clear in the email that I was not complaining and I am not complaining here, just interested in the design. The ball in my 3137 3/8" bit holder definitely looks and feels like it clicks into the indent in bits so I'm still puzzled about the intention of the design on the 1/4"
Anyway, it was good of Koken UK (UKTools) to take the time to reply and to offer a solution especially on such a small/cheap item.
Problem solved.
The 1/4" bit holder is one of the few Ko-ken tools I've been dissapointed with. I have no issues with their 3/8 and 1/2 drive bit holders though.
Nice of UKTools for the detailed response!
I have the 121
40 which is a 1/4 drive for 5/16" bits. Pictured here next to 3138 which is a 3/8 drive 5/16" bit holder:
<a data-flickr-embed="true" href="https://www.flickr.com/photos/ccassan/49692151446/in/dateposted-public/" title="Ko-ken 5/16" Bit Holder"><img src="https://live.staticflickr.com/65535/49692151446_d5dfcb4079_c.jpg" width="450" height="800" alt="Ko-ken 5/16" Bit Holder"></a><script async src="//embedr.flickr.com/assets/client-code.js" charset="utf-8"></script>
<a data-flickr-embed="true" href="https://www.flickr.com/photos/ccassan/49692151471/in/dateposted-public/" title="Ko-ken 5/16" Bit Holder"><img src="https://live.staticflickr.com/65535/49692151471_feef4b37bb_c.jpg" width="568" height="800" alt="Ko-ken 5/16" Bit Holder"></a><script async src="//embedr.flickr.com/assets/client-code.js" charset="utf-8"></script>
A clearer shot of the internal ring. The machined groove on most any standard 1" bit mesh with that internal ring.
<a data-flickr-embed="true" href="https://www.flickr.com/photos/ccassan/49691611588/in/dateposted-public/" title="Ko-ken 5/16" Bit Holder"><img src="https://live.staticflickr.com/65535/49691611588_8915b20056_c.jpg" width="584" height="800" alt="Ko-ken 5/16" Bit Holder"></a><script async src="//embedr.flickr.com/assets/client-code.js" charset="utf-8"></script>
I haven't seen anyone offer a T-55 in a 1/4 drive, so I use this combination to create what I want:
<a data-flickr-embed="true" href="https://www.flickr.com/photos/ccassan/49692151571/in/dateposted-public/" title="Ko-ken 5/16" Bit Holder with T55 Torx bit"><img src="https://live.staticflickr.com/65535/49692151571_9bb3718c11_c.jpg" width="450" height="800" alt="Ko-ken 5/16" Bit Holder with T55 Torx bit"></a><script async src="//embedr.flickr.com/assets/client-code.js" charset="utf-8"></script>
Compared to the 3138 type of retention method, it does exhibit a little bit of play. It definitely holds bit more securely compared to the 2137 bit holder (pictured below).
Mine is from 10 years ago, and appears to be spec'd the same as yours, built in 2018.
<a data-flickr-embed="true" href="https://www.flickr.com/photos/ccassan/49692151421/in/dateposted-public/" title="Ko-ken 1/4 drive 1/4" bit holder"><img src="https://live.staticflickr.com/65535/49692151421_99d85f951a_c.jpg" width="579" height="800" alt="Ko-ken 1/4 drive 1/4" bit holder"></a><script async src="//embedr.flickr.com/assets/client-code.js" charset="utf-8"></script>
Your solution in the end is

. I really like my 1/4 drive Torx and in-hex bits from them. They look good, and for a "standard height" variety, the Ko-ken's are more shallow than other "standard height" bit sockets from most other manufacturers/brands.