Where does the crank go?

sfcpiet said:
...place the LH outer race towards the locating half ring, button it up....

With all due respect, if you don't know what the half-rings are for, I get the impression you are exceeding your capabilities....
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It's impossible to place the the roller bearing race against C ring! The 1/3 of a C ring in the ball bearing end stops that.
I've given my view of what the rings are for above - albeit in question form to encourage discussion...have I got it wrong?

P.S. Thanks for the other info :)
 
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olly said:
Let's be SUPER CLEAR here - I've not said he has! I'm just trying to learn and understand what's what.
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Was just a comment towards Rob.
olly said:
It's impossible to place the the roller bearing race against C ring! The slinger hits the case way before then.
I've given my view of what the rings are for above - albeit in question form to encourage discussion...have I got it wrong?

P.S. Thanks for the other info :)
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You certainly have got something wrong...

Why shouldn't you be able to move the OUTER race towards the locating ring? From your pic I see the inner race is not stepped (which is correct), allowing the outer race and the rollers to float on it, no need to move the crank itself. The race does not actually NEED to be against the ring, the ring simply prevents it from moving any further and falling out. In service, it WILL move. Thinking it will remain where you put it is an illusion. The gap to the ring is absolutely irrelevant.

The only main bearings that were shimmed by the factory were RH balls on triple cranks. The outer crank pin may protrude from the outer web in certain cases, allowing contact to the outer race of the bearing. In rare cases, a 0.2mm shim can be found here.
 
I dont have the bike with me but i guess you're right that the outer race can slide up flush. Why though. Is it because when everything is at operating temp its then inner and outer are then aligned?
 
Who said they were? The roller bearings need space to move axially due to crank expansion, at a different rate than the case casting to boot. Everything finds its sweet spot by itself, all depends on bearing quality and how true the crank runs. A wonky crank can exert enormous side forces, causing all sorts of havoc.
 
Yep. The info that Kieth rebuilt the crank takes out all those variables, I was assuming it was an unknown item.

I gather you're trying to sit the crank hard up against the LH roller bearing when as Piet alludes the requirement is the opposite of that, it needs clearance, which you sound like you have. Perfect.
Just lift the crank a little at the left, butt the LH outer race hard up against the half ring and reposition the middle ones as well so they fit nicely on the stepped key in the top case. Compared with vertically split engines it is all extremely simple.

In operation all the bearings are clamped by the cases and can not move (fretting in extreme cases notwithstanding). The RH ball bearing locates the crank axially and the rest of the crank expands and contracts through the other three cylindrical rollers without ever having contact between rollers and inner race lips or experiencing any side load at all.

Clem's comment about ball middle bearings relates to the triples, not applicable to twins.
 
Hmm - there's a bit of confusion. I asked about the gap between the C ring and the roller bearing.

Piet said 'place the LH outer race towards the locating half ring'. He then says 'The race does not actually NEED to be against the ring'.

Breganzane says 'butt the LH outer race hard up against the half ring'

It seems odd to deliberately misalign inner and outer race which is what I'd have to do to achieve no gap.
 
A cylindrical roller bearing is not designed to take ANY axial load. The clearance allows for expansion so that the rollers do not contact the lip of the inner race. It is not misaligned, it was designed that way. (y)
 
breganzane said:
A cylindrical roller bearing is not designed to take ANY axial load. The clearance allows for expansion so that the rollers do not contact the lip of the inner race. It is not misaligned, it was designed that way. (y)
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I'm completely lost now. You said push the outer race against the C ring - if I do that the inner race will not be central in the outer. To the lay man that doesn't seem ideal.
 
Not sure I can put it clearer than I have. You're not understanding the bearing arrangement, sorry.

In Kieth you have sourced the services of a true professional in the rebuild of the crank. I strongly suggest you direct any questions regarding reassembly to him. Ye cannae go wrong wi' 'im.
 
Aye yup - but he's a busy chap and I figured I'd be able to get the answers here without bothering him. No worries - I'm sorted now.
 
Wow. Just tuned in on this one. Here is what you need to do in simple steps.
1. Position the crank so that the groove in the RH ball bearing is sitting in the C-ring.half-ring, whatever you want to call it.
2. Optional ... if theres a little play (0.40mm you say) tap the crank in either direction until you are happy that the slingers are not scraping the cases or to get it as close you think to cam chain in the middle
3. Either leave the the outer race of the LH roller with a gap to the C-ring/half ring, whatever you want to call it (let's call it the retaining ring) or tap the outer race so it contacts the retaining ring. There is plenty of overlap between the outer race contact surface and the rollers to allow it to be spaced a few mm. The LH crank will still be fully supported. If the flywheel scrapes the cases, take a little bit off the cases with a die grinder.

The thing to remember is that the RH ball LOCATES the crank - in terms of positioning, none of the other three bearings matter as long as the middle two are sitting between the separator in the cases.

I had to grind some side wear out of one of my rods that was slightly bent and had also worn a groove in the side journal of the big end on the crank web. I fitted a shim equal to the total amount removed to retain alignment and total crank length. Don't overthink it!!!
 
Is there any chance Keith has had to remove any metal from the sides of either your crank web big end journals or the rods? Knowing his reputation i would say with certainty that if he did, he will have added a shim to compensate - as i did.
 
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