Drag on transmission mainshaft excessive?

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springs75

springs75

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I have the inner primary off to change the sprocket and also changed the clutch hub as the old one was notchy and finding neutral was sometimes problematic. Anyway, while apart I noticed that when the trans is in neutral, turning the trans mainshaft has quite a bit of drag on it. I can turn it with one hand with a hub on it but wasn't expecting that much drag. I can't turn it by hand without the hub on the end. I realize the 4th gear sleeve just has a bushing on the mainshaft and that could account for more drag than a bearing, but still. The bike sat for 38 years and I've recently gone through all systems except for the core engine and trans which seem fine. I've ridden it 200 miles and all seemed good except for the neutral issue. Anyway, is this amount of mainshaft drag normal? I have to twist kind of hard to turn it with just a loose clutch hub on it. Am I worrying too much?
 
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As you state the bike has sat for 38 years, I would expect to get the gearbox cover off just to have a "look see" if the mainbearing is OK.
 
springs75 said:
I have the inner primary off to change the sprocket and also changed the clutch hub as the old one was notchy and finding neutral was sometimes problematic. Anyway, while apart I noticed that when the trans is in neutral, turning the trans mainshaft has quite a bit of drag on it. I can turn it with one hand with a hub on it but wasn't expecting that much drag. I can't turn it by hand without the hub on the end. I realize the 4th gear sleeve just has a bushing on the mainshaft and that could account for more drag than a bearing, but still. The bike sat for 38 years and I've recently gone through all systems except for the core engine and trans which seem fine. I've ridden it 200 miles and all seemed good except for the neutral issue. Anyway, is this amount of mainshaft drag normal? I have to twist kind of hard to turn it with just a loose clutch hub on it. Am I worrying too much?
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Yes.
Yes.
 
Mine was stored 38 years also with only the motor kicked over monthly.... didn't try the tranny only changed oil in it and the primary when done tinkering with the motor. It took a bit for the shifting to really smooth out, but not before pulling the plates and cleaning up the clutch before riding.
 
I've gone through most everything on the bike except disassembling the engine or trans so it's in good order. I've had the outside kicker cover off the trans and everything looked good. When changing the trans oil, nothing scary came out. Shifting was smooth during the long ride. The inner primary is off so it's just the trans mainshaft with the sprocket. I can barely turn the bare shaft by hand. If I slide on the old clutch hub for leverage, I can turn it fairly easily albeit with drag. Id rather not take the trans out and disassemble unless there is a red flag here. So to refine the question for someone familiar with the Norton trans, should I be able to just grab the mainshaft and turn it easily with it in neutral or is it normal to feel quite a bit of drag by hand?
 
You can pull it and clean out the goo that's set, or run it in with fresh oil as I did and allow to flush changing oil after a couple of hundred. Your choice.
BTW.. I can't rotate mine without the hub either and it's been on the road for 2 years now.
 
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Trans has already been run and flushed once. However I think I can answer my own question. Admittedly I am used to newer Harley transmissions and they have all ball bearings for the main and countershaft and needle bearings on all the gears and turn pretty freely in neutral. In looking at the parts manual, the Norton has bushings in all the gears so when I'm trying to turn the mainshaft by hand in neutral, there is friction from three gear bushings on the mainshaft (2 on 4th and 1 on second) and two gear bushings on the layshaft (1st and 3rd). After understanding the Norton trans better, it seems the amount of drag I feel would not be abnormal, just more than I am familiar with.
 
Welcome to the latest tech. You'll soon come to realize yours is not just a machine.... there is a soul in there and you must learn to commune with it.....
 
The effect you are experiencing is called "leverage". The shaft is hard to turn because you took the leverage out of the equation by removing the hub. With the hub engaged it turns easily... so as far as that goes there's no issue to worry about...

......However, just the fact that it turns normaly doesn't mean you've inspected the gearbox with it's bearings and bushings and found them to be "good". But that also doesn't mean you should assume they are bad either. There are a few things with norton gearboxes worth mentioning regarding the hard to find neutral condition.

1) it's an acquired skill to lightly lever the selector arm to get that light "click" to be in neutral.

2) Things like a tight primary chain or not enough lift in your clutch engagement or a notched hub splines or sticky clutch plates can all effect how easily your gearbox shifts or finds neutral, without there being any internal gearbox problems involved....
 
I'm not aware of the layshaft bearing issue, however the layshaft shouldn't be turning in neutral except from drag from the gear bushings so it should not be related to my issue. This is a MKIII if that matters in regards to the questionable bearing.
 
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All lay shaft bearings should be checked it's not hard, you might as well do it now whilst the clutch is off.
 
springs75 said:
I'm not aware of the layshaft bearing issue,
Click to expand...

springs75 said:
This is a MKIII if that matters in regards to the questionable bearing.
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The standard ball bearing can potentially break up with little or no warning which is something you really don't want to have happen at high speed (or any speed).

Drag on transmission mainshaft excessive?


The 850 Mk3 with the Portuguese brass-cage ball bearing has the highest failure rate of all so it should be replaced with the FAG NJ203E roller bearing upgrade (or FAG 6203TB P63 phenolic cage ball bearing) at the earliest available opportunity, like...now.

andover-norton.co.uk

Motorcycle parts and spares for Norton motorbikes - Genuine Andover Norton Spare Parts - Andover Norton Motorcycles Parts - Original Andover Norton Parts

Motorcycle parts and spares for Andover Norton motorbikes: Andover Norton manufactures and supplies all Genuine Factory Spare Parts for Norton motorcycles built before 2002.
andover-norton.co.uk
Drag on transmission mainshaft excessive?


Failures aren't confined to the Portuguese bearing so any layshaft bearing found to be a standard 6203 ball bearing should be replaced with one of the upgraded bearings and this can be done with the gearbox in situ.

Layshaft Bearing Upgrade

Of and for Norton Motorcycles
www.doov.com
 
Coincidently, my 71 Roadster also sat for 38 years and was recently revived. My experience with the gearbox is different than yours in that my mainshaft turns easily by hand without the hub. I have renewed all the bearings and all the bushes (except 3rd layshaft), but I don't recall the mainshaft being more difficult to turn before I did that.

I'm no expert, having only done the 1 gearbox rebuild, but couldn't it be possible that the sticky mainshaft is contributing to your difficulty finding neutral?
 
Ok, you guys are convincing me I need to start taking things apart. L.A.B, given your post, can you comment on the following taken from the Oldbrits article on taking apart and inspecting the transmission, which seems to indicate that you need to remove the trans to replace the layshaft bearing and that it's more of a pre-MKIII problem. Is the Oldbrits article not entirely accurate? Thanks

"You can perform limited work on your gearbox in the frame, but any serious work like replacing the lay shaft bearing, which is recommended for all pre-MK3 gearboxes, should be done on the bench"

Update: I looked at the link you provided and understand how to do it in situ.
 
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Springs. The advantage of working on your g/box in place is that it is held securely. With the right pullers and the right amount of heat, even the layshaft and main shaft bearings are easy to replace.
 
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