Crank axial clearance.

i don't feel there is a problem with the mains moving on the crank weed? i think there's a good chance they'll start to move in the cases if they aren't gripped well!

the best is the best you know as someone here always used to say and i believe that you can't discount something in the left cover stopping the crank from expanding?

and i always considered the axial clearance to be for all occasions and most especially when warming up and not about maximum heat and expansion. for me it was always the opposite = the damage is done at starting on all these things and then flat out gets the blame!

that 0.1mm is very telling mate!

regards

Taffy

Ok got some time to work on the bike engine today. Fitted the crank into the case with the balancer, shim and ktm ball-bearing on the left and the roller on the right (with no shims behind the inner race). I get about 0.45mm endfloat but wouldnt say that it was exact as ive already fitted the oil seals so had to measure again one of them). I know 0.45mm is abit much on a 450 acording to the manual but i think ill stick with that as im sure it will close up abit as the crank "settles".

I had to take the crank back out the lhs case as one of the teeth on the balancer had some slight damage i fergot to clean up and sure enough it was binding :evil: When thats all cleaned up im going to put the crank back in the case with a bit of bearing fit on the lhs and leave it at that. After all its only a 450 MOPED!!!! 8O :lol:

cheers

Rab

Taffy said:

i don't feel there is a problem with the mains moving on the crank weed? i think there's a good chance they'll start to move in the cases if they aren't gripped well!

the best is the best you know as someone here always used to say and i believe that you can't discount something in the left cover stopping the crank from expanding?

and i always considered the axial clearance to be for all occasions and most especially when warming up and not about maximum heat and expansion. for me it was always the opposite = the damage is done at starting on all these things and then flat out gets the blame!

that 0.1mm is very telling mate!

regards

Taffy

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Interesting to note some of the stroker RFS builders like to actually set the TMB series balls (same bearings as used in the 'Bergs, as you know) up with operating clearance between the inner race and crank shaft.

Theory being inner race can float and find its own "happy place" on the crank.

That way, providing you have allowed enough axial space for max crank width, the balls are never getting any axial loading, just radial.

Just for the record, its suprising just how much axial float is present in a new,installed ball bearing.

,it was something like 20mm,so to my way of thinking its never going to bind with a c3 or c4 bearing..non issue to my way of thinking.
the real problem is the bearing inners move.the fit between the bearing inners & the crank is not always a tight fit.when that moves because of heating/cooling/vibration/whatever, the endfloat can eventually become nil.
i know i measured mine a couple of rides back,.1mm cold/.3mm hot ,scary hey,especially when i cut/ ground the crank spacer down so it had .4mm cold ,when i assembled it.
any reaction ??

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ahh thats good about the misalignment

FWIW I have the same problem with stuff moving around when hot

I put my RHS main inner on with loctite, and the LHS without

my endfloat vairies 0.1 to 0.5 , i set it up at 0.5.

I check it all the time. with the oem setup it was the same problem except that Im pretty sure the RHS inner was the loose one.

now if its less than 0.5 hot (real proper race pace hot) I can push the crank from R to L with welding gloves; gently it won't move but give it a thump with the heel of my hand and feel it move accross. endfloat back up to spec.

that tells me its something on the LHS loose when hot........ but its gotta be real hot like after 2 hours hard work.

after seeing what my engine does and hearing weeds does the same, maybe, just maybe everything needs to be locked down properly loctite/screws outers and loctite or collars on the inners. even if only on our 2 bikes

its great there are many solutions to the main bearings "problem" but it seems that nobody really knows why their favourite solution works. the ball LHS is supposed to be good but there are more than a few instances of that system going boom. what went wrong?

just a guess that Weed and I may be the only ones who noticed the wandering endfloat but i bet it happens in most bikes a lot. then as taffy says start her up with possibly zero float and you get a bit of wear, do it enough times ......

had a big crash with the origional bearings did a wind gust/WP shock induced bubba scrup flat whip over a big jump. I bailed out bike hit the deck pretty hard on its side I broke the handlebar mounts bent the bars and some other bits. bike got home in the trailer. the crank endfloat was zero. locked solid axially. o crap I thinks its rooted but idled it for 5 min and it losseded up a bit, rode gently for a while and when the engine was hot it was back to 0.5. thats what got me checking it all the time.

if it was a ball/roller set up id not have been able to check it but it still could have been zero.

not trying to reinvent anyones favourite setup, I just wanna make mine better. possible zero endfloat cold is not very confidence inspiring. peace of mind is worth 50 extra engine hours, its a must have :lol:

good luck with the lil moped rabno

don't really know mate, but i've heard a few times on this site people saying the either a ball race or bearing inners been loose-ish on the crank.mostly on the right side,i think it might have been swedish steel that said his left side bearing inner was loose & been spinning.
think about it,if he was for example to put a ktm roller on the right side because thats the done thing now & a roller on the right.
i would say that motor would be a candidate for a roller failure on the right.
a ball can only control end float if its tight fit & does not move.
i used 3 bond bearing retainer on the on everything & was sure it was strong enough,but be buggered it must have been the hot /cold thing that made it let go.
whats everyone use?
taffy are you saying that you haven't come across a loose fit yet?
they must only send the bodgie sheit to aust,after all we are only descendants of convicts.
..weed..