Crankcase superblends revisited

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I've watched Mick's DVD several times and it is not apparent what bearing he uses in the timing side to replace the ball bearing. It does look like he is using a superblend brass cage roller in the drive side, but I don't remember that he especially addresses the bearing issues or types. I'll watch it again tonight.

It also looks like Mick is using the old slotted style pistons in the DVD rebuild too, which he doesn't recommend any more as far as I know. When I asked Angie about slotted pistons, she seemed like she didn't understand, but then said their new (GPM) pistons are improved over the old (hepolite) ones.

I'm thinking for my use, it won't matter much which bearing I use, C3 or not C3.

Thanks,
Dave
69S
 
DogT said:
It also looks like Mick is using the old slotted style pistons in the DVD rebuild too, which he doesn't recommend any more as far as I know.
Click to expand...

I just checked that part of the video and I don't think they are slotted pistons. I think you could be mistaking the (oil drain?) cutouts for the slots?





DogT said:
When I asked Angie about slotted pistons, she seemed like she didn't understand,
Click to expand...


Although Angie has a good knowledge of Commando parts, don't expect her to know absolutely everything about Commandos.
 
L.A.B.

Thanks for that clarification. I was ignorant of where the slot was. I see it now having taken the rings off my pistons.

Crankcase superblends revisited


Thanks once more.
Dave
69S
 
DogT said:
Did a bit of my own research on the bearings this morning. Looks like the NJ306E.M1 vs. the NJ306E.M1.C3 is that the C3 means that it has a larger than normal radial internal clearance. I have no reason to question Angie and Mick, plus other sources specify the C3 bearing, including the INOA site. I don't know why Les is talking like this. I can't seem to find much info on the Timkin MR1306EL, so I think I will steer away from that.


Dave
69S
Click to expand...

Dave,
The clearance spec's for cylindrical roller bearings go like this:
C1 5-15microns (for 30mm ID)
C2 5-30
C0 25-50
C3 45-70
C4 60-85
C5 85-110

C1 and C2 are considered undersized. C0 is standard, C3, C4, C5 are oversized. There is an ideal running clearance within the installed bearing. The different sizes are used to get that clearance in different situations. The installed clearance is affected by the fit, or interference, of the inner race on the shaft, the fit of the outer race in the housing, and the temperature it's going to be run at. The inner race will expand and the outer will shrink in press fits. You can see that, depending on how the tolerances stack up, the difference between a C0 and a C3 can range from negligible to 3x. So maybe it's not that big a difference. (The difference between a C2 and a C3 is significant.) Considering the high probability of flex and misalignment, the temp range the things live in, and the entropy that surrounds Commando motors, I'd think about a C3 bearing though.
 
L.A.B. said:
Also, according to earlier service sheets, a "2 dot" (equivalent to C2) extra clearance was specified for the previous pre-Superblend roller bearings.
Click to expand...


Sorry, typo, C2 should read C3
 
Bob,
Thanks for that info. I did read the FAG brochure on roller bearings but they did not specify any numbers, just general information. What you are saying is pretty much what I gleaned out of the article and other things I have been reading. I am tending towards the C3 bearing despite what Les says. I want to check a few more sources.

Dave
69S
 
For what it's worth - I looked at the bearings I purchased from TC at Sunset Motors for my Mk 3 ES 880cc.
For the drive side he sold me a FAG NJ306E.M1 and for the timing side a NTN BL306 heavy duty 10 ball bearing.
Bill G
 
Now I'm curious, There is no where on the FAG box or bearing that it says C1, C2 etc. How do you tell what the bearing is?
Bill G
 
Bill,
I would assume that C3 would be marked on the bearing somehow.

Clubman Racing on their Norton Factory Parts page recommends the C3 on low mileage or first time rebuilds. The more rebuilds or more mileage, they then recommend a standard bearing, and in between is a tossup. More evidence to go with the C3 for me.

Dave
69S
 
Hi dogt
In my 850 i have a fag nj306e c3 on the drive side with a skf high load ball race on the timing side [sorry i have an old one here and the only number i can see on it is 306] I have been using these ball races for years including in a supercarged methonel burning speedway unit i campained in the late 70s early 80s,
I have a set of fag bearings here that are marked on their box nj306e.m1.c3 one of which along with the skf bearing will go into the 70 that i am building at present.
Al
 
There is nothing following the NJ306E.M1 on the label of my my box. Could that mean it is a C0? It seems like the C3 is the bearing to have. Now I am wondering if I should get another bearing. One with the C3 designation.
Thoughts?
Bill G
 
LAB,
thanks for the serial info on the 72 combats ane 1973 info.
I was looking for a response from anyone in the know.
I was just curious as to those who have cracked open their cases around mid year
1972 had what they found inside as far as orig. main bearings.
My combat was made June 1972 so it's probably got older style bearings.
It has 9500 miles on it as of this week.
I bounce between 4000-5000 on shifts so it is not getting flogged too hard.
At some point I'm going to have to take her apart.
But as of right now I'm enjoying her to much to put her down.
And if it ain't broke I figure I have time.
Marshal
 
Bill,
From what I have read, I wouldn't break it open just to go from a C0 to a C3. I have not heard of someone losing the bearing because of that, but I am just one guy and it is a "forum". Unless you are flogging it around the track things will most likely be fine. Most bikes also run a HD ball bearing in the timing side and probably the C0 on the drive side.

This has been a good thread, even if I did start it.

Dave
69S
 
+1 David,
I learned allot about the bottom end bearings. Good forum post.
Sorry if I mixed in but thought it was better than starting another line w/ similar topic info.
Marshal
 
I received this responce from CNW to a question conserning a set of bearing they were selling.

"The only marking on the bearing is NU 306 E. There is no C3 stamp so I assume its a standard. This was pulled out of an original Commando engine. We dont find any C3 bearing in the original engines we pull apart."
 
pvisseriii said:
I received this responce from CNW to a question conserning a set of bearing they were selling.

"The only marking on the bearing is NU 306 E. There is no C3 stamp so I assume its a standard. This was pulled out of an original Commando engine. We dont find any C3 bearing in the original engines we pull apart."
Click to expand...

I can't say for sure, but original Commando main bearings would not necessarily have been known or marked as "C3", as I don't think the "C" clearance classification would have been in common use the UK?
The Norton factory service sheets refer to the previous main bearings as increased "two dot" clearance (although two dot clearance wasn't specifically mentioned in connection with either the R&M/RHP Superblend or the FAG main bearings).
 
The "C" classification for bearing fits is from an ISO standard, before the ISO standard each manufacturer designated the different fits in their own way, this could be by dots or by circles stamped on the ring after the bearing number.
 
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