Something Failed, let’s find it! Transmission Analysis.

[Claviger]

I posted a video on page 1 of this thread to illustrate HOW the cascade failure gets started.

Is it partly a design flaw? Yep. Is it exacerbated by rider inputs? Absolutely.

I do not believe bigger circlips are the answer, the answer is gentle 5 to 4 shifting, but they certainly can't hurt to have put on!

 

[mr hunt]

Yeah I've got no qualms about my input as the rider amplifying the problem. Although I've never missed a 4/5 shift I've certainly gone up and down hard over time (leave that alone Jim/Norm!)

My gripe is that my riding style hasn't really changed in 25yrs of riding many different bikes and I've never had a trans issue intil now

 

[Claviger]

Yeah I've got no qualms about my input as the rider amplifying the problem. Although I've never missed a 4/5 shift I've certainly gone up and down hard over time (leave that alone Jim/Norm!)

My gripe is that my riding style hasn't really changed in 25yrs of riding many different bikes and I've never had a trans issue intil now

When I get the new stuff in place, I'll do the same thing, set the shafts on top of each other. My bet, 3rd will still have that little bit of wobble. If it does, it's definitely a design flaw. They could have used another dual dog ring instead of a shared 3/4 with 5th dogs on it and avoided the problem. I am willing to bet, when I go look into the trans on other bikes (and im going to, because now I'm curious), this potential for side load of a gear and circlip is not present as in the rocket.

 

[mr hunt]

I still have trouble believing that given the amount of mechanical loss from the shifter (a reasonably short lever so not a whole lot of torque generated)) through to the circlip that it can be hit with enough force so as to become dislodged by shifting alone. Then physics isn't my forté...

 

[Claviger]

Two levers to magnify your input force:

Lever 1 pedal to pivot.
Lever 2 the shift shaft arm (the one outside that the linkage connects to).

EDIT: On second thought, it's only 2 levers.
EDIT 2: On third thought, it's actually a compound lever.

 

[Claviger]

What are the kill times in m/sec on you PCV speedshifter table?
Have you used the search function on this board regarding gear box shimming?

I went back and reviewed a bunch of posts on the topic.

I do believe I've found where to take up an extra slack in the transmission, but, I won't know for sure until I have all the replacement parts in place on the shafts, the extra clearance could be from a damaged splined bush.

 

[Rocket Scientist]

Mine came off during a 5th to 4th downshift. I'm not a stomper. From the looks of the circlip that failed in mine, it had been trying to get out of it's groove for some time. My fourth gear dogs were a little rounded, so I think they were trying to reject each other under load, which put constant stress on the clip that holds 3rd / 4th gear until it finally failed. I think the back cut on fourth gear alone should eliminate the problem (belt) The heavier clips were just a little added insurance (suspenders). When you get the failed clip off take a pic and see if it looks like this.

 

[cootertwo]

VERY interesting reading all. Thanks for taking the time and pictures.

 

[Claviger]

Thought I’d add a point on disassembly of the trans.

The manual calls for two M6 bolts to be used to slide the input shaft out evenly loading the bearing to the case as it does so.

Well in all their wisdom Triumph stopped threading those holes, so, you can’t temove it that way.

To get it out, firmly, but not violently, slide the 3-4 input gear back and forth impacting with the 5th gear input and acting as a “slide hammer”. It will slide it out evenly, but ensure you support the back end of the shaft so it doesn’t fall when it comes loose.

Pic shows no threads in hole on the bearing retention plate:

 

[warp9.9]

Thought I’d add a point on disassembly of the trans.

The manual calls for two M6 bolts to be used to slide the input shaft out evenly loading the bearing to the case as it does so.

Well in all their wisdom Triumph stopped threading those holes, so, you can’t temove it that way.

To get it out, firmly, but not violently, slide the 3-4 input gear back and forth impacting with the 5th gear input and acting as a “slide hammer”. It will slide it out evenly, but ensure you support the back end of the shaft so it doesn’t fall when it comes loose.

Pic shows no threads in hole on the bearing retention plate:

Slide hammer/wrench front of input shaft using the 22 mm clutch basket nut. Newer manuals show that which means triumph figure out them two threaded tabs are about as useful as a c_nt full of cold water.