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walshy

Re assembly of gearbox 03wr450

10 posts in this topic

Got the motor pulled apart to do a rebuild!!!

Have found plenty of information on how re assemble crank shaft and cases.

What I need now are some tips on putting the gears and shafts back in the case in the correct order without forgetting anything.:thumbsup:

Maybe I can learn from someone else's mistakes :thumbsup:

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hi,

as long as you havent pulld the gears off the shafts the hardest thing will be holding the full gear set, shift forks and drum all at once and placing it back into the case. It took me several attempts to get it in, and once you get it in you will prob need to wiggle, push, twist things to get things to drop correctly in place. i assume you have a manual, just check how you have things together against it, prop the case on the work surface so it wont move around much while you attempt the place everything. It will only go back together one way so if it just wont go then somthing is amiss.

one another note since you have the crank out i would recommend having it balanced. it will take some vibration out and add some lifespan to the motor. i did this to mine also had the crank pin tig welded in place. the guy who did the work recommended it so i went with it. he ran the weld 180 around both sides of crank. looked great when i got it back couldent hurt. good luck

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thanks drc02

All the gears look to be in good condition, so it's all still on the shafts..

Didn't really want to go any further than that anyhow. :thumbsup:

There weren't any transmission issues before the tear down but have noticed that couple of the bearings in the box are a bit on the coarse side so will be replacing all bearings and seals, etc> The crank weld and balance sounds interesting, they do vibrate a bit at the higher speeds!!!!!

Still a bit concerned that I might put it back together and the gear selection isn't in the right sequence>>> :thumbsup:

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The shafts and gears go in first and mated together. The shift forks on their shafts go in next, but do not put the shafts into their respective holes in the case, spread them away from the shift drum that goes in next. Then align shift forks in their respective grooves.

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The shafts and gears go in first and mated together. The shift forks on their shafts go in next, but do not put the shafts into their respective holes in the case, spread them away from the shift drum that goes in next. Then align shift forks in their respective grooves.

So is it possible to put the shift drum in wrong, therefore, gears out of sequence??????:thumbsup:

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No, it will only go together one way, put it together with the drum in the neutral position.

Make sure you can get all the gears before you put the rest of the motor together. (and remember you will have to rotate the shafts for the dogs to line up and engage as you shift through the gears)

You can even do a dummy run without the crank to make sure you're doing it right. :thumbsup:

Also you can check the parts fiche on the yamaha site to make sure you have everything there and in the right order.

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The shafts and gears go in first and mated together. The shift forks on their shafts go in next, but do not put the shafts into their respective holes in the case, spread them away from the shift drum that goes in next. Then align shift forks in their respective grooves.
Wouldn't it be nice if you could do that? But you can't.

The difference is that in the Yamaha , the shift forks and shafts are a single part. The shafts slide in the case, the forks don't slide on the shafts. That means you have to pick up both shafts and the 2 or 3 (depending on whether it's a 4 or 5 speed) shift forks as an assembly and start them into the case, just to the point where all the shift fork shafts have started into the case. Then engage the shift cam to the forks, and slide everything the rest of the way in.

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Here's what worked really well for me:

assemble the shafts and shift forks on the bench - I was also able to install the drum at the same time, but like Grey said - it can be added after as long as you keep the forks and shafts just barely in their holes.

At this point, I wrapped the whole thing in string, staying away from the ends of the shafts.

You don't have to crank the string on - actually, loose is preferrable since you'll need to align about 5-6 holes, but make sure it's tight enough so the assembly doesn't blow apart when you go to put it in - the string acts like an extra pair of hands allowing your hands to focus more on getting everything seated in their respective places.

Once done, cut off the string and verify it's all gone before trying out the tranny to verify it shifts all 4/5 gears.

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