[SIZE=-1]And the winner is…[/SIZE]
[SIZE=-1]Of these three movements which one do I like the best? If accuracy is your only criteria, then it doesn’t matter which one you choose as there really is virtually no difference between them in that regard. Sure some individual movements might time out marginally better than others, but overall the differences in time keeping between them is insignificant. All three are capable of exemplary accuracy in all six positions, and do so with a minimum of variation and loss to the balance amplitude. More importantly, they should provide excellent accuracy and reliability under real world conditions too.[/SIZE]
[SIZE=-1]As for me, please keep in mind that no movement is perfect and that they all have their strengths and weaknesses.[/SIZE] Having said that though there is absolutely no question in my mind, that I prefer the ETA 2892-2A over the other two.[SIZE=-1] Okay, so it’s been around almost half a century and in many ways isn’t as sophisticated as the Rolex – no Breguet hairspring, or Parachrom hairspring material etc – but during its long lifetime in its best available chronometer version, it has proven itself to be an exceptionally accurate, reliable and tough movement. Its two main advantages over the 3135 are that it’s quite a bit thinner, only 3.6mm thick versus 6mm, and has only one major weakness – the inefficiency of its automatic winding system, as I mentioned in my earlier review of it. While good enough for most reasonably active folk, it is not efficient enough for those people, young or old, who lead a sedentary lifestyle. [/SIZE]
[SIZE=-1]I wouldn’t have any qualms about someone who preferred either of the other two movements though. At 8mm high the 7750 is the thickest and ugliest of the three. It also has the noisiest rotor of any automatic watch that I have worked on, but one cannot question its accuracy, reliability and toughness. [/SIZE]
[SIZE=-1]The 3135 is the youngest, most sophisticated and best looking of these three and it has many admirable strengths. A longer power reserve and instantaneous date change to name a few. As for the weaknesses of the 3135? In my honest opinion there are only two glaring weaknesses. The first is that the oscillating weight pivots on a steel post that is riveted to it and held in place by two jewels. The small circumference of said post, coupled with Rolex’s simple and efficient reversing wheels and gearing ratios, greatly improves the winding efficiency of the automatic unit. This is probably the most efficient automatic winding system available today. But unfortunately its tiny diameter doesn’t give enough support to the weight to stop it from hitting against the movement plates every time the watch is subjected to even light perpendicular blows, let alone strong ones. I think that an upgrade to an oscillating weight pivoting on ball bearing races, like they’ve done in their new chronograph movement caliber 4130, is long overdue in order to eliminate this problem. It would be even better if they used lubrication free zirconium oxide ball bearings like JLC, PP and others that are doing so today, not only for their strength, but also for their efficiency over steel ones.[/SIZE]
[SIZE=-1]The other weakness is something that may or may not manifest itself as readily, depending on the circumstances and how often the watch is serviced. This potential problem is easily understood by any watchmaker who has serviced a lot of these movements. The problem is that the 2 setting wheels under the dial, and the two small and thin posts that they pivot on, can be easily damaged if the lubrication runs dry. If the grease on the canon pinion dries up due to age or moisture in the watch case, the teeth on these small thin wheels will break off. The more severe problem is if the lubrication on the posts runs dry, then the first post will be worn away in no time at all, as shown in the photo below. This is less of a problem on the second post as it is a steel pin that is not riveted into the main plate. So it can be easily replaced if it is worn or damaged. Unfortunately the first post is part of the main plate, and is made of brass just like it. Therefore if this post gets damaged like that, the only way to repair it is by replacing the entire main plate. An expensive proposition at best. It’s worth noting that this was not a problem on Rolex’s older caliber 3035 because the diameter of the post was quite a bit thicker, as was the set wheel itself. Please note that this shouldn’t be a problem for those who take care of their watches and have them serviced at regular intervals – every four to five years as recommended by most factories today. I am 100% in agreement with this recommended service interval.[/SIZE]
[SIZE=-1]Whether Rolex is interested in making any more radical upgrades to this movement is anybody’s guess, but my feeling is that by now they probably have a replacement waiting in the wings for it. With the economy being in the shambles that it’s in right now, the timing might not be right just yet. Only time will tell. But hey, if anybody gets an email from Bruno Meir about their new movement be a sport and tell your friends on Time Zone about it.[/SIZE]