If split-pins/cotter-pins are PROPERLY installed they will not fail in use,
but I have seen a number of instances where split-pins not properly
installed have in fact failed.
In my experience, there are a number of mechanics and amateurs who do not
know the correct way of installing a split-pin.
It is fundamental that you always use NEW split-pins, and you never try to
reuse split-pins that have been previously used or are damaged in any way.
You must use the correct diameter split-pin, as a split-pin of a smaller
diameter than intended is more likely to fail, and this can now be a problem
in countries such as Australia where we now buy primarily metric-size split
pins to use in our imperial sized XKs. (I purchased a large supply of new
split-pins in from USA where imperial sizes still dominate)
Then the actual installation must be as per “Rolls Royce” method (a term I
have heard a couple times - not sure what basis is) where the split pin is
inserted in side-ways (and not flat) such that the head of the split-pin
nests totally within the slotted-nuts SLOT up against the hole in the bolt.
The short leg is bent down axially along the flat of the hexagon nut to be a
snug fit, and if too long a split-pin has been used the excess length can be
cut to size, although a small amount of diagonal-wedging of leg is useful.
The longer leg is bent back over the end of the bolt and again bent to
position snugly.
Once a correct size split-pin is installed correctly there should be no
looseness evident in the split pin.
The WRONG way to fit a split pin is to have the head sitting flat, and on
the outside of the slotted-nut slot, with the two legs bent exiting and
being bent around the sides of the hexagon nut.
A correct size split pin, installed correctly will not fail nor cause any
problems.
Roger Payne - XK140MC OTS; E-Type 4.2 S.1 OTS; DSV8.
Canberra.-----Original Message-----
From: owner-xk@jag-lovers.org [mailto:owner-xk@jag-lovers.org] On Behalf Of
D J
Sent: Tuesday, 20 May 2008 9:30 AM
To: xk@jag-lovers.org
Subject: Re: [xk] piston rods and cotter keys
It’s been a while since I looked inside an XK engine. I’m assuming
that ‘cotter key’ is american english for what we call a ‘split pin’?
If that is correct you use them once only. I’ve never seen the legs
break off in use, only when you straighten them out to remove them,
and I’m drawing on 40 years experience.
Next ,and this is where my memory may let me down, on the end off the
oil pump pick up pipe I’m fairly sure there is a gauze filter unless
I’m confused.
If this is the case, I cannot see the split pin legs getting through
it into the pump.
DJ
On 19 May 2008, at 14:02, MikeSpoelker wrote:
In reply to a message from Ellis sent Sun 18 May 2008:
Ellis,
Your experience is not unusual. I’ve found too many of them in
pieces in the bottom of the sump. On ocassion, I find bits of them
ingested in the oil pump, where they cause much damage and flood
the engine with metal shavings to boot. There is really no good
engineering reason to use them. The installation of the pin
generally requires you to either under or over torque the bolt so
that the slots and the holes line up so you can fit the pin. What
sense does that make??? Not good on a threaded fastener that is
loaded almost purely in tension. In my opinion, they are
worthless, or worse, on a properly torqued threaded fastener. I
find the pins less objectionable on suspension bolts where the
applied loads are in shear. There the installed torque is not
critical, so a little loose to line up the slot-hole is no
potential issue.
Personally, I don’t use the cotter pins. Either use the later 4.2
nuts and bolts, which did away with them, or use GOOD (ARP or such)
aftermarket fasteners. And DO NOT be tempted to use a chemical
locker or nylon insert nut on a connecting rod bolt. Both are just
bad practice on conn-rods.
Regards,
The original message included these comments:
I pulled the sump on my 3.8 150 yesterday and to my dismay found
bits of
cotter keys in the sump. One nut on the #1’s bearing cap had no
trace of
Ellis
–
Mike Spoelker 672027
Louisville, KY, United States
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