Transmission Bearings

Dont Andover sell new gearbox cases ? , that could be another option . Cheers

Shelby-Right said:

Dont Andover sell new gearbox cases ? , that could be another option . Cheers

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That may end up being the option if this does not work out. Would like to avoid affording that if possible.

maaseyracer said:

That may end up being the option if this does not work out. Would like to avoid affording that if possible.

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Gearbox cases are often available on eBay in good shape. The one I bought last month cost me $49.57 delivered and there is nothing wrong with. Once in a while you'll get one with an issue which you can usually send back. There are three companies I know of parting out bikes and of them ebvc is the most reliable and easist to deal with if there is an issue.

I can't imagine paying for machining unless you're building a bike for concours shows and need the serial number not to change. In that case, a new shell won't work either.

marshg246 said:

I can't imagine paying for machining unless you're building a bike for concours shows and need the serial number not to change. In that case, a new shell won't work either.

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The only money out is my time in this hobby. Also happy to use this stainless scrap and NJ206 bearing I have here.

Was able to bore the case today. Not sure this is the best solution, but I still think it is worth a try. The set up in the mill is not for the faint of heart, and took some patience to figure out. The case flexes a lot more than I had realized. Boring head size is an issue and I ended up buying a new boring head to get the job done. Ran out of time before I could recheck bearing alignment so I will have to check it on Friday. Once I can verify the alignment I will choose whether or not to run a ball bearing or roller bearing.

I ended up having to cut around 0.020" out of the case to get the bore true, which was about 0.010" more than I wanted. This was not as straightforward as I thought it was going to be largely because the case mounting points were not inline with the bearings. On top of that checking alignment for the bearings really cannot be easily done inline. You have to assume the case pins are in there as right as they can be and check for round. After a lot of setup and patience I have confirmed that the bearings are in line and spaced appropriately from the layshaft.

I ended up sleeving a brass cage roller bearing with a scrap piece of stainless, and I opened up the ID of the bearing race with some very cool Sumitomo (AC510) indexable cutters I found that cut and leave a beautiful finish on the 52100 hardened bearing race. While I am very impressed with these cutters I have to admit this is the part I am most concerned about as I do not know how the race will hold up, but the amount I removed really was not all that much in the end and I did not even get into the text on the bearing race, which is where I was hoping this would end up.

I have fitted everything up and the spin test is really nice. No binding or catching, no excessive play on anything. I bolted everything up and nothing seems out of the ordinary, so I guess it is time to test it out. I am tracking down some new nuts and washers, however I am looking forward to getting back out there with this.

maaseyracer said:

I'm looking for high-quality mainshaft bearings for my 1975 MK3 transmission. About 20-30K miles ago, I installed bearings from a popular Norton Supplier, but both mainshaft bearings are toast. Meanwhile, the bronze-cage layshaft bearing is still in perfect working order.

I know there are some decent bearings coming out of China, but sourcing is critical. The failed mainshaft bearings have no brand markings, and the seals are labeled "China."

Does anyone have a reliable source for reputable, steel-cage bearings? I've come across some plastic-cage options that fit, but that seems like a bad route. Any recommendations?

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Just received both Main shaft bearings from Andover Norton . 04.0099 and 04.0098. Both are KSM and made in Japan.
I will be putting these in my 74 Gearbox very soon.
I have the NJ203. TVP2.C3... Made in India for the layshaft bearing all going in a 100k gearbox rebuild.
Nothing too exciting but there you have it.


Cheers,
T

CanukNortonNut said:

Just received both Main shaft bearings from Andover Norton . 04.0099 and 04.0098. Both are KSM and made in Japan.
I will be putting these in my 74 Gearbox very soon.
I have the NJ203. TVP2.C3... Made in India for the layshaft bearing all going in a 100k gearbox rebuild.
Nothing too exciting but there you have it.


Cheers,
T

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The KSM is a good quality bearing I have one in front of me the cage on it looks good. It is not a top spec, but it will work. On the kick start side you can get an SKF still, they are all 2RS so you will need to gently pull the seals off of them. I think I got mine off ebay.

If you are going all in you might want to consider REM polishing the gears, shafts, forks, etc. As well as take a ball hone to your shift for bores and bushings. I cannot believe how smoothly this all moves and feels and I have still only dry fitted this setup, no Oil, yet. It feels tight and spins like a worn in and oiled transmission. It feels like a good reduction in friction and it shifts by hand smoothly. I measured the shafts before and after and I could not measure a difference in material removed in the polishing process. I have done this on a couple other bikes now and it is how I am going to go about all of them now when I rebuild.

Additionally I bought a few ball hones and cleaned up the bores on the shift forks I was shocked at how rough the bore was left in there.

Once again, the level of workmanship on this forum is delivers!!
Nicely done!!

maaseyracer said:

The KSM is a good quality bearing I have one in front of me the cage on it looks good. It is not a top spec, but it will work. On the kick start side you can get an SKF still, they are all 2RS so you will need to gently pull the seals off of them. I think I got mine off ebay.

If you are going all in you might want to consider REM polishing the gears, shafts, forks, etc. As well as take a ball hone to your shift for bores and bushings. I cannot believe how smoothly this all moves and feels and I have still only dry fitted this setup, no Oil, yet. It feels tight and spins like a worn in and oiled transmission. It feels like a good reduction in friction and it shifts by hand smoothly. I measured the shafts before and after and I could not measure a difference in material removed in the polishing process. I have done this on a couple other bikes now and it is how I am going to go about all of them now when I rebuild.

Additionally I bought a few ball hones and cleaned up the bores on the shift forks I was shocked at how rough the bore was left in there.

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What's the reason to pull the seals from the bearings? If it's too allow oil in then don't forget the oil could be contaminated and shorten the bearings life
Especially in a gearbox
The bearings are sealed for a designed lifetime with their own lubricant

maaseyracer said:

The KSM is a good quality bearing I have one in front of me the cage on it looks good. It is not a top spec, but it will work. On the kick start side you can get an SKF still, they are all 2RS so you will need to gently pull the seals off of them. I think I got mine off ebay.

If you are going all in you might want to consider REM polishing the gears, shafts, forks, etc. As well as take a ball hone to your shift for bores and bushings. I cannot believe how smoothly this all moves and feels and I have still only dry fitted this setup, no Oil, yet. It feels tight and spins like a worn in and oiled transmission. It feels like a good reduction in friction and it shifts by hand smoothly. I measured the shafts before and after and I could not measure a difference in material removed in the polishing process. I have done this on a couple other bikes now and it is how I am going to go about all of them now when I rebuild.

Additionally I bought a few ball hones and cleaned up the bores on the shift forks I was shocked at how rough the bore was left in there.

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What is REM polishing?

baz said:

What's the reason to pull the seals from the bearings? If it's too allow oil in then don't forget the oil could be contaminated and shorten the bearings life
Especially in a gearbox
The bearings are sealed for a designed lifetime with their own lubricant

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Interesting comment.

BMW allegedly fitted sealed bearings to R1150 gearboxes to address premature bearing wear caused by oil contamination from gear tooth wear.

Maybe better to keep the bearings sealed?

I think

Skoti said:

Interesting comment.

BMW allegedly fitted sealed bearings to R1150 gearboxes to address premature bearing wear caused by oil contamination from gear tooth wear.

Maybe better to keep the bearings sealed?

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I was talking to Mark at PES engineering
He builds racing BSA/CCM engines
And leaving the seals on massively increased bearing life
He said if a bearinng is designed to last say 100,000 miles, that's how long it'll last in it's own lubricant
If you introduce clean oil maybe it'd last indefinitely
But if the oil is contaminated they won't last long
I never peel the seals off of wheel bearings when I fit them

baz said:

What's the reason to pull the seals from the bearings? If it's too allow oil in then don't forget the oil could be contaminated and shorten the bearings life
Especially in a gearbox
The bearings are sealed for a designed lifetime with their own lubricant

Click to expand...

Skoti said:

Interesting comment.

BMW allegedly fitted sealed bearings to R1150 gearboxes to address premature bearing wear caused by oil contamination from gear tooth wear.

Maybe better to keep the bearings sealed?

Click to expand...

Bearing i pulled out had both seals on, no grease left in it, just oil. Those seals do not seal forever in the heat that an air cooled engine/transmission produces. The Gears shedding is greatly reduced from the REM polishing. Oil changes come out clean after the process. Also a magnet on the drain is the way to go if you have concerns about this.

However, that is not the reason I pull the seals, I pull the seals due to the issues with the shaft alignment and flex that shaft goes through. It is not well supported and while my alignment is good now, it was not perfect before and that shaft is not well supported. It is a double edge sword as you will wear the bearing from gear wear and you will wear the bearing from axial load on the seals. If you change your oil frequently, you will get more life out of an open bearing.

seattle##gs said:

What is REM polishing?

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A surface polishing process that removes the high spots on the gears, reduces friction, smoother operation, and it looks cool.

maaseyracer said:

Bearing i pulled out had both seals on, no grease left in it, just oil. Those seals do not seal forever in the heat that an air cooled engine/transmission produces. The Gears shedding is greatly reduced from the REM polishing. Oil changes come out clean after the process. Also a magnet on the drain is the way to go if you have concerns about this.

However, that is not the reason I pull the seals, I pull the seals due to the issues with the shaft alignment and flex that shaft goes through. It is not well supported and while my alignment is good now, it was not perfect before and that shaft is not well supported. It is a double edge sword as you will wear the bearing from gear wear and you will wear the bearing from axial load on the seals. If you change your oil frequently, you will get more life out of an open bearing.



A surface polishing process that removes the high spots on the gears, reduces friction, smoother operation, and it looks cool.

Click to expand...

If the bearing you pulled out had the seals intact but no grease inside only oil
Why would you want to remove the seals?
I'm not seeing how the seals can affect shaft alignment?

maaseyracer said:

Bearing i pulled out had both seals on, no grease left in it, just oil. Those seals do not seal forever in the heat that an air cooled engine/transmission produces. The Gears shedding is greatly reduced from the REM polishing. Oil changes come out clean after the process. Also a magnet on the drain is the way to go if you have concerns about this.

However, that is not the reason I pull the seals, I pull the seals due to the issues with the shaft alignment and flex that shaft goes through. It is not well supported and while my alignment is good now, it was not perfect before and that shaft is not well supported. It is a double edge sword as you will wear the bearing from gear wear and you will wear the bearing from axial load on the seals. If you change your oil frequently, you will get more life out of an open bearing.



A surface polishing process that removes the high spots on the gears, reduces friction, smoother operation, and it looks cool.

Click to expand...

Have you tried it? Results?

..and about what does this cost?

maaseyracer said:

Bearing i pulled out had both seals on, no grease left in it, just oil. Those seals do not seal forever in the heat that an air cooled engine/transmission produces.

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Were they rubber seals or metal shields?

baz said:

If the bearing you pulled out had the seals intact but no grease inside only oil
Why would you want to remove the seals?
I'm not seeing how the seals can affect shaft alignment?

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The seals don’t affect shaft alignment, but they do impact how the bearing handles flex and lubrication. If the transmission shaft has any flex under load which in this case the main shaft really does not have great support so it flexes a ton. Because of this a sealed (2RS) bearing can cause more issues than it solves. Sealed bearings have tighter internal clearances due to the seals, which increases friction and wear when the shaft moves out of perfect alignment. Open bearings, on the other hand, allow for better lubrication and can accommodate slight misalignment more effectively. Since Norton transmissions run in an oil bath, sealed bearings don’t provide much benefit—oil keeps an open bearing lubricated continuously, whereas a sealed bearing relies only on its internal grease, which can break down over time. The seals also trap heat, which can accelerate wear in high-load conditions. This is why you often see higher RPM and load limits on open bearings.

Contamination is a concern here, but with all the shaft movement open is still a better option because it runs cooler, lasts longer, and allows for better lubrication in a flexing shaft scenario. In a modern water cooled BMW that has good support and reasonable cooling seals are probably a good thing.

seattle##gs said:

Have you tried it? Results?

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The polishing? Yes I have tried it. I will build everything going forward with it. There are issues, not all providers are created equal, with these transmissions it helps to prep before you have it done. Everything feels like

Onder said:

..and about what does this cost?

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The polishing? It ranges, usually i have the whole engine done as it does not cost more than having just the transmission done.