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Big End Bearings for Dummies (longish)



Malcolm, Niall
I think maybe you both are thinking of the main bearing cradle? The main
bearings are what the crank rotates in, the big end bearings are what
connects the crank and the connecting rods. (They are called big ends
because they go at the big end of the con-rod). The 1HD-T uses a main
bearing cradle - i.e. all the seven main bearings have to come apart at
once, the lower half of each bearing being supported by the 'ladder frame'
style cradle.
Big end bearings will always have individual caps. It will make sense when
you take the sump off.
The main bearings are made of similar material to the problematic big end
bearings, but are subjected to lower stresses and involve a lot more work to
change (quite possibly involving taking the engine or transmission out), so
aren't usually changed with the big end bearings.
Niall, you don't have to do the timing belt at the same time, there aren't
any common areas with the BEB job, but many recommend changing the BEB's at
similar intervals to timing belt. If you change the belt, at the very least
inspect the idler and check the free length of the tension spring. Replacing
them will give you peace of mind, as will genuine parts.
Maarten from All American in Holland recommends going one size tighter with
the big end shells, and he has much experience with these. OTOH, some might
argue that any wear will be in the soft bearing shell material, not the
hardened surface of the crank, and so the size indicated by the original
markings on the con-rod and cap should be used. Also that reducing clearance
will reduce oil flow and hence cooling. (Bearings getting too hot due to
overly viscous oils may have been part of the original problem).
AFAIK Milners only supply one size of bearing shell for the big ends. If
this is the right size you're ok, if not you might be storing up future
Getting the sump off and cleaning the old sealant off it is the hardest part
of this job, otherwise it should be quite plain sailing.
Sorry for the essay,
All the best,


Serious food for thought and further research on the sizing......

Bingo if the numbers match with Milners.


I wrote it but can't believe I did "some engines have a single piece bearing
cradle as opposed to
the individual big end bearing caps" sure would add to the rigidity - stop
the whole crank spinning!
Yes I meant the bearing cradle replaces the individual main bearing caps,
sorry didn't engage both cells that make up my brain.
Malcolm Bagley
Stafford UK
FJ45 '75 & FJ45 '76
-----Original Message-----
From: [Email address removed] [mailto:[Email address removed]] On
Behalf Of Toby Welburn
Sent: 17 April 2007 17:45
To: [Email address removed]
Subject: RE: [ELCO] Big End Bearings for Dummies (longish)
Malcolm, Niall
I think maybe you both are thinking of the main bearing cradle? The main
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