Magician

I'm about to buy a set of rear control arms and a panhard bar from Spohn.

I'm trying to figure out if I should go for the Chrome Moly or Mild Steel. My car is only used as a daily driver. I want it to look good and have good parts, but I don't want to spend alot of money on things that aren't really needed for my application.

I know chrome moly is better but, i always thought it was better suited for racers or performance junkies.

How should I pick?

colonboy14

iTrader: (7)

Get the mild steel. It's cheaper and only a little heavier. It's more forgiving on a daily driver than moly, as well.

grafx

what do you mean more forgiving??

colonboy14

iTrader: (7)

I'm no expert, but I've asked this question before, and what I've been told is that the MS is softer, so it "absorbs" vibrations and impacts and stuff. If you wail on it hard enough, it will bend. CM, on the other hand, is very stiff, so they can use a thinner wall tubing (light weight). But because it is so stiff, it will crack with vibration and impact. (Probably not under normal driving, but it could). If you stress it too much, it will break, not bend like MS.

I know this isn't very technical, and someone else can give a better explanation, but that's a summary of how it works.

Kandied91z

iTrader: (7)

before i turned my car into a showcar weekend cruiser i had all kenny brown chromoly pieces underneath.. going 5 years strong and over 60,000 miles with no show of wear.

which is better? i think it's preference or in reality a luxury more then necessity of choice. i put chromoly everything on the last car from the cage to all tubular suspension to save weight. that way i could have a car with full stereo and large wheels still be lighter then stock. everything worked well for me but i paid a bit more.... particularly now with the metal being even more expensive the parts are pricey.

one or two piece aren't going to be worth much however it all of your suspension is that's a different story. would i buy chromoly again... you bet but only if budget wasn't a concern.

vsixtoy

This is a fact and should be a debate ender. Race cars rely on Chromoly roll cages for safety and lightness to retain power to weight ratios for competition.

Those race cars are stringently inspected and certified that the cages are fabricated up to par 'OR' the car is denied entry in its Logbook.

As long as the Chromemoly is TIG welded and is a specific wall size for its use, it is preferable over mild steel by far.

Spohn builds his Chromoly pieces to meet and exceed those type of requirements that are present in racing safety. His products are extremely strong and extremely durable over years of use.

I have CM everything on my car from him and I based that decission to by them on inspection of his quality before I ever bought anything from him- I am not just saying this after the fact because I have his products and am bias- He is the best out there.

Ever see a roadrace car with a chromemoly roll cage flipover at 100+mph and grind on the tubing all the way down a straightaway- BUT NOT SHATTER- I know I have lots of times, and you have too.

Go Chromemoly, the little extra cost is worth it. Lightness of suspension parts is what makes a car ride well.

vsixtoy

This is Mild steel (Off a truck , not F-body) and I have news for you- His twin brother bent and broke because the guy that welded in was on crack. Its not the metal, its the fabricator you need to be worried about. Spohn does CM properly, most don't even do mild steel correctly. And from what I've seen, I will boldly say that a few of those names come up around here sometimes.

Look at the welds on this A-arm were the tubing meets the ears (mounts). looks fine don't they- "looks" is the key word. magnaflux this thing and you will see lack of penetration on some of the welds, thats why the other side broke.

cali92RS

I think the misconception is that just because chromemoly is lighter than steel, its not as strong.
There is a reason chromemoly is as pricey as it is, its both light AND strong.

Kandied91z

iTrader: (7)

yes but for some teenager just looking to get some better performance out of the car it isn't necessary. it's a wasted expense in that case. for someone building a car to race or whom plans to keep like the rest of us it's a valuable investment.

oil pan 4

iTrader: (1)

Hey vsixtoy can you post a pic of the under side of that LCA?

CrazyHawaiian

I'd say if weight is a concern (as in you race the car) then go with the CM. Especially if its unsprung weight. If you dont race the car then you might as well save some $$ and go with MS. Both work good. Just one is lighter then the other and costs more hehe.

vsixtoy

??? I stated above its not a 3rdgen arm. Its either stuffed in a box somewhere or I threw it out a few years back- most likely threw it out since I no longer have the matching other side.

USA_Rally

I agree, I would go with chromemoly if you can afford it.

laiky

for those who don't know, chromoly is the standard in the aircraft industry. this is because it is stronger than mild steel and has good properties as far as toughness and fatigue resistance. It requires more in the way of welding though as improper welding processes will cause it to harden and crack. It should be TIG welded and at least slightly preheated to eliminate moisture. That is the minimum required for a good weld. In more critical apps the requirments are much higher. The point is its more expensive because its a higher quality alloy, and is harder to work with. It is lighter because pound for pound it is stronger.

It is purely a money issue for a street car. Not necessary but nice!!


on a side note: those running the spohn dual spherical LCA'S, what kind of life do you get out of the ends? My car is a toy now, and sees few miles

slowTA

iTrader: (1)

T6 aluminum.... light and strong.

http://www.jonaadland.com/Z28/Mods/L...minumLCAs.html

But if you want to use rubber or poly bushings then I'm not sure what your best option would be. I can say that some people who REALLY abuse their cars avoid chromemoly unless they KNOW it is welded properly.

If you search the link I posted I'm sure he says how long the rod ends last.

colonboy14

iTrader: (7)

So why aren't there companies making suspension components out of aluminum for our cars? Just the stigma that it isn't strong?

laiky

alluminum is plenty strong if designed properly. It will take more alluminum so the parts will be bulky, they will need to be forged or machined so they are harder to make. Steel tubing comes in bulk, its easy to cut and weld and is light and strong. It also doesn't work harden like alluminum, it has a near infinite fatigue life and is harder and less prone to cracking from nicks and scrapes.

i believe a company called metco makes some alluminum components for our cars

rx7speed

I remember seeing something about roll cages with cromemoly vs the other metal type they commonly use

the cromemoly while is stonger and lighter they also allow a thinner tube wall......


the problem they where saying though is while it is very strong to initial impact it can't keep absorbing impacts being it soon gives out. the other material while it is heavier and even a little weaker if given repetative stress is able to hold on to it a lot better and deal with it for longer then cromemoly

rx7speed

I don't know
on my car a lot of the suspension stuff is aluminum
the only ones I can recall off the top of my head are the trailing arms though and the arms on the front of the car are aluminum also

they seem to hold up fairly well

The Doc

I couldn't agree with you more Kandied. For those requiring the best parts with money not being an object then of course go CM with as many parts as you can.

Magician:- It depends if by 'daily driver' you mean daily driver that's going to get run into the ground and sold in a few years - or 'daily driver' that's being gradually resored and modified and will kept for a much longer time.

blacksheep-1

I'm a weight freak, so I would go with the C/M. But, as has been already stated, it's the guy doing the work. If you ever get the chance to look at an Indy car sometime, Those ittsy-bittsy c/m struts and 5/16 bolts that hold them together. It's almost scary, but it's all in the engineering. Of course they only weigh about 1500 pounds.

rx7speed

yeah but think about how mnay g's they pull

4+ which would be what? 6000 lbs of lateral load?