Adam2001WS6

iTrader: (1)

When it comes to suspension, is chromoly the way to go hands down? Is there ever an advantage to going steel over chromoly? Is the only difference in the strength of the piece and weight reduction?

Sam Strano

iTrader: (41)

Price is the advantage mild has over CM. And CM is not actually lighter for a given amount. The trick is when a part uses thinner wall CM tubing vs. thicker wall mild steel--that's where the weight savings comes from, it's not because CM is just lighter than mild steel.

There are some places I like CM, and some places it's often a waste of money IMHO. And that generally comes down to the amount of weight saved and the use of the car.

And yes, I sell chassis and suspension parts in both versions, mostly from UMI, but we have a few other suppliers as well.

Adam2001WS6

iTrader: (1)

For a DD that is used aggressively on the street, where would you recommend steel? CM?

I want a strut tower, SFCs, Springs and Shocks... not necessarily in that order, but the strut tower is definitely first on the list as it is the least expensive and easiest to install.

Sam Strano

iTrader: (41)

Again, hard to say because different things happen in different places. On a STB, it's $20 difference for CM over Mild. On that part there is no difference in weight as the same size tube is used. But because CM is tougher, it'd be a little stronger. I don't think it'd matter at all in that position on the car myself, but some folks want what they want, and others might say $20 something a bit stronger is worth it.

If you CM on the SFC's you save a bit @ 2-4 pounds depending on what type of SFC's you get. I'd say mild on those. I can't really say where you should and where you shouldn't, neither is wrong, just different.

I'd recommend springs and shocks over SFC's and STB though, they matter to how the car drives a lot more. And I'd do SFC's over a STB as well, but we have our CSP setups that combine SFC's and STB's at a bit of a discount if you were looking to buy them together.

2FAST4U

From what I read CM is stronger due to a "memory" in the steel is flexes more than Mild steel.

The way I looked at is I was upgrading for a performance so if it is only a few buck did it. I bought even upgrade available so got a huge discount.
K-member,arms upper and lower,sways,STB,SFC,Control arms,Koni, springs,Tq arm,PHB upper,PHB lower, Trans member.

CW00BlackTA

iTrader: (31)

Chrome-moly is stonger than mild steel because it has chromium and molybdenum added as alloying elements. These change the microstructure of the steel making it stronger. Like Sam said, it only makes a difference if the piece you are looking at was designed with the strength advantage in mind (i.e. thinner tube walls).

Adam2001WS6

iTrader: (1)

So... thinner tube walls = stronger?

2FAST4U

Yes...LOL

If the material is stronger. then you can go thiner and save weight but have same durablity.

I did the math once years ago on my cage and with all that metal it save a good amount.

Adam2001WS6

iTrader: (1)

Well then I have to ask, what's the difference in strength and durability between the box and tubular designs?

Sam Strano

iTrader: (41)

You get varying opinions..... I don't know you'll get a consensus.

Big Bird WS6

iTrader: (9)

cm sucks. if you order cm make sure the company only welded it once. if it has to weld passes on it in the same please it makes it britle. ( and so every one doesn't yell or say i am stupid) look it up. Chormoly can't take as much heat as mild. it is gets britle. this is why everyone tig welds. to control heat better. i have seen a chromoly set break on a hard launch. after looking them over. the heat signs were all messed up so it was determind that it had to weld passes.

Sam Strano

iTrader: (41)

I don't think you'll be anyone who knows about these things arguing with you. And yes, if the welder does not know what he's doing you can have problems.... but that goes for mild steel too. A poor welding operation is a poor welding operation. Yes, CM is more labor intensive to weld and fwiw, that's part of why it costs more it's not just material costs.

But to say that all CM parts are "junk" because you've seen some bad welds isn't really accurate. In fact my car was in an accident in 2006, and it messed some stuff up really, REALLY badly including my CM PHB from UMI. It bent (but then so did the axle housing, and a wheel was snapped off), but the welds were perfect.

I do think that mild steel is a better value simply because you don't often save a lot of weight in the grand scheme with CM, but it's not "junk" unless someone messed up the welding. And I can tell you that in UMI's case at least, welders that mess up don't stay employed there.

CW00BlackTA

iTrader: (31)

Yes, that's another story. Chrome-moly steels develop higher strength only when heat treated properly. When you weld it you lose most of the strength benefit unless you heat treat the welded piece afterwards--which isn't always practical (think of a roll cage). The design has to take this into account or parts fail prematurely.

Black02SLPSS

iTrader: (5)

That is true, but with respect to that if the welder did a good job and the weld has proper penetration into the base metal, the base metal around the weld should fail before the weld fails.

99345hp

I dont mean to steal this thread, but does anyone know the percent of chromoly the suspension pieces are? At work we weld pipe that has many different percentages of chromoly in them. Just curious.

Black02SLPSS

iTrader: (5)

I would think that question needs to be directed to the suspension manufacturers

01CaMMMaro

iTrader: (25)

im a mechanical engineering student and have one semester of welding experience... ill weld it for you for free haha but expecet it to snap off

Adam2001WS6

iTrader: (1)

Sam -- I would definitely purchase a spring and shock package from you... however, I'm budgetting pretty hard right now. I'm doing the brakes first, then doing a full tune up... suspension next Hopefully within the next few weeks... I'll be in touch for sure!

Adam2001WS6

iTrader: (1)

Back to the box vs. tubular design though.... is there any truth to the corners of the box shaped SFCs acting as "stress risers"? Whereas the round tubes have no such areas preventing the possibility of bending?

Adam2001WS6

iTrader: (1)

Sam? Anyone?