Sleeve Gear Bearing

Hi,

I am new to Nortons and rebuilding a 1970 Commando. I have been slowly tearing down for the last 3 years - I am now trying to push the project to completion - I need to ride!

Upon inspection of the gearbox sprocket and main shaft - they seem to have twice the vertical play than the horizontal play(almost none).
I have a hunch that I may have damaged the bearing undoing the nut - as it required hurculean torque to undo with my budget torque wrench.

Should there be play? If so, shouldn't it be equal? Is this the bearing.

Any thoughts or feedback are most welcome.
Thanks in advance.

Phil

fastback,

I'm confused as to exactly what is moving in your gearbox. In general, there should not be any play/slop in the gearbox bearings. These bearings are not very expensive, so I recommend replacing them.

Also, I recommend that you replace the stock layshaft ball bearing with a roller bearing; this bearing is available from Raber's Parts Mart in San Jose, California.

You will have to heat the gearbox case in the oven in order to remove the main and layshaft bearings.

Regards,

Jason

Hi Jason,

Thanks for the super quick response! I took another look, to clarify here is what I find:

1. The sprocket slides on the main shaft about 2mm. (as if you were removing the sprocket from the shaft).
2. The sprocket rocks about .5mm on shaft.
3. The main shaft rocks about 1.5mm up and down, about .5mm back and forth.

I assume the main shaft movement is not good- and will be rectified by the new sleeve bearing. I am planning on replacing the sprocket anyway (20) - I assume the new sprocket will remove any play (unless the shaft itself is worn).

I was hoping to get away with just bolting the transmission back on - and doing a rebuild this winter... (ok, ok - I should know better as every component I have taken apart contains a "surprise" :shock: ). I guess I will have to dismantle it and give it a good once over. Can you suggest what else I should replace while I am in there other then the 2 bearings you mentioned?

I am looking at a Norvil Gearbox Kit:
http://www.norvilmotorcycle.co.uk/gboxrebuild.htm

Kit Includes The Following Parts:
1 x sleeve gear bearing
1 x lay shaft bearing
1 x main shaft bearing
1 x sleeve gear oil seal
1 x inner cover gasket
1 x outer cover gasket
1 x inspection gasket
1 x gear lever O ring
1 x kick start O ring
1 x ratchet spindle O ring
2 x quadrant O rings

Thanks again - any and all feed back is much appreciated!

Phil

Having done more than a few gearboxes, be prepared to replace the bushes as well as what Les supplies in his kit. They are not that expensive and it's a job you only want to do once. In particular, the two sleeve gear bushes and all the gear bushes. I always replace the layshaft bush in the kickstart spindle when I replace the layshaft gear. This is a @##% to remove. The best option is a large tap to cut threads, then screw in a bolt and nut and use spacers to pull it out. Alternatively you can use a dremel and burr and cut slots to collapse it.
This is the support for the end of the layshaft opposite the one you will put a new bearing (ball bearing stock, I suggest the roller replacement).
If your outer cover is currently oil tight, then replacing the o-rings might be sufficient. However, I replace the o-ring around the kickstart shaft with a lip seal and use X-rings at the gear shift shaft to prevent weeping.

Sounds like a plan - a round of bushes, bearings & seals.

I am not familiar with x-rings... I seek enlightenment!
Could you list the part # and supplier for the lip seal and x-ring you mentioned.

I am curious, the NOC Service Notes recommend replacing the kickstart pawl- especially on 70-71. Any experience with this issue? I will tear the transmission apart to look for the "m" before ordering the pawl.

Thanks!

I can speak from personal experience that replacing the ball bearing on the layshaft is important. On my old 850 that bearing came apart when I was riding down the highway. It gave no warning, the tranny just locked up and I skidded to a stop in the middle of the road. Fortunately nobody was behind me and I'd just come out of a curve. If that thing fails at the wrong time it could kill you. So please make sure you have the roller bearing in there before you put it back together!

Debby

The x-ring is also known as a quad ring. It provides double the sealing surface than an o-ring. Here's a link with a picture http://www.marcorubber.com/quad_rings.htm. I have an assortment so I don't know the size off the top of my head, but it would be the same as the o-ring in the shifter bushing of the outer cover.
The seal for the kickstart can be the MKIII seal (066145), but it requires machining the outer cover. Many Norton shops or a competent machine shop can do it. However, being the lazy person I am, I prefer to replace the O-ring between the kickstart bush and the outer cover with a lip seal 1"X1.25"X0.125" by warming the cover and tapping out the steel bush, then clean the hole well and apply a thin coat of silicone sealer and push the new seal home from the inside of the outer cover. Replace the steel bush after warming the cover and/or freezing the bush.
The seal number I have here at work is 10121VM and is available from TCM, Chicago Rawhide and others. Check your local bearing and seal supplier.

Thanks for the information and part #'s!
Very much appreciated.

Phil

Hi Ron,

I assume you replace both the gear change spinde o-ring (D90, 04.006) as well as the ratchet spindle o-ring (D51, 04.0079) with x-rings.

I have sourced a local dealer for the lip seal, but I am stuck on ordering the x-rings. Do you know the dimensions of these rings?

I really like the idea of x-rings and wonder why I wouldn't replace all the o's for x's!

I opened up the gearbox and discovered "gold" as well as a brazed pawl spring :shock: - a full round of parts is on order.

Phil

Hi Phil,
I have the two gear change quad rings in stock in my shop. Send me your address and I'll mail them to you, gratis. I buy them in bulk. My e-mail address is norton 8) golden.net

Cheers,

Derek

I'm in the middle of this job now.

Can anyone advise on where to obtain the seals for the gear change and kickstart? Part numbers and website or the like would be most appreciated.

I do not want to machine anything, just looking for drop-in upgrades if possible.

Thanks - Brian

BrianK said:

I'm in the middle of this job now.

Can anyone advise on where to obtain the seals for the gear change and kickstart? Part numbers and website or the like would be most appreciated.

I do not want to machine anything, just looking for drop-in upgrades if possible.

Thanks - Brian

Click to expand...

If you want to put seals, you need to machine the gearbox cover. The seals themselves are not expensive, it is the machinist's time that raises the price. If you have access to a lathe, it is not hard to do, check my pictures at:
http://www.pbase.com/jeandr/image/109626788
http://www.pbase.com/jeandr/image/109626789
http://www.pbase.com/jeandr/image/109626790
http://www.pbase.com/jeandr/image/109626792

I made a plug that I could mount in the tailstock to make the rough alignment for the kickstart and the gearchange, this speeded up the setup many time over. To insure the best possible seal, the original O-ring groove is still there and new O-rings are in place... belt and suspenders as always :lol:

Jean

Re:

fastback said:

I am curious, the NOC Service Notes recommend replacing the kickstart pawl- especially on 70-71. Any experience with this issue? I will tear the transmission apart to look for the "m" before ordering the pawl.

Click to expand...

Personally, I would replace the pawl, pin, spring and plunger anyway as the box is being stripped down, the pawl will very likely be worn ("M" type, or not) and the parts are not expensive.

http://www.nortonmotors.de/ANIL/Norton% ... &Plate=006 Items- [20], [21], [22], [23].