The introduction of the Rolex Explorer II 216570 revealed a few new modern touches to Rolex watches. The outside differences between the 216570 and earlier Explorer II are obvious. But what is not so obvious is the new Rolex 3187 movement inside the case. Rolex, known for its evolutionary rather revolutionary designs, introduced a new movement, the Rolex 3187 movement in the Rolex Explorer II. This adds to the venerable 3185 and 3186 caliber found in earlier Explorer and GMT watches.
Rolex’s new 3187 movement builds upon the technology and evolution found in other Rolex movements. The 3187 utilizes the same rhodium plating on the plates and bridges found on other Rolex movements. The 3187 also utilizes the same bidirectional winding rotor. Also, teflon coated wheels within the winding mechanism that are commonplace in Rolex watches. Additionally, the 3187 uses a full bridge holding the balance wheel rather than a balance cock. A balance cock is usually held by one or two screws and does not allow for adjusting balance end shake. Rolex started utilizing a full balance bridge in the 313x movements to keep the balance steady. It also allows for balance staff end shake using two star nuts located just under the bridge.
Like the 3185 and 3186 movements found in the older GMT’s and Explorer II’s, the Rolex 3187 movement possesses a 24 hour hand and independently adjustable 12 hour hand. And like the 3186 movement, it also incorporates a Parachrom hairspring inside a Glucydur* free sprung balance wheel. Like the 3186, the 3187 has updated drive wheels that has less hand play as compared to the 3185.
From this point on, the 3187 differ from its older brothers. The primary difference is Rolex’s use of its in-house balance staff shock system, Paraflex. Paraflex is a shock absorber developed and patented by Rolex. It claims to increase shock absorption by 50% over other industry standard shock systems such as KIF or Incablock. Rolex introduced Paraflex in the updated Rolex Day Date II / President five years ago. Like the Parachrom hairspring whereby Rolex relied upon outside manufacturers to produce, Rolex is moving away from KIF shock systems used in its watches for the last 20 years such that it is not dependent upon other companies in the supply chain.
The Rolex 3187 movement is slightly larger in diameter than the 3186 movement, and slightly thicker and one of the reasons why the Explorer II 216570 comes in at a slightly larger 42mm case over the standard 40mm cases seen in Rolex sport watches. The updated shock system, combined with the other updates (Parachrom, Chromalight, larger Twinlock crown) makes the Rolex Explorer II 216570 one of the most modern Rolex watch.
*Glucydur is comprised of beryllium, copper, and beryllium bronze iron. Glucydur is resistant to shape changes resulting from changes in temperature. Less expensive brands use a bimetallic balance wheel and some older balance wheels have expansion/contraction slices in them to allow for shape changes.”
Like many Rolex watches, certain models are inextricably linked with adventures and personal stories. The Explorer and Explorer II are no different. Rolex Explorer facts reveal an interesting beginning when two climbers, Edmund Hilary and Tenzing Norgay were the first to reach the summit of Everest on May 29, 1953, of course, wearing a Rolex Explorer.
According to the facts, Rolex first introduced the Rolex Explorer in 1953. It had one look throughout its life; a black dial with luminescent Arabic numbers at 3′, 6′ and 9′, no date, smooth bezel, and triangular marker at 12 o’clock. Also, included were an Oyster bracelet and a stainless steel 36mm case. Except for the updates that all Rolex watches have received, it remained essentially the same watch.
Rolex introduced the Explorer II model in early 1971. However, they never distributed the watches until 1991. Also, its popularity didn’t develop until then. They produced the original model until the next generation model, released in 1985. The engraved steel bezel was stationary and designed for speleologists (cave explorers) who had a hard time determining if it was am or pm.
The movement inside the Explorer II was identical to the movement used in the GMT-Master models. This also featured a 24-hour hand. Rolex used Caliber 1570 and 1575 movements for the entire line-up of 1655 Explorer II watches.
The Explorer II reference 16570 featured a newer type of movement, the caliber 3185 and later the 3186. It also only had one obvious visual change from its predecessor, the use of black hour marker rings and hands on the white dial version. The cream-dial model had white gold hour markers and hands, just like the Submariner and GMT-Master for example. Our Rolex Explorer facts note that the hour markers and hands are still white gold beneath the black paint.
Rolex replaced the Explorer 40mm (16570), with a new 42mm version with an orange hour hand (216570). They introduced this new version at Basel World in March 2011 and released it to the public later that fall. This time, Rolex equipped it with the new 3187 calibre. You can browse a great collection of used Rolex Explorer II timepieces here at BeckerTime.