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Override transmission DYI


eagle

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it's ALMOST simultaneous that the currently selected gear is disengaged and then the next selected gear is engaged, but not quite, unless it's overridden.

 

You know what they say, close only counts in Horshoes and ............. Anyways, the trick of the matter is that the "original" gear in the equation, (the one your in BEFORE the shift) cannot be dislodged from it's mating gear while under load. Hence the reason it needs to be seperated from the next gear. And the almost simultaneous, if ya think about it, it has to be disengaged from the previous gear, and then once it's disengaged, slide into the opposite side, where it will engage the following gear. In reality, it can only really happen simultaneously in an override tranny! :blink:

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The difference as it was explained to me long ago between a true override tranny, and what is done here is that one is useable anywhere, and one is useable track only. In most of the mods discussed in this thread, the engagement dogs have been removed. Every other "dog". What that does is let the gears mesh with each other quicker, and eliminate missed shifts. A missed shift can occur when the dog from the incoming gear hit head to head with the gear it's trying to mesh with. if you are not applying pressure long enough to let the dogs "skip" over and alow them to properly line up, than the bike will hang in gear, or stay in the previous gear. When I speak of the engagement, and the dogs, I am not speaking of actual gear tooth mesh. I am speaking of the wonderfully provided pics of where BenBB ground out every other dog, (just to clarify).

 

Now, an override transmission is something totally different. In a basic sense, the shift drum "pathways" are welded closed. This removes the tempering in the drum, due to the heat. Now, new pathways are cut. Now, what does this do? Well, you need to understand that when one gear is trying to be selected, the previous gear needs to be disengaged, before the other one can be engaged. This is done with the shift forks, and the stock shift drum. Next time you have your cases split, run the shifter through the gear with the gearset in the lower case half, and watch what happens for each gear. Now, that being said, one way to a faster shift is to allow the previously engaged gear to stay "engaged" while the next gear takes over. Now, the problem with this application after the new pathways are cut, and everything is set up is that once you select a gear, usually past second, you CANNOT let off the throttle without disengaging the clutch. That's why most trannies are only overrided for 3rd gear and up. If you let the tranny engage on decelleration, it wil lock up, and grenade. There are "double" engaged gears in the tranny, which I believe are cut in half, so they allow independant motion from one another. By double gears, I mean that when they are slid one way on the shaft, it is one gear, and when slid the other way to mesh with another gear, that is a diferrent gear. The trouble is that when that "first" gear is engaged, and you are on the throttle, it is tough to disengage that cog to allow the engagement of the next gear, but if you split the collar, and allow independant engagement of either gear, now you can shift under load. This post may be hard to follow, but this is my understanding of overridden trannies. If confused, re-read, and look at an actual tranny and how it works. it didn't make sense untill one night while assembling mhy motor for whichever time it was, I ran it through the gears, and watched what happened, and it made sense. With an override, just don't let off without pulling the clutch....

Great explanantion! I didn't have the energy to post up the information. :thanks:

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  • 4 years later...

I have a 2-5 override with neutral in the stock position cut by WCR and a 2-5 neutral down transmission cut by tim @ titan racing. I will sell you either one if you want something to look at to try and duplicate yourself.

 

- Jared

really? this thread was made in 07... the newbie bumped it...

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