What's a "Superblend"?

The main bearings in the cases of my 850 Commando are a bit different than bearings I'm used to. These are roller bearings and the rollers sort of "float", in that there are no inner races just a ring that binds the rollers together.

Is this the latest bearing type that Norton used? And how does one determine if they're worn?

Yes and no. The "true" superblend is an F.A.G. bearing. there are other brands of equivalent parts.

The only way to test absolute integrity is with a precision measurement of run-out.

maylar said:

The main bearings in the cases of my 850 Commando are a bit different than bearings I'm used to. These are roller bearings and the rollers sort of "float", in that there are no inner races just a ring that binds the rollers together.

Is this the latest bearing type that Norton used? And how does one determine if they're worn?

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The 850 main bearings would normally be brass cage FAG NJ306E type that have a double lipped outer race that retains the roller cage, and a single lipped inner race. http://www.norvilmotorcycle.co.uk/064118.htm

The FAG NJ306E is the standard replacement main bearing for all Commandos

Without more information on the actual bearing type I would suggest that you replace them?

To answer the question in the thread title, a superblend bearing is one in which the bearing rollers are slightly barrel shaped. This allows the crank to flex a bit.
I believe that before these bearing were introduced, Norton had a number of crankshaft failures as the crank tried to flex but the bearings tried to keep it straight.

It seems that the inner races of both bearings are attached to the crankshaft. That's what confused me... I didn't see inner races on the bearings. I assume this is not normal, and the bearings need to be replaced?

maylar said:

It seems that the inner races of both bearings are attached to the crankshaft.

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Can you give the make and the bearing number?

As that type of bearing is probably "NF" type, and not "NJ"? NF bearings would not normally be found in any 850 Commando engine?

hi maylar,going back to your original question, what is a superblend,it is a main bearing that norton commissioned the bearing manufactures(FAG)to (combat)the problems with the combat motor,ive only seen 2 types of superblend bearings one has a steel cage the other one has a brass cage ,both had the same nj 306 number but as LAB mentioned the one to have has the E (BRASS CAGE)nj306e ,

maylar said:

It seems that the inner races of both bearings are attached to the crankshaft. That's what confused me... I didn't see inner races on the bearings. I assume this is not normal, and the bearings need to be replaced?

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No it doesn't mean they need to be replaced. Some bearings retain the rollers and cage on the inner race and some retain them on the outer race. it depends on the bearing design and both of them work fine.

However, if I had stripped an engine of unknown origin back that far, I would replace the bearings just to be safe.

chris plant said:

main bearing that norton commissioned the bearing manufactures(FAG)to (combat)the problems with the combat motor,

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Well.....actually, no, as the "Superblend" name was originally applied to the "R&M (later RHP) 6/ MRJA30" bearing as used on the detuned Combats and later 750 models from serial 211891-on from August 72, supplied under part number 063906.

A new "high capacity roller bearing" was introduced in early 1973 under part number 064118. This was the FAG bearing NJ306E which is still supplied under the same part number today.
And there has been some controversy as to whether these so called Superblends did actually have "barrell shaped" rollers, or if the bearing was merely an extra heavy duty version with parallel rollers (that maybe had a little extra radius at each end) and was not a true barrel shape roller bearing at all?

Thanks for the replies. I love this place.

The bearings have the brass retainer. I guess that makes them "E" (extended service) type. My local bearing shop will no doubt have replacements, or I can get them over night from Fred & Ella.

It's not the cost that scares me about replacing them, it's the extraction procedure. The factory manual says to heat the cases then bash them against a wooden block. Seems barbaric.

I have access to an environmental test chamber that I can heat the cases slowly and evenly with. I assume 100* C would suffice. The races frozen to the crank however... they're too close to the flywheel to get a puller behind and I don't want to risk scratcing the journals with a prybar. How does one extract those puppies?

The bearings look pristine by eye, but I found a badly worn camshaft lobe and end shells at end of life when I got inside this motor. I'll replace the bearings if I can figure out how to get the old ones out without doing more bad than good.

Thanks again.

well i beg to differ lab

if norton had the super blends before the combat there would be no reason to detune it

chris plant said:

well i beg to differ lab

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I'm not quite sure what you are differing with?

I suggest you have a good read through of the Norton service releases?

chris plant said:

if norton had the super blends before the combat there would be no reason to detune it

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I think you missed my point there?

As Superblends were introduced when the Combats were detuned (so they were no longer Combat spec.) along with thicker head gaskets to lower compression.

As by that time the factory had learnt their lesson that the Combats were overtuned.

Maylar, heating the cases is not really barbaric and if they're good and warm, only a sharp tap on a wooden surface is needed to let them drop out. I have always used the domestic oven (clean the cases first and make sure all other occupants are away !) The cases are hot enough when spit bounces off (very scientific this).

Reverse the procedure to re-install but put the bearing in the freezer first. They should drop in with a clunk which lets you know that you haven't taken any of the housing with it. If it sticks half way then it is a case of re-heating and shocking it out again.

I've a feeling that with the rollers on the crank, you'll have to dismantle the cage before using one of the special clamp-on pullers with knife-edge jaws. I wouldn't attempt it without the proper tool because a nick in the crank is asking for trouble.

so what was the problem with the combats lab

maylar said:

The bearings have the brass retainer. I guess that makes them "E" (extended service) type.

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I wouldn't guess, I'd check the bearing numbers?

maylar said:

It's not the cost that scares me about replacing them, it's the extraction procedure. The factory manual says to heat the cases then bash them against a wooden block. Seems barbaric.

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If the cases are hot enough then a smart tap on a wooden block should free the bearings? There's no need to BASH anything!

In fact if you get the cases hot enough they should drop out: http://www.oldbritts.com/b_removal.html

I 'm not sure about Old Britt's idea of tapping them in. I've never found it a problem to drop the bearing in square and tapping will bring the possibility of a small burr stopping the bearing seating properly. The gearbox is another matter 'cause I usually burn my knuckles on the case and let go of the bearing too soon

chris plant said:

so what was the problem with the combats

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The Commando engine was already overstressed and in a high state of tune before the Combat version was introduced (the engine having started out as a 500cc unit putting out about 35 BHP) , and premature main bearing failure had been a problem even before the Combat models were introduced.

So in early 1972, when the factory management decided that what every Commando owner really wanted was an even more powerful and thus even more overstressed engine, they skimmed the cylinder head to give a 10:1 compression ratio, fitted a 2S camshaft and 32mm carbs so that it "went like a bat out of hell" and made around 65 BHP. Consequently the things normally blew up or ate their main bearings in 4,000 miles or even less, if they were regularly used to the full.

This resulted in so many warranty claims that cost the factory much money and bad press that they had to make an about-turn and stop manufacturing Combats, and many Combats were sent back down the production line (sometimes twice) in order to be detuned (2s camshaft removed, thicker head gasket) and around that time the bearing known as "Superblend" was introduced. The original Superblend bearing was the R&M/RHP 6/MRJA30. Subsequent 750 models had the standard camshaft and two different cylinder heads were introduced, one "high", and one "low" compression, both types kept the 32mm carbs.

Much has been written about this in various publications.

http://en.wikipedia.org/wiki/Norton_Commando

79x100 said:

I 'm not sure about Old Britt's idea of tapping them in.

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I think that part is really about making sure they go in squarely? Not that they recommend hammering or forcing the bearings in?