How do I replace the outer transmission cover on a Mark III?

nortonmargie · Oct 30, 2022

I have been trying for hours. It won't line up properly. I checked the book, I seem to be doing everything right, but the shaft won't go into the captive ball bearing. I am exhausted.

THANK YOU for all your help!!

L.A.B. · Oct 30, 2022

nortonmargie said:
I have been trying for hours. It won't line up properly. I checked the book, I seem to be doing everything right, but the shaft won't go into the captive ball bearing.

It sounds as if you are trying to fit the outer cover with the ratchet plate installed in the outer cover which can be done but isn't the procedure described in the Mk3 manual, section D10,12 and Fig. D8 which shows the ratchet plate fitted and thus engaged with the knuckle pin roller prior to the refitting of the outer cover.

How do I replace the outer transmission cover on a Mark III?

Note that there is no "O-ring" on the Mk3 "ratchet plate spindle" as stated in D10,12 because it's an error from the pre-Mk3 manual ratchet assembly that has the gear position indicator spindle and although listed and drawn in the Mk3 parts book Group 7, item 19, the amendment list in the Mk3 parts book shows it as "Deleted - Not required".

nortonmargie · Oct 30, 2022

Thank you. I tried it both ways. I now have the cover on, but the bike will not shift properly. I think there is a problem with the crossover.

L.A.B. · Oct 30, 2022

nortonmargie said:
Thank you. I tried it both ways. I now have the cover on, but the bike will not shift properly. I think there is a problem with the crossover.

That's more likely to be the quadrant mis-timed to the cam plate as there's no way to mis-time the cross shaft.

nortonmargie · Oct 30, 2022

L.A.B. said:
That's more likely to be the quadrant mis-timed to the cam plate as there's no way to mis-time the cross shaft.

where is the quadrant and the cam plate? I do have the parts manual. Thank you for your help!

L.A.B. · Oct 30, 2022

nortonmargie said:
where is the quadrant and the cam plate? I do have the parts manual.

Group 7.

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Quadrant, item 21.
Camplate, item 28.

L.A.B. · Oct 30, 2022

nortonmargie said:
the bike will not shift properly.

Were you rotating the sleeve gear by turning the rear wheel (assuming the drive chain is fitted) as you attempted to select the gears? If not, that could be another reason for the gears not engaging properly.

nortonmargie · Oct 30, 2022

The bike is all together and running- I was just trying to deal with a leaky transmission. I did not rotate the rear wheel and will do so. Thank you!

nortonmargie · Oct 30, 2022

Just tried rotating the rear wheel. It is stuck and I don't want to force anything. Will hang it up until tomorrow

nortonmargie · Oct 31, 2022

Removed the tranny cover (for about the twentieth time) and tried replacing it, using your good advice. I think I am closer. Need to put in a couple of Allen head bolts before further testing. Need to get back to work

MichaelB · Oct 31, 2022

Try shifting the gears on the quadrant bolt before putting the cover back.
Make sure it goes through all the gears..

L.A.B. · Oct 31, 2022

MichaelB said:
Try shifting the gears on the quadrant bolt before putting the cover back.

That would be the Mk3 camplate bolt because the Mk3 quadrant is retained by a circlip, not a bolt.

nortonmargie · Oct 31, 2022

Worked on bike some more. Problem seems to be that the splines on the crossover shaft are not mating correctly. Suggestion from another Norcal Norton clubber was that problem was dirt buildup inside the splines. Plan to clean out with WD40 and a 3M pad cut to finger width

L.A.B. · Nov 1, 2022

nortonmargie said:
Worked on bike some more. Problem seems to be that the splines on the crossover shaft are not mating correctly. Suggestion from another Norcal Norton clubber was that problem was dirt buildup inside the splines.

So, has the "stuck rear wheel" apparent problem been eliminated?

Another possibility could be that the primary end of the cross shaft is no longer located in its bush in the outer primary cover if the cross shaft mechanism locks up when the gearbox outer cover is tightened.
The splined coupling would normally have a protector sleeve to keep dirt out.

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nortonmargie · Nov 2, 2022

The protector sleeve is present (I installed a new one when I had the primary case cover off a few months ago. I cleaned out the splines with WD40 and a 3m pad, cut to finger size. Still no luck. Nortonclub friend suggests that the problem is that the crossover is not properly seated and that I tap it into place with a dowel and a rubber mallet. This has been tiring and frustrating

L.A.B. · Nov 3, 2022

nortonmargie said:
The protector sleeve is present (I installed a new one when I had the primary case cover off a few months ago.

Nortonclub friend suggests that the problem is that the crossover is not properly seated and that I tap it into place with a dowel and a rubber mallet.

Do you mean tap the cross-shaft into the primary case?

As you recently removed and replaced the primary cover and the same problem didn't occur at that time then it shouldn't be necessary to do so now and if the cross shaft is not seated in its bush in the outer cover Edit: and if screwing down the gearbox outer cover didn't seat it then I doubt tapping will either or the outer circlip '8' has possibly become dislodged from its groove so the splines are out of alignment as I previously said the two gears could have dropped out of mesh but I now think the plate on the hydraulic tensioner would prevent that.

Also, the cross-shaft and gearbox splines normally slide into the coupler '5' (with internal circlip '6') and are often a loose fit resulting in excessive play at the gearchange pedal.

nortonmargie · Nov 3, 2022

The circlip is present between the shift lever and the primary case. The crossover moves when I move the shift lever. I have narrowed the problem. The crossover shaft is not mating with the shaft from the gearbox cover. I need to (carefully) push the boot back and see what is going on

Torontonian · Nov 3, 2022

Good luck. Don't forget to grease those engagement splines , same as a BMW. Don't force anything.

nortonmargie · Nov 4, 2022

Bike is back together, thanks to machinist friend who stopped over and notice that burrs on the shaft that goes into the ball bearing were keeping the shaft from going into the bearing. Three minutes work with a file and I was tightening bolts. Whew!

How do I replace the outer transmission cover on a Mark III?

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