crossmember cracks

[llutman at yahoo.com (Lisa Lutman)]

Mine developed 2 cracks that were slowly growing so we
welded them up and they've holding strong for awhile
now. I should get a bar though for some xtra support
though. 

Lisa

 --- "T. Reed" <treed2@wsu.edu> wrote: > So there has
been some talk about crossmember
> cracks.. here is what I
> have to say on the topic:
> 
> My crossmember started cracking about 15 months ago.
> There are five or six
> cracks in all. I designed and built my own bolt-on
> bar, and installed
> it exactly 12 months ago. (I had planned to sell
> copies of the bar to
> interested parties but unfortunately that fell
> through.)
> 
> Since then, no new cracks have appeared and the
> pre-existing cracks have
> not lengthened, according to my measurements and
> photographs. I haven't
> toned down my driving style at all (quite the
> opposite ;) so I feel like
> the bar might be helping things (perhaps not, wtf do
> I know)
> 
> When I get together enough dough for a nice MIG I
> will weld up the cracks,
> brush off the slag and douse 'em with a little paint
> and primer. After
> that it's game over as far as I'm concerned, other
> than the occasional
> checkup.
> 
> Welds, when done properly, are stronger than the
> surrounding metal and I
> am confident that crossmember damage, if caught in
> time, can be adequately
> repaired with welding alone. Although it is
> definitely advisable to add
> some sort of reinforcement.
> 
> I have never welded on a car chassis before (i know,
> i know.. disconnect
> the battery), so I don't know just how big the
> heat-affected zone is. A
> chassis is a pretty big heat sink, but I'm sure the
> paint surrounding the
> weld would be burned off or at least discolored by
> all that heat.
> 
> I've seen several more complicated repairs:
> 
> - cutting a crossmember out of a donor and welding
> it up. probably not as
>   easy as it sounds as the crossmember is spot
> welded and if you seam weld
>   it there are a lot of seams.
> 
> - drilling out the spot welds on the bad
> crossmember, and using small
>   nuts+bolts to install a donor crossmember.
> attractive because no welding
>   is involved, but removing the spot welds would be
> a big pain, as well as
>   installing the bolts. you'd have to be sure the
> bolts aren't going to
>   depart one by one until you engine hits the
> pavement.
> 
> - cutting apart and welding two donor crossmembers
> together in to a
>   "double thick" crossmember. cool, but not very
> practical, and there's
>   the added weight.
> 
> - simply welding a plate where the front motor mount
> attaches. a bad idea
>   imho because it does nothing to strengthen the
> rest of the crossmember;
>   I have cracks rather evenly distributed along the
> whole length
> 
> - welding a bar or tube across the whole front end.
> worthy of
>   consideration but guaranteed to get in the way
> when you want to drop a
>   motor or something like that. personally, i prefer
> a more removable
>   solution.
> 
> Anyway, my recommendation is to weld up the cracks
> and add a removable
> bar. But it depends on what you use the car for,
> really.
> 
> My 2 cents..
> 
> -Toby
> 
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=====
Lisa
Vancouver, BC

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