I've seen on thunder racing's website where they list strut tower braces, although I keep hearing they are really shock tower braces, anyways the description says:
Strengthen your front subframe assembly and minimize tower deflection by tying the shock mounts together. Standard model is made with strong 1/4" mounting plates and 1.25" x .095" tubing while the chrome moly version is 1.25" x .065" tubing to insure zero deflection under load.

Am I missing something, how come the "stronger chrome moly" version is thinner metal? Shouldn't that cause it to be weaker?
Bill

 

the thinner chrome moly steel is still stronger then the mild steel one

 

And therefore lighter, too.

 

It depends. If the 4130 (CrMo) has been carefully gas welded (or maybe Tig welded) to 4130 plates so it wasn't annealed, or if the whole brace was heat treated after fabrication (chances are slim to none), AND the mild steel .095 wall was HRW or hot rolled welded tubing, the CrMo might be stronger.

If however, the .095 wall mild steel tube was DOM or drawn over mandrel tubing which is probably 1020-1026 carbon steel, which many if not most good aftermarket tubular products are, the strength is probably very close considering the 46% thicker wall of the mild steel. DOM is quite a bit stronger than plain HRW.

Also if the brace isn't perfectly straight, load from the shock towers will tend to bend it rather than just load it in tension and compression. Here perhaps the extra wall thickness might resist bending loads quite well. Dare I say better than the .065 CrMo? Remember, tubing works best in pure tension/compression loads. Thin wall tubing isn't very good for resisting bending loads.

Now, if there is about 4 feet of tubing in that brace, the .065 wall saves about 30 ounces over the .095. So why do you need 1/4 inch mounting plates with 1/16" (.065) wall tubing? Isn't that a little overkill? A pair of 4 inch square 1/4 inch plates weigh about 18 ounces more than 1/8 in plates.

So, if you used .095 plates and formed them into a shape which matched the area they mounted against and maybe curled the edges a bit to increase strength in bending, you would be about 22 oz. lighter than 1/4 inch plates. These could be cold finished mild steel and the total weight difference from 1/4 in. plates with .065 CrMo tubing to .095 formed plates and .095 DOM tubing would be about 8 ounces. Strength might be a push..or perhaps a little better for the .095 DOM.

FWIW, there is no such thing as "zero deflection under load". How much deflection is the key.

Sometimes hype sells product. This may or may not be the case here.

So how much do 4th gen F-body shock towers actually move anyway?

My highly-opinionated $.02.

 

What does annealed mean?

 

It's a process of changing the properties of a metal (generally through rapid cooling?), so that the result is more rigid (brittle). There is another process that strenghtens metal in a different way that I can't think of.

I may be completely wrong.

 

Better go back and check your definition.
ANNEAL: When not preceded by a descriptive adjective, annealing consists of heating to and holding at a suitable temperature, then allowing to cool slowly. Annealing removes stresses, reduces hardness, increases ductility and produces a structure favorable for formability.