Gearbox Gear Changing Problem

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May 16, 2016
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I have a '74 MK2 Roadster I am restoring.
I rebuilt the gearbox about a year ago and have since installed it in the frame with the engine etc.
I needed to change the box into top gear to be able to tighten the clutch centre nut and I accomplished this ok by rotating the rear wheel and moving the gear lever downwards.
However, when it was in top gear I was unable to change down through the gears by doing the same procedure (rotating the back wheel [drive chain attached] and moving the gear lever upwards) but nothing happens. No matter what technique I used I could not get the box to change back down through the gears to neutral.

I am hoping it is a selector adjustment and not something that requires the gearbox to be stripped again.

Thanks for any advice that can help me out.

Cheers Don
 
However, when it was in top gear I was unable to change down through the gears by doing the same procedure (rotating the back wheel [drive chain attached] and moving the gear lever upwards) but nothing happens.

Does the ratchet mechanism engage when you operate the gear lever so there's mechanical resistance or is there only return spring resistance? If you only feel spring resistance then as concours said, the hairpin spring probably needs 'adjusting' (bending).

You should be able to use the camplate (Edit: or quadrant) bolt to shift the gears while rotating the rear wheel as before.
 
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Does the ratchet mechanism engage when you operate the gear lever so there's mechanical resistance or is there only return spring resistance? If you only feel spring resistance then as concours said, the hairpin spring probably needs 'adjusting' (bending).

You should be able to use the camplate (Edit: or quadrant) bolt to shift the gears while rotating the rear wheel as before.
Thanks Les, I will try that - moving the camplate via its bolt head.
The outer cover has to come off to adjust the spring?
 
Make sure the dog leg bend of the ratchet spring is on the downward run. I've seen this fitted the wrong way around an that P11 had shifting problems.
 
Make sure the dog leg bend of the ratchet spring is on the downward run. I've seen this fitted the wrong way around an that P11 had shifting problems.
Ok thanks. I will check that when I take the outer cover off. I plan to do that this afternoon.
When I get the outer cover off I plan to check if I can get the tranny back into neutral by levering the knuckle up and down.
And then look at the spring shape and position and see where I go from there.
 
Ok thanks. I will check that when I take the outer cover off. I plan to do that this afternoon.
When I get the outer cover off I plan to check if I can get the tranny back into neutral by levering the knuckle up and down.
And then look at the spring shape and position and see where I go from there.
Well I removed the outer gearbox cover and checked if the gearchange return spring and flat washer that goes over it were in place correctly and that the hairspring was in correct orientation which it was . I adjusted the hair spring a tad. Then refitted the outer gearbox cover a total of five times and still not gear change happening either way either up or down. I was able to lever the knuckle in the gearbox slot through the full range of gears and then left it in neutral.
About to give up.
Does the box need to be in any particular gear to refit the outer cover successfully?
Thanks All.
P.S. I even watched the Mick Hemmings gearbox overhaul video again and followed his tips - all to no avail.
 
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Did you check the ratchet movement when the outer cover was still off by operating the gear lever to see if the spring was doing what it is supposed to do.
 
Yes, I did check that. It is a strong spring and seems to be doing its job.

Sounds like you are describing the return spring...
... not the ratchet spring...

With the outer cover in your hand, moving the gear pedal in either direction then the upper or lower leg of the ratchet spring should force the pawl into almost immediate engagement with a ratchet plate 'tooth'.
Further pedal movement should advance the ratchet plate by one tooth.
Gearbox Gear Changing Problem


I was able to lever the knuckle in the gearbox slot through the full range of gears and then left it in neutral.

If, however, the quadrant was mistimed to the camplate (by one tooth etc. when you rebuilt the gearbox) then it would still be possible to select gears and neutral by manually moving the quadrant with the outer cover removed.

Does the box need to be in any particular gear to refit the outer cover successfully?

No.
 
My mistake on the springs.
I was always under the impression that if the quadrant and camplate were mistimed by even 1 tooth then the quadrant would hit the case at the top or bottom affecting the selection of 4th and 1st gears.
When I was fitting the outer cover I fitted the quadrant to the gearbox knuckle first as per Mick Hemmings video. Is there a better option such as fitting the quadrant to the outer cover first before fitting the cover to the gearbox?
As an aside, when I was tightening the clutch centre nut with the engine locked solid to 40 ft/lbs I thought I heard a sound from inside the gearbox like teeth jumping each other. Maybe I will have to venture back inside the gearbox if all else fails.
But at the start of this thread I was able to change up from 1st to 4th using the gear lever but it would not change down. Now it won't change up or down and there is no feel of the gearshift pawl trying to catch onto teeth on the rachet plate. All that is felt at the lever is the spring resistance as the lever is moved up and down.
 
I was always under the impression that if the quadrant and camplate were mistimed by even 1 tooth then the quadrant would hit the case at the top or bottom affecting the selection of 4th and 1st gears.

Possibly not.
When I was fitting the outer cover I fitted the quadrant to the gearbox knuckle first as per Mick Hemmings video. Is there a better option such as fitting the quadrant to the outer cover first before fitting the cover to the gearbox?

It can be done either way but shouldn't cause a gearchange problem as long as the ratchet plate pin engages with the knuckle roller.

As an aside, when I was tightening the clutch centre nut with the engine locked solid to 40 ft/lbs I thought I heard a sound from inside the gearbox like teeth jumping each other.

In top gear? I can't think of a normal explanation for what could have been heard to jump.
Now it won't change up or down and there is no feel of the rachet trying to catch onto anything. All that is felt at the lever is the spring resistance as the lever is moved up and down.

If the pawl spring is set correctly and the pawl does not engage with the ratchet (so no mechanical resistance) then that might indicate the ratchet plate (therefore, quadrant) could be out of position.
 
Possibly not.


It can be done either way but shouldn't cause a gearchange problem as long as the ratchet plate pin engages with the knuckle roller.



In top gear? I can't think of a normal explanation for what could have been heard to jump.


If the pawl spring is set correctly and the pawl does not engage with the ratchet (so no mechanical resistance) then that might indicate the ratchet plate (therefore, quadrant) could be out of position.
Thanks Les. I'll revisit it tomorrow.
 
I couldn’t get fourth gear with the outer cover on just like you. It turned out to be a misstimed quadrant/camplate. Moved it one tooth and all was well. L.A.B. set me straight on that one. Sounds confusing but an easy fix. Easier than fitting that outer cover for sure!
 
Timing a Norton g/b is very easy.

1) install the sleeve gear
2) install and tighten the cam plate
3) install and tighten the spring loaded detent plunger
4) set the cam plate on the 1st gear notch
5) install the quadrant engaging 2 of it's teeth with the other end up, the bolt just needs to be snug
6) loosely fit the inner cover and the quadrant should just fit the upper end of the rectangular "window"
7) carefully move the quadrant to the bottom of the window, check to see that the 4th gear detent is engaged

You may have to do some trials, but when 1st and 4th snap into their detentes the g/b is timed.

The dog leg spring is always a curse, in the center position you should have .010 or 0.015, maybe more, clearance between the pawl and the spring.

Best.
 
Thanks guys for the replies. The problem was not the timing. That was never an issue. I knew I had that right.

On the other issue of not being able to select any gears I am slightly embarrassed, but more of that later or maybe not.

The secondary issue was that the "gear selector pawl" which is sitting inside the two arms of the "gearchange ratchet spring" was tilting out of position (spinning on its shaft) as I fitted the outer cover so then the pawl was out of position to pick up the ratchet teeth.

So the answer to my problem was to fit the ratchet, pawl carrier assembly and dog leg spring to the out cover and to then fit the cover that way.
Problem was the knuckle pin roller would spin in the quadrant assembly as I had well oiled it on assembly so the ratchet shaft would not line up and the cover would just not go on any further. So I was able to remove as much oil as I could from the roller and then coat the roller with a few dabs of grease. This held the roller horizontal so the shaft could then align and slip into place.
On the 2nd try at pushing the cover on it slipped into place. Then I was able to select all 4 gears successfully.

I hope this has not been a too long winded explanation, but maybe it might help someone else.

Thanks all.
Cheers Don
 
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