What I want to know is which one is better, mild steel or the 4130 chrome moly. I plan on purchasing a pair from Spohn Performance and was wondering if the 4130 is worth the extra $40. What are some of the advantages and disadvantages of both?? I will be doing some auto X and road tracks too.....

 

Someone correct me if I'm wrong, but I believe that the chrome moly is lighter, but weaker. I think mild steel is a better choice for a daily driven street car.

 

it is lighter, but more BRITAL, not weaker

 

Save your money and get the standard Rear LCA's unless you are going to try and impress people. Like, I have 4130 Chrome Moly LCA's on my car and what do you have??

 

i just installed spohns lca's in mild steel. i thought they are great and pretty light anyways. i'd save the money and buy a set of relocation brackets for the lca's.

 

What are the relocation brackets for? I see people talking about them all the time. Are they needed? I will be installing an Eibach Pro Kit when I do LCA's too.

 

You will absolutely need the reloc brackets if you lower the car and expect to be able to apply any power to the rear wheels. You really already need them, you just don't know yet how bad. Lowering the car makes the design geometry malfunction even worse.

What they correct, is the problem where if you have any power at all, and get the car to hook up at all, the rear end tries to lift itself off the ground; which causes the car to lose traction; which then allows the spring to push the rear end back down toward the ground; which then causes it to get some more traction; which then tries to lift the rear end off the ground, breaking the traction; etc. etc. etc. In other words, wheel hop.

 

Which relocation bracket is better.... the bolt ins or weld ins???

 

weld-in

or you could get bolt-ins and weld them in

they will not stay still if they are only bolted, eventually the holes will wallow out and you'l end up with a couple of extra joints back there that don't belong

 

Are the Spohn chromoly ones heat treated?

 

Ask Spohn if they are..

 

Hey Steve Spohn!! Are your chromoly LCA's heat treated?

 

hahaha!

chrome-moly is lighter and will resist deformation at a higher point than mild steel will. However, steel will bend with a high enough force applied to it (which means it can be bent back). Chrome-moly will shatter with enough force (which means you better save up another $150 to $275 (depending on what LCAs you got from Spohn).

 

Spohn makes the best products I have seen- There are others that are equal in quality, but none better. His chromemoly products are top notch and plenty safe for street use. He uses thick enough moly with state of the art threaded tube ends that countersink and then welded in place. You want the best, buy Spohn's chromemoly products.

 

I have head of people on this board with Chrome-molly LCA’s that broke. I rather have my LCA’s bend then shatter if subject to extreme stress. Just a scary though of something on the rear braking while driving hard it could put you into a tree or light pole.

 

This is how rumors start- "people that have heard of people". Lets hear if it has actually happened.

I personally have had two different mild steel tubular products break on me- The result of two different lets say "crack heads" doing shabby welding without adequate penetration- I have learned what to look for over the years- again Spohn's chromemoly products are very high quality tubing combined with aircraft insert style threaded tube ends then TIG welded- You aren't going to shatter one of these

Funny how the SCCA allows 4130 chromemoly .087 rollbar tubing for safety cages incase the car flips- but of course- SCCA is wrong because it could shatter right? Its a myth! The only trouble with chromemoly is people trying to MIG weld it- the welds are not safe that way.

 

AGood2.8:-
1. So should those getting Spohn LCA's go with the chromemoly as long as cost is not an issue?

2. If you can't MIG weld the chromemoly what do you do? TIG weld? Excuse my ignorance - no welding experience yet.

Thanks.

 

I'm no expert either- I am just going off of racing experience and the expert opinion of a very good friend who happen's to be the "president" of the "sheet metals union". Paul has mention to me a time or two that I should not ever try to MIG any chromemoly- that it is not considered safe, and yes TIG is the way to go. Spohns chromemoly products are lighter weight than his mild steel products, so yes they are better(less unsprung weight.)
Everything I have from Spohn on my vehicle is chromemoly, except the new tubular subframe connecters.

 

Why all the talk about welding, if you are installing the Rear LCA' they do not require welding. so if you install Relocation brackets they can be bolted or welded, and they are not chrome moly.

 

It is essential how the product was manufactured- This basis determines its safety. Don't trust every aftermarket suspension product you see. Trust me, I have personally broken a few and am lucky to be here.

Anything most home mechanic will tackle, usually will be with a MIG welder- most don't have access to a TIG (expensive) so mild steel is best for the do-it-yourself home fabricator (like myself- I installed my own SFC and Relocators-thus they are mild steel.)

 

Chrome Moly comes in many various "conditions". For chassis and suspension components all (at least the ones who know what they're doing, but that's another story) manufacturers use Condition "N" = Normalized. Normalized can be bent, it is not heat treated that shatters when bent.

You guys gotta use a little common sense before you post some of these things If chrome moly shatters, how do we bend a chrome moly roll cage? Our torque arms can be had in chrome moly, and they require bending, etc.

I have NEVER seen or heard of a 4130N component "shattering", isn't gonna happen, especially on an LCA that takes a compression "end to end" load, not a lateral load.

The long story short is that 4130 is right around twice the strength of mild steel. Therefore you can use a lighter wall tube and have the same strength as it's mild steel equivalent.

In other words, you can have a mild steel LCA that weighs 4 pounds, and a chrome moly LCA that weighs 2 pounds, and they both have the same strength.

Due to the composition of 4130, the proper welding method requires the use of an inert shielding gas, that is accomplished with TIG welding (using an Argon shield). 4130 should NEVER be MIG welded.


Steve

 

chromemoly must be properly TIG welded.

the propertys of metal are true... steel bends, chromemoly can shatter..

however, id like to point out that the amount of stress needed to do so is HUGE. and you would not see that normally.. and if the part is overdesigned, you wont see it ever.

 

thanks for all the info and help guys...

 

nm

 

I finally decide to order a set of the 4130 LCA's. I got them in the mail the other day. All I have to say is they are very light and look to be very good quality. I will let you guys know when I finally get them installed. should be a week or two.

 

ok...as a metallurgist, I have to weigh in on this one. We heat treat landing gear for aircraft that are made out of 4130 heat treated. No...not some backyard dude's idea of a plane...commercial ones like Boeing.

Steve is correct that most times 4130 comes in the normalized condition. This is perfect for any forming or machining operations needed.
Heat treated incorrectly, 4130 can become very brittle (known as temper brittleness) if tempered between 350 and 700 degrees F.
However, if it is tempered above 725 degrees, it becomes very tough.

If I was selecting, I'd use 4130, tempered at 1025 degrees F to give me about twice the stiffness as mild steel. At this level, I have NEVER heard of 4130 shattering.

 

I use chrome moly on a lot of differant things and it is not brittle if heat treated correctly. It is a very easy metal to heat treat because it does not require nearly as fast of a quench time as normal mild steel. Look up a TTT diagram if you want for this info... By the way, you can mig chrome moly just not with the standard filler and sheilding gas. People say you can't so that somebody that doesn't understand welding doesn't try it with there normal setup. The only real differance is that mig will cause a bigger heat affected zone. I work in the aerospace industry and alot of our chrome moly is automated mig welded. Most of the rework and repair is tig however because it allows you better control.
Tyler

 

Oh..boy... I used to design and build kart chassis, and we used both kinds of metal. The chromoly won't bend as easily as the mild steel, but in some cases you may want it to flex. The mild steel, when bent will stay bent , the chromoly will try to return to it's original shape. There was an old guy, who's dead now that used to build the best chassis in the world, he would tig them out of chromoly and heat treat them in the chassis jig. I would say that heat treating chromoly is very important after welding to prevent cracking. That being said, most kart chassis today are made out of 4130 and mig welded and recieve no heat treating what so ever. In order to make parts stiffer, I've frozen a tube, then heated a bigger tube, slid them together and welded the ends, this was very strong and light. So, if it was me, and I had a tig welder, I would build the parts out of chromoly and tig them. This makes for a much-much lighter race car, then you can add weight where you need it. With a mild steel cage, the weight is up high in the car, this might work for the drags, but for road racing it stinks. I don't even want to start talking about titanium. Needless to say, I'm a weight freak.

 

Just personal opinion but I think titanium is extremely overated. It is great at 1000degrees + but for normal use it is not much better than some other alloys that are much cheaper or my personal favorite Inconel.

 

Well, yes, titanuim has issues, have you ever tried to straighten a bent shaft made out of titanium? You have to bend it in a press about 6inches to get a minor bend out of it, the stuff really has a memory....never mind, I said I wasn't going to talk about it..

 

Talk about getting off the Subject Post.

 

Yeah... sorry 'bout that.