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Discussion Starter #1
Hi all,

First off lets have a game of spot the difference shall we?
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Ill keep this thread up to date as I progress but the main thing is proven - that the 6 speed tranny can fit in the 900 casing, I'm not calling it a success until the bike is running again as im hoping the ECU doesnt decide to excrete a brick when the GPS tells it that its in 6th gear.
Also, I'm hoping the clutch basket thread doesnt snap or shear when tightening, looks like whoever removed the transmission used quite a bit of heat to undo the bolt!

Whilst I have the casings open, if anyone wants any information or close up photos of anything then give me a shout.
 

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Great project, is this a world first?
Wish you all the best, way above my levelo_O
I presume you need the 6sp selector drum, is the rest of the selector mechanism the same?
Like you said it would be a shame if you get all the mechanical bits to work and the ECU throws a wobbler when it reads 6th gear from the GPS but here's hoping it just carries on as if its in 5th, fingers crossed(y)
 
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Which way are you planning on doing this?

Swapping both shaft sets?

Or swapping just the gear onto the 5 speed?
 

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Discussion Starter #4
Great project, is this a world first?
Wish you all the best, way above my levelo_O
I presume you need the 6sp selector drum, is the rest of the selector mechanism the same?
Like you said it would be a shame if you get all the mechanical bits to work and the ECU throws a wobbler when it reads 6th gear from the GPS but here's hoping it just carries on as if its in 5th, fingers crossed(y)
Thanks, im hoping its a first ;)
Dont doubt yourself, I was expecting there to be way more complicated parts and mechanisms in the block but once some research was done and the engine was apart I was surprised to how simple and little equipment there seems to be in there.
The scariest part is if it goes south by damaging something then its going to be expensive!
The transmission I bought came with all the drum and selector forks so everything will be swapped just to be sure.
The tune ECU map for the scrambler does say 3rd to 6th on one of the map tables so if the parameters are there then im hoping there wont be a problem, especially when the gear position sensor has the same product code as the 1200 engine.

@Skwirl just going to swap the whole units out as per the pics, cant be bothered messing about with pulling bearings and making it all fit on the original shafts, would have to check to make sure that would be possible as it could be a cost effective swap to purchase the brand new required gears new from triumph and convert the original shaft though.
 

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You're right, you don't what you're capable off until you try, my biggest motorcycle job so far was removing the cams on my Daytona 675, knowing that everything is going to be whizzing round at 14500rpm after I put it back together was a bit daunting at first, hope I never have to get to the stage of splitting engine cases though.

I noticed the GPS was the same, not sure how it works though, thought it may be a BCD output but it only appears to have two outputs (plus power) so maybe it just gives pulses at each change, plus a neutral signal, and the ECM works out the gears, but then it would have to remember the last gear when you powered off so maybe not.

Hopefully the map will be ok, like you said various aspects of the program may be standardised across the range even if they are not selected by that particular model of bike. Maybe you could have tried it beforehand by removing the GPS and turning it one more "step" to 6th gear on a paddock stand and see what the reaction was?

As we're playing spot the difference what the significance of the small grooves on the 6sp gears that are missing on the 5sp?
 

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Discussion Starter #6
Honest answer, not a clue, could be something to do with the machining process if they decided to change it or maybe put there for oil distribution in some unexplainable crazy way, my bike is 2017 model, the box is from a 2018 thruxton, also its from an American market bike so it could be for identification purposes?

My theory for the change indicator is it could be a resistive contact, bit like a scaletrix trigger then the ecu will read the value and throw a number on the dash 🤷‍♂️
 

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Good thought singlin.
What if he could assemble the shift parts with the case split. I'd like to see how it works together.
 

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In for this. Gonna go Google the gear ratios right now to see how this will affect things as well. This will be my next mod if you successfully guinea pig this idea.
 

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I think you're right on both counts, couldn't find any other explanation online for the grooves so could well just be for identification, although it seems a bit old school.

I was totally overthinking the gear position sensor, makes sense to just be a resistive element giving different voltage levels back to the ECM for each gear, DOH!
Keep up the good work(y)
 
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This is a really cool project!
Anything behind the detent wheel that could be misaligned to cause the shift down problem?
The drum does seem to want to catch a little here and there against the selector forks which was one of my thoughts that I never really voiced, havent taken it out of the casing yet or had a proper play though!

There's a motorsport tuner next door to my work who claims he can machine in titanium but if not then definitely steel, he was waving the spare pivot plate I gave him in my face saying it was poo for use of a better word, especially after he saw the MIM cast lobes.
Hes going to machine the pivot plate up for fifty quid as a one off so if it solves the issue then Ill be pleased.
If after all said and done and its a proven fix then I could ask him to make more and I'd probably just charge postage for anyone who might be interested, all who have experienced that problem are all in this together so id be happy knowing I've helped someone out really.
Also he drilled the MIM pivot plate and gave me the feedback, really hard exterior, like butter after the getting through the skin.

@Skwirl I can do a video if you want, what is it you'd like to see?
@speedfoos I used gearing commander and the research showed that across all the models with the same w/c twin they share she same ratios but just alter the sprockets on some models, the additional gear will just act as the final dropper and let me cruise at 80 saving just under 400rpms
 

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A video might do it. Just in case I have a problem in the future. You can only learn so much from pics or a book. I'm a diesel mechanic by trade, never worked on a bike before. The best way to learn is to tear it apart, lol.

Mim parts are like that. When I saw it in a previous thread, the info posted by another member made sense. His post stated improper heat treat on a batch of parts.
All that said, if you get a machined piece to work, I'd be interested in one.

Pretty good project you have.
 

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In for this. Gonna go Google the gear ratios right now to see how this will affect things as well. This will be my next mod if you successfully guinea pig this idea.

1st to 5th gears are identical in both transmissions. The only difference is a dirty great space where 6th should be in the 5 speed boxes. The only difference on any Bonnie engined bike (drivetrain wise) is the final gearing - ie chain and sprockets.
 

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Discussion Starter #16
Appreciate the feedback and all the positivity on this guys! I've just compiled a list as long as my arm for o-rings, gaskets and the like, added a couple of cam bolts too so that if they get left on the desk at work long enough then the tec cam will get purchased.

@Skwirl I totally agree, was definitely the child who took things to bits as a kid to see how they worked, sometimes going back and forth in all the Haynes manual sections cam get a bit tedious but its nice to know what to put loctite on and which bolts and other parts are classed as one use only.
Will get a mock up video on the disassembly of the cases etc with a good walk round sorted soon as I'll have to wait for all the new bits to come to seal it all back up anyway.
Beats doing nothing in lockdown part 3!
 

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Hi all,

First off lets have a game of spot the difference shall we?
View attachment 744243 View attachment 744244

Ill keep this thread up to date as I progress but the main thing is proven - that the 6 speed tranny can fit in the 900 casing, I'm not calling it a success until the bike is running again as im hoping the ECU doesnt decide to excrete a brick when the GPS tells it that its in 6th gear.
Also, I'm hoping the clutch basket thread doesnt snap or shear when tightening, looks like whoever removed the transmission used quite a bit of heat to undo the bolt!

Whilst I have the casings open, if anyone wants any information or close up photos of anything then give me a shout.

where did you get the parts? junked or crashed bike?
 

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Discussion Starter #18
Ebay, description didnt say what condition the bike was in but im guessing it must have been a write off for a 2018 model.
 

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When Polaris took over the Indian brand they introduced the new Scout. It comes in two models, the standard Scout and what they call the Scout 60, which is a reduced spec bike. One difference is that they removed 5th gear. The 60 has only five gears but the ratios are 1,2,3,4,6. I had a 60 and never missed 5th at all as the bike has such a good torque curve.

It looks like removing 5th for a reduced spec model is more widespread than I knew. Good luck with the project.
 

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When Polaris took over the Indian brand they introduced the new Scout. It comes in two models, the standard Scout and what they call the Scout 60, which is a reduced spec bike. One difference is that they removed 5th gear. The 60 has only five gears but the ratios are 1,2,3,4,6. I had a 60 and never missed 5th at all as the bike has such a good torque curve.

It looks like removing 5th for a reduced spec model is more widespread than I knew. Good luck with the project.
So they ended up with a 4speed plus overdrive? Strange! The 900s are missing 6th not 5th.
 
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