On Wed, 15 Jul 2015 14:06:59 -0500, "Terry Coombs"
wrote:

wrote:
On Tue, 14 Jul 2015 21:30:30 -0500, "Terry Coombs"
wrote:

also posted at sejw

OK , here's what I have :
A good friend runs a car resto business , and he's working on a
Ford T I think it is . Single transverse spring , ladder bars , and
aftermarket bracketry welded to a Ford 9" rear axle housing . They
pulled it to move one of the transverse spring mounts inboard to
clear brake hardware - the mounts were NOT centering the axle under
the car . What they found was a real mess , stress cracks in the
axle tubes , holes burned thru and leaking oil . The welds look like
they were made by a monkey on crack , just gobbed on . My plan is to
grind out the cracks 90% of the thickness of the tubes , with stop
holes drilled at the ends . Grind off the ****ty welds on the
brackets , leave the few that look decent there but feather the
ends . I want to TIG this thing , because the MIG isn't big enough
and because I'm not that good with a stick . I have on hand
308/309/312 and ER70S2 TIG fillers and 6011/6013/7018 in rod . The
axle housing and brackets are mild steel . The arc rods are going to
be a bit big for filling the cracks but they might be the best
choice for re-welding the brackets . I'm looking for
recommendations on what to use where . Oh , and the reason for the
stress cracks - they're all near the end of the bracket welds - is
because of the ladder bar attachments to the frame . Bolted to a tab
that was bolted with a single bolt to the frame - they moved under
accel/decel , and this sled has a motor that has been "modified" ...
a lot . I plan to recommend some mods to tie that axle down a lot
better .

--
Snag

Greetings Terry,
If it was me I would TIG the thing. Are the axles going to be in the
housing when the welding is being done? If so it will be harder to
keep oil from trying to get back into the crack. If you can remove the
axles then you should be able to use brake cleaner to wash the oil out
of the crack and from the surrounding area before welding. I would
wash the crackmout, then grind, then wash again. I would use the 70S2
rod or the 308SS rod. The 308 will be a little more ductile than the
70S2. I wouldn't bother with stick or MIG. Tif will probably be a
little more work to get it clean enough for a good weld but you will
know that it is a good weld when you are done.
Eric

It's stripped to the bare housing , and has been "degreased" with a
water-based solution . It's actually pretty clean except what's trapped in
the cracks and in the porous welds . If I use a brake cleaner it'll be a
non-chlorinated one , I've read about the potential to produce phosgene gas
under the right conditions . More likely I'll use carb spray as someone
upthread suggested .
I use both types of brake cleaner Terry. The non-chlorinated stuff
mostly but the chlorinated stuff when cleaning for Loctite. The
chlorinated stuff can indeed create phosgene gas when passed through a
flame and I am very careful to avoid that. Always have been. I like
brake cleaner netter than carb cleaner for weld zone cleaning because
it leaves no residue. Grind out the cracks and porosity, clean with
the flammable brake cleaner as a final clean, heat before welding to
drive off any water or cleaners, and weld. One thing I like about TIG
is that if there is any dirt in the weld zone you can tell right away.
Then the metal can be cleaned properly and welding can start again.
Eric