1. You have to remove everything to take the crank out.
2. Do not use force to remove or seat the bearings, the case will not
handle the physical loads and will crack. Instead, use your oven set at 250
degrees for about 20 min. Stand the case up on the real flange and the old
bearing will fall out when warm and tapped on the table (NOT hard enough to
mar the table!). Put the new bearing in the freezer for a few hours before
heating the case so that when the old bearing falls out, you can drop the
new one right in.
Good luck...
Hmm..Saito.... top dead center with the '0' mark on the cam gear at the top
if I recall correctly.
I have seen this technique recommended often. Just tried it and it didn't
work. I turned down a piece of oak to a 5/8 diameter and used it with a
single whack of a persuader to push the bearing out (after removing the
front bearing).
Sometimes it will work if the bearings are not real tight, but many
times it won't.
When you put the engine in the oven it heats the whole engine slowly
and everything heats more evenly , including the bearing. You really
need to heat the case only and very quickly.
I use my Monokote heat gun and go around the case outside the bearing
for three or four minutes.
The aluminum case will then heat quicker and expand more than the
bearing.
Then a sharp rap on a block of wood and the bearing will fall out.
I have used this method many , many times over the years and it's
never failed.
Also , as someone else mentioned , if I remember and have the time ,
I'll put the bearing in the freezer overnight. This will shrink it and
it wall fall in place.
I used to use the heat/freeze method a lot back in my drag racing
engine building days.
Sometimes I will use a propane torch if it's more handy than the
gun. You need to be very careful , however , if you use a torch.
In most cases , just 30 seconds or so of heating is all that is
required if you use the torch.
This works much of the time , but not always , And , I prefer not to
drive anything out of the case.
Ken
<SNIP>
Hi
OT, but many years ago when I was in the British Merchant Navy, we
used your method to remove old bearings from (electric) motors. To
fit the new bearings we heated them in oil so they would expand and
slip over the motor shaft easier (the oil was heated with a propane
torch in an old sawn off metal tin we kept for the purpose).
This worked fine until one day the oil set alight as myself and
another engineer were "boiling" a bearing. We grabbed the nearest CO2
fire extinguisher and in our panic rather stupidly pointed it directly
at the tin of oil; which neatly blasted a couple of pints or so of
burning oil onto the bulkhead where it ran down into the engine room
bilges - still blazing merrily away!!!
Fortunately, the oil went out fairly quickly before the ship set on
fire but we learned a lesson. We never admitted our cock-up to anyone
and were more careful in future, but I still shudder thinking of the
potential consequences - especially as it was a passenger ship halfway
across the Pacific with several hundred passengers on board.
Regards
KGB
Ken
The heat gun approach seems to make sense, If I have the misfortune of
having to do this again I will try it, as, like you, I would prfer not to
use violence on a thin casting.
Ed
wrote:
Marty did expound....
"I keep the torch moving and rap frequently so that I find out as soon as
possible when I've reached the right temp.
Marty"
Not sure how this helps, but could you post the words to the rap for the
edification of the rest of us jive turkeys....
Bill
It be frozen and clankin'
So it's time for yankin'
The bearings within
that let the thing spin.
Hot! Hot! Hot!
Gotta hit the right spot.
Burn blue but true:
If it bend I'm blue.
I don't want it glowin'
That'd be a no-win.
I can't see the heat
but I know the beat.
Marty
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Don't let the piston go up into the cylinder head as the piston ring
will expand and jam it in there. Its OK when assembled but without the
conrod to limit the movement it can go up too far.... So I've been
told.....
snipped-for-privacy@sbcglobal.net writes
I got the new bearings installed and while I wait for my gasket set to
arrive I am trying to figure out how to get the timing gear installed
correctly. I know there is an alignment dot on the gear, but when I try to
lower the cam box onto the crank case it seems that there is no way to
guarantee that the meshing of the gears is exact. It seems to be very easy
to be off by 1 tooth in either direction.
I have seen postings advising to use a push rod or small tool to hold the
gear orientation but I can't figure out how that could work. I see a hole
in one of the cams which appears to be 180 degrees (opposite) from the dot
on the gear that i think the tool should go into but I don't see any
corresponding hole in the cam box cover.
The oil on the gear and seeems to keep it from rotating as I position it so
this may not be a big problem, but I just cant help thinking it may mesh off
1 tooth.
Ed
Like other four strokes, the timing gear assembly and valve installation
command some careful attention. A spot of oil will hold the teflon
spacers in place in the cam gear housing until you put in the timing
shaft. The crankshaft gear has a roll pin between two teeth that mesh
with a marked tooth on the timing gear. After rotating the crankpin to
its highest position (TDC), lay the timing gear on the shaft so their
teeth will mesh in that manner. With a little care, the timing gear
cover will go on without disturbing the teflon spacers. Use an allen
wrench or piece of wire to align the holes of the spacers the gear and
the housing, then insert the timing gear shaft. Tighten the setscrew on
the timing gear shaft. Oil the timing gear mechanism through the valve
lifter holes, and then the lifters can go in. That should complete the
timing gear installation.
HTH, Vance
I guess I am going to have to take the gear and the cams out of the gear
housing. I was hoping to put the whole unit on without taking the cams out.
When I had the crank out I did see the roll pin you mention but I cant seem
to find it now that the the crank is back in the case. I'll look again with
better lighting.
Ed
Also, the gasket set you are waiting for to complete assembly probably
includes new teflon washers/spacers and would be ideal to replace with
new. However, it won't hurt to reuse the old ones if they show no signs
of excessive wear.
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