On Sat, 13 Apr 2019 12:59:34 -0500, Terry Coombs
wrote:

On 4/13/2019 12:30 PM, Leon Fisk wrote:
On Sat, 13 Apr 2019 11:50:09 -0500
Terry Coombs wrote:

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...

* Well , it's such a small amount ... this race is a really tight press
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 ...
Modify and repairthe '39 - which you KNOW works