Cross Member Cracks

0neoffive

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In Tiger Tales I noted Buck's fine article on the common cross member failures. We are quite familiar with them here, as owners ship in their wounded parts & pieces for rehab. We beef up the internal structure a bit in an effort to stave off mother nature and good old wear & tear. Attached is a photo of a couple of strange cracks we've never seen before?:confused:
 

drbill

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In Tiger Tales I noted Buck's fine article on the common cross member failures. We are quite familiar with them here, as owners ship in their wounded parts & pieces for rehab. We beef up the internal structure a bit in an effort to stave off mother nature and good old wear & tear. Attached is a photo of a couple of strange cracks we've never seen before?:confused:

Looks like someone hit a big-azz pot hole. :)
 

65sunbeam

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The cross member failure article didn't mention what caused the cracks that were shown. Is it just old age and normal wear and tear or did wide wheels or stress of track/autocross use cause them? Thanks, Eric
 

0neoffive

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Long Winded Opinings

The cross member failure article didn't mention what caused the cracks that were shown. Is it just old age and normal wear and tear or did wide wheels or stress of track/autocross use cause them? Thanks, Eric

Formed sheet metal still flexes, even though it is fairly well engineered for stress exposure. It also ages and the gauge gets a bit thinner with rust & moisture over the 50 years. One (but not all) of the mods we place internally is a welded- in "stiff back" from the fulcrum mount tabs up to the actual frame mount location which takes a lot of the stresses away from the lower X sheet metal where the A-arms are constantly pushin' & pullin'. This is not as good as those new custom fronts available, but then, most are not doing hard race tracking.
 

67 Tiger

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TIME BOMB

Thats the Headline in the June 1981, Vol. 11, No. 6, Tiger Tales. Written by Herb Mosley, The story is about shock tower failure, which is different than this new artical, but included in the Time Bomb story are three pictures showing popular spots where cracking happens.
View attachment 4572
The areas are highlighted, as you can see the area around the fulcrum pin mounts is a weak spot.
The first photo shows reinforcing welds right were your frame is cracked.
 
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DD (CA)

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Fusion /= strength

perhaps my amateur status will seep through here...

IF these are points of stress where the cracking is taking place, simply adding welds wouldn't seam (sic) to be the solution? It would only add to the rigidity / hardness in the area, no?

I do see (more lately?) some are adding plates to spread the energy over a wider area, this makes sense, IF the ductility remains similar.

Any metallurgists on here?

More simply, the original part failures are known. How about failures in these weld 'reinforced' crossmembers? Any history from those performed around this time of TT tech note publication or later fixes?

(I've a plan to swap out original for a reinforced unit. But may need to reconsider HOW the reinforced unit was prepped.)
 

67 Tiger

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My experence

DD-
In 1982 I had my subframe reinforced by Larry at Weldcraft, just like the article. In 1984 I hit a curb at about 10 or 20 mph. The subframe was removed, taken back to Larry. He checked it over, none of the welds broke or cracked, and the subframe was not bent or tweaked. Thats not saying there was no damage. The lower right a-frame, and fulcrum pin were bent, and the right frame rail, at the arch, just behind where the subframe bolts up was ( still is) bent. Now this is my experence, I have read an article on another Sunbeam website, that claims the Herb Mosley article is way offhttp://teae.org/crossmember-crisis-is-not-that-common/. I have also spoke with a Tiger repair shop that claims they have had to FIX work that Larry messed up. But I have also heard people badmouth THAT shop. The bottom line is subframes need to be inspected and reinforced. How to do it depends on who your talking to.
 
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spmdr

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Yup, they crack

I don't do a LOT of X member repair, BUT, I have only had ONE that I could not SEE SOME cracks in the X-membr.

...And that was a car that was totally stock and owned by an old guy ( not saying much here...:rolleyes:).

It really didn't need to be rebuilt but he was thinking it was time...

This was some time LAST century ( when I was a YOUNGER GUY)!

BTW, powder coating plays HELL with SEEING cracks, as MOST of you know...

DW
 
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