Is there a way to bench test a transmission?

Oops, I mean gearbox.

I have finished my rebuild on the gearbox. I used the old brits tech pages and checklists. Bearings seals and all bushings are new. Seemed to go together as intended, all parts bathed in 90w as it went together. (no gear oil fill yet) The gears mesh fine and continue to spin. I can't seem to shift.

I spun the drive sprocket and gear selector moved a couple of spots, but now is stuck in what i think is 1st. The mainshaft spins about 2 1/2 times for every revolution of the drive sprocket/sleeve gear.

I haven't really put any force into it yet. Should I be able to operate the gearbox on the bench? I have backed off the ball and spring on the camplate. I have backed off the camplate and quadrant bolts in case a washer is hanging up.

I am a bit stumped where to start. Thanks Brian

Check the hair pin spring around the shifter shaft. It can give all kinds of grief if not adusted right. It's also easy to get on upside down. You are spinning the sprocket while trying to shift?

Did you install a new kickstart inner bush? If so, did you make sure it was press fit all the way in?

Using heat and hand tools, I could only get it in t .49" to .52" from the face end of the KS shaft to the mating face of the inner cover. I had .41" of depth from the face of the open end of the KS shaft to the face of the bush inside it.

I took the KS shaft in to an engineering shop near me , and he pressed the bushing in. It gave a bit of resistance and then pressed in to 12.6 mm deep - bang on half an inch deem inside the shaft.

Assembled and shimmed to .005 - so all good after that.

Consider that turning of the mainshaft by hand doesn't come close to what a running engine does, even at idle, never mind that the sleeve gear (where the sprocket is attached) is spinning at a good clip going into 2nd and higher gears.

When I bench test a newly assembled gear box it's clamped in a large vice w/soft jaws, I mount the sprocket and the clutch hub with hand tight nuts and turn both, the hub needs to turn a lot more than the sprocket, having an assistant is nice, but not necessary. By pulling the shift lever up (standard 1 up 3 down pattern) you should be able to find 1st, remember to spin the hub and, to a lesser degree, the sprocket. One click down should be neutral where the hub will spin independently of the sprocket. Then down to 2nd, spin, spin, then 3rd, spin, spin, then 4th. then reverse the process. If you can get up and down, if won't feel great, your good, if not then check the hair spring as htown 16 has suggested; you should have, according the Norton Tech Digest, about .010" clearance between the upper and lower extremes of the shit pawl and the spring; if the spring touches the pawl it will not engage the quadrant consistently.

Best wishes.

Brian,
I went through exactly the same process as you by using the Old Britts guide. Once finished it would only shift into first. Getting that hair spring spot on as the others have said is imperative. After decades of Japanes gearboxes I was expecting a tractor gearbox full of grinding and mis-shifts.I'm actually surprised how smooth and quiet it is.
Dave

htown16 said:

Check the hair pin spring around the shifter shaft. It can give all kinds of grief if not adusted right. It's also easy to get on upside down. You are spinning the sprocket while trying to shift?

Click to expand...

So which way is up?

I'm not sure that getting this point wrong will prevent ability to change but, if wrong, it will definitely make changes much more difficult (thanks to Oldbritts for photos)
This is wrong - don't want gaps like this above/below pawl:



This is what it should look like - I used a feeler gauge to ensure small (0.005") but equal gap top and bottom.
Have to manually bend the spring to achieve correct result:

For me, at least, this changed a shitty and clunky box into one that is now smooth as butter.
Hopefully this also answers Olympus' question above.

Hope this helps
Cheers
Rob

Thanks all, Spring clearance and bushings were set correctly.

I think I made a mistake in the order of assembly. I couldn't get the gear change ratchet to align in the quadrant pin by leaving it in the outer cover on assembly, so I preset it into the bushing and knuckle pin, this may have allowed the shift pawl to spin 180* as I put the outer cover on. I'll take it apart today.

Before I do I will try Roadscholars procedure. When I think about it its asking a lot to power movement of the gear slide, selector forks, camplate, quadrant, ratchet, pawl arm, from a 1/2" movement on the gearchange lever on a static gearbox.

I meant to add a more philosophical footnote to my post that applies to, virtually, any problem solving adventure: When a repair/rebuild doesn't yield the expected results, start your investigation from the outside in, look for the easy fix(s) first before disemboweling the organs of the beast. A good example is when your TV stops working, check the plug first, when your gas powered tool stops dead, check the tank first...

I have seen, on this forum, posters write in with a question wondering why they can't start their Norton after doing a simple maintenance task and seen responses that range from: 1) what position was the moon in when you changed the plugs. 2) time to split the cases. Simple problems usually have simple fixes. I learned this strategy the hard way and hope that members inclined to think worst-case will be incented to think more positively; it sure is easier, and if you do encounter a worst-case situation the let done is more gentle.

Best wishes

I think it is possible to get the timing of the camplate wrong. I rediscover how to do it every time I reassemble a Norton gearbox.

robs ss said:

I'm not sure that getting this point wrong will prevent ability to change but, if wrong, it will definitely make changes much more difficult (thanks to Oldbritts for photos)
This is wrong - don't want gaps like this above/below pawl:

View attachment 6977

This is what it should look like - I used a feeler gauge to ensure small (0.005") but equal gap top and bottom.
Have to manually bend the spring to achieve correct result:
View attachment 6978
For me, at least, this changed a shitty and clunky box into one that is now smooth as butter.
Hopefully this also answers Olympus' question above.

Hope this helps
Cheers
Rob

Click to expand...

Many thanks Rob, I have no clearance top or bottom, I bend the spring to achieve 5thou

A few tips, there are many, when reassembling a Norton gearbox, but these three have made the reassembly easier and even more fun.

1) The mainshaft shifting fork doesn't like to stay up against the camplate: Insert a Philips screw driver through the threaded hole on the drive side, you can also extend the screw driver to capture the layshaft fork. When you are ready to insert the shift fork shaft simply let it push the screw driver out.

2) Put the cam plate in the first gear detent from the get-go. When you are ready to fit the inner cover simply insure that the quadrant is as high as possible without hitting the inner cover casting.

3) Aligning the pin on the ratchet plate to the shift roller that sits in the quadrant is almost like doing your own dentistry. Assemble the ratchet plate to the quadrant/shift roller/inner cover first, then fit the outer cover.

Best wishes