Where's 6th Gear?

[Feffman]

Hi All:

OK got the Busa engine (2003 engine) out and split the case as I've not been able to get 6th gear. The shifter forks look fine. Does slight wear or un-detectable (to the eyeball) bending effect shifting? Is there something else that would keep me from getting 6th gear?

Any help is MUCH appreciated. Happy Motoring!

Feff

 

[Feffman]

"Bueller?, Bueller? Anyone?"

Feff

 

[Professor]

What does the wear pattern look like on the shift forks? What about the drum where the fork pins ride? With the gear pack in place, does the gear that slides to engage 6th, slide in correctly?

 

[Feffman]

What does the wear pattern look like on the shift forks? What about the drum where the fork pins ride? With the gear pack in place, does the gear that slides to engage 6th, slide in correctly?

The shift forks, in my opinion, look damn good, but then I have nothing to compare them too. See the attached photos of one of the two (6th gear fork) that are on the same shaft. Not sure if the drum is working properly or not. The star shifter mechanism looks good and goes through all six positions.

Feff

 

[CarGoWOT]

This is weird, seems like today I was shifting into 5th or 6th and it went into neutral and it felt very loose. But I was able to down shift it and made it back home and it was fine.

 

[Professor]

From that picture it is kind of hard to tell.

Looking at the top picture, I suspect a bent fork, although it does not appear bent enough 100% prevent it going into any gear. It looks like a gear rub mark (Yellow) and the wear on the corner (green) of the pad. Like I say it is hard to tell from the picture. But the pad wear should straight, and exactly perpendicular to the shift shaft bore. If that is a gear rub mark (yellow) instead factory machined clearance, it would have to be bent. I’d have to get out some of my spares but I don’t believe there is a factory machined mark like that on a busa fork. The pad appears to show excessive heat (to the point of smearing the metal) and it looks like it was not from a correct contact with the groove in the gear, another sign it bent.

Here is a link to some things to look for (although I might not agree with his solution) The fork in the top picture is exactly like I’m thinking yours is, but more severe. The shafts needed to be placed in v-blocks and checked for straightness also. Of the half dozen Busa trannys I’ve seen apart all but one had a shaft with a problem. 2 had bad drums.
Link

As much as a pain it is to R&R and split the case, I really recommend sending it someone that specializes in working them. I’ve done quite a few years ago on other bikes. More recently I’ve messed with a few busa trannys. When I got ready do some engine work on mine, I sent bought a spare and sent to Mark at R&D and had him inspect everything, backcut it, as well as a couple other mods. That work is not cheap however. There are some used stock ones out there but you have to watch what you are getting there as well. You might end up with one with as many problems as you are pulling out. I wouldn’t put one back in with the stock shift shafts, good ones are not that expensive and good insurance.

 

[gigdeth]

I actually had a similar problem with my bike on Saturday, and dont quite know what the problem is. I was going along in 6th when mine felt like it went into neutral and then downshifted itself into 5th. I put it back in 6th and almost instantly, it went back to 5th on its own. And now it acts as though 6th isnt even there. Could this perhaps be a fork problem as well, or possibly something else?

 

[Feffman]

I actually had a similar problem with my bike on Saturday, and dont quite know what the problem is. I was going along in 6th when mine felt like it went into neutral and then downshifted itself into 5th. I put it back in 6th and almost instantly, it went back to 5th on its own. And now it acts as though 6th isnt even there. Could this perhaps be a fork problem as well, or possibly something else?

After speaking with a friend last night, I'd say your dog rings are shot on 5th/6th gear.

Feff

 

[gigdeth]

and the only way to do those is by pulling the entire tranny apart, correct?

 

[Feffman]

and the only way to do those is by pulling the entire tranny apart, correct?

Let's just say my engine is out to split the case opening the tranny up. I'm replacing the shift forks, the shifter fork shafts (uprated APE shafts) and the shift star (Factory Pro Upgrade - Thanks for the suggestion Professor) mechanism on the cam. Hope this does the trick.

feff

 

[Feffman]

Good Morning All:

Looks like the new shifter forks, upgraded shifter fork rods and upgraded star shifter did the trick. Just got a call from my buddy Eric (we own the car together) letting me know we now have 6th gear in the Radical SR3 race car (Busa powered). Seems the small oil leak has been repaired to with re-sealing the engine upon assembly. Thanks for all who chimed in to pick your brains. Now we can go to Road Atlanta, Watkins Glen, etc. without worrying about running out of gearing.

Feff