[SEL] remetaling brass bearings LONG

[Russell Gilbert]

Howdy folks; some time back I posed the question of just simply 
building up the brass bearings for my graham with white metal (like 
building up with solder) instead of making whole new brass bearings. 
These are quite large bearings and would be quite expensive to 
reproduce in brass/bronze. With very little ware really it seemed 
like an option to just fill/coat the bearings with about a 1 to 2mm 
thickness if white metal and machine them to the correct thickness 
and replace etc. Well this has now been done and I have to say I'm 
very pleased with the results.   ......................................
......................... HOWEVER!

There is no such thing as simple!  from the start. On the firing 
stroke of the engine one could see a "jump" (if you like) in the 
crank and flywheel on the side shaft side of the engine when running. 
This made me check the bearings out to find that on the side shaft 
side, one could quite easily stick a credit card into the gap found 
between the top eage of the bottom bearing and crank shaft.  When I 
removed the bearing cap and top bearing from the opposite side all 
looked pretty good.  So time to remove the bearings. When cleaned up 
I could see where a distinctive ware mark in the troublesome bearing 
(bottom half) had been made. So this area was to get a little more 
white metal than the rest. The other 3 bearing peices looked pretty 
good so off to dads place for the big white metal soldering job to be 
done. I left the bearing with dad as I had to work etc. Anyway dad 
called to let me know the job went pretty good. He had a little bit 
of mucking about to get the white metal to stick to the brass; a 
little more heat and soldering flux got it done. The soldering iron 
hot and some extra heat to the bearing and all looked like it was 
going well. A nice looking coating of white metal had gone on the 
bearings apart from one which had a slight crusty apearence to it 
which we think is from getting just a little too hot.
this link is to show a pic of what they now looked like :
http://home-and-garden.webshots.com/photo/2621978930036399874BmBbHr

Well being more than happy at this point I took my bearings around to 
a mates place for machining. We fixed the bearings together with hose 
clamps and placed into the lathe and used a michrometer to get them 
centred best we could. All going well so started to machine 
them.  This was pretty easy; however it was a bit of a shock really 
to see that there was simply just not enough white metal in there to 
machine out.
This link you can see clean white metal and plenty of pitting where 
it is shallow:
http://home-and-garden.webshots.com/photo/2530864950036399874qhfQqN

This next link shows the first bearing (side shaft side) after 
machining. The top section come up pretty well but the bottom half is 
in need of the soldering doctor once again.
http://home-and-garden.webshots.com/photo/2556790590036399874vdJrao

Well to the next side; it was not until know that I had even pick up 
the fact that when these two bits were placed together they were not 
anywhere near close to being round! There didn't seem to be any cause 
for alarm before removing them so I never studdied them before all 
this work started. Well I recon this was the main cause for the ware 
in the other side.  Two problems! Firstly at some stage the top shell 
has had a huge amount of machining done to the sides of the bearing 
to help bring it down tighter onto the crank shaft! Why would this be 
needed? Well theres the second problem, you can see in the pics that 
the bottom of the bottom bearing is worn somewhere in the tune of 
3mm. I can tell you now that the coating of white metal dad placed 
onto these two shells was going to go know where near close enough to 
fill these holes!
This pic shows the gap needing to be filled again; the cliper shows 
the difference in wall thickness from the bottom of the crankshaft 
bearing to the bottom of the other side!
http://home-and-garden.webshots.com/photo/2052053360036399874eRzuDB
In that pic you can also see that the top white metal is not to bad 
but the bottom was hardly touched during machining

this next pic shows the shims thickness (4mm) need to get the outside 
of the bearing round again. You can visually see the difference in 
wall thickness from the top to the bottom of the bearing.
http://home-and-garden.webshots.com/photo/2773022770036399874vEZdXM

So back to dads for the second filling. This was now much harder to 
do than the first time because of the amount of metal/thickness 
needed. We had trouble keeping the white metal that we built up 
enough to stay put as we moved alone to put more in. It would be fair 
to say that IF! .... at the start I had picked up that the amount of 
metal need to fill this bearing  was going to be as needed; I would 
have tried my hand at pouring it in after setting it up with a wooden 
shaft etc through the middle. Anyway this was not done. We had to go 
onto using the oxy to concertrate our heat onto a smaller area 
allowing more control to a smaller working area. No soldering iron 
but just the stick of white metal melting and poking it into place.

All looked well so back to gregs place for another machining. Very 
pleasing result this time around. The bearings do have some minor 
pitting hear and there but overall very neat. (the pitting will hold 
oil anyway right  :-o ) The engine is now back together and ready for 
the Junction Rally in a few weeks time. It runs much smoother now, No 
jumping of the shaft and know knocking because of this problem 
also.   So there you go; ............. We learn't something here I 
recon. Would I do the same thing again? Most deffinately! The result 
is great. Advice; check the bearing out properly for ware before 
making the decission to build up or poor the white metal.
cheers, Russell





Russell Gilbert
Sunny Sunraysia
russell at ncable.com.au
http://community.webshots.com/user/russellsrelics