Gearbox will shift down, not up.

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MexicoMike

MexicoMike

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WTF?
I was doing the final assembly on my gearbox this morning. It shifted correctly into all gears when the shift fork (or whatever its called) was pushed up/down by hand. However when installing the outer case and using the shift lever, if the tranny is in fourth when the cover is installed the shift lever will correctly run from 4th to 1st. BUT if I then try to shift up, the lever just moves against its spring but nothing happens in the gear box. Obviously the shift pawl is not engaging with the shift cam but ONLY when shifting up. WIth the outer cover off and looking at the shift mechanism and working the lever, it appears to work correctly. All the parts are in good shape and none of them were changed from before, when the bike shifted just fine. I am obviously missing something very obvious here but I don't know what it is. I am totally mystified.
 
MexicoMike said:
if the tranny is in fourth when the cover is installed the shift lever will correctly run from 4th to 1st. BUT if I then try to shift up, the lever just moves against its spring but nothing happens in the gear box. Obviously the shift pawl is not engaging with the shift cam but ONLY when shifting up.
Click to expand...

That's a symptom of an incorrectly set ratchet spring.

http://www.oldbritts.com/gearbox_a.html
Gearbox will shift down, not up.


Additional information in the NOC Service notes p.37 (pdf p.39): http://archives.jampot.dk/Book/Workshop ... _Notes.pdf
 
Thanks - Mine looks exactly like that and I was careful to check it per the Norton service manual/the OB tranny rebuild tech article. It seems to work perfectly when holding the outer cover and watching the mechanism. None of those parts were changed or adjusted. But I'll check it again..
 
I had the same problem when I replaced the outer cover recently, having replaced the return spring. The ratchet spring looked like it was OK, but it needed tweaking slightly. When you shift, using the gear lever, the pawl should flick round so that the flat on the pawl lies against the inside of the arm of the ratchet spring, as per the Old Britts article. Then it can engage with the ratchet. The pawl must be completely free to rotate on its pivot in either direction.

Have you double-checked that the quadrant is engaged with the camplate in the correct position?
 
"Have you double-checked that the quadrant is engaged with the camplate in the correct position?"

Yes, I checked that a couple of times and I don't see how it could be wrong - in 4th the fork almost touches the top of the cutout in the inner case and in 1st it almost touches the bottom. A tooth different would make it jam before it could get to either 4 or 1.

I tried some adjustment of the spring, even though it was set as per specs - just a barely noticeable bit of clearance for the pawl between the spring arms. Didn't help.

I'll go over it again - I'm sure the problem is in one of those two areas though at the moment I don't see how.
 
Mike, did you disturb the cam plate setting at all ??? If the indexing is off by just one tooth, you'll have the problem you describe. (been there, done that.) Baring that, I would just take it ALL apart and start over from scratch. Easier that way than "troubleshooting" I think. Then pay special attention to all settings and indexing on assembly. Cheers !
 
"I would just take it ALL apart and start over from scratch."

Good advice and that's my plan!
 
I also had that same issue and found that I was off on the camplate indexing by a tooth. Took it all apart, reset the camplate and put it back together and it shifted up and down through all gears.
 
"the problem is in the outer cover PERIOD no need to go deeper."

It seemed that way to me as well but it all worked previously. I replaced the large washer that goes between the cam and outer cover because it was rusted/pitted and I replaced the heavy spring that returns the shift lever to center for the same reason. They both worked fine but I wanted new parts since the old were rusted/pitted. THe ratchet spring worked perfectly before and was not changed/adjusted in any way.

But I admit that if something was replaced and now doesn't work, it's the first place to look...
 
I too think your problem is most likely in the outer cover. You can check that all the gears are being selected, with the outer cover removed, by levering the knuckle on the end of the quadrant up and down. If all the gears click into place, then it's definitely in the outer cover. I had the same problem when I replaced the gear lever return spring and it took a while to tweak the ratchet spring into the right shape so that the pawl flicks round with no resistance to engage in the ratchet. Also, check that the ends of the return spring (not the ratchet spring) are engaged properly either side of the tang on the plate, so that the spring is centred.
 
Thanks guys. I've concluded that it is the cover. All gears select perfectly without the cover installed. By messing with the spring (should have bought a new one - don't know why I didn't) I have managed to make it act differently though as of last night, still couldn't get it to reliably select all the gears both up and down. So that will be my focus. But I still can't understand why it worked perfectly before and now, upon reassembly, it requires something different from the spring. The spring and pawl were unchanged. I'll futz with it until I get it right.
 
Mike, you didn't by any chance mount the spring the wrong way up? it is not symmetrical and the arm with the 2 bends has to be face down. The air gap between both spring arms and the pawl is critical and can easily be disturbed.
 
"it is not symmetrical and the arm with the 2 bends has to be face down. "

I dIdn't realize that initially though I did read this in both the service manual and the Norton Owners club info:

" it must then either just touch or just clear the pawl with its double cranked leg downward. "

But I didn't have the faintest Idea what "a double cranked leg" was! However, I put the spring back in with the same orientation that it had before (wear marks on the pawl lined up with the spring). If I flipped it over, the marks didn't align.
 
Mike, at rest the pawl is not supposed to touch the spring at all, it only contacts it once it moves, there is supposed to be a minimum of 0.010" gap on each side, otherwise the pawl will get stuck in one position and not index through the gears. If there is clearance on one side and not the other, then typically it will shift either up or down OK, but not both - this is exactly the symptom you have described. In order to get the appropriate gap you simply bend the arms of the spring with a pair of pliers, if you bend the arms in a bit it gives more clearance as then the arms contact the stop bracket sooner pushing the centre part of the arm near the pawl further out. One other thing to check is that the bottom tang of the pawl carrier that engages with the thick spring underneath does not foul the radiused slot underneath, this is best done with the thick return spring removed and then move the fitted assembly through it's arc. This can sometimes get disturbed if you have taken the bracket off for polishing or some other reason.
 
All DONE!

Gearbox back together, shifting perfectly, filled with ATF and back on bike!

Thanks to all for the info re the shift spring/pawl and how to set it up. Though I'm still a bit stumped by the fact that the spring/pawl/gear selector worked before and when reassembled, it didn't. Oh well, it's fine now.

I had no idea that the pawl/spring could be that "fiddly." ;)
 
Glad everything worked out well in the end! It should be good for many thousands of miles.
 
Mike, I don't think ATF is viscous enough for use in the gearbox, it is fine in the primary drive of non electric start models, but you really need a good gear oil in the gearbox for the amount of load that it takes.
 
Dave,

Thanks - I'm calling it an "experiment." There was a thread recently that included some posts re ATF in the gearbox and based on some good reports, I decided to give it a try. I guess the worse thing that could happen is I get to buy all the bushings/bearings again PLUS all the gears! ;)
 
Thanks for letting us all know how this turned out ! My favorite posts are troubleshooting. As far as gearbox oil, I stick with Amsoil synthectic 90W myself. I would not have the "cahoonus" to try the ATF as you are. Let us know how it turns out ...

As far as "experimenting" I did rebuild my 750 with DRY piston rings and a lightly lubed skirt. ( I read alot on this and decided to try it, as the worst that could happen is it would seize; and I would have to buy all new parts and start over.) And ya know, those rings seated like "in a couple minutes" of hard riding ...bike runs GREAT.

I guess that would be another subject post though, eh ???
 
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