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krisbeetle
Samba Member
Joined: September 30, 2005
Posts: 779
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 Posted: Thu May 24, 2018 9:43 pm Post subject: Endplay when warm |
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Just testing my engine I rebuilt. Set to .004 endplay.
Just running for short periods with no fan using a fluke temp gun on outside surfaces. 300f at sparkplug surround on the head and about 150 at oil cooler. So.... warm.... I certainly can't feel the eND play much.... when turNed off the compression stroke as to "feel" the endplay.... I certainly don't feel as much of that .004 as when cold....
This is obviously subjective as it will expand...... however it begs the question... how much is endplay when warm or " operating temp".... how much is taken up?
I want to know as this is the 2nd time tearing into this and I am paying careful attention... learning..... and learning alot....
If you are someone who may be able to answer this question in a semi quantifiable manner who has experience please participate... If your a parrot that doesn't know.... dont bother please....
Thanks
Kris |
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modok
Samba Member
Joined: October 30, 2009
Posts: 26787
Location: Colorado Springs
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| Posted: Thu May 24, 2018 9:44 pm Post subject: Re: Endplay when warm |
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| At temp, about .001 less |
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overdrive
Samba Member
Joined: November 21, 2016
Posts: 75
Location: Not Sure
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| Posted: Thu May 24, 2018 10:28 pm Post subject: Re: Endplay when warm |
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| krisbeetle wrote: |
If your a parrot that doesn't know.... dont bother please....
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LOL |
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mark tucker
Samba Member
Joined: April 08, 2009
Posts: 23937
Location: SHALIMAR ,FLORIDA
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| Posted: Fri May 25, 2018 12:50 pm Post subject: Re: Endplay when warm |
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| not a real good idea to do that to the heads. but there not mine so..... the aluminum/ mag case and the aluminum bearings expand at diferent rates then the steel/cast crankshaft. also not all parts get hot at the same rate, some come up to temp faster than others.some clearances will open up then come back down some will close up them open. if the case expands before the crank....there go's some your clearance. when crank warms it comes back up some. thus the reason why some people set to tight and grab the bearing. or dont run the fan and the case gets hot and the crank dosent and grabs the bearing... |
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krisbeetle
Samba Member
Joined: September 30, 2005
Posts: 779
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| Posted: Fri May 25, 2018 4:00 pm Post subject: Re: Endplay when warm |
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| modok wrote: |
| At temp, about .001 less |
Thanks modok, was hoping you would chime in |
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krisbeetle
Samba Member
Joined: September 30, 2005
Posts: 779
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| Posted: Fri May 25, 2018 4:07 pm Post subject: Re: Endplay when warm |
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| mark tucker wrote: |
| not a real good idea to do that to the heads. but there not mine so..... the aluminum/ mag case and the aluminum bearings expand at diferent rates then the steel/cast crankshaft. also not all parts get hot at the same rate, some come up to temp faster than others.some clearances will open up then come back down some will close up them open. if the case expands before the crank....there go's some your clearance. when crank warms it comes back up some. thus the reason why some people set to tight and grab the bearing. or dont run the fan and the case gets hot and the crank dosent and grabs the bearing... |
Ohhhh ok, I have never read about that, but makes sense, lesson learned I will get my tin and fan on there.
So if the crank is expanding at a slower rate than case and this could well account for some tightness on the end play due to no fan?
You mention it grabbing the bearing when set to tight, you referring to end play and running with no fan correct? |
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Max Welton
Samba Member
Joined: May 19, 2003
Posts: 10697
Location: Black Forest, CO
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| Posted: Fri May 25, 2018 5:18 pm Post subject: Re: Endplay when warm |
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The case has nothing to do with crankshaft endplay except to hold onto the #1 bearing.
It's just the crankshaft snout passing through the bearing and the shims to meet the flywheel.
Now if the bearing itself warms up and expands enough to take up the available end-play you get friction ... and trouble.
Max
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[email protected]
Samba Member
Joined: August 03, 2002
Posts: 12785
Location: Salt Lake City, Utah
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| Posted: Fri May 25, 2018 6:39 pm Post subject: Re: Endplay when warm |
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The hotter the engine gets, the tighter the end play is. Too hot gets expensive when the bearing grabs the crank, spins and wipes out the case.
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mark tucker
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Joined: April 08, 2009
Posts: 23937
Location: SHALIMAR ,FLORIDA
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| Posted: Sun May 27, 2018 11:17 am Post subject: Re: Endplay when warm |
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| Max Welton wrote: |
The case has nothing to do with crankshaft endplay except to hold onto the #1 bearing.
It's just the crankshaft snout passing through the bearing and the shims to meet the flywheel.
Now if the bearing itself warms up and expands enough to take up the available end-play you get friction ... and trouble.
Max |
so if the case expands...and the crank dosent....what is the bearing going to do shrink? dosent your case transfer heat to and from the bearing? as john said. hot grabs bearings. |
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Danwvw
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Joined: July 31, 2012
Posts: 8892
Location: Oregon Coast
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| Posted: Sun May 27, 2018 12:09 pm Post subject: Re: Endplay when warm |
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I don't know about hotter meaning more end play. I can't even get my crank to move in or out when it's hot? But Cold, in Neutral, At a TDC or BDC it moves in and out a little. Maybe it's just when it is warm it doesn't move? Not sure?
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PumaVW79
Samba Member
Joined: January 31, 2012
Posts: 487
Location: WGS84: 22.9083° S, 43.1964° W
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| Posted: Sun May 27, 2018 6:40 pm Post subject: Re: Endplay when warm |
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| krisbeetle wrote: |
| If your a parrot that doesn't know.... dont bother please.... |
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Max Welton
Samba Member
Joined: May 19, 2003
Posts: 10697
Location: Black Forest, CO
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| Posted: Sun May 27, 2018 8:24 pm Post subject: Re: Endplay when warm |
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| mark tucker wrote: |
| so if the case expands...and the crank dosent....what is the bearing going to do shrink? dosent your case transfer heat to and from the bearing? as john said. hot grabs bearings. |
The bearing is what ... some variety of babbitt?. The coefficient of expansion is pretty close to Mag on this chart. And a fair bit more that steel. So I think the bearing and case material expand at similar rates so they don't bug each other much at all. Probably by design.
http://www.repairengineering.com/coefficient-of-thermal-expansion.html
Crankshaft endplay is determined by the length of the bearing, the length of the crank snout ... and the three shims for fine-tuning the end-play. I think for a given temp increase the bearing grows a little more (in length) than the crank snout does and endplay is decreased.
If end-play was set a bit on the tight side and that bearing runs a little on the hot side ... the crank grabs the bearing and you get trouble with a capital T.
So yeah, I agree with John. Enough heat kills. Also Modoc, endplay reduces as temp increases. I just don't think the case plays a role in how end-play changes.
That's all I'm saying.
PS: It is theoretically possible to set crankshaft endplay using only the crank, the #1 bearing and the flywheel sitting on the bench and not in the case at all. But I've never been able to get consistent enough measurements that way. Maybe I'm just a klutz.
Max
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Under the Knife https://shoptalkforums.com/viewtopic.php?f=24&t=151582
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modok
Samba Member
Joined: October 30, 2009
Posts: 26787
Location: Colorado Springs
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| Posted: Sun May 27, 2018 8:44 pm Post subject: Re: Endplay when warm |
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The bearings are a aluminum/tin alloy.
expansion with heat approx 2-2.5x more than steel |
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