It was oh so well fitted in the '39 tranny case ... the main clutch
gear/thrust bearing race . Had a perfect fit , rolled smoothly ,
everything was going oh so well . But then I found a 1940 trans that was
pretty much complete , and a lot of the parts were in better shape than
the '39 trans I had . Two factors influenced my decision to swap to the
'40 case , there's a (non-critical) piece broken off the '39 , and the
'40 has a spring loaded ball and detent system to lock the shifter drum
. So I pressed the race out of the '39 case and into the '40 . And all
at once the rollers didn't fit so well . Clutch gear wants to walk into
the case when rotated one way , out of it when turned the other . Turns
out the hole in the case is egg shaped , .0015" wider than it is tall .
So here's the question : I want to set the case up in the milling
machine and use my boring head to make it round . This will take about
.00075" from the top and bottom , and I'm worried I won't have as tight
a press fit as I think is needed . So I'm wondering if using a Loctite
sleeve retaining compound will be acceptable to keep things stationary .
Having that race spin in the case would be a Very Bad Thing ... My other
option , is to repair the '39 case and re-machine the shift cam plunger
hole to accept the '40 spring plunger assembly . Shift cams are the same
except for the locking area and will swap . I'm finally getting to a
point that I have room to work on at least the sub-assemblies to get
this bike back on the road . I'm not worried about "ruining" original
parts , this bike is a mutt anyway and a modified part that I can use
beats a broken part any day .
Could you build the worn egg-shape area up via TIG and then machine to
proper size? Even if not perfect it would give you solid material on
four sides for the press fit and maybe some loctite too for insurance...
fit now , and I'm hoping that it will still be tight enough after
rounding the hole out . A thou and a half split between the sides leaves
a mighty fine cut . A couple of things concern me about the build up and
re-machine approach . Well , actually 3 things . Finding zero on the
hole , this thing has to be dead nuts . Welding on an 80 year old
casting in a critical area - it's gotta have some oil soaked in and that
means weld grind weld grind repeat until you get a clean repair ,
welding will also draw whatever temper that casting has , again in a
critical area . Whatever I end up doing , pulling the race and miking
that hole to make sure I'm right is the first step . If the hole is
actually round that means the other one ain't . That's not likely , the
race was ground in the lathe while gripped lightly and ran well after
installation . Just a very light touch-up to clean up the bearing
surface . It ain't likely I'll get to this very soon , just want to have
a plan when I do start . Then there's the crankshaft rebuild ... got new
bearings and crank pin , by the time I'm done the motor and trans will
be completely rebuilt . Now if I could find a set of hi-perf cams for a
45 Flathead ...
father got this bike in 1952 and it had a broken countershaft in the
trans . As far as I know he never even fired it up much less rode it .
It sat around in Grandad's chicken coop (half was storage) until 1965 ,
when Dad pulled the trans and had a countershaft made - somebody in the
machine shops at Hill AFB musta owed him a favor or six . But alas , he
never put the bike back together . And so when he passed in 1998 I put
all the pieces in a trailer and hauled it home to Memphis from Utah .
I've been collecting parts since I got it , very little left to buy now
, just gotta put it all together . And it looks like in the fairly near
future I'll have room to work on it . If I had a bucket list , getting
this machine back on the road would be at the top .
"It was oh so well fitted in the '39 tranny case ... the main clutch
gear/thrust bearing race . Had a perfect fit , rolled smoothly ,
everything was going oh so well "
This is what I meant by "you know it works"
The parts fit and turn as designed.
Loctite, the correct part number and used properly, will hold the race
in place. It can even help centralize the race in the hole because the
Loctite will try to form an even film on the race and bore surfaces.
Loctite has developed many new retaining compounds since I first
started using the stuff over 40 years ago. They now make at least one
retaining compound that works very well on bronzes. I have been using
#638 for the last few years when the parts are made from steel alloys.
You should check their website to see which compound is best for steel
the guys there suggested line lapping it ... that may well be how it was
originally fitted in 1939 , I don't know . But that would definitely
make sure alignment was spot-on . Several years ago when I discovered
this problem I started to make an adjustable lap system , several sizes
since other stuff may also need to be lapped in place . I abandoned that
project because my skills at that time were not up to the task I set for
myself - accuracy wasn't even close to the precision called for . I'm a
better machinist now , and have decided on a different approach to
making laps for these bearing races . I'll still use the same mandrel
and the slugs I was going to use , but I'll machine them smaller then
cast a "skin" of maybe lead but more likely wheel weight alloy which
will then be machined to the size I need . I've been out in the shop
today working on that original lap system , checking it out and cleaning
things up . The center drilled in the drive end ain't centered , but
dialed in with the 4 jaw chuck and supported with a live center at the
other end it has way less than a thou runout . I'll cast a couple of
laps and see how that goes , but I'm pretty sure this is the way I'll go
with this .
I guess I don't understand what you are trying to do. I thought you
had a bore that was out of round and so a bearing race would walk out
of it. Are you just going to lap to roundness instead of bore to
roundness? Once you do have the bore the way you want it will you
still need to Loctite the bearing race in? Or bush and then press the
race in? I don't know anything about Harley transmission cases and
where the bearings are located.
pressed into the left side of the transmission case , it carries the
clutch gear (main input shaft to trans , carries the clutch on the
outside) and thrust for the clutch . When this race was pressed into
another case I have the bearings rolled perfectly - these are loose
rollers with retaining washers on both ends . In the case it is
currently pressed into , it ain't workin' so well . The race now
measures .0015" larger horizontally than it is tall - it's oval now .
What we're talking about lapping is the inside diameter of the race , to
make it round IN THIS ORIENTATION in the case . If it's R&R'ed it will
have to be indexed to the exact same orientation . Or I can make the
hole it's pressed into round . Six of one , half a dozen of the other .
I can go either way with what I have on hand except for loctite sleeve
retaining stuff .
OK, now I think I see what you are trying to do. If the race is
pressed into an out of round hole and then takes on this out of
roundness condition the ID of the race will be out of round. Then if
you lap the ID of the race roundness is then restored.
If the race is lapped into roundness it will now be a larger
diameter. Is this OK? The rollers will now be able skid. Maybe they
could in the original configuration. I don't know how the bearing was
If the race is lapped round after pressing it in is there a
possibility of the race moving in the bore? That would be bad. How
much of a press fit is the race in the bore?
It seems to me that the shaft that rotates in this bearing will
rattle around if the race is lapped oversize. That would bother me.
Maybe I should look online at Harley transmission cases. Maybe there's
a good drawing or two showing how everything works.
As an aside, today I had to remove the distributor from my 1939
Ford 9N tractor. To adjust the points. Sheesh! At least the
distributor drive slot is off center so that it only goes on one way.
Still, needing to remove the distributor to adjust the points???
oversize rollers for just that . I don't recall for sure but I think the
rollers in there now are stock or .0004" oversize . Yup , that's four
tenths . Not much chance of a roller skating as long as I get the
clearances right . As it is now the race is a tight press fit , I just
remember it was fun getting it in without a press . Nuts and bolts and
washers and sleeves will work , but not that easy .
These rollers are available in steps of 0.0002" in dia.
After the bearing race has been lapped rollers are
tested for fit looking for a plug fit. At this plug fit
is no clearance so they are removed and the next
smaller size is used. Be sure not to mix up the rollers,
keep them separate! As you mentioned earlier the
shaft will behave erractically if the rollers are a plug