Main Bearing Specs

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B.Rad

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I know all about the hype regarding Superblend main bearings. The term Superblend does not exist in the Engineering world, only the Norton world.I am Ok with NJ306e. the E is for extra capacity, and all good brand roller E bearings have the modified roller ends to prevent digging in.By the way i have information saying that the rollers are not barrel shaped , this is for spherical roller bearings. My questions also applies to the NU style which only differs whether the race is on the inner or outer roller. I believe NU style was also fitted by the factory but may stand corrected.
1. The bit that gets me is the cage suffix especially for brass cages. . there is M1 and M1a. what do these different suffixes mean. something to do with roller or ring guided cages but what is the effect of using the different suffixes. Also are the modern phenolic resin cages any good, has anyone experience with the resin cages given the temperatures that may be applied in a hot motor. does the resin cage disintergrate.
2. internal bearing clearences. my information says thet Normal clearence is the correct one. however there seems to be a tendency to go for C3, greater than normal clearence. As the difference is only a few microns, is there really any practical difference that affects the life or performance of these bearings.

Can some tech guru please enlighten me on these subjects. I am after some hard facts here please, either technical explanations or experience based anecdotes.

I am of the belief that any good reputable bearing, eg made in Japan , UK, USA regardless of brand, that is specified NJ 306E M1 or M1a would be suitable. Is this wrong and please tell me why. However I would not put Chinese bearings in my Norton.
All advice is appreciated
B.Rad
 
My local bearing supplier told me what you have been told, all bearings with that serial number are the same ie "superblend".

I used an NSK with a steel cage in my race bike for several years with no problems. I only changed it when it got rusty while the engine was apart.

It now has a FAG with a brass cage, but I'd be happy putting another quality bearing with a steel cage.

Sorry I know nothing about resin cages.
 
In reply to B.Rad on the question of main bearings: the NOC forum contains a good thread on this subject, and FAG's website contains good data. The forum debates the merits of rollers vs heavy duty ball bearings on the timing side. After digesting the considered opinions of some very knowledgable contributors, I am about to rebuild my engine with "superblends" both ends. Purchased from Norvil, they are FAG NJ306-E-M1. The M1 stands for a roller-guided 2-piece solid brass cage. Personally I would not like to risk the polyamide cage (suffix TVP2) in my engine.
 
B.Rad said:
My questions also applies to the NU style which only differs whether the race is on the inner or outer roller. I believe NU style was also fitted by the factory but may stand corrected.
Click to expand...

NU (cage captive on inner race) bearings were used, however the NJ type was the only FAG bearing fitted by the factory (under part number 064118) as far as I'm aware.



B.Rad said:
2. internal bearing clearences. my information says thet Normal clearence is the correct one. however there seems to be a tendency to go for C3, greater than normal clearence. As the difference is only a few microns, is there really any practical difference that affects the life or performance of these bearings.
Click to expand...

C3 is now the recommended clearance, and what is supplied by Andover Norton.
post130338.html - "ZFD"
 
Norvil will supply the C3 bearing if you ask and he will whine.

Dave
69S
 
Les whine? You don't say!
The C3 option was debated on the NOC forum, and the consensus seemed to be that the extra clearance bearing is designed to compensate for a reduction in clearance caused by a heavy press fit of the bearing on the shaft. Using a bearing with extra clearance on the Norton was concluded to be undesirable. Admittedly, these discussions took place over 10 years ago, and although our Nortons have not changed since then, maybe some real-world experience has proven that conclusion wrong.
 
Oh dear. Look what happens when you come in late:
I've just read Andover's reasoning for specifying C3 bearings, as well as some posts from DogT and others dating back to 2010. Now I don't know whether my new bearings have been the right choice until I reach the assembly stage. They are marked FAG X-life NJ306E.M1 INDIA G251 supplied by Norvil.
The bearings just removed are the ones I fitted in 1983. They are RHP bearings marked simply N306, bought from Ryan's motorcycles. At the time all I knew was that two rollers must be better than roller/ball, right? I don't know when I first came to know about "superblend" bearings, but I thought that I should use the best for this new rebuild. Time will tell.
 
Yeah, I wonder if I have pictures of the Emory bearings I got and where they are made. They were C3, I did see that on them.

If I had to do it again....just ask.

A lot of it may have to do with how you thrash it. I probably could have gotten by easy with a roller on the drive and ball on the timing side the way I drive. But someone in OZ that's running 100 for miles in 100+F could probably use all the good juice they can get.

Dave
69S
 
Most standard cases will work fine with either bearing clearance.

If you are using Maney cases then you must use C3 clearance as the cases are designed with extra interference to keep the bearing from moving around so much.

If your standard cases are worn a bit and the fit is on the loose side- then I would use some blue steel shim stock in the bearing bore to get to the maximum crush and a C3 would then be necessary. Jim
 
OK, here's what Les sent me. Looks like FAG NJ306E M1 C3. It did come in an Andover package if that means anything.

Main Bearing Specs


Dog
 
In my last post I had some concerns about whether I should have gone for the C3 version when I bought the bearings, although at the time of purchase I hadn't learned of the new specs from Andover.
Having now assembled the crankcase, it seems that I may now have a problem.
Firstly it appeared that I had no end play in the crankshaft. This was despite making very careful measurements and then shimming the inner races to give me .012" play, in theory.
The crank would turn freely enough, it just had no end play.
I could not live with the possibility of having pre - loaded bearings, so I started to dismantle the cases.
Strangely, even when the cases had started to separate, the crank still would not move freely out of the case, particularly on the drive side.
I had noticed when fitting the races to the crankshaft that the fit on the drive side quite a bit tighter than the timing side, which is what my shop manuals indicate as normal.
As an experiment, I tried inserting the drive end of the crank into the timing case and vice versa. This seemed to prove that the race at the drive end has grown more than the timing end due to the tightness of fit.
Now it seems that I may well have the end play that I wanted, but I just can't verify it.
Even the timing side is a bit reluctant to slide endways, compared to the old bearings which slid easily even when first fitted.
Given that the crank turns freely when cold, and should gain some clearance when hot, I'm thinking it may be OK after all.
Can anyone offer any advice?
Cheers
Martin
 
Martin,
I ran the standard clearance FAG bearings but had a nip up in the bore and some metal through the engine, no issue with the mains. But next time I used C3 FAG bearings, I could not notice perceptable difference in end float or fit. It is easier to use Old brits shim under the outer cup than the standard Norton shim on the crank. Seems like a C3 on the drive side and a normal on the timing side?

Sorry I can't be more help.

Cheers Richard
 
Thanks for the reply Stockie2.
I just re - read the C3 vs CN thread, which just about covers all the bases on this topic. I had thought about doing what you suggested - ie putting a C3 on the drive side.
Given the closesness of the specs of these bearings these days, I don't see any harm in doing that.

I didn't know about the Old Britts shims for the outer races: that sounds better than the crankshaft shims, which only give you one shot at getting it right.

Cheers - Martin
 
I think if I did it again, I'd use a roller in the timing side. But I'm not sorry I used the superblends on both sides. It's just the way I drive.

It's not impossible to use the inner race shim, it just means if it's not right the first time you need to take the bearing off again. Apparently the outer shims are not very available in EU, I had a spare set of OB outer shims and sent them to a fellow in FR, marinecommando I think.

Chances are if you do things right, it will only take one try, at least that's what happened to me but I didn't put sealant on the flanges until I knew.

Dave
69S
 
Hi Dave
I think you meant to say you'd use a ball bearing on the timing side?
I understand your viewpoint; I'm no rev - head either, except for an occasional burst. I like to think of myself as a gentleman motorbicyclist.
Do you have a puller capable of removing the races from the crankshaft?
I made one when i attempted to remove the bearings just replaced, which had the rollers fixed to the inner races. I made the puller to work on ther rollers themselves, as there is precious little room between the race and the crankshaft web. It didn't work, although it WAS the drive side that I tried it on. The puller remained intact, that's the only plus.
In the end, I removed the rollers and ground the races down VERY carefully until they loosened.
It looks like you made the right call in going for the C3 version.
As an aside in my saga, I initially tried to source my bearings locally. My local CBC outlet only had one FAG "superblend" in stock and it was a C3. Having read the discussions on the NOC forum and not yet discovered this one, I shied away from it. He checked his stocks Australia - wide and could not locate any; he would have import them for me. Hence I included them in a block order from Norvil in December. It's a shame that Norvil seems to be out of step with Andover on this matter. Could have saved me some trouble and expense.
Cheers
Martin
 
Ball, not roller, on the timing side, yes. I didn't have a puller, I used the Hemmings method of a chisel between the bearing and crank. I wouldn't do it again, I ended up with a few marks on the crank cheek. I had a shop press the new ones on for about $20.

I got all the bottom end parts from Norvil in their kit. He didn't want to send the C3 bearings, but he relented and did. I guess since the roller is included for both in the kit, it really doesn't matter and may be better in the long run.

Dave
69S
 
hisel....ouch!
Velocettes have tight Taper rollers, Some carefull work with a 5 inch disc cutter save's the chisel rash :!: Slice nearly through and the inner gives up it's bite! But dont cut into the shaft. Last one i did when i was near the race cracked allowing easy removal..Just an idea.
DogT said:
Ball, not roller, on the timing side, yes. I didn't have a puller, I used the Hemmings method of a chisel between the bearing and crank. I wouldn't do it again, I ended up with a few marks on the crank cheek. I had a shop press the new ones on for about $20.

I got all the bottom end parts from Norvil in their kit. He didn't want to send the C3 bearings, but he relented and did. I guess since the roller is included for both in the kit, it really doesn't matter and may be better in the long run.

Dave
69S
Click to expand...
 
john robert bould said:
hisel....ouch!
Velocettes have tight Taper rollers, Some carefull work with a 5 inch disc cutter save's the chisel rash :!: Slice nearly through and the inner gives up it's bite! But dont cut into the shaft. Last one i did when i was near the race cracked allowing easy removal..Just an idea.

Yes that's the way I did it in '83 when I restored the bike, and again recently when I fitted superblends. Now I have to remove the new superblend to fit a C3. Drive side only. The timing side is ok.
As an experiment I tried the timing end of the crank in the drive side case and it slid in nicely, whereas the drive end crank is tight in both cases. This indicates to me that the inner race on the drive end has expanded too much.
Another point: I used a small smear of Loctite 641 on the outer race when I dropped it into the heated crankcase and I can confirm that it works: I could not remove it by the heat and shock method.
Plan B was to slip a piece of 25mm x 3mm flat bar, suitably shaped, behind the rollers, and drive it out. Also with heat of course.
Click to expand...
 
A word of caution - AVOID BEARINGS MADE IN INDIA - worse than Chinese! mate building an Atlas 750 ordered from Norvil and was gobsmacked at the poor quality. And that is not the only example I have come across of motor parts made in India. There's a bloke here in Oz who rebuilds Enfields from new just to get the bottom ends right!

Mick
 
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