Crankcase superblends revisited

If they came in the bag behind the bearing than Norvil have given you Andover sourced spares, so C3 is the correct fit and Les was talking from his rear orifice as orginally surmised.

Yes, it came in the Andover Norton International bag, part number 06-4118. I'm not going to say anything bad about Les, he gave me what I wanted and all the other bottom end parts were packed very nicely and the GPM pistons are what I asked for too. The Volcano slowed it up a wee bit.

Dave
69S

So here is the drive side bearing out of my '69. MRJA30, has a circle to the right of that label, 97 on the right, England on the left, and R&M on the bottom with a hand inscription of B36. Same thing on the inner race except no England stamp. Can someone identify this bearing for me? Has a brass cage for the inner race.



Dave
69S

Just found this thread:

super-blend-help-t1047.html

The first Superblend. One dot clearance.

The first Superblend. One dot clearance.
This would suggest at least 1 but probably only 1 rebuild.

So you are telling me I really didn't need to break this bottom end apart? The sludge trap had next to nothing in it, the con-rod shells I could scratch more with my fingernail, and the crank journals looked almost like new. As far as I know, 13K miles on this bike, had it since maybe 4K. Oh well, at least I know what I have. Only cost me $530 for the bottom end parts from Norvil including new pistons and the cases are being blasted to clean up as I speak.

Why would a '69 have a superblend in it? Replaced or original?

Dave
69S

pvisseriii said:

The first Superblend. One dot clearance.

Click to expand...

The two dot clearance R&M "MRJA30" was used from October 1971 under part number 063114, along with a reduced width "R"-stamped crankshaft part 063106 to accommodate the extra bearing width.

The 6/MRJA30 bearing known as "SUPERBLEND" was introduced at engine number 211891 around August 1972.

I didnt say any of that. This maybe the first Superblend but still more than likely a 35+ year old bearing.

pvisseriii said:

This maybe the first Superblend but still more than likely a 35+ year old bearing.

Click to expand...

DogT said:

Why would a '69 have a superblend in it? Replaced or original?

Click to expand...

Unless it has the etched 6 prefix, an MRJA30 isn't a "Superblend" bearing.

L.A.B. said:

pvisseriii said:

This maybe the first Superblend but still more than likely a 35+ year old bearing.

Click to expand...

DogT said:

Why would a '69 have a superblend in it? Replaced or original?

Click to expand...

Unless it has the etched 6 prefix, an MRJA30 isn't a "Superblend" bearing.

Click to expand...

You are right again, L.A.B.
So this could possibly be the original bearing. Over 40 years old.

Hey it lasted 40 yrs and 14,000 miles so unless you are hammering on these engines the superblend scare is just that a scare.
I think allot of Nortons reputation came from unit failure but how was the bike being operated?
I've corresponded under the old INOA Yahoo site in the past and some riders are logging 20+ thousand miles w/o failure on
original bottom ends.
Just my 2 pence.
Anyway, Dave I've been following the post and at least you know you have a dependable bottom end for another 40 years.
I for one have learned from following along.
Marshal

I'm not sure I want to last another 40 years, being 67 later this year, I doubt if I could start it at that point, but then who knows, maybe the world's oldest Norton owner?

I think it is the original bearing. The only thing I see that involves any rebuilding is one of the bolts from the primary into the crank is a size larger than the others, but who knows, maybe that happened at the factory because they stripped it? As far as I know it had 4K on it when I got it and appeared to have been slightly abused, original clutch pack, looked like someone had busted a bit out of the timing cover and welded it, but ran like a freight train and pulled the blood out of your head, especially in 2nd gear from about 15mph to 70, love that broad torque band. It probably had been raced a bit.

Anyhow, there are 2 NJ306.M1.C3 bearings going back in as soon as I get the cases back from cleaning and I have the Norvil bottom end rebuild kit and new pistons, so I should be ready to go.

Dave
69S

What do you all suspect that inscribed "B36" means?

Dave
69S

DogT said:

I'm not sure I want to last another 40 years, being 67 later this year, I doubt if I could start it at that point, but then who knows, maybe the world's oldest Norton owner?
Dave
69S

Click to expand...

Dave, There is statistical data that suggests that if you live to 70 in reasonable health you will not only probably see 80 or 90, but you will continue to enjoy good health in those years. In otherwords, if you have genetic or lifestyle timebombs in you, they would have gone off by now. Also 70 is the new 50. Most important, knee replacements are guaranteed for 20yrs.
So try to eat right, get plenty of rest, and take your Geritol everyday.

MarshalNorton said:

Hey it lasted 40 yrs and 14,000 miles so unless you are hammering on these engines the superblend scare is just that a scare.
I think allot of Nortons reputation came from unit failure but how was the bike being operated?

Click to expand...

I think premature main bearing failures only became a serious problem after the Combat models were introduced. That's not to say it never happened prior to that, but it wasn't the regular occurrence it soon became with the Combats-due to the significantly higher power output, lower gearing and stiffer crankcases that didn't flex along with the crankshaft quite as much at high revs which allowed the edges of the rollers to dig into their tracks, and also that the Combat engines were supposed to be safe to run up to 7,000 RPM for extended periods.

http://www.nortonownersclub.org/support ... e-releases

This is a collection of Service Notes that came out of Norton during the bearing debacle. It includes an explanation by an NOC writer. It appears as if Norton was scrambling to fix a very real problem if you look at the dates and the wording. Take into account that these bikes were being marketed as the quickest motorcycle on earth, not an alternative to a BMW. Why else would anyone buy one except to 'hammer' it?

It looks like they might have spec'ed the wrong bearing clearance that also happened to be the cheapest one they could get. The maximum capacity bearing was available all along and is the standard now. I dislike the term Superblend, they might as well have called it SuperDooper. BTW, by enlarging the dimensions of the bearing housing in the case to get less crush on the bearing they introduced the new problem of spinning the outer race.

I was just on Frank's Clubman Racing site and apparently there has been a statement from Andover about SuperBlend bearings:

About Superblend Main Bearings - A recent Andover Dealers Newsletter contained the following: “Some may have noticed we now offer main bearings in "C3" condition, i.e. in a slacker fit than specified. As any experienced Triumph dealer can tell you, bearing tolerances have gone down towards the "tight" end of the norm in recent years, leading to main bearings seizing up when the crankcase cools down after the new bearing and the crank with the inner race was put in. On Triumphs a 70-2879 is a C2 (tight) fit, which on new or well-maintained crankcases is now too tight. Triumph dealers then switch to a 68-0625 BSA bearing, which is a standard (looser) fit and does the trick. On Nortons, the spec for a 06-4118 ("Superblend" bearing) is standard fit which, again on newish crankcases, 850s in particular, is now mostly too tight. We therefore - at the request of Mick Hemmings and my engine man Rudi Kolano- started to stock and sell bearings in "C3" condition. These are available under part 06-4118/C3”