Countershaft freeplay

[petejw]

Im in the pocess of swapping out my siezed engine,
with the the engine of my parts bike.

Ive pulled the countershaft out of the engine, to check all the gears,
all gears looked fine, so Ive attempted to put it all back together,
the problem Im having is when I tighten the bolt/washer to the countershaft ive got about 2mm free play/slop with the shaft, Ive put all the gears, circlips, thrust washers in order as per clymers, I cant figure out what ive done to cause this freeplay, can any1 think of something i may have done or missed, any help will be appreciated.

[DGXSER]

I do not know the answer to your query, however, if you have the gears out and you have a dremmel tool, I'd go ahead and gack cut the gears now. It can only help and keep you from being back in there later. JMHO

[petejw]

I was quite surprised with the gears,
both bikes have over 130 000ks and all the gears
look like new, other than the washer swap im quite
happy to leave the rest alone, just need to figure out
this shaft.

[petejw]

I found the problem with the free play, apparently
the 5n5 series motors have a washer that sits between the bolt
and case bearing, which takes up any free play.

Ive got it all put back together and using my gears from my original engine
which are in excellent condition, the problem im having now is i when i engage 1st gear, the gears arent meshing and when i release the clutch i get the 'machine gun ' sound, if im stationary and put it into first the shift locks up and i have to turn the engine off and rock the bike to be able to get it back into neutral. All other gears work well.

Any ideas what would cause 1st gear not to mesh properly, especially that the gears worked fine in the original engine, the gears looked good, the shift forks look straight, the shift pawl is alligned correctly. any help appreciated.

[DGXSER]

Purely a guess, but the first and fifth shift forks look identical and could be switched. Here is s pic of mine in place



Note the longer side faces out. If you perhaps had them with the shorter side out, switched, could it cause your issue?

[petejw]

Im pretty sure i have the shift forks in the right
order, my next thought might be the shift drum,
im going to have to pull it apart again and have a good look around.
Thanx for the suggestions.

[petejw]

I figured with the amount of 1st and 2nd gear repairs,
Id get a better response, so no one else has any thoughts or theorys?

[DGXSER]

Hey Pete, alot of the folks that have done this work extensively are at the MOTM rally in Texas this weekend, so may be monday before you hear some moer on this.

[petejw]

Cheers Don,
didnt realize it was this weekend.

[TopCatGr58]

Hey Pete,

I've done this a few times. The one time I experienced difficulty shifting was when the shift chamber cover was being put on, and got pulled back out slightly, enough to allow the shift pawl to slip and fall out of alignment, the dots on the gear/teethed faces didn't line up, and the bike would only shift INTO 1st and neutral, but not higher. Once "we" pulled the shift cover back off, we found the misalignment, repositioned it, and it then shifted just fine!

Your problem does sound like the shift fork isn't fully engaging 1st gear, and so the gear is hanging up with the pinion gears, engaging 2 different gear wheels at the same time, thereby LOCKING the shaft up. So...either the shift drum isn't spinning to it's full 1st gear engagement position, or it is, and the wrong shift fork is in the wrong place?

I've never done the washer swap on the ones I've repaired, the undercutting has been sufficient to keep the gears engaged.
T.C.

[trbig]

If you look at DGXSER's photo, as you look at it, the shift fork on the left is on 4th gear. That shift fork moves back and forth.. sliding to the left (Again as you see in the pic) so that 4th goes into 1st gear lands. Later, it will slide to the right to operate 3rd. 4th gear has dogs on both sides of it.

I tried at one point to swap the the washer between 4th and 1st like some do with 2nd gear. Instead of taking a full step, I found some washers that were the right size and exactly half the thickness as the original. I put one where the washer originally goes, then one behind 1st gear.. moving 1st just half the distance towards 4th for a better engagement of the gears. This experiment failed. While in 4th gear, you could hear it meshing with 1st and it prematurely wiped out 1st gear by rounding off the edges of the lands on 1st and the dogs on 4th.

My long winded version of what may have happened could be a simple washer being in the wrong place on re-assembly, the button on your shift fork being worn where it goes into the shift drum, as stated, possible shift fork order wrong (THey are numbered 1-3 and stamped on the forks and would be in order from right to left in the pic).

My main thought is to get more infor on what you were saying in the beginning. With an extra washer added in the wrong place, like inside the case between the starter gear and the case, it would make the gears in the pic not get pulled far enough to the left.. essentially pushing the shaft and first gear too close to 4th. 4th stays where it is because the shift fork holds it there.. but the other gears would be out of alignment. I'm not sure, but are you saying certain motors having a washer that others don't? If so, all the motors, from 78-84 use the same gears, transmissions, shafts, washers, clips, etc. There is no washer between the starter gear and the case. If you look at an exploded view of the gears, there is a clip shown but that is in the case holding the bearing there.

Tod

[TopCatGr58]

Tod,

The Yamaha Bulletins describe a possible problem with the later 81 model trans, because they went to a slightly narrower bearing on that countershaft, and so a thicker washer was required to take up the space that the narrower bearing left behind, vs. the older thicker bearing. There was warnings about ensuring that the correct edge of the washer was oriented properly. There is a bevel rounded edge vs a sharp edge that needs to be in the correct position against the bearing. I can't remember the exact details, but the bulletin is viewable on the Yamaha Online parts fiche site.

IT's the 4th Tech Bulletin in the 81SH listing: However, the washer is already installed between the bearing and the engine case, and is not removed during the tranny repair process. The gears, and shafts are still the same, and so swapping them from the newer engine to an older engine should not cause any problems. I know when I did mine, I just had access to the same parts that are on the fiche, didn't have to worry about any extra washer on the shaft.

I think SCOTT/3Phase had a similar experience with his countershaft nut working loose, and IIRC had tried to put an extra washer in there trying to shim things closer??
T.C.

[trbig]

I stand corrected.. or sit anyway..


Tod

[oldnortonrider]

Tod,

The Yamaha Bulletins describe a possible problem with the later 81 model trans, because they went to a slightly narrower bearing on that countershaft, and so a thicker washer was required to take up the space that the narrower bearing left behind, vs. the older thicker bearing. There was warnings about ensuring that the correct edge of the washer was oriented properly. There is a bevel rounded edge vs a sharp edge that needs to be in the correct position against the bearing. I can't remember the exact details, but the bulletin is viewable on the Yamaha Online parts fiche site.

IT's the 4th Tech Bulletin in the 81SH listing: However, the washer is already installed between the bearing and the engine case, and is not removed during the tranny repair process. The gears, and shafts are still the same, and so swapping them from the newer engine to an older engine should not cause any problems. I know when I did mine, I just had access to the same parts that are on the fiche, didn't have to worry about any extra washer on the shaft.

I think SCOTT/3Phase had a similar experience with his countershaft nut working loose, and IIRC had tried to put an extra washer in there trying to shim things closer??
T.C.

Hey; TC~~ where are you accessing "....Yamaha Bulletins describe.....IT's the 4th Tech Bulletin............" this from? "...viewable on the Yamaha Online parts fiche site. ......." (??) I know it's there; cain't find it.

[TopCatGr58]

Hey Norton,

Follow this link: http://www.yamaha-motor.com/sport/parts/home.aspx

Then to parts, motorcycle, 81 SH model, scroll down the listing says TECH BULLETINS, the 4th one down.
T.C.