Scott Donnelly / Journey's End Marina wrote:
> Removed the front splinned hubs this weekend in preparation of bolt on hub
> conversion. Removing the passenger side hub with brake disc, I found that
> the brake dust shield was significantly damaged along the lower most
> portion. Degreasing the stub axle revealed a few small pits/depressions just
> inboard of the threaded end. There was no corrosion of any sort but the stub
> axle did appear to have some machining marks that were not visable on the
> drivers side. I am guessing that at some point in its life, my SV lost its
> passenger side front wheel and ground to a stop on the brake disc, damaging
> the dust shield. Perhaps the axle stub broke and was subsequently rewelded
> as evidenced by the pits and machining marks. The passenger side brake disc
> exhibits no evidence of this theory, however, the driver side disc has a
> flat spot/chunck missing that extended about 1/4" in from the edge.
> Strange... Trying to imagine how this senario could have played out leaves
> me a little perplexed. If the stub axle did in fact break just inboard of
> the threads, wouldn't the brake caliper retain the hub and wheel? Has anyone
> ever heard of front stub axle failure? Most important, could a broken stub
> axle be reliably welded and returned to service?
Scott:
A common cause of catastrophic wheel loss is bearng failure followed by the
overheating and eventual burning-off of the stub axle. You see this quite often
in small-wheel trailers which have been towed at high speed with little
maintenance. However, I haven't seen this often in cars, and the marks you
describe seem to be in the outer bearing area (but failure in this area would
likely tear everything off, if it ocurred at high speed).
In answer to your final question, no reputable licensed weldor would weld any
suspension, brake, or steering parts.
The reason is that it is impossible to heat-treat these parts back to
manufacturer's specs., and without heat-treating, the heat-affected zones in
and beside the weld have a different crystalline structure and residual
stresses that may lead to eventual
failure and possible loss of life. Replacement of these parts is the only safe
option.
Ron Tebo
This archive was generated by hypermail 2b30 : Tue Sep 05 2000 - 10:40:35 CDT