swedishsteel said:
Hallo Again.
Well, you can try and please let us know if it works, learning by doing.
//Thomas
MAIN BEARINGS FAILURE, MUST CHANGE
- Thread starter ORANGEBERG
- Start date
Hallo Again.
Well, you can try and please let us know if it works, learning by doing.
//Thomas
Joined Jun 2001
1K Posts | 3+
Berkshire, England
Enginehardware said:
Then, with the utmost respect, I have to say they're somewhat misguided. :wink:
For some reason even with a lighter balance weight the single bearing is a problem on a 650 engine. I know, because I was running them (as in lighter weights) back in 2001 and had no end of troubles - and in that I mean extremely reduce lifespan on the balancer bearing. I completely threw them in the bin..........
The only solutions I found was either to run the double bearing, double bearing with a lighter weight, or re-balanced crank shaft. Of course, the rebalanced crank shaft gives the best overall reliability on this one and of course you can tune out the vibrations your rider doesn't like.
All the best,
Simon
Joined Jun 2001
1K Posts | 3+
Berkshire, England
Hey All,
Just a little note about what I have used mains wise that may be of interest.
Roller bearings both sides, balancer removed, spaced and crankshaft properly shimmed for float clearance.
I addition, I have also tried used a "collar" that sits on the crank that when you tighten up the crank nut it "pulls" the crank into the left hand bearing leaving all clearance on the right. I know there was quite a lot of talk about this being an "update" at some point but I don't know whether this is standard fitment on the crank?
I have never experienced a pre service main bearing failure and any of my engine builds.
I can also strongly suggest a good read through Dale Lineaweaver's threads on this topic.
Fundamentally, I believe that simply looking at the type of bearing is like using a plaster when you need stitches.
One engine guy I spoke to, who designs engines as part of an academic groups, mentioned what he thought were issues with harmonics.
All the best,
Simon
Just a little note about what I have used mains wise that may be of interest.
Roller bearings both sides, balancer removed, spaced and crankshaft properly shimmed for float clearance.
I addition, I have also tried used a "collar" that sits on the crank that when you tighten up the crank nut it "pulls" the crank into the left hand bearing leaving all clearance on the right. I know there was quite a lot of talk about this being an "update" at some point but I don't know whether this is standard fitment on the crank?
I have never experienced a pre service main bearing failure and any of my engine builds.
I can also strongly suggest a good read through Dale Lineaweaver's threads on this topic.
Fundamentally, I believe that simply looking at the type of bearing is like using a plaster when you need stitches.
One engine guy I spoke to, who designs engines as part of an academic groups, mentioned what he thought were issues with harmonics.
All the best,
Simon
Joined Mar 2005
514 Posts | 6+
Sunset desert/ Murray River. S.A/Victoria Australi
swedishsteel said:
Patrik, I thought about it and heres my thoughts.......
Good idea, but I believe you want to control axial movement on the primary drive side.
After all, isn’t that where some of it may be generated from- the driving force between primary drive gear and clutch basket as the clutch basket floats in and out depending on gear/shaft loadings etc ???.
If you want a good main bearing configuration, you need look no further than the 250/300 2 stroke KTMs.
A large ball (6232) on the primary drive side- so all axial float is only what is built into the bearing.
The crank is a loose fit in the balls inner race- a spacer between the primary drive gear and the bearings inner race locks the bearing firmly on the crank as the primary drive nut is torqued up.
So its easy to dismantle- no puller needed to separate crank from main bearing/cases.
On the flywheel side, an NJ207 allows for expansion/contraction and flex and has enough clearance so the cylindrical roller ends never contact the inner rings flange/thrust face- and they don’t have too because axial float is all controlled by the ball bearing on the clutch side.
Interesting that a 250cc 2 stroke bike has “biggerâ€Â
Joined Nov 2001
17K Posts | 774+
Ely, England
if they were to put in a main with a larger od you might find cracking between two bearing housings.
just another point while i'm here: even ball-race bearings need shimming corectly becaus ethe ball eeds to run in the bottom of both the inner and outer race otherwise you get a rolling and swirling effect and as that can't happen the word for it is SKIDDING. and when that happens - well, the end is nigh!
regards
Taffy
just another point while i'm here: even ball-race bearings need shimming corectly becaus ethe ball eeds to run in the bottom of both the inner and outer race otherwise you get a rolling and swirling effect and as that can't happen the word for it is SKIDDING. and when that happens - well, the end is nigh!
regards
Taffy
I recently went through a main bearing replacement due to bearing failure at 30hours .I decided to have the bearings replaced and crank rebalanced by someone that builds loads of race motard motors mainly KTM’s ,the first thing he said was “seen that happen loads of timesâ€Â
we haven't got luxury of having enough meat in the cases to machine it out & put larger bearings in , so we have to go with what we got.
it would be interesting to see a picture of a *** nj206 & a skf nj206 to see if the inner shoulders of the bearings look thicker.picture 1 is the ibs nup206 inner compared to ntn nj206
inner there is a compromise between roller width & flange width.
seems like simons doing something right,what bearings and what end float can you remember simon.
don't know why someone hasn't tried spherical roller yet on a 650.its got the strength & the ability to control loads in sideways directions.it would have to be worth considering,to go in the clutch side with the c/b removed.
i would have tried it in mine,but i had a mishap & cracked the outer ring pulling it back off the crank.
..weed..
it would be interesting to see a picture of a *** nj206 & a skf nj206 to see if the inner shoulders of the bearings look thicker.picture 1 is the ibs nup206 inner compared to ntn nj206
inner there is a compromise between roller width & flange width.
seems like simons doing something right,what bearings and what end float can you remember simon.
don't know why someone hasn't tried spherical roller yet on a 650.its got the strength & the ability to control loads in sideways directions.it would have to be worth considering,to go in the clutch side with the c/b removed.
i would have tried it in mine,but i had a mishap & cracked the outer ring pulling it back off the crank.
..weed..
Joined Apr 2004
518 Posts | 0+
Arizona
My bottom end is getting a bit noisy, and upon dissassembly I plan to assemble it in the following manner. If some one sees a disaster in the works from this please let me know. Am going to try weeds spherical roller on the left side. Will hone it with a wristpin hone if needed to a zero tolerance slip fit. Standard roller on the flywheel side. Set axial play to around .4mm. Last, plan to make a spacer on my lathe to length so that when the primary gear is tightened the inner race is pinched in place with about a .1mm preload. I have said in older posts that I feel the crank is flexing and rollers digging in on the edges cause the failures. Popping the flanges off is usually due to flex not axial pressure. With the crank not directly against the main bearing (because of the balancer) flex is probably worse on that side and a spherical roller will tolerate the flex. I'm rambling on in an old school manner relating experience on Norton motors, so none of this may be appropriate on a Husy today. Fun thinking back though. 
dan
dan
Joined Jun 2001
1K Posts | 3+
Berkshire, England
popup said:
Hey weed,
I have had an end float as much as .6mm (actually more once) but normally shimmed to about .4mm on ball bearings, not the roller bearings.
I looked into spherical roller bearings and discussed it at length with Dale many years ago and after considering the SKF specification on the spherical roller bearing it wasn't feasible (I can't exactly remember why). Good luck to anyone who might try.
However, I personally think that side loads are not the issue. If the crank is flexing or there is axial misalignment then if you can't fix that you need a bearing that can tolerate that misalignment and the ball bearing will do that to a few degrees of the arc.
In fact the ball bearing is the most tolerant for this and easier to assemble and dissassemble.
One of the reasons why I looked at the spherical rollers bearing was for their load tolerance and ability to cope with misalignment, not side loads. I can't remember specifically but I also wonder whether there was an issue at the time with max. rpm on these not being sufficient, I don't know.
I also don't think any of this stuff has got anything to do with the bearing manufacturer or brand.
All the best,
Simon
Have bean thinking about this for some days more and talking to some people, and I don't think its going to be solved with the currently design of the bottomed.My first tough was to come up with a mod that don't needed some machinework on the crank and housing, and to still have the c/b in place,
Here are some point off what i come up with and what i think are happening down there.
1
The crank is flexing heavily on high rev/full-load, the crankhalf is going apart in the opposite side off the bigend-crankpin, then the shafts are forced to go off right-angle in the bearings, and also the L/R shaft are going in and out in an oscillating-motion.
2
So if we fix the right side bearing as i was suggestion and as it would be if we use a ballbearing, and have a roller on the left. then when the crank if flexing as mention earlier all the back and forth motion is forced to happen on the right side.
Was talking to a Husaberg seller mechanic that has worked with Hsb sens 1990. when a asked him about my idea, he said it could work in therm of the broken innerring on the right side but, and there must always be a but. When Hsb come up with the idea off using ballbearings on the leftside, this was first tried on race-bikes and it worked quite well, in a lifespan of a ordinary service cycle off a race engine = not to many hours as they rebuild quite often, then this dealer got some bearings-kits to try. and to ordinarily Hsb users that don't want to do rebuilds each 20hr, it didn't work. (And my first point was to have longer life than standard setup.) and when they looked later in this broken engines they find that the outerrace on the (roller) inner-ring the was completely worn up, and it must have to do with the back/forth motion that now just happen on the right-side.
3
I was assembling my crank today and first a measured the outer with on the inner-ring by itself and later when i had it on the crank and it grow 0,02mm in dia, offcours it must do that when you have a press fit, but is the bearing design to cope with this decreased play??
I can tell one reallife experience that i Had with to small clearance. I'm working as a technician with printing-presses and i did some work on a printing station ,changing bearings (neaddlebearings) with innerring on a axel, and every things went smooth, but when we started the press is was coming some noise from that station that i had fixed, and when i was looking, i saw that axel press hard to one side, i taught that this was strange and then i tried to move the shaft in the opposite direction with a big screwdriver, and i was able to get it out, but i had to use really much force, when i let it lose it was going to the same side again. (And this was on a shaft that turned 100 rpm.) And looked everything up and the only thing i could find was that the innerring had gone bigger off the pressfit, a round in the lathe with fine grindingpaper and took of some 003 of an mm and if workout perfect.
so the point that i was coming to, is if this decreased play can do some harm in the Hsb engine.????? maybe one should try to grind the innerring down to what it is unassembled?
Regards Patrik
Here are some point off what i come up with and what i think are happening down there.
1
The crank is flexing heavily on high rev/full-load, the crankhalf is going apart in the opposite side off the bigend-crankpin, then the shafts are forced to go off right-angle in the bearings, and also the L/R shaft are going in and out in an oscillating-motion.
2
So if we fix the right side bearing as i was suggestion and as it would be if we use a ballbearing, and have a roller on the left. then when the crank if flexing as mention earlier all the back and forth motion is forced to happen on the right side.
Was talking to a Husaberg seller mechanic that has worked with Hsb sens 1990. when a asked him about my idea, he said it could work in therm of the broken innerring on the right side but, and there must always be a but. When Hsb come up with the idea off using ballbearings on the leftside, this was first tried on race-bikes and it worked quite well, in a lifespan of a ordinary service cycle off a race engine = not to many hours as they rebuild quite often, then this dealer got some bearings-kits to try. and to ordinarily Hsb users that don't want to do rebuilds each 20hr, it didn't work. (And my first point was to have longer life than standard setup.) and when they looked later in this broken engines they find that the outerrace on the (roller) inner-ring the was completely worn up, and it must have to do with the back/forth motion that now just happen on the right-side.
3
I was assembling my crank today and first a measured the outer with on the inner-ring by itself and later when i had it on the crank and it grow 0,02mm in dia, offcours it must do that when you have a press fit, but is the bearing design to cope with this decreased play??
I can tell one reallife experience that i Had with to small clearance. I'm working as a technician with printing-presses and i did some work on a printing station ,changing bearings (neaddlebearings) with innerring on a axel, and every things went smooth, but when we started the press is was coming some noise from that station that i had fixed, and when i was looking, i saw that axel press hard to one side, i taught that this was strange and then i tried to move the shaft in the opposite direction with a big screwdriver, and i was able to get it out, but i had to use really much force, when i let it lose it was going to the same side again. (And this was on a shaft that turned 100 rpm.) And looked everything up and the only thing i could find was that the innerring had gone bigger off the pressfit, a round in the lathe with fine grindingpaper and took of some 003 of an mm and if workout perfect.
so the point that i was coming to, is if this decreased play can do some harm in the Hsb engine.????? maybe one should try to grind the innerring down to what it is unassembled?
Regards Patrik
Have bean thinking about this for some days more and talking to some people, and I don't think its going to be solved with the currently design of the bottomed.My first tough was to come up with a mod that don't needed some machinework on the crank and housing, and to still have the c/b in place,
Here are some point off what i come up with and what i think are happening down there.
1
The crank is flexing heavily on high rev/full-load, the crankhalf is going apart in the opposite side off the bigend-crankpin, then the shafts are forced to go off right-angle in the bearings, and also the L/R shaft are going in and out in an oscillating-motion.
2
So if we fix the right side bearing as i was suggestion and as it would be if we use a ballbearing, and have a roller on the left. then when the crank if flexing as mention earlier all the back and forth motion is forced to happen on the right side.
Was talking to a Husaberg seller mechanic that has worked with Hsb sens 1990. when a asked him about my idea, he said it could work in therm of the broken innerring on the right side but, and there must always be a but. When Hsb come up with the idea off using ballbearings on the leftside, this was first tried on race-bikes and it worked quite well, in a lifespan of a ordinary service cycle off a race engine = not to many hours as they rebuild quite often, then this dealer got some bearings-kits to try. and to ordinarily Hsb users that don't want to do rebuilds each 20hr, it didn't work. (And my first point was to have longer life than standard setup.) and when they looked later in this broken engines they find that the outerrace on the (roller) inner-ring the was completely worn up, and it must have to do with the back/forth motion that now just happen on the right-side.
3
I was assembling my crank today and first a measured the outer with on the inner-ring by itself and later when i had it on the crank and it grow 0,02mm in dia, offcours it must do that when you have a press fit, but is the bearing design to cope with this decreased play??
I can tell one reallife experience that i Had with to small clearance. I'm working as a technician with printing-presses and i did some work on a printing station ,changing bearings (neaddlebearings) with innerring on a axel, and every things went smooth, but when we started the press is was coming some noise from that station that i had fixed, and when i was looking, i saw that axel press hard to one side, i taught that this was strange and then i tried to move the shaft in the opposite direction with a big screwdriver, and i was able to get it out, but i had to use really much force, when i let it lose it was going to the same side again. (And this was on a shaft that turned 100 rpm.) And looked everything up and the only thing i could find was that the innerring had gone bigger off the pressfit, a round in the lathe with fine grindingpaper and took of some 003 of an mm and if workout perfect.
so the point that i was coming to, is if this decreased play can do some harm in the Hsb engine.????? maybe one should try to grind the innerring down to what it is unassembled?
Regards Patrik
Here are some point off what i come up with and what i think are happening down there.
1
The crank is flexing heavily on high rev/full-load, the crankhalf is going apart in the opposite side off the bigend-crankpin, then the shafts are forced to go off right-angle in the bearings, and also the L/R shaft are going in and out in an oscillating-motion.
2
So if we fix the right side bearing as i was suggestion and as it would be if we use a ballbearing, and have a roller on the left. then when the crank if flexing as mention earlier all the back and forth motion is forced to happen on the right side.
Was talking to a Husaberg seller mechanic that has worked with Hsb sens 1990. when a asked him about my idea, he said it could work in therm of the broken innerring on the right side but, and there must always be a but. When Hsb come up with the idea off using ballbearings on the leftside, this was first tried on race-bikes and it worked quite well, in a lifespan of a ordinary service cycle off a race engine = not to many hours as they rebuild quite often, then this dealer got some bearings-kits to try. and to ordinarily Hsb users that don't want to do rebuilds each 20hr, it didn't work. (And my first point was to have longer life than standard setup.) and when they looked later in this broken engines they find that the outerrace on the (roller) inner-ring the was completely worn up, and it must have to do with the back/forth motion that now just happen on the right-side.
3
I was assembling my crank today and first a measured the outer with on the inner-ring by itself and later when i had it on the crank and it grow 0,02mm in dia, offcours it must do that when you have a press fit, but is the bearing design to cope with this decreased play??
I can tell one reallife experience that i Had with to small clearance. I'm working as a technician with printing-presses and i did some work on a printing station ,changing bearings (neaddlebearings) with innerring on a axel, and every things went smooth, but when we started the press is was coming some noise from that station that i had fixed, and when i was looking, i saw that axel press hard to one side, i taught that this was strange and then i tried to move the shaft in the opposite direction with a big screwdriver, and i was able to get it out, but i had to use really much force, when i let it lose it was going to the same side again. (And this was on a shaft that turned 100 rpm.) And looked everything up and the only thing i could find was that the innerring had gone bigger off the pressfit, a round in the lathe with fine grindingpaper and took of some 003 of an mm and if workout perfect.
so the point that i was coming to, is if this decreased play can do some harm in the Hsb engine.????? maybe one should try to grind the innerring down to what it is unassembled?
Regards Patrik
Joined Jun 2001
1K Posts | 3+
Berkshire, England
swedishsteel said:
Hey there Patrik,
I certainly don't want to criticise your ideas but how do you know the crank is flexing heavily?
I have heard over the years many people talk about too much crank flexing but I've never seen anyone back it up with hard evidence.
Before I would begin to think that is the problem I would want someone to produce the data and calculations. I would certainly like to see how much it is thought the crank flexes - thinking off the top of my head the moment of area of the various components involved.
The other issue that puts this in doubt, at least in my mind, as to the problem is that not all engines suffer the dreaded main bearing issue. Some 650 engines can be run and even raced for long periods, others go bang in an hour or so.
Roller one side and ball the other has been used on a number of engines in the past to good success.
All the best,
Simon
Joined Mar 2005
514 Posts | 6+
Sunset desert/ Murray River. S.A/Victoria Australi
[quote="Simon
I have heard over the years many people talk about too much crank flexing but I've never seen anyone back it up with hard evidence.
Simon[/quote]
Hi Simon,
Wouldnt the fact that Husaberg themselves destroked the 644,fitted a 35mm pin and give the 650 a lot more end float clearance then the 450 & 550 allude to the fact that even the Husaberg engineers know what a lot suspect......
Why else does the 650 get such a large end float spec??
I know its not hard evidence, but it makes you wonder...... :?
Recommended Husaberg axial crank float= 450 .25 - .35mm
550 .45 - .55mm
650 .55 - .65mm
I have heard over the years many people talk about too much crank flexing but I've never seen anyone back it up with hard evidence.
Simon[/quote]
Hi Simon,
Wouldnt the fact that Husaberg themselves destroked the 644,fitted a 35mm pin and give the 650 a lot more end float clearance then the 450 & 550 allude to the fact that even the Husaberg engineers know what a lot suspect......
Why else does the 650 get such a large end float spec??
I know its not hard evidence, but it makes you wonder...... :?
Recommended Husaberg axial crank float= 450 .25 - .35mm
550 .45 - .55mm
650 .55 - .65mm
Joined Jun 2001
1K Posts | 3+
Berkshire, England
AUSBERG said:
I remain to be convinced :wink:
That still doesn't explain the inconsistencies apparent in main bearing problems.
End float is not only going to be there for the purposes of dealing with flex but also with regard to expansion, no?
Husaberg have gone through multiple revisions of crank shaft in the period of time there have been significant main bearing problem.
The big end pin is also not only going to be important with regard to flexing but also in regard to the big end dealing with combustion pressures, for example. With the increase in compression comes increased load to the big end. Don't I know it. I used to go through a lot of big ends. Partially because of oil related issue but also the problem was there when I ran high compression pistons but not when I didn't.
With regards to the big end pin, it would be interesting to know the percentage difference in moment of area of the 35mm compared to the 32mm pin
There are so many variables that I don't think it is simply a question of reductionism to the extent of basic linear causation which is what is going on here on this thread.
But out there, there are some simply work arounds that work very well, are very cheap and they don't require a completely new engine design :wink:
I've been around on this forum since before it existed (IYKWIM) yet this thread is scarily perpetual as in that you could, if it still existed, reread a thread from 6 years ago and it would be identical, but with only member names being different. I just wanted to add a couple of ideas to the discussion but I'm certainly not going to get dragged in to it any further...... :wink:
All the best,
Simon
dan,just a couple of things before you try the spherical roller.
like simon says ,it has a reference speed of 8100 rpm.in other words, the more you rev the engine over 8100 rpm the more the bearing is going to heat up , it still has a limiting speed of 13000rpm which isn't bad..i have a 650 which i use for trail riding & an occasional race ,i would rarely rev it over that,a 650 race bike they might.i don't know what sort of bike you have dan,but if you have a 450/550 these engines might rev too much for this sort of bearing.
remember to get a least c3 if not c4.
its a one piece bearing and will have to go into the case 1st( not onto the crank),otherwise you can't keep the outer of the bearing from going crooked into the case.
remember when you press the crank through the inner of the bearing ,only to press on the left side of the crank, i had a 8mm piece of steel flat plate that slid between the both halves of the crank, and pressed on that,otherwise you will stuff the alignment of the crank.
i don't know what everyone uses for bearing retainer,but all i can say is that 3 bond bearing retainer works good with a capital "G".when i tried to press the bearing out of the case a day after my little mishap.i thought i broke the case in half,it let go with that much of a bang,same when i had a puller on the crank end to get the spherical roller off",my heart just about popped out of my chest" when it let go.
it would probably be a good idea to put a slot in the case for extra lubrication,like the pictures in my gallery.
all the best ..weed..
like simon says ,it has a reference speed of 8100 rpm.in other words, the more you rev the engine over 8100 rpm the more the bearing is going to heat up , it still has a limiting speed of 13000rpm which isn't bad..i have a 650 which i use for trail riding & an occasional race ,i would rarely rev it over that,a 650 race bike they might.i don't know what sort of bike you have dan,but if you have a 450/550 these engines might rev too much for this sort of bearing.
remember to get a least c3 if not c4.
its a one piece bearing and will have to go into the case 1st( not onto the crank),otherwise you can't keep the outer of the bearing from going crooked into the case.
remember when you press the crank through the inner of the bearing ,only to press on the left side of the crank, i had a 8mm piece of steel flat plate that slid between the both halves of the crank, and pressed on that,otherwise you will stuff the alignment of the crank.
i don't know what everyone uses for bearing retainer,but all i can say is that 3 bond bearing retainer works good with a capital "G".when i tried to press the bearing out of the case a day after my little mishap.i thought i broke the case in half,it let go with that much of a bang,same when i had a puller on the crank end to get the spherical roller off",my heart just about popped out of my chest" when it let go.
it would probably be a good idea to put a slot in the case for extra lubrication,like the pictures in my gallery.
all the best ..weed..
Joined Nov 2001
17K Posts | 774+
Ely, England
i've read the thread with a great deal of interest and written a few pertinent notes at the end of it but below are a few more. i didn't join in initially becaus ei hadn't got a clue what swedishsteel and a few others were on about! we don't say flange, we say inner race and outter race. hope i got that right anyway!
orangeberg
thanks for bringing this up and reporting it. from what i can read in the specs supplied by 'weed; it would appear that the NJ206 is given zero sidefloat and surely this is the problem? surely it's in the wrong application? the NTN as you've found with the 13 rollers is a far better proposition - it has 1.5mm. the *** NU206 E TVP2 looks an excellent proposition because it's handed and can deal with float. this begs the question - do people know that they are handed bearings and therefore how do they fit them?
nsman
i don't think you should get the spherical bearing if the rev ceiling is 8,000 revs. it's not that you'll go near those revs but the fact that the rev limit is also an indication of what a bearing 'can take'. 8k is too low!
another point:
ktm 6-8 years ago and gas-gas till 3-4 years ago also had mains failures on their 2-strokes. the crank was too tight in the main bearing to crank fit and i believe the specs must be wrong. i never reported it but i can tell you that taking off and putting on the ball-race mains on my 400 was a bast...d!!!! is there not a lesson in the fact that the ball races are a bast....d to get on and off yet the rollers etc aren't?
enginehardwear
you talk of a SKF 6206/C3 TN9 and also of a hardened cage? is this the self-same bearing? i also would ask you to explain why the inner ring/flange doesn't match up to the counter balancer? please tell us a bit more?
anon
are we agreed that a big end that goes from 32mm to 35mm actually strengthens the whole crank assembly?
i see the ball-race as going backwards even though it is a short-term solution that works. i think a roller is the way to go but it must have endfloat! and that endfloat must be less than a roller if that is the other bearing of choice?
therefore i think that the:
NJ206E - TVP2 and/or HJ206E (don't know the difference?) are the way to go. these and the NTN equivelant that orangeberg mentions. (is it the 6206/C3 TN9?). the *** equivelant being a 'NUP206-E TVP2.
the crank must float left to right and have bearings that stay within spec as they do it. a ball race on the right would do this but the roller on the left that matches it must have axial float!
another thing: we get end floats for the crank without even knowing which type of bearing is fitted? surely this is important? we should have one for a roller and one for ballrace fitted crank?
withthe ball race bearings fitted to my crank, i look for a nice free turming crank with NO rumbling! but i don't have any endfloat. so if we have been given these numbers by lineaweaver we must get the specs on 'which type of bearing?'.
i think if you have a tighter fitting crank into the mains you aren't getting the best results and may lead to trouble. you should be able to tap a bearing on the crank and not have to do what i did which was to beat the crap out of it (because once you've started you have to finish. right?
i've not heard it said but everything from radial throw-out, to oval rod, to twisted rod, to tight bearing should now be put in the picture. factory specs to a thou must be revisited.
something has been done out of spec at the factory!
ausberg
C4 is looser than C3? i'm also told this! never seen it written but have also been told. however that isn't a problem! to have all balls or rollers (as well as the races) perfectly made is still the right direction. you simply need to take it into account and remember that only 3/9 or 10/13 of those balls/rollers were taking a loading on that "inferior" bearing!
it might not be the bearings fault but the specs we have and the materials we use!
congrats to weed for checking the trueness of the cases. whilst i value lineaweaver's opinion, it might just be that the factory has started getting the cases within spec! if so we are left with a few good reasons why the rollers gave up. i believe that 'whip in the crank' would be seen in wear on each roller - and it isn't so i think it's that they suffer with the endfloat malaise!
regards
Taffy
orangeberg
thanks for bringing this up and reporting it. from what i can read in the specs supplied by 'weed; it would appear that the NJ206 is given zero sidefloat and surely this is the problem? surely it's in the wrong application? the NTN as you've found with the 13 rollers is a far better proposition - it has 1.5mm. the *** NU206 E TVP2 looks an excellent proposition because it's handed and can deal with float. this begs the question - do people know that they are handed bearings and therefore how do they fit them?
nsman
i don't think you should get the spherical bearing if the rev ceiling is 8,000 revs. it's not that you'll go near those revs but the fact that the rev limit is also an indication of what a bearing 'can take'. 8k is too low!
another point:
ktm 6-8 years ago and gas-gas till 3-4 years ago also had mains failures on their 2-strokes. the crank was too tight in the main bearing to crank fit and i believe the specs must be wrong. i never reported it but i can tell you that taking off and putting on the ball-race mains on my 400 was a bast...d!!!! is there not a lesson in the fact that the ball races are a bast....d to get on and off yet the rollers etc aren't?
enginehardwear
you talk of a SKF 6206/C3 TN9 and also of a hardened cage? is this the self-same bearing? i also would ask you to explain why the inner ring/flange doesn't match up to the counter balancer? please tell us a bit more?
anon
are we agreed that a big end that goes from 32mm to 35mm actually strengthens the whole crank assembly?
i see the ball-race as going backwards even though it is a short-term solution that works. i think a roller is the way to go but it must have endfloat! and that endfloat must be less than a roller if that is the other bearing of choice?
therefore i think that the:
NJ206E - TVP2 and/or HJ206E (don't know the difference?) are the way to go. these and the NTN equivelant that orangeberg mentions. (is it the 6206/C3 TN9?). the *** equivelant being a 'NUP206-E TVP2.
the crank must float left to right and have bearings that stay within spec as they do it. a ball race on the right would do this but the roller on the left that matches it must have axial float!
another thing: we get end floats for the crank without even knowing which type of bearing is fitted? surely this is important? we should have one for a roller and one for ballrace fitted crank?
withthe ball race bearings fitted to my crank, i look for a nice free turming crank with NO rumbling! but i don't have any endfloat. so if we have been given these numbers by lineaweaver we must get the specs on 'which type of bearing?'.
i think if you have a tighter fitting crank into the mains you aren't getting the best results and may lead to trouble. you should be able to tap a bearing on the crank and not have to do what i did which was to beat the crap out of it (because once you've started you have to finish. right?
i've not heard it said but everything from radial throw-out, to oval rod, to twisted rod, to tight bearing should now be put in the picture. factory specs to a thou must be revisited.
something has been done out of spec at the factory!
ausberg
C4 is looser than C3? i'm also told this! never seen it written but have also been told. however that isn't a problem! to have all balls or rollers (as well as the races) perfectly made is still the right direction. you simply need to take it into account and remember that only 3/9 or 10/13 of those balls/rollers were taking a loading on that "inferior" bearing!
it might not be the bearings fault but the specs we have and the materials we use!
congrats to weed for checking the trueness of the cases. whilst i value lineaweaver's opinion, it might just be that the factory has started getting the cases within spec! if so we are left with a few good reasons why the rollers gave up. i believe that 'whip in the crank' would be seen in wear on each roller - and it isn't so i think it's that they suffer with the endfloat malaise!
regards
Taffy
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