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Synchromesh vs. Dog Box - Gearbox Beatdown - Import Tuner Magazine

Synchromesh Transmissions vs Dog engagement

Synchro vs. Dog Box : Racing by LotusElan.net



Dog engaged transmissions aka the “Dog Box” | Automotive Thinker - Discussing the finer points of automobiles

Dog engaged transmissions aka the “Dog Box” | Automotive Thinker - Discussing the finer points of automobiles

Ask the Best and Brightest: Dog Engagement vs. Synchromesh - The Truth About Cars

Originally Posted by sugarwood

Does the 915 fundamentally differ from modern gearboxes? Or does it have more in common with a modern gearbox than you'd think? More specifically, synchros.

The 915 is a full synchro box. It's "modern".

Is the 915 meant to be operated in a fundamentally different way than a G50 or a Sentra gearbox? When I shift my 915 gearbox, I don't force it. Sometimes, if I feel a resistance, I lightly maintain pressure on it, and then it slides into gear. I understand this to be normal. Would this also be the case in a G50 or Sentra? Or are they totally different?

Your 915 is probably worn, and would do with a refreshing. I once drove an '84 or '86 911 with a 915 that shifted up and down like butter.

Is this attributed to the synchro? Does the synchro (or something else) need to speed up to match or something?

Yes, it does, that's how they work.

Does this not apply to modern gearboxes?

Nope, that's how they work too.

Is the 915 part of the "Syncromesh" paradigm?

Yes it is

What about "dogbox" ? Is dogbox even more primitive than the 915 ?

They are often used for racing and can be faster than a synchro box. I guess they could be called more primitive, but I'm not sure if that's actually accurate or not.

Or is the 915 a dogbox style gearbox?

Absolutely not, unless it's been modified which I believe is possible, but I'm pretty sure you'd know.

Where does the G50 and a 2005 Sentra gearbox fit into all this?

There are multiple ways to synchromesh a trans. The G50 uses a different type. I believe it's quite a bit more robust than the system in the 915. I have no idea what style is used in the Sentra, but the 915, G50 and Sentra manual trans are all fully syncro.