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Main Bearing Replacement

Posted: Sun Mar 11, 2012 10:03 am
by 1949E27N
Hi, Well I think I may have found out what was causing the knock in the E27N.
The Centre Main Bearing appears to be broken???
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It just appears to be breaking away, you can see the edges in the photos.
It only appears to the be the centre bearing however.
I am the first to admit I actually have no idea about any of this but am really enjoying learning.
Maybe it's only the edges protruding which are breaking away, I haven't removed the bearing cap yet to see what's going on.
Is there anything I need to look out for by removing the bearing caps?
What can be done to replace the bearing as I believe they are poured and not slippers? I heard of guys making aluminium slippers and "pinning" them in. This certainly is not a job for myself however...
Any help/advice is very much appreciated.
Thanks in advance guys.
Chris

Re: Main Bearing Replacement

Posted: Sun Mar 11, 2012 3:19 pm
by Dandy Dave
Looks like you will need to have it rebabbitted. All the mains should be done at the same time. The bearing you are showing looks like the thrust bearing that keeps the crankshaft in place. (IE, Keeps the crank shaft pulley and flywheel from moving in and out in a forward to rear motion.) Popping the clutch repeatedly will hammer the babbit apart after a time. I think the only thing at this point you need to worry about removing the bearing cap is pieces of the failed bearing dropping in your eyes. To do this job right, the engine will need to come apart and all the oil galleys cleaned. And also have the crank checked for cracks. Dandy Dave!

Re: Main Bearing Replacement

Posted: Tue Mar 13, 2012 9:33 am
by moretoot
Hi Chris,
The rear main bearing is used as the 'thrust' bearing controlling crankshaft end float which should be no more than .010". Note the rear main cannot be removed for adjustment without removing the flywheel. Warning it can cause the crankshaft to break if the front two bearings are adjusted without the rear also being done.

If it were mine I remove your centre main cap to see if the white metal has detached itself from the engine block / bearing cap. Do note which way round the cap is and note the position of any shims present. Once the condition is known you can decide what to do next.

Regards Moretoot