Override transmission DYI

[eagle]

When i had the Rz drum and forks put in they cut every other tab on the gears.Makes it shift alot smoother and can shift under throttle alot easier.I'm not sure if Walt(Banshee370) still has his website up,but he gave a description on there about the mod,i think.

I found his website,but didn't see the stuff he used to have on there. RoostFest

 

 

I did not find what you are talking about on the site but you say tabs, what are you talking about? gear teeth? cogs? There are generally only 3-4 cogs so that would concern me taking half of them off.

[535banshee]

i have sold overrides for a long time. LET SOMEONE DO IT. ITS NOT WORTH THE TIME.

[eagle]

i have sold overrides for a long time. LET SOMEONE DO IT. ITS NOT WORTH THE TIME.

 

 

Well I honestly at this point just want to know what is being done to the parts. I am rather concerned that this could reduce tranny life considerably. I and really not scared to take this on. From an engineering standpoint, the sequential transmission was not designed to shift under load and I am really curious to better understand the concept. If there are a bunch of shops doing this mod, that tells me it can be done. Doesn't anyone have an override on the bench they can take a pictures of?

[NYUK]

do what every other builder in the country did after rudy kurtz. send him a tranny . then copy it. i had one in my drag bike 5 years, never had a problem except sharpened forks. rz forks solved that.the drum is modified, shift star radiused and some dogs are cut from the sides of the gears.i had just about every bad situation happen when draggin with my override. never had a failure.

[FireHead]

I did not find what you are talking about on the site but you say tabs, what are you talking about? gear teeth? cogs? There are generally only 3-4 cogs so that would concern me taking half of them off.

I am pretty sure he was talking about the shift star and not the actual transmission. :thumbsup:

[FireHead]

From an engineering standpoint, the sequential transmission was not designed to shift under load and I am really curious to better understand the concept.

Well, that's just not true at all. :ermm:

[BenBB]

I can post pics tomorrow of Walt's and my own backcut gears...although I've never really known what constitutes an "override", anyone care to elaborate? What I did was take off every other engagement dog (there were six, now three) on 2nd-5th with a die grinder, a boonman modded shift star, RZ drums & forks...

[eagle]

I can post pics tomorrow of Walt's and my own backcut gears...although I've never really known what constitutes an "override", anyone care to elaborate? What I did was take off every other engagement dog (there were six, now three) on 2nd-5th with a die grinder, a boonman modded shift star, RZ drums & forks...

 

 

That would be super. That is kinda what I am getting at is what is being done. I have no idea what an override is but I know what back cut gears are. So your trans shifts without clutch? No shift drum mods?

 

 

In response to shifing under load, I have worked with designers of F1 class sequential transmissions and they absolutely do no want people shifting them under load for wear purposes. Unload the trans, then shift. That is done in F1 electronically. That being said, those setups are pushed to the max. Apparently the Banshee has plenty of beef in the trans or you would never get away with taking off HALF the gear cogs.

 

 

Please post some pics, I am very interested in this deal. Thanks

[FireHead]

In response to shifing under load, I have worked with designers of F1 class sequential transmissions and they absolutely do no want people shifting them under load for wear purposes. Unload the trans, then shift. That is done in F1 electronically. That being said, those setups are pushed to the max.

I am going to call B.S. on that too. :thumbsup:

[eagle]

I am going to call B.S. on that too. :thumbsup:

:thumbsup:

[BenBB]

Ok here's some pics...

 

Gears to backcut (#6, 20, 21, 22 below):

 

B370's (Walter) gears:

 

Crappy pic of my gears (incidentally RZ350 gearset):

 

Pic of the die grinder and one of my gears with 2 of the three dogs cut (which I found mildly amusing heh, tha peace symbol and all):

 

I clutch most of the time...well sometimes heh. The combination of the backcut gears, modded shift star (rounded off points done by boonman), RZ shift drum and forks seems to shift smoother and lessens missed shifts and false neutrals. I still do that on occasion but it's more a function of being exhausted on the last lap of a desert race and not shifting fully (operator error heh). Never had any problems and I have put alot of hard miles on this tranny; 7 races and 112 hours give or take.

Edited April 9, 2007 by BenBB

[Shee-Male]

^^^got this info from Ben last year and did it to my tranny, works awsome!

[boonman]

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....

[BenBB]

Ahhh ok I get it, thanks boonman. Sorta. From what I remember of watchin' the tranny shift, other than wondering how anyone would come up with the whole damn thing (somebody alot smarter than I), 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. It makes enough sense to avoid in my application haha!

[racer]

Good to see you around Boonman. I get what youre saying about the gears and I am glad to have finally had someone explain it with a knowledgeable background in it.