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Joined case halves... trans problem??

  • hackman101
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Joined case halves... trans problem?? was created by hackman101

First a question, how many ways can a transmission be put together? Specifically setting the shifter forks in their "proper" locations.

I allowed my transmission to become a "non-cluster" at one time during the disassembly/reassembly of my 73 MX250. Upon looking at how it all goes together, it appeared to only go together one way to allow the shifter drum to do it's thing. So that is the way I set it in place, checked the operation, making sure gears moved, the drum rotated, what have you. Everything appeared good.

As a mention none of the shafts were disassembled, just the shafts were not nested together with the drum and shifter forks for a short time. They came apart after the zip ties slipped that was holding them together.

Upon setting the crank and getting the cases together and adding the shifter allowed me to make a more real time run trough the gears. It seems when I shifted into what is supposed to be first gear, (pulling up on the shift lever) when I turn the input shaft by hand while I am doing this, the output shaft really turns much faster in that gear, and slower when I am presumably shifting to a higher gear (pushing down on the shifter).

On noticing that, I removed the plug that holds the shifter detent and rotated the shift drum until it was back in neutral, spotting the notch in the "plate stopper" (item #5 in Partzilla) as it is called in the parts line up. Ran through the gears again and seems like it did the same thing again, output spins faster in what is presumed to be first and slower when shifting in other gears.
1973 MX250
Past rides 45 years ago (and longer)
1964 Honda 50cc C110
1960s Yamaha 65cc scooter
1960s Honda 65cc w/ 90cc engine mashup
1971 DT1-E modified to MX kinda...
02 Jan 2022 17:58 #1

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Replied by MarkT on topic Joined case halves... trans problem??

I'm often confused easily...  isn't shift pattern starting in neutral, click down for first and then up for second, etc?

In any case, there is no real way to reverse the pattern by assembling it that I can think of. 
1963 YG1-T, 1965 MG1-T, Allstate 250, 1970 CT1b, 1971 R5, 1973 AT3MX, 1974 TS400L, 1975 RD350, 1976 DT175C, 1976 Husqvarna 250CR, 1981 DT175G, 1988 DT50, 1990 "Super" DT50, 1991 RT180, 2017 XT250
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02 Jan 2022 18:09 #2

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Replied by RT325 on topic Joined case halves... trans problem??

Yep as Mark says, down for first. Unless the motor is on the bench & lever pointing backwards i guess. Anyway--top gear turning the mainshaft by hand will have the output shaft turning fast. I think you have it right. Hard to do it wrong without being Very Wrong & obvious.
02 Jan 2022 19:20 #3

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Replied by hackman101 on topic Joined case halves... trans problem??

@ Mark T, yes 1 down, 4 up is what I thought. Maybe I am just missing something when I push down on the shifter lever. It sure does seem that the sprocket shaft is spinning faster that when I pull up to shift to higher gears.

@ RT325, The shaft I turn is the input shaft that the clutch assembly resides on, I do not have the clutch on yet, I determined I need all new friction discs and springs, so the clutch install is not quite the priority just yet. I have the motor pointing forward. I learned a long time ago that I have to have many things oriented the proper way to make sure I am tinkering with the right thing the right way. Making sure I got the trans right is my main focus for now. Maybe I had a brain fart and was pulling the shifter the opposite way it should have been. Even so, the speed the countershaft sprocket was turning didn't jive with shifting.

I will look into it more. I really don't want to have this thing assembled and running and have to tear it all back down again because I assumed too much.
1973 MX250
Past rides 45 years ago (and longer)
1964 Honda 50cc C110
1960s Yamaha 65cc scooter
1960s Honda 65cc w/ 90cc engine mashup
1971 DT1-E modified to MX kinda...
02 Jan 2022 19:40 #4

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Replied by hackman101 on topic Joined case halves... trans problem??

I may have had the shift pattern in my head backwards, as in 1 up, 4 down. It has been so long since I have needed to recall that.
1973 MX250
Past rides 45 years ago (and longer)
1964 Honda 50cc C110
1960s Yamaha 65cc scooter
1960s Honda 65cc w/ 90cc engine mashup
1971 DT1-E modified to MX kinda...
02 Jan 2022 19:42 #5

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Replied by RT325 on topic Joined case halves... trans problem??

You'll be ok i'm sure. With the plunger & spring in you'll need to twiddle the main shaft a bit & maybe hold the output from turning to click from gear to gear. Without thinking too hard--first gear you'll need to turn the mainshaft about about 3 times to get one turn of the output shaft.
02 Jan 2022 20:29 #6

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Replied by MarkT on topic Joined case halves... trans problem??

In first gear you have to spin the clutch shaft a few times to get the output sprocket to rotate once.  In 5th gear, sprocket turns about the same speed as clutch shaft so countershaft does spin faster as you shift up. 

Anyway, I'm sure you're okay....  there isn't any way to mess up shift pattern.  Assembling wrong will result in locked up trans or no shift in my experience.

 
1963 YG1-T, 1965 MG1-T, Allstate 250, 1970 CT1b, 1971 R5, 1973 AT3MX, 1974 TS400L, 1975 RD350, 1976 DT175C, 1976 Husqvarna 250CR, 1981 DT175G, 1988 DT50, 1990 "Super" DT50, 1991 RT180, 2017 XT250
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02 Jan 2022 21:50 #7

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Replied by hackman101 on topic Joined case halves... trans problem??

Well I finally know the condition of the transmission after all this time, IT WORKS!!!! Got the bike going today. Update on my other post.
1973 MX250
Past rides 45 years ago (and longer)
1964 Honda 50cc C110
1960s Yamaha 65cc scooter
1960s Honda 65cc w/ 90cc engine mashup
1971 DT1-E modified to MX kinda...
03 Apr 2022 21:26 #8

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Replied by PDXtyist on topic Joined case halves... trans problem??

I am going through similar issue on my TY250A motor. I have gearbox assembly in correctly but as soon as cases are together (as a mock-up) and shift mechanisms in place, the shift lever claws don’t seem to bite into dowel pins consistently to rotate shift drum. Perhaps my claw is too worn out? The dowel pins don’t look too worn. Is there a way that shift claw can move up to bite more? I do know how to center it vis a vis the dowel pins.
Also, when centering it, is there a particular gear it needs to be in?
Thanks fellows.
05 Oct 2022 08:58 #9

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Replied by MarkT on topic Joined case halves... trans problem??

You need to spin the shaft(s) to shift on the bench. 

You can assemble in any gear as far as I know but I always do it in neutral. 
1963 YG1-T, 1965 MG1-T, Allstate 250, 1970 CT1b, 1971 R5, 1973 AT3MX, 1974 TS400L, 1975 RD350, 1976 DT175C, 1976 Husqvarna 250CR, 1981 DT175G, 1988 DT50, 1990 "Super" DT50, 1991 RT180, 2017 XT250
05 Oct 2022 09:13 #10

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