One of my never-ending projects is the restoration of a '39 Harley . One of
the broken parts is the transmission sprocket cover . It's made of cast iron
, and one of the bolt hole/cover standoff's is broken out . I have machined
a part out of mild steel , and ground out the jagged edges on the cover to
fit . Both pieces will be bolted to the tranny end cover for correct
alignment .
I was planning on brazing it , but am concerned that heat distortion will
be a problem . I'm also concerned about strength , as this cover supports
the throwout bearing for the clutch . I'm limited on arc welding eqpt to a
flux core wire feed (Lincoln Weld Pak) , but the guy at the machine shop
around the corner from work will likely weld it for cheap if I decide to go
that way .

--
Snag aka OSG #1
'76 FLH "Bag Lady"
"A hand shift is a manly shift ."
shamelessly stolen

Terry Coombs wrote:

One of my never-ending projects is the restoration of a '39 Harley . One of
the broken parts is the transmission sprocket cover . It's made of cast iron
, and one of the bolt hole/cover standoff's is broken out . I have machined
a part out of mild steel , and ground out the jagged edges on the cover to
fit . Both pieces will be bolted to the tranny end cover for correct
alignment .
I was planning on brazing it , but am concerned that heat distortion will
be a problem . I'm also concerned about strength , as this cover supports
the throwout bearing for the clutch . I'm limited on arc welding eqpt to a
flux core wire feed (Lincoln Weld Pak) , but the guy at the machine shop
around the corner from work will likely weld it for cheap if I decide to go
that way .

Brazing is really cool, but I would be uncomfortable doing it on a
highly-stressed part. I'm no expert, but if I were left to my own
devices I'd probably make the repair part out of cast and see if I could
find somebody willing to get it hot and weld it with a cast-iron stick
-- or I'd restore that old forge I have out back and do it myself (which
may be worse than just using JB weld, given my welding skills .

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Tim Wescott wrote:
Terry Coombs wrote:

One of my never-ending projects is the restoration of a '39 Harley
. One of the broken parts is the transmission sprocket cover . It's
made of cast iron , and one of the bolt hole/cover standoff's is
broken out . I have machined a part out of mild steel , and ground
out the jagged edges on the cover to fit . Both pieces will be
bolted to the tranny end cover for correct alignment .
I was planning on brazing it , but am concerned that heat
distortion will be a problem . I'm also concerned about strength ,
as this cover supports the throwout bearing for the clutch . I'm
limited on arc welding eqpt to a flux core wire feed (Lincoln Weld
Pak) , but the guy at the machine shop around the corner from work
will likely weld it for cheap if I decide to go that way .

Brazing is really cool, but I would be uncomfortable doing it on a
highly-stressed part.

I brazed the lower kingpins back into my '58 Chevy 4X4 front axle , been
several years and they're still hangin' in there . This part isn't what I'd
call highly stressed , and there are 3 other bolts .

I'm no expert, but if I were left to my own
devices I'd probably make the repair part out of cast

I've never machined cast , but I think I know where there are some old
window balance weights ...

and see if I
could find somebody willing to get it hot and weld it with a
cast-iron stick -- or I'd restore that old forge I have out back and
do it myself (which may be worse than just using JB weld, given my
welding skills .

The problem with getting it hot is that the cover I'm using to align it is
also cast , and is highly machined . It also has a brass bushing
(countershaft , which mounts the kicker arm) and a (loose roller) bearing
race in it for the mainshaft . I have no idea what stresses are in the cover
, and if I warp it , I'm screwed . Parts for this tranny are rare and
expensive .
--
Snag aka OSG #1
'76 FLH "Bag Lady"
"A hand shift is a manly shift ."
shamelessly stolen

Both pieces will be bolted to the tranny end cover for correct
alignment .
I was planning on brazing it , but am concerned that heat distortion
will
be a problem


Why don't you take a piece of flat, 1/2" thick, steel and transfer the
hole pattern to it? This way you can bolt the cover to this piece of
steel and braze it.

Lewis.

If it is cast iron. you need to use a nickel rod. Pre heat the parts
to around 400 deg. in a oven to " boil " out all the oil. Then while
hot weld.

I used this method years ago to make a vega steering box work on my
29 dodge street rod. The oven baking and nickel rod were mentioned
very specificly in all the articals I found on welding cast iron.

The Part has over 200,000 miles on it and has withstood the shocks of
Idaho, Washington, Oregon and worst California roads.

Steve E.




On Sun, 26 Dec 2004 16:30:18 -0600, "Terry Coombs"
wrote:

One of my never-ending projects is the restoration of a '39 Harley . One of
the broken parts is the transmission sprocket cover . It's made of cast iron
, and one of the bolt hole/cover standoff's is broken out . I have machined
a part out of mild steel , and ground out the jagged edges on the cover to
fit . Both pieces will be bolted to the tranny end cover for correct
alignment .
I was planning on brazing it , but am concerned that heat distortion will
be a problem . I'm also concerned about strength , as this cover supports
the throwout bearing for the clutch . I'm limited on arc welding eqpt to a
flux core wire feed (Lincoln Weld Pak) , but the guy at the machine shop
around the corner from work will likely weld it for cheap if I decide to go
that way .

In article ,
Terry Coombs wrote:
Tim Wescott wrote:

[ ... ]

I'm no expert, but if I were left to my own
devices I'd probably make the repair part out of cast

I've never machined cast , but I think I know where there are some old
window balance weights ...

*Don't*! Window counterweights are probably the worst possible
cast iron in existence. Unknown alloy, chilled in casting, full of
carbide inclusions, probably destroy a brazed carbide lathe tool. (At
least it did for me, the one time that I tried to use it for anything
other than as window counterweights.

You might be able to heat it up enough and cool it slowly enough
to make something machinable out of it -- but for something which you
really care about -- buy some good quality cast iron. It is not *that*
expensive.

Good Luck,
DoN.
--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

In article ,
"Terry Coombs" wrote:

The problem with getting it hot is that the cover I'm using to align it is
also cast , and is highly machined . It also has a brass bushing
(countershaft , which mounts the kicker arm) and a (loose roller) bearing
race in it for the mainshaft . I have no idea what stresses are in the cover
, and if I warp it , I'm screwed . Parts for this tranny are rare and
expensive .

What about JB welding it in place, then tack welding it and remove the
JB and finish it off the cover?

--
Free men own guns, slaves don't
www.geocities.com/CapitolHill/5357/

Brazing is really cool, but I would be uncomfortable doing it on a
highly-stressed part.

I brazed the lower kingpins back into my '58 Chevy 4X4 front axle , been
several years and they're still hangin' in there . This part isn't what I'd
call highly stressed , and there are 3 other bolts .

A well-made brazed joint in cast iron can be around 65,000 psi tensile
strength. (Many bicycle parts are brazed, and while bicycles may seem
like toys, a 15 lb bicycle frame can handle a 240-lb rider stomping on
the pedals and bounding over cobblestones.)

If you're looking to minimize heat distortion, I'd take a look at silver
brazing options -- many silver fillers flow when the base metal has
barely reached a dull red glow, less than 1400F.

--
is Joshua Putnam
http://www.phred.org/~josh/
Books for Bicycle Mechanics and Tinkerers:
http://www.phred.org/~josh/bike/bikebooks.html