CMS-Japanese Motorcycle Supply Parts

Koken Zeal 3/8 Ratchet Wrench 3725Z Review


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Today I am reviewing the Koken Zeal or Z-series 3/8" ratchet wrench 3725Z - one of the Japanese brand's premium ratchet offerings. It's available from a variety of sources (eBay US, eBay AU, Amazon, Rakuten).

Here's a review of the Koken or Ko-Ken 3725z 3-8 inch or 9.5mm ratchet socket wrench - made in Japan - from their Z series or Zeal lineup.

The ratchet comes in a fairly unassuming box - you're definitely not paying for fancy presentation here, but it's a ratchet not an iPhone so I can't imagine anyone cares about this:

Here's a review of the Koken or Ko-Ken 3725z 3-8 inch or 9.5mm ratchet socket wrench - made in Japan - from their Z series or Zeal lineup.

The country of origin is marked very discreetly on the underside:

Here's a review of the Koken or Ko-Ken 3725z 3-8 inch or 9.5mm ratchet socket wrench - made in Japan - from their Z series or Zeal lineup.

Model number on the end:

Here's a review of the Koken or Ko-Ken 3725z 3-8 inch or 9.5mm ratchet socket wrench - made in Japan - from their Z series or Zeal lineup.

The ratchet inside:

Here's a review of the Koken or Ko-Ken 3725z 3-8 inch or 9.5mm ratchet socket wrench - made in Japan - from their Z series or Zeal lineup.

Country of origin on the shaft:

Here's a review of the Koken or Ko-Ken 3725z 3-8 inch or 9.5mm ratchet socket wrench - made in Japan - from their Z series or Zeal lineup.

The handle is a plastic-like material:

Here's a review of the Koken or Ko-Ken 3725z 3-8 inch or 9.5mm ratchet socket wrench - made in Japan - from their Z series or Zeal lineup.

Here's a review of the Koken or Ko-Ken 3725z 3-8 inch or 9.5mm ratchet socket wrench - made in Japan - from their Z series or Zeal lineup.

It's hard to see but it is subtly contoured for the fingers. The end:

Here's a review of the Koken or Ko-Ken 3725z 3-8 inch or 9.5mm ratchet socket wrench - made in Japan - from their Z series or Zeal lineup.

The ratchet is 178mm end to end and weighs 254gm:

Here's a review of the Koken or Ko-Ken 3725z 3-8 inch or 9.5mm ratchet socket wrench - made in Japan - from their Z series or Zeal lineup.

There's a ball and spring arrangement for socket retention, as is standard. The Zeal lineup does not feature any ratchets with a quick release button at the time of writing, though there are variants of their non-Zeal ratchets which do feature a button - such as the 3753NB (eBay US, eBay AU). The "B" at the end indicates that the Ko-ken ratchet model has a quick release button.

Here's a review of the Koken or Ko-Ken 3725z 3-8 inch or 9.5mm ratchet socket wrench - made in Japan - from their Z series or Zeal lineup.

The back of the head just has the direction toggle and a single bolt holding the head together.

Here's a review of the Koken or Ko-Ken 3725z 3-8 inch or 9.5mm ratchet socket wrench - made in Japan - from their Z series or Zeal lineup.

A closeup of the texture around the toggle:

Here's a review of the Koken or Ko-Ken 3725z 3-8 inch or 9.5mm ratchet socket wrench - made in Japan - from their Z series or Zeal lineup.

Combined with one of the Zeal sockets - which fits nice and firmly - it's quite a slim setup:

Here's a review of the Koken or Ko-Ken 3725z 3-8 inch or 9.5mm ratchet socket wrench - made in Japan - from their Z series or Zeal lineup.

Ko-Ken's Zeal lineup is not the only one with super low backdrag, though - as an example, one of their regular ratchets in the 3753N is also low drag and less expensive (eBay US, eBay AU).

Compared to a regular run of the mill Taiwanese-made ratchet (in this case a Kincrome K2944 unit) the 3725z is about the same overall thickness:

Here's a review of the Koken or Ko-Ken 3725z 3-8 inch or 9.5mm ratchet socket wrench - made in Japan - from their Z series or Zeal lineup.

It is, however, a good deal narrower:

Here's a review of the Koken or Ko-Ken 3725z 3-8 inch or 9.5mm ratchet socket wrench - made in Japan - from their Z series or Zeal lineup.

As a point of note, if you are looking for a 3/8" Koken ratchet that has a smaller head than the this one Koken make a 3/8" drive ratchet with a 1/4" head - part number 2725Z-3/8 (L160) is what you're looking for there. The basic, much easier to find 2752Z-3/8 (i.e. the one without L160 in the part number) is a 114mm long unit, which is a fair bit shorter than the 3725Z. It's the same principle as the more-expensive Nepros NBRC390L, where the trade-off is presumably a lower maximum torque handled by the mechanism - though having used the latter for six months I have not found that it skipped once so it may be a non-issue if you don't put a cheater bar on your tool.

Compared to the Kincrome K2944, a selection of older Sidchrome ratchets and a variety of Chinese ones on-hand the backdrag on the Koken is notably lesser, though when compared back to back with a more-expensive Nepros offering in the NBRC390L the difference is indiscernible. The difference in tooth count, on the other hand, is noticeable - both when comparing to the 48 teeth of the Kincrome or the 90 teeth of the Nepros. When working in an open space there isn't really any functional difference but when working in a cramped engine bay or a tight space inside a motorcycle frame the 36 teeth of the Koken work against it. At least there's minimal slop in the gears - the head design seems to be a quality one.

The plastic handle is surprisingly nice in the hand for a slightly contoured piece and seems to deal well with oil being spilled on it. One advantage that the Ko-ken has over the other two ratchets mentioned above is that it lacks the quick release button, which makes it harder for dirt and debris to make their way into the gear mechanism - so the ratchet may need less maintenance long-term. The one negative thing I noticed about the 3725Z's build quality was the direction selection toggle was very loose - in that it was able to be jiggled in a loose-feeling fashion. I have a video of that that I'll upload and add to this review. It didn't affect the toggle's functionality, but it also didn't line up with the feel of the rest of the wrench.

Assuming that you don't mind a ratchet without a quick-release mechanism, the Ko-ken 3725z is a quality, well-made ratchet with low backdrag that's a pleasure to use. The low tooth count will rule it out for some people but for some the low backdrag and overall quality is going to more than make up for it. Check it out on eBay US, eBay AU, Amazon or Rakuten.

If your budget will stretch a bit further, check out this Nepros.



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