Author Topic: Crankshaft shimming  (Read 3167 times)

Offline Wayno

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Re: Crankshaft shimming
« Reply #45 on: 07.07. 2018 13:18 »
Yes, they are the ones as supplied by Draganfly.  They do look very sturdy and well made. I'm now looking into acquiring a bearing separator to fit around the rollers (as suggested by muskrat) so I can remove the inner race without damaging it and adjust the end float.
I suppose one idea to avoid removing the race too many times is to temporarily place the shims between the crank and the bush (if that's possible) just to achieve the 0.001 - 0.003 thou end float then remove the inner race once and place the shims in their correct position.
Any comments on that thought guys?

Online muskrat

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Re: Crankshaft shimming
« Reply #46 on: 07.07. 2018 15:14 »
G'day Wayno.
Theoretically that would work BUT! Every time the outer race is inserted and removed from the case the crush on the race may diminish. The race is a C3 fit meaning it needs a certain amount of crush to bring it to the right dimensions (roller clearance). First you would need to assemble without shims and measure the end float to work out the shims needed. Then remove the race and put the shims in and assemble to check the end float. Then pull it all apart again to put the shims where their supposed to be behind the inner race. Seems like a lot of unnecessary work and risking the outer race fit in the case. 
The correct way (mine anyway) to remove the outer race is to heat the case to about 200C, the race usually falls out. To insert heat the case and freeze the race. It will drop straight in.
With the shims where their supposed to be (behind the inner race) and the cush nut is done up to 65 ft/lb they are trapped and can't move. If its set up with one or two thou" end float and the shims are behind the outer race there is a possibility the outer race can move that amount and the shims are loose.
Just do it the right way and we won't have to get the trailer to rescue you! LOL.
Cheers
Edit: Some people have an inner race with a honed bore that slips on the shaft easily to take the end float measurement. Then replace with the new race. I don't subscribe to that method as there may be small differences in the race/roller dimensions, but it works for them.
Double edit: DOH, just re read your last post re shims on the other side. That could work.
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Offline duTch

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Re: Crankshaft shimming
« Reply #47 on: 07.07. 2018 16:49 »
 
Quote
......I suppose one idea to avoid removing the race too many times is to temporarily place the shims between the crank and the bush (if that's possible) just to achieve the 0.001 - 0.003 thou end float then remove the inner race once and place the shims in their correct position.
Any comments on that thought guys? 

 I'm not sure what Musko is on  *whistle* or if I just read it wrong, but Wayno if you mean between the sprocket bush and crank, it won't achieve anything, as it's just packing the bush out and they still move together... *spider*...- or if you mean the T/S Main bush, it's a bigger diameter so also fairly unlikely to work.... *conf2*
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Offline Wayno

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Re: Crankshaft shimming
« Reply #48 on: 08.07. 2018 10:51 »
Gents-  I think the heat is affecting what few brain cells I have!!  I did mean to temporarily put the shims between the crank and the T/S bush but of course dutch you are quite right the dia is bigger so no go.  I have removed the old inner race using muskrats method of boiling water and I was stunned when it came off so easily leaving plenty of water for a well need cuppa :)
Armed with that knowledge, it should be straight forward to slip the new one on/off to adjust shims as you recommend.
Thank you all again for your experience.  Now need to sort crank either find a better one or risk grinding further.
Cheers all

Online RichardL

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Re: Crankshaft shimming
« Reply #49 on: 17.01. 2021 04:08 »
This will be a new thread under this topic. Chose not to go in "Main Bearing Shimming" topic because of the unique method used there. Nothing unique here.

I was hoping everything would go smoothly and I wouldn't need help with shimming, which I've done several times.

Given that I wanted 0.001"-0.0015" float, I guess I miscalculated my shim stack, because I now seem to have zero float. The crank is not completely free-wheeling, but it's not bound-up either. I wanted a way to exprees the feel of turning the crank, so I tested it by mildly sqeezing the flywheel between the spread ring and pinky fingers of my weak hand. No problem turning whle using very little sqeezing force. Do I have an issue here or accidental perfection? I don't like to think of wear as a solution if it is, indeed, an issue. Maybe the smear of sealer between the crankcase halves should be thicker than usual.

I reeealy don't want to pull the bearing to adjust the stack. After a small debacle, it went on nice and tight. "Debacle," what debacle? Froze the crank and baked the bearing. That worked all too well, as there was enough clearance to allow the bearing to go on the shaft at an angle, THEN shink to the interference fit. Out comes the home made Frankenstein puller.

Richard L.
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Online RichardL

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Re: WAIT! Crankshaft shimming
« Reply #50 on: 17.01. 2021 04:34 »
It turns out I have about 0.0005' float (not zereo) and the crank is moving freely now. I had not lubed the main bearing during shim calculations. A few shots of oil and it now seems things are darn good. You could say I'm "chuffed" because it means the bottom end will go into the frame this weekend.

Richard L
Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020. This year it's a solo or pillion ride in dapper attire. Watch website at https://www.gentlemansride.com for details.


Online muskrat

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Re: Crankshaft shimming
« Reply #51 on: 17.01. 2021 07:56 »
G'day Richard.
The only purpose of the 1.5 thou" when cold is to give just that "clearance when cold". As the motor warms the clearance grows as the cases expand more than the crank. Although 0.5 thou" is a little tight you might get away with it.
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
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Online Greybeard

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Re: Crankshaft shimming
« Reply #52 on: 17.01. 2021 10:03 »
More by luck than skill * I got mine to about half a thou. I was rather pleased.

* The dial guage I bought to do the job was metric so reading microns

Online RichardL

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Re: Crankshaft shimming
« Reply #53 on: 17.01. 2021 14:12 »
G'day Richard.
As the motor warms the clearance grows as the cases expand more than the crank.

That seems to be right on the money. After reading, I went into the garage to check that I wasn't imagining 1/2 thou. I don't think I was, but it's back to zero (with the slightly stiffer turning) now that the garage is colder (snow overnight). Struggling with the thought of pulling the bearing. eee *work* *problem* *countdown* *conf2*

Richard L.
Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020. This year it's a solo or pillion ride in dapper attire. Watch website at https://www.gentlemansride.com for details.


Offline RDfella

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Re: Crankshaft shimming
« Reply #54 on: 17.01. 2021 14:43 »
Richard - remember Velocette cranks (albeit taper roller bearings) are actually under compressive pre-load - ie no clearance whatsoever.
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Online berger

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Re: Crankshaft shimming
« Reply #55 on: 17.01. 2021 14:43 »
Richard if you have doubts gently blow lamp the cases and see how it frees up when warm

Online RichardL

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Re: Crankshaft shimming
« Reply #56 on: 17.01. 2021 15:12 »
Richard if you have doubts gently blow lamp the cases and see how it frees up when warm

Good idea. Going with a lamp, right now. 15 minutes should tell a story. Bear in mind, my garage is proobably around 40 deg. F. Right now. I don't ride in 40 deg. F.

Richard L.
Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020. This year it's a solo or pillion ride in dapper attire. Watch website at https://www.gentlemansride.com for details.


Online RichardL

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Re: Crankshaft shimming
« Reply #57 on: 17.01. 2021 16:55 »
So, to avoid giving some wrong idea about rate of crankcase expansion, I'm correcting myself to say garage started between 45-50 deg. F.  After about 20 minutes under the light, with case still kinda cool, clearance got to just under 0.001". A few minutes ago, after another hour passed, I remembered I own an infrared surface-temperature themometer "gun." With case around 80 deg., just over 1.5 thou.  I gotta think this will be OK. Any further warnings or agreement? Offical Notice: No blame will be ascribed to your opinions.

Richard L.
Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020. This year it's a solo or pillion ride in dapper attire. Watch website at https://www.gentlemansride.com for details.


Offline Swarfcut

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Re: Crankshaft shimming
« Reply #58 on: 17.01. 2021 17:08 »
Well, My opinion is that you are a vey lucky fella, moreover a true mechanical genius working to tolerances beyond my skills. So there.

 Swarfy.

Online chaterlea25

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Re: Crankshaft shimming
« Reply #59 on: 17.01. 2021 18:21 »
Hi Richard,
Have you fitted the spacer, cush drive assembly and tightened the nut to see if this affects the figures
If not, do so and then check the end float again ?

John
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