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

[Claviger]

UPDATE:
Mufasa is fixed.

The short version: Circlip was out of place, 2 gears tried to engage at the same time, bad things happened.

Read on, for a swervy, curvy, roundabout thread that follows my repair and some upgrades along the way. With quite a few pics.

Scenario:
Riding up hill about 4000 RPM in 3rd, 30-40% throttle, kick the shifter to go to 4th, false neutral. Pull clutch try again, false neutral + grinding + no drive force.

Pull off, kill bike, fight with lever by hand because it’s stuck. Get it to 2nd and try to baby it home. Try 1st, 2nd, 3rd, 4th all work try for 5th does a repeat with a stuck shift lever buy not in gear.

Get it eventually to go back into 2nd and get it home without shifting anymore. As I’m pulling into my driveway I hear a grinding sound from he clutch area when I pull the clutch.

@Sam had a very similar failure, almost to a T back in 2015 at almost identical power level 240hp/180tq.

Bikes not going back together until I find the cause and figure out a permanent fix.

Point of clarification:

I do not, in any way, believe this was an assembly error while at Carpenter Racing, I take full credit and honors for munching this transmission.

 

[Claviger]

Consolidating Pictures a bit:

 

[Claviger]

After ripping into it, I've discovered the singular reason we have issues with the transmission in the first place. Design.

Our 5 speed is by all visible accounts a 6 speed with the input gears removed from the 2-3 dog and the output gear, simply removed from the output shaft. There is absolutely enough room to install the 6th gear on the output shaft. The removal was a marketing decision not an engineering decision, clearly, there is NO reason the Rocket has only 5 speeds other than Triumph wanted it to only have 5 speeds, likely because the competition in 2002/2003 were only 5 speeds.

Had triumph designed the transmission with 10 fixed gears which do not slide and simply used 3 dog rings instead of 2 dog rings and a 3rd/4th/5th dog ring hybrid the trans would be ridiculously simple and strong. Sadly, it appears they just grabbed an age old 6 speed design, scaled it up, and removed 6th gear. The draw back to the 10 fixed gear, 3 dog ring concept would be length. The shafts would need to be an inch or two longer to achieve it.

The biggest advantage to 5 fixed gears on the ouptut, means no circlips, it could be achieved without use of a single clip.

The triple dog ring input would still require circlips, 6 of them, however, all axial loading would essentially be eliminated and the design wouldn't apply force to the circlips.

I should add, every single recent transmission I've looked through in a bike, and I've looked at a lot of pics now, uses this "floating gear/dog ring" hybrid" design. It's **** imho and all bikes with it are flawed in my eyes.

Could have, should have, didn't...

Finally evidence of a failure, I was worried I’d get it open and everything would look healthy, these appear to be chunks of gear teeth:

 

[Claviger]

Root Cause Analysis Post:

Reserving this post for the end when I find what the root cause was.

Original Working theory (wrong):
Bent a shift fork, leading to circlip migration, leading to trying to be in two gears at once, leading output shaft shifting forward slightly, moving the clutch basket, leading to the scoring on it.

Current Theory, Supported by damage analysis:
3rd Gear circlip was not in it's groove.

What caused 3rd gear's circlip to jump out of the groove, now there's the question. The direction it moves when it's forced out of the groove is in the direction of a 5th to 4th downshift (3/4 share a input gear), and that is the only normal movement that can cause side loads onto 3rd gear. Side load could also be generated in a failed 4-5 upshift if the dogs bounced instead of engaging when you shifted. I've never had a failed 4-5 up shift, so I can only conclude that being heavy footed in 5 to 4 downshifts is the cause, as there is no other normal action in the transmission that could possibly cause the circlip to get pushed.

Unless one of the much smarter guys here knows something I don't about how this whole apparatus works, I consider the mystery solved.

CAUSE:

Lead foot 5-4 downshifts = dislocated 3rd gear circlip = wobbling third and fourth ouput gear = time bomb waiting to explode when and if 3rd wobbles.

 

[Claviger]

Costs will be tracked and updated in this post as well as a consolidation of part numbers etc. I figure while I’ve got it apart I might as well upgrade stuff.

This is the final parts listing, exactly what it will all cost me:

Tech Measurements:
- Connecting Rod Length Center to Center 6.693”

- CP X100A 11:1 SCR Piston Equivalent Volume 6.3cc (volume of dome compared to a flat top piston)

- Headgasket bore diameter 102.22 mm

- Headgasket thickness: 0.41mm - 2 Layer

- Output Shaft Shim Size - 32mm ID/ 36mm OD


CAM SPECS BELOW FOR CARPENTER 265 KIT CAMS:

Intake Clearances - .2
Exhaust Clearances - .24

Measurements at 0.04” lift:
IVO - 18 BTDC
IVC - 61 ABDC
EVO - 57 BBDC
EVC - 12 ATDC

Tappet Lifts:
Intake - 0.455”
Exhaust - 0.4105”

Centerlines:
Intake - 111
Exhaust - 112

Duration:
Intake - 259
Exhaust - 249

Cam specs from the manufacturer
0.465 lift intake
264 duration intake at 0.04”
0.427 lift exhaust
258 duration exhaust at 0.04”

Remeasured the 0.006” as well
IVO - 43 BTDC
IVC - 75 ABDC
EVO - 75 BBDC
EVC - 37 ATDC

Duration:
Intake - 298
Exhaust - 292

 

[Scorp]

Detent spring?

 

[barbagris]

Reading output shaft shifting forward slightly, moving the clutch basket, leading to the scoring on it.

I think your interpretation of SLIGHTLY and mine my differ a bit.

 

[joesoap]

I think your quest for high rpm and super fast gear changing/sport riding may have just slapped you in the face matey...why dont you leave all that manic stuff for bikes that where built for it and give the old girl an easier life not being negative here when i read your posts i feel your riding style would be better suited on a sports bike. No ime not a boring old harley rider as i have silly high power bikes myself and i loving killing them on a sunday morning Anyway my friend thats a piss poor bit of luck there but ime sure with your know how it will be split and fixed in no time..watching with interest

 

[BigNorm]

I have to agree with Joe although I love how you literally push your bike to the limit and rebuild it stronger. I'm curious to see how you will resolve this showing every step along the way. Your posts have helped me organize my own future projects in my head. For example: lower radiator hose spring. I plan on getting one because of your radiator cap post. I also plan on a higher bar cap because of you. Thanks for being the r3 r and d department .

 

[barbagris]

kick the shifter to go to 4th,

these appear to be chunks of gear teeth:

So you kicked it in the teeth. Bad Deadpool!