? about Dog box transmissions.
 

i was mainly wondering how it functions...

whoops....

In general a dog box is more compact and robust while allowing quicker shifts at the expense of being noisy and intolerant of improper rev matching or shifting. They also always make a swell "ka-chunk" noise when you put them in first ;) The dogs themselves are large flat teeth on the faces of the gears that interlock when meshed together; they are what provide the physical coupling of the gears to the output shaft.

Pic 1 shows the dogs on the gear faces. These will mesh with the shift select collar that also has dogs on it's faces. The collar is indexed to the output shaft so whenever it is pressed against a gear that gear is selected.


pic 1

pic 2

pic 3

I don't know about you guys but when I see all those pics of transmissions with all those gears, it makes me feel good....

thank you damon... that one paragraph was more insightful than most websites i was able to find..

The "dogs" are similar to the corresponding pieces of a synchro box. The difference is that the synchro ring rides between the sets of dogs and helps match the speeds of the gearsets. In most dog boxes not only are the dogs themselves much more robust but the gears are generally straight cut (as the one Damon posted pics of) versus the helical cut of a production transmission. Not only are the straight gears stronger but they give that o-so-sweet whine. :D

I've only worked on dog boxes so I have never opened up a regular tranny. The gears on a dogbox are much stronger but the dogrings do not hold up to improper shifting. We have run a whole season (10,000 miles) without replacing anything on a tranny, but that is only with a driver that knows how to shift without damaging the tranny. I've also seen a Porsche GT car blow a tranny in 20 laps on a synchro box. I guess it all depends on the driver

how can one convert a t2 tranny to full dog box? where do you find the parts to convert it over?

yeah, its all driver. at the last enduro driver one gets out and says keep it in 3rd the synchro (with all of 3 hours on it?) is toast, driver #2 gets out of the car at the end of the race and said it was fine....

Does that mean you have to double-clutch and/or match the speeds manually?

You must match the revs. If you are perfect, you can do it without a clutch.

The closer the ratios are in the tranny, then the less rpm change with each shift, so the easier it is to match revs.

When upshifting, with my very tight tranny ratios (only 1000 rpm drop with shifts) and my light flywheel, light 7" clutch and light rotors (lets my engine be willing to change revs quickly,) then I can rip off lightning fast upshifts for very quick acceleration.

Downshifting the dog ring tranny is tougher than downshifting a synchro box. I can double clutch downshift a synchro tranny very smoothly at any speed, but every now and then I mis match the revs downshifting the dog ring box and it makes the rear tires snap loose.