Why ball bearing mains?

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I always put crank shims, as I find them very easy to put on or take out when you have the right tools.
I would hate to heat the cases to remove the bearing just to swap case type shims and I would hate even more to R&R the bearing from cold cases.
I always put them on the timing side since the bearing is captive by the timing gear nut. The crank is 99% always thrusting against the timing bearing because the 3 or 6 start oil pump gear is thrusting to the right to turn the oil pump. For this same reason the timing side bearing should always stay seated in the bottom of the pocket even if/when it turns in the case.
 
dynodave said:
I always put crank shims, as I find them very easy to put on or take out when you have the right tools.
I would hate to heat the cases to remove the bearing just to swap case type shims and I would hate even more to R&R the bearing from cold cases.
I always put them on the timing side since the bearing is captive by the timing gear nut. The crank is 99% always thrusting against the timing bearing because the 3 or 6 start oil pump gear is thrusting to the right to turn the oil pump. For this same reason the timing side bearing should always stay seated in the bottom of the pocket even if/when it turns in the case.
Click to expand...

There is a very small amount of thrust keeping the crank to the timing side. Keep in mind the oil pressure applied to the right end of the crank is opposing the pull of the oil pump gears.
I have used a crankshaft position sensor that was a slotted disk running between a magnet and a hall sensor. With too much end play in the crankshaft the slotted disk would show wear on both sides so it doesn't always stay to the right.

I will always put the case in my oven for a shim. It is so easy to let it warm up till the bearing falls out with a light tap and drop a shim in place. Then there is no wear taking place.
I have good pullers for the bearing race on the crank but I never liked the fact that a small amount of interference fit is given up every time a bearing is pulled off and put back on. Jim
 
On the late Mr. Hudson instruction video he makes a point of hand sanding TS crank end til the ball bearing slipping on/off by hand stone cold. Doesn't compute to me.

Case bearing bore slackness needs to be solved somehow. I'd rather not JBW in that hot spot as JBM tends to soften with heat and has poor adhesion just internal high shear force resistance so the bores and races would have to be scored or dimpled or such to give the JBW sometime to bite into. With set screws or staking how would ya keep alignment right, or would that even be an issue with the innate slack?

Somewhere I'd saved a file on the load and rpm ratings of ball vs superdupers.
In the mean time here's past NOC collective bantering to draw you right in on more confusion what works best and why not. Teaser viewpoints below.

What Dave also says, is that crankshaft flexing is a problem on all Norton engines when run hard. Paul Dunstall confirms this in his tuning notes by recommending bearings to be pegged. He also mentions that in 1969 the factory changed to tighter fitting drive side roller bearings to prevent moving of the outer race in its boss. Note that this modification was made to all 20M3 and 20M3S engines from then on. Bearing problems may not be an acute problem on an Atlas when ridden gently, but in my opinion it's an area of concern. That is sufficient for me to fit Superblends. As a side effect it will alleviate strain on the crankcase as well and thus prevent future cracks.
Click to expand...

Crankshaft flex
I've been reading some commentary to the effect that two Superblends are far too rigid, and will send the flex through to the crankcases, which will start to suffer as we all know so well. The underpinning of the argument for using one of each is that flex happens, and it's better to take the bullrush approach instead of the oak tree approach. Although I'm not an engineer by training, I must admit to a certain bias towards this argument, particularly since the gentlemen most recently to espouse it has been doing it with allegedly great success for a number of years on his racing Nortons.
Click to expand...

http://www.nortonownersclub.org/support ... n-bearings
 
comnoz said:
I recall reading about the pinning the bearing modification (Dunstall?) but do not recall if it called out for doing both sides. The problem I see with doing a both sides with ball bearings is that the cases and bearings will go in a bit of a bind with temperature change.
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You sure wouldn't want to do both sides with ball bearings. Dunstall just did the timing side.
I think he did two or three retainers like the one in Ken's picture. Jim[/quote]

When Dunstall wrote his tuning book, he only recommended one retainer, similar to what I do, and only showed it on the drive side. In the text he says "For racing purposes, the mainshaft bearings should be pegged to prevent their moving in their crankcase housings." That's bearings and housings plural, so he may have meant both sides should be done, or maybe not. When he wrote his tuning book, Norton still used a ball bearing on the timing side. Because I use Superblends on both ends of the crank, I also pin the timing side race.

I'm out of time now, but I'll post a scan of the relevant page from the tuning manual tomorrow.

Ken
 
pommie john said:
How do you machine the indent in the bearing ?
Click to expand...

After I've drilled, tapped, and counterbored the case for the retainer, I install the bearing outer race and use a small grinding stone in the mill, like this

Why ball bearing mains?


Ken
 
lcrken said:
pommie john said:
How do you machine the indent in the bearing ?
Click to expand...

After I've drilled, tapped, and counterbored the case for the retainer, I install the bearing outer race and use a small grinding stone in the mill, like this

Why ball bearing mains?


Ken
Click to expand...


That's how I did my one, many years ago. The hassle I had was wear on the stone I think because it was running too slow. A grinding stone likes to run very fast and most pillar drills run really slowly.

The sharp edges of the stone wore out and gave a big radius at the corners.
 
I use an old Superblend inner race for setting the clearance. The old race has been relieved on the inside with a Dremmel to give a sliding fit on the crank shaft. I can therefore try different shims until I am satisfied that I have the clearance correct before pressing the new inner race onto the crank. This saves having to either heat the cases to remove the bearing outer or else use a puller on the inner. Bearing manufacturing tolerances are such that any inner in any outer will be close enough for measuring end float. I have used this method many times and the final clearance is always the same as my test clearance with the dummy inner race.
 
I like all the gussetts welded into the cases - and very neat too.

Does that stop the cases grenading - until higher revs.
Or stiffen them, for more sustained hp
Where is the thinking here ?


lcrken said:
Why ball bearing mains?
Click to expand...
 
Cases tend to fracture horizontally in half through the crank hole so the plates help hold top to bottom and if also done on the TS too it gives a place for 11th clamp bolt like Peel had. Cases can really distort their seams after this is done and can be a real headache to beat back to seal again.
 
If you got your local Glass Cutter to get some Holy Glass :) , the hole being just over the flange diameter . YOU could
lap the suckers flat on the plate glass , with grinding paste .
Youd have to stress relieve it after hammering . And then do it all again . :p ( just kidding ) .
 
Dunstall thingo . live :) or viewable , anyway . http://www.squidoo.com/paul-dunstall-tu ... e133890091

Why ball bearing mains?


Now , just being awkward . But tecnically for scientific types .IF the PEG secures the outer race , it as the outer race is not always tight .
therefore if its not tight and the pegs secureing it , its irregularly secureing it . Three would regularly ( 120 deg or 3 sector , one dimension - Laterally )
locate it in One Plane . ( Now we've gotem worried . :p oops . better run & hide . :) )

This case is likely persnickity rather than pertanant . STUDY of the area of the single peg arrangement after severe use will reveal any witness marks .

The thermal expansion & secureing of fit gets a bit problematic . Ancient evolution or a raceing design , cutting edge at the time & emulated
for a few decades after in engine evolution . These international competition F2C team race engines have considerable THERMAL consideratios
primarilly resulting from restriced FUEL USEAGE / regulation limited supply sees insuficient to adequately evaporative cool , Lubrication being
pre mix is critically tested also . Therefore the whole thermal / clearance issue is tantamount to its sucess .

Why ball bearing mains?


http://home.wxs.nl/~wakke007/fmv/fmv_2.htm

Why ball bearing mains?


Later ( current ) competion engines are largely Russian build Aerospace grade material , machineing & fits . Just the types to do my Twin Cam . :p

http://stalkerf2b.narod.ru/ ( current commie aerobatic El Cheapo issue . evolution of 60s Italian design . chief improvement metalurgy & machineing )

these improvements allow vastly improved reliability & consistancy ( of operation ) from essentially the same design . :D
EVEN the bleedy artical on Dave Rawins factory Hot rod from recently refers to DATED design .
INTRESTING the terrm was SELDOM USED in relation to the more DATED V-Twin H.D. Sportster.
( yes V twins have been around a while too , like twin overhead cam 4 Valves from 1908 . :x

Thus our current prissy updated Sportster ( or whatever the call the H.D. 1200 ) stayed in evolution ( :oops: :lol: :wink: )
our antiquated :shock: :roll: type was sheved / cold shouldered . FUDGE .
 
The only main-bearing failure in my mega-mile Combat--after the original bearings were replaced with Superblends in late '72--involved a timing-side ball bearing installed by a rebuilder circa 1998--I have never had a Superblend roller bearing fail in hundreds of thousands of miles--ever



Tim Kraakevik
kraakevik@voyager.net
 
kraakevik said:
The only main-bearing failure in my mega-mile Combat--after the original bearings were replaced with Superblends in late '72--involved a timing-side ball bearing installed by a rebuilder circa 1998--I have never had a Superblend roller bearing fail in hundreds of thousands of miles--ever



Tim Kraakevik
kraakevik@voyager.net
Click to expand...

I've never had one fail in a race bike either, but I have seen them start to wear the rollers, and that's when I replace them. For me, pegging the races is just insurance. I've never actually had a problem in an engine because the outer races were spinning in the cases, but it didn't seem like a good idea to let them keep doing that. I figure if I peg them from the start, they can't spin, and maybe that will prevent them from getting loose. There are clearly plenty of Commandos running around with main bearings that spin in the case and never cause a problem. For the crankcases in these pictures, they had a lot of race miles on them, and the bearings were so loose that I had to bore the cases and put bronze sleeves in. While I was at it, it wasn't much more effort to do the retainers, so I did. It may not be necessary at all, but it can't hurt, and it gives me one less thing to worry about.

Ken
 
pommie john said:
That's how I did my one, many years ago. The hassle I had was wear on the stone I think because it was running too slow. A grinding stone likes to run very fast and most pillar drills run really slowly.

The sharp edges of the stone wore out and gave a big radius at the corners.
Click to expand...

Me too. I had to dress the stone regularly to keep the edge sharp. And I did run it at max speed.

Ken
 
dave M said:
I use an old Superblend inner race for setting the clearance. The old race has been relieved on the inside with a Dremmel to give a sliding fit on the crank shaft. I can therefore try different shims until I am satisfied that I have the clearance correct before pressing the new inner race onto the crank. This saves having to either heat the cases to remove the bearing outer or else use a puller on the inner. Bearing manufacturing tolerances are such that any inner in any outer will be close enough for measuring end float. I have used this method many times and the final clearance is always the same as my test clearance with the dummy inner race.
Click to expand...

That's a clever idea, Dave, and I'm a little embarrassed that it never occurred to me. In my case, I use shims behind the outer race, but the same principle should apply if I just take a little off the O.D. of a used outer race. That would save me from repeatedly heating the case to remove and reinstall the race. Thanks for the hint.

Ken
 
Doesn't the balance factor affect crankshaft flex at max revs ? That might be the main reason that standard commando engines shit the crankcases if you over-rev them. At 7000 rpm my 850 motor has very little vibration using a factor of 72%.
 
Rohan said:
I like all the gussetts welded into the cases - and very neat too.

Does that stop the cases grenading - until higher revs.
Or stiffen them, for more sustained hp
Where is the thinking here ?
Click to expand...

As hobot mentioned, that's where the cases like to split. I had several crankcases in race bikes that cracked from the drive side main bearing bore all the way around the rear to the joint between the crankcase halves. I originally started welding the gussets in to save cases that had already started to crack at the rear, by the upper cradle bolt, but later, for cases like this one that I added the gussets to, along with other reinforcements, when first building the engines. In most of the other engines I'm building now, I'm using new cases that are already much stronger, either from Steve Maney or a couple that I got from Kenny Dreer, and I don't think there's any need for welded reinforcements.

This shot shows the other reinforcements on this particular set of cases. FWIW these are MKIII cases.

One other little tidbit. This method is not bulletproof. I managed to split a set of cases just like this at Daytona in 1990 in a 920 cc Commando Production Racer. I think it got over-revved a bit too much.


Why ball bearing mains?


Ken
 
Hmm, the ancient Egyptian's and others would cut T shaped channels in tops of stones then pour lead or such in to strap stones in place. What would happen if a hick with only a bench grinder, hand drill and stove ground a couple-3 hollows out of the bore side and outer race face then poured in metal to cool in place. I long ago lost any concern of frying pan oil burning hot upper 400' F case to get tipped trapped bearings out. I used Cerometal, Woodmetal, white metal or Fussing alloy in the 1/4" copper tubes for sharp bends in Peels submarine air station same as sand in exhaust pipe bending but better. Boiling water melted it to pour in then boiling water to pour it back out. What temp range would a slightly smart but rather lazy caveman pick?

Why ball bearing mains?


There are metal alloys that can be ordered in a range of melting points from below boiling to many hundred F.
Why ball bearing mains?

http://www.shop.boltonmetalproducts.com ... PAodaz4AZA
http://www.rotometals.com/product-p/low ... 5alloy.htm
http://answers.yahoo.com/question/index ... 304AAzfWQn
 
But first, lets talk about bearings.
If you shaft is rotating, then the shaft to bearing fit must be tight..like a press, or "interference" fit.
The OD does not need a press fit as you are dealing with precession only, so you want a snug fit. Loctite will work, but you may loose center.

To fix
Go buy a brand new Rigid Pipe cutting knife. This is the little rolling blade used by a Rigid Pipe cutter for 1/2" to 2" pipe. They are about 3/4" OD and very hard and as sharp as a tack.
Mount it on the end of a round bar (like 5/8" ie)
Put the bar in a boring bar holder and go into the bore, and then feed outward.
When you hit metal, go in about .005 to .010 .
This Roller will upset the metal, and raise it on either side of the groove you make. Pull it out, and move in about 1/8" deeper in the bore and repeat.
Do this for what ever you need in depth.
the material is displaced out of the groove bore
Now, Rebore the work piece.
You will have ridges and hollows, but the ridges will be to size and fully capable of supporting the bearing as they are parent material.

You can do the same on OD surfaces fellows if you have an undersize shaft.
The work will look like minature ring grooves, but it works and can be done very fast

Because these are single grooves, they are not messy like Knurling , nor are they hard to do. Make sure it is a sharp cutting wheel !
Click to expand...
http://bbs.homeshopmachinist.net/thread ... g-Bore-Fix
 
Some excellent historical perspective on the subject. Also some good tricks to checking for end float (using old inner or outter races that have been relieved a bit for slip fit), excellent.

One thing that dawned on me is if replacing roller main bearings, check end float prior to dismantling. As mentioned above in this thread, bearing tolerance are so tight that replacements are going to be near identical to what you have in place. If the end float is unacceptable to you before dismantle, then you have the shim plan in hand. You still need to check after assembly to assure everything is seated in properly.

As for outer races spinning in the cases, I have also seen the witness marks but nothing dramatic. My take on it (maybe rationalizing) is light duty single cylinder engines use aluminum con rods without babbitt so how bad can an outer race (which is somewhat polished) be running against the aluminum; granted there's probably not much of a hydraulic wedge there. Just my perspective, from someone who has not seen evidence of bad spinning. Most of my recent builds are with Steve Maney equipment and the bearing boss starts tight and remains tight.

As for roller versus ball bearings, I did quite a lot of research a few years back in trying to source a bearing that would allow a 35mm main journal and determined that roller bearings have higher dynamic and static load ratings than ball bearings within the same envelope - across the board. Not that the extra capacity is necessary but that is what I found.

Flexing of the crankshaft. I suspect there's a whole lot of flexing going on down there regardless of whether balls or rollers are used though balls have generally higher allowable tolerance for angular misalignment which can be a good thing on a Norton big twin. I smile when I read someone stating that the ball bearings will constrain the crankshaft flexing better than rollers - I don't see it that way because the main bearings are supported in a relatively thin aluminum web which is relatively compliant (like jello) compared to the steel.
 
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