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viiking Samba Member
Joined: May 10, 2013 Posts: 2666 Location: Sydney Australia
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Posted: Thu Jun 21, 2018 1:34 am Post subject: Tight main bearings |
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When trying to fit new main Kolbenschmidt bearings into my engine, I note that the circular bearings are tight and need a small tap with a rubber mallet to seat into the saddles.
However the split number 2 bearing needs a decent whack to get it seated.
I replaced the bearings like for like for the old ones. The workshop advised I did not need to line bore and provided the replacement bearings.
When removing the old bearings, they come out with a bit of a tug but understandably the new ones are much tighter. So it appears that the saddles are OK. I did measure these with a bore gauge and satisfied myself that they were within spec, but I can't now find the readings.
I attempted to measure the "ovality" of the new split bearing. Not sure if this method introduces too much error or not. I clamped the two bearing halves together with a soft faced clamp. The length measured from the split to split was 65.7 mm i.e. 0.2mm wider than the nominal saddle size (65.5mm - 1st case cut) whereas the diameter of the non-split side was 65.5mm. Measuring the original bearings in the same manner, I got 65.5 which is spot on.
Is this normal i.e. the width at the split is wider and should pull in when the bearing is pushed into the saddle. Or is it possible I have out of specification bearings. |
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Multi69s Samba Member
Joined: January 24, 2006 Posts: 5360 Location: Lefty, CA
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viiking Samba Member
Joined: May 10, 2013 Posts: 2666 Location: Sydney Australia
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Posted: Fri Jun 22, 2018 4:34 pm Post subject: Re: Tight main bearings |
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OK. I've learned something more.
Bearing spread apparently is within the tolerance of 0.2mm. That is, the diameter one way is larger than the saddle diameter.
Bearing spread is there to help hold the bearing in place during assembly and assists in keeping it in place during operation.
Still it appears MUCH tighter than any bearing I have installed before. I will attempt to install the crankshaft, torque up and see if it spins ok. |
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VW_Jimbo Samba Member
Joined: May 22, 2016 Posts: 9880 Location: Huntington Beach, CA
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Posted: Fri Jun 22, 2018 9:41 pm Post subject: Re: Tight main bearings |
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When you bolted the case halves together, what did the bores measure?
And without the bearings installed? _________________ Jimbo
There is never enough time to do it right the first time, but all the time necessary the second time!
TDCTDI wrote: |
Basically, a whole bunch of fuckery to achieve a look. |
67rustavenger wrote: |
GFY's Xevin and VW_Jimbo! |
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viiking Samba Member
Joined: May 10, 2013 Posts: 2666 Location: Sydney Australia
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Posted: Mon Jun 25, 2018 3:09 am Post subject: Re: Tight main bearings |
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I tried to do this with expanding internal telescopic gauges but cannot get an accurate enough reading use those and my external micrometers.
I'm going to try and borrow a proper internal micrometer to get an idea, but given my information I've posted on bearing spread being up to 0.2mm, Im more comfortable now than I was before.
Thanks for all the inputs. |
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Max Welton Samba Member
Joined: May 19, 2003 Posts: 10697 Location: Black Forest, CO
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