1967 Norton Atlas main bearings

jms

jms

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The Atlas that I recently purchased came with two new main bearings in anticipation of a rebuild.
1. One is a roller bearing branded as Consolidated but is actually a Steyr NU-306 E on the outer race and NU-306 E
2. The other is a Fafnir 306W ball bearing

Here's the question. Once I get around to the rebuild do I use these bearings?

Thanks
 
jms said:
The Atlas that I recently purchased came with two new main bearings in anticipation of a rebuild.
1. One is a roller bearing branded as Consolidated but is actually a Steyr NU-306 E on the outer race and NU-306 E
2. The other is a Fafnir 306W ball bearing

Here's the question. Once I get around to the rebuild do I use these bearings?

Thanks
Click to expand...
Well I've got more information on the drive side Steyr bearing haven spoken to the Steyr rep in Germany. It is dimensionally the correct bearing but here's the catch, bearings come in varying clearances between the inner and outer races. Specifically C2, C0 (standard), C3, C4, and C5. C2 is the least clearance and C5 is the most. In the case of the Norton you might need some clearance to compensate for crank runout and or drive side/ time side miss alignment. The question is how would one determine what is really needed? The Steyr bearing that have is standard meaning it provides clearance range of .0008- .0017. the C3 provides .0013-.0024. I am also told that fequently people that rebuild Norton engines opt for then C3 version.The Fafnir time side bearing is correct. I'm curious which clearance version of the drive side bearing people do opt for on this forum. Thanks
 
What is the cage type? Got any pics?

I'd likely run them. Ball on the timing side, roller on the main side.
Consolidated is an old bearing re-marketing company. Your bearings were likely made before they were available in "C" designations.
 
I've reached out to Steyr and they confirm that the cage is plastic. Doesn't sound good. Here's some pics of what I have
 

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jms said:
The Atlas that I recently purchased came with two new main bearings in anticipation of a rebuild.
1. One is a roller bearing branded as Consolidated but is actually a Steyr NU-306 E on the outer race and NU-306 E
Click to expand...

The correct roller bearing is NJ306E

1967 Norton Atlas main bearings


andover-norton.co.uk

Norton Parts Drawings - Genuine Norton Factory Parts - Commando Parts -

Andover Norton Parts are the only Norton spare parts in the market manufactured to original drawings, within the factory-approved tolerances, from the correct materials, and with the correct finish.
andover-norton.co.uk
andover-norton.co.uk

Andover Norton - CRANKSHAFT MAIN BEARING (NM17822/4) - 06.4118

CRANKSHAFT MAIN BEARING (NM17822/4)
andover-norton.co.uk
 

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jms said:
I've reached out to Steyr and they confirm that the cage is plastic. Doesn't sound good. Here's some pics of what I have
Click to expand...
Don't know if it helps but I've run a plastic caged roller bearing on the drive side of my BSA A10 for many years without issue
 
IMO, it would likely work fine if you run the ball bearing on the timing side. Pulling its inner race off the crank, if you ever had to, would be more difficult.

The risk is the bearing could migrate out of the case and come into contact with the spinning crank.

I have a few NOS NJ306E Germany (mostly M1 standard clearance) FAG roller bearings, and some from Andover (India C3), if you are looking for a particular one, or country of manufacture.
 
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NU will work as long as you use a ball bearing on the other side, NJ's are needed if both bearings are roller as the crank floats and you need stops to prevent the roller inners going in too far which is provided by the lip on the inner of the NJ. The ball bearing stops the crank from floating so no need for the NJ. Norton used std clearance until later in the Commando build when they changed to C3 at some point, so an Atlas would have no issues with C0 (also known as CN). I have had nylon caged rollers in several BSA Unit singles over the years with no failures.
 
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kommando said:
NU will work as long as you use a ball bearing on the other side, NJ's are needed if both bearings are roller as the crank floats and you need stops to prevent the roller inners going in too far which is provided by the lip on the inner of the NJ. The ball bearing stops the crank from floating so no need for the NJ. Norton used std clearance until later in the Commando build when they changed to C3 at some point, so an Atlas would have no issues with C0 (also known as CN). I have had nylon caged rollers in several BSA Unit singles over the years with no failures.
Click to expand...
Very interesting. Thanks
 
elefantrider said:
Can you remove the inner race on yours from both sides?
Click to expand...
When I got it the inner race drive side was on the crank...so I removed it and the outer race of a ball bearing was in the time side case. with heat i was able to get it drop out.
 
kommando said:
NU will work as long as you use a ball bearing on the other side, NJ's are needed if both bearings are roller as the crank floats and you need stops to prevent the roller inners going in too far which is provided by the lip on the inner of the NJ. The ball bearing stops the crank from floating so no need for the NJ. Norton used std clearance until later in the Commando build when they changed to C3 at some point, so an Atlas would have no issues with C0 (also known as CN). I have had nylon caged rollers in several BSA Unit singles over the years with no failures.
Click to expand...
Just a thought. Because the Atlas used a much less compression ration than a Commando and now that you can't get the Atlas dished pistons any longer are we now in Commando territory in that we have to use a Commando piston in an Atlas engine. Would this fact necessitate the use of the NJ? I suppose a thicker base gasket might rectify somewhat but might not get you back to the original 7.5
 
jms said:
Just a thought. Because the Atlas used a much less compression ration than a Commando and now that you can't get the Atlas dished pistons any longer are we now in Commando territory in that we have to use a Commando piston in an Atlas engine. Would this fact necessitate the use of the NJ? I suppose a thicker base gasket might rectify somewhat but might not get you back to the original 7.5
Click to expand...
You can reduce the compression by using a plate under the barrel, the Commando until 72 used ball on timing side and roller on driveside. The 72 saw the introduction of the Combat and its higher power possibly nudged them to two rollers but the whippy crank caused the roller outer edge to dig into the bearing track and a major issue ensued, increasing the chamfer on the edge of the roller was the cure which later was identified with the E as on your roller. I don't see an issue with roller/ball combo with an Atlas in early Commando mode unless you plan huge miles.
 
jms said:
When I got it the inner race drive side was on the crank...so I removed it and the outer race of a ball bearing was in the time side case. with heat i was able to get it drop out.
Click to expand...
I mean does the inner race drop though the bearing from both sides.
 
Simple example: I've got the roller bearings Andover sells that LAB posted a link to on both sides in '67 750 cases with higher compression pistons, a composite head gasket, and no gasket at the base of the barrels. Probably over 9:1 compression, but not 10:1. Not an issue on the street.

You can use those NOS bearings you have if you want to. Myself, I would buy new roller main bearings from Andover and not think about it much. I also wouldn't worry about using Commando flat top pistons in your '67 engine. Jim Schmidt of JS Motorsports sells different thickness copper base gaskets if you want to get the compression down as mentioned by kommando.
 
Ok I've totally screwed up communicating what was on the crank and in the cases when I received the bike. Drive side was a R&M roller bearing MRJA30. The outer race was what was so difficult to get out but when I final did the race was lipped on one side. The lip was facing in. The rollers and inner race were not attached and I found them in a box. The timing side of the crank had just the inner race of a Steyr NU306E roller bearing. The outer race and rollers again were found in a box.13 rollers to be exact. The inner race was simply able to be removed from either side of the bearing so no lip. From what I can see someone intended to use a new Fafnir timing side 306W ball bearing (10 balls) and a new Steyr NU306E roller bearing (13 rollerson the drive side. The edges of the rollers are definantly radiuses.
So here's the question If I decide to go with two new Superblend FAG's and they Are NJ's, the lips are installed closest to the crank so that the inner race can't migrate?
 
Yes lips to the inside so the inners are on the crank, the outers go in the cases and then you assemble the crank to the cases. The inners should have an interference fit to the crank, less important on the timing side as the crank nut will grip it but it has to be there on the driveside as the tapered sprocket stops the crank nut from applying any sideways force to the bearing inner. So it has to have the interference fit so it does not spin on the crank.
 
Just came across this thread and I have a question.
I'm working on a 56 Domi 88 and it came with new main bearings. ball timing and roller drive side.
The ball bearing is a sealed unit and I was wondering if I should remove the shields or install the bearing as it is?
Thanks in advance for your help.
John in Texas
 
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