Before decoding synchromesh and dog gearboxes, it is critical to understand the beast. It’s all about engagement; how the gearsets are selected within the transmission is the difference between synchromesh and a dog box. Most modern cars are fitted with a synchronized engagement gearbox from the factory to deliver smooth, reliable, and quiet operation, which is paramount for a daily driven vehicle. Synchromesh transmissions operate using a collar that applies force to a cone-shaped clutch attached to the gear. The collar allows the shaft speed of the gearset and the input shaft to be matched or “synched” to the output shaft prior to the collar locking into place and initiating a shift. Synchromesh gear engagement is best at lower engine speeds and requires a bit more time compared to a dog box, to facilitate shifts. Limitations of synchromesh gearboxes in high-performance applications include slow upshifting at very high engine speeds—e.g. 9,000 rpm—and slow downshifting, as well as the need to fully use the clutch.

Dog engagement is normally used in racing applications where fast, precise shifting is needed. Dog gear engagement is facilitated by numerous large teeth (dogs) that mate into matching openings machined into the opposite surface of the drive gear. Unlike the synchro engagement, there is no synchronizing mechanism to assist in equalizing speed. Ideal gear selection—e.g. minimal clashing and wear of the dog rings—is achieved by quick shifts; the motto here is “the quicker the better”, so bang away. There is no depressing the clutch in the conventional sense like with the synchromesh transmission. A momentary break in engine load until the shift is achieved by a quick throttle blip or clutch depression. The driver will then experience the dog ring engaging with the next gear and the throttle can be reapplied. With practice this can be done in milliseconds. In fact, a driver can preload the stick shift in the direction of the next shift, and then when he either blips the throttle or clutch the shifter will quickly click in the desired gear.

With all else equal, dog-engagement gears are much stronger than synchro-engagement gears because without needing to make space for synchro rings, the gears themselves can be made thicker. The number of dogs (teeth) and the size of the openings determine the window of opportunity that the dogs have to engage during the shift event. Rings with a smaller number of teeth provide a more efficient, smoother shift quality. The downsides to this easier engagement are increased noise and abruptness on the shift. The most destructive method of shifting dog gears is attempting to change gears in a “passenger car” or “synchromesh” manner. This involves slow shifting and use of the clutch—i.e. lifting off the throttle, depressing the clutch, moving the gear lever slowly, releasing the clutch, and applying the throttle—a scenario typically found in stop-and-go traffic. The belief that dog boxes inherently feature straight-cut gears is a long-standing misconception. In fact, either type of gearset can be fitted with straight cut—also known as spur–gears as well as conventional helical-cut gears.

The cut of the drive gear is a separate characteristic of the gearbox and does not affect the engagement of the gears. Dog engagement can be introduced to a stock gearbox by swapping gearsets. motorcycle jacket canberraAftermarket dog sets are usually made of higher-grade material and feature bigger, stronger teeth, and better profiles. used ducati motorcycles utahAlbins Gear, located in Australia, has moved to the forefront of the dog-box revolution, offering a wide range of dog-engagement gearsets as well as fortified synchro sets for Honda, Porsche, Nissan, Subaru, Mazda, VW, and Mitsubishi applications.motorcycle short film vimeo All Albins dogs feature a CAD “pent-roof” pentagon-shaped surface that deflects the dogs apart on a mis-shift, drastically extending the life of the gear. motorcycle for sale danbury ct

Albins dog gears are verified using a robotic CMM (coordinate measuring machine) to assure perfection with tolerances better than 0.015 mm on each and every part. vintage motorcycle trials tyresFurthermore, Albins has been able to produce its own proprietary steel alloy with a consistency far superior to mass-produced, low-cost sets.motorcycle accident in salem wi Synchromesh Versus Dog Box Gearset Comparisontron ducati motorcycle for sale Notice the thicker gears and teeth of the Albins unit (below) and the cuff that replaces Fifth gear (unneeded in the quarter-mile) and ties the two shafts together for added strength. The Albins gears and teeth are not only thicker, but they are also made from the company’s proprietary steel alloy for superior metallurgical strength.

Here is the big difference between synchro and dog boxes. The synchromesh ring (left) uses a cone that a brass clutch ring pushes against to equalize the speed between the gear and the input shaft to ease gear engagement. Once this happens, the small pointed teeth around the perimeter deflect off the engagement ring and allow the slider to engage the gear. The dogs have four large engagement teeth that drop into large windows in the slider, and can engage the gear even when spinning at a different speed than the input shaft. Here we see the rings on their appropriate gear. This is how they would be installed in the transmission. Albins gearsets drop right into the stock transmission case, delivering nearly “sequential-fast” shifts without the sequential box price tag. Albins offers dog-engagement gearsets as well as fortified synchro sets for Honda, Porsche, Nissan, Subaru, Mazda, VW, and Mitsubishi applications. SpeedFactory’s Outlaw-class Civic has been a rolling 1,100-whp gearset cruncher.