Tips for reassembling transmission

Edited Date/Time 11/3/2014 9:51am
I'm close to putting my cases back together and watched this video to get an idea of how to assemble the transmission (it was easy to take apart!). Is there a better way of assembling the gears, shift forks and drum and putting into the case? Is it always better to put in the left side case (like the video says)? Should I put the crankshaft in the left case before installing the transmission assembly?

Bike is a 89 kx125 if that matters. There are only two shift fork rods. One rod has two forks.
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scooter5002
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Nanton Alberta, CA
11/2/2014 9:13am
All parts in whatever case has the holes for the bolts, I use a couple of longer bolts to pull the second case half down onto the first. One on each side of the crank, go slowly, and be sure it's going down uniformly. Spin the countershaft to be sure it's free, and keep an eye on the gap at both ends of the cases. If the crank and countershaft are spinning freely, you're golden. Be sure your shift forks and shafts are exactly where they're supposed to be, sucks to have to take it apart again.
mxtech1
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Galesburg, IL, USA
11/2/2014 9:17am
It's not hard, but it can be a little tricky getting all the pieces into place. Personally, I install everything into the left side case and then put the ride side case on last. I have found that if you can freeze the crank and all the transmisssion parts and then work fast the right side will go on alot easier.

When the case halves are together, run about half the case bolts in and then check to make sure the tranny shafts spin smoothly and it shifts through all the gears.
dogger315
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11/2/2014 10:05am
I'm close to putting my cases back together and watched [url=https://www.youtube.com/watch?v=X8UL93dgpsU]this video [/url]to get an idea of how to assemble the transmission (it was easy to...
I'm close to putting my cases back together and watched this video to get an idea of how to assemble the transmission (it was easy to take apart!). Is there a better way of assembling the gears, shift forks and drum and putting into the case? Is it always better to put in the left side case (like the video says)? Should I put the crankshaft in the left case before installing the transmission assembly?

Bike is a 89 kx125 if that matters. There are only two shift fork rods. One rod has two forks.
I don't know if it matters which case half you put everything in or not. I install everything in the Right case half.

Install the crankshaft first:



Then put the two gear clusters in at the same time:



Then install the shift forks and spread them out:



Install the shiftdrum and rotate the shift forks so that the pins engage the drum:



Install the shift fork pins:



Turn the gear clusters by hand and make sure they turn freely with no binding. Install the Left side case. I use a crankshaft
installing tool to draw the cases together, but you can use a case splitter or case bolts and a mallet. The key is to keep the
two halves parallel all the way down.



I need to make a video of this process someday.

dogger



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notme
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CA
11/2/2014 10:26am
Great tips by dogger yet again. Notice one thing....CLEAN CLEAN CLEAN!
What size is your 2x4 cradle? I made mine too big..

The Shop

motofab36
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Cowden, IL, USA
11/2/2014 3:01pm
I do it exactly as dogger does including the crank installer tool. Its pretty simple really.
slipdog
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Nor Cal, CA, USA
11/2/2014 3:56pm
X3 like Dogger does.

I've always done the right side because it's the way I learned, but it doesn't really matter. You have come this far so I suggest you get a crankshaft installer, the tusk one in Dogger's photos can't be more than $60-$75. For the love of God, don't use a hammer...
11/2/2014 7:54pm
slipdog wrote:
X3 like Dogger does. I've always done the right side because it's the way I learned, but it doesn't really matter. You have come this far...
X3 like Dogger does.

I've always done the right side because it's the way I learned, but it doesn't really matter. You have come this far so I suggest you get a crankshaft installer, the tusk one in Dogger's photos can't be more than $60-$75. For the love of God, don't use a hammer...
X4.

Don't use the case bolts to put it together, that will put stress on the crank and could throw it out of alignment.
This is what you need: https://www.rockymountainatvmc.com/p/989/17166/Tusk-Crank-Puller-Instal…

Whichever side of the cases has the shift drum, that's what I'd suggest starting with. As Dogger wrote, put the crank in first. I use zip ties or rubber bands to keep the con-rod centered and out of the way (don't want to accidentally get it between the cases as you're closing them up).
scooter5002
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Nanton Alberta, CA
11/2/2014 8:38pm
I'd agree that dogger's way is the proper, and obviously best, way of doing it. I've always used the bolts to pull the cases in, but you do have be careful, as stated, there are inherent risks using this method. Never really got around to buying a puller, usually only wind up doing a case split every few years.

Anyone else use a harmonic balancer puller to split cases? Another backyard trick I use.
lumpy790
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9/18/2007
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York, SC, USA
11/3/2014 5:20am
it all goes in the side the clutch is in. I never pull the shift cam out.
OldMechanik
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Charleston, SC, USA
11/3/2014 9:51am
Wish I could "like" a post.....good job Dogger!
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