FlyingLow

I'm in the process of piecing together my sas. I plan on long arms up front, and wanted to know what type of tubing to get. Thanks

ZachsXJ

Minimum of 2" .188 wall DOM

FlyingLow

I plan on running a d30 and 35's to start. Eventually going to a d44 and 37-39 tires. What would you recommend.

ZachsXJ

What are you asking about a recommendation on?

PLEASE do a build thread, I just realized you have a liberty....

FlyingLow

The size / type of tubing. I only wanna have to build the arms once, which is why I included axels and tire size. And I will do a build thread. Everyone thats done a sas liberty usually does coil overs up front and a 4 link rear. I'm not doing either. It's not paid off yet, but once it is I'll start the build thread.

89eliminator

i used 1/4 wall 2" OD DOM for my longarms.

ZachsXJ

Awesome, I'm looking forward to this build.
For long arms I'd say go with 2" or 2 1/4" .188 wall DOM tubing minimum. .25" wall would be a smarter choice.

5-90

You're getting dims called out - which is good. That's half of your question.

"DOM" means "Drawn Over Mandrel" - it's different from rolled/welded tubing in that it doesn't have a seam (it also usually doesn't have scale - so it doesn't need to be pickled - and there's more control over ID and OD.)

Material would be indicated by an AISI alloy number - it's a four-digit number that tells you what family of alloying elements are used (first two digits) and how much carbon is in the steel (decimal fractions of a percent - last two digits.)

For instance, AISI 1020 is a mild steel, unhardened, with .20% carbon by weight (a decent general-purpose steel.) If there is an "L" in the middle, it's got a percentage of lead added. "S" indicates sulphur. (Ex. 10L20 or 10S20.) Either sulphur or lead would be added to increase machinability.

For your application, you may want to go with a 41xx steel - it's the milder chrome-molybdenum steel. It provides strength advantages (which you'd need for a suspension member - particuarly column strength) and it welds well - and it's the easier to work between 41xx and 43xx.

If you don't want to spend that much money (41xx/43xx can get spendy!) going with a 12xx or 13xx steel isn't a bad idea - but ramp up the wall thickness accordingly. If the ID is critical, this means you'd have to go up an OD size to get a thicker wall. You may also have difficulty finding DOM in mild steels, but it's out there.

DOM can be identified "in the field" with a visual check - HREW/CREW (Hot Rolled Electrically Welded/Cold Rolled Electrically Welded) steel tubing does have a visible seam - made more visible by the HAZ inherent in welding. It also tends to have a "flash" inside the seam that is not drawn out after welding - which makes the seam quite obvious. HREW/CREW tubing shouldn't be used in applications where it is subject to forces in flexion - the seam forms a discontinuity, and is therefore a stress riser.

AISI - American Iron & Steel Institute. Governing body for alloy composition and nomenclature in the US.
CREW - Cold Rolled Electrically Welded. Typically no scale, but suffers from the "seam" flaw. In this process, the metal is heated - but not to the "transformation point" of the alloy. There is usually still some scale in the HAZ (q.v.,) but not overall like HREW/hot rolled steel.
DOM - Drawn Over Mandrel. The mandrel sets the ID of the tubing, the die sets the OD. This is usually a "cold" draw, so little to no scale. There is also no weldment/seam.
HAZ - Heat Affected Zone. Every weld has this, unless the part is heat-treated after welding (annealed and rehardened) to eliminate it. Every weld. In everything.
HREW - Hot Rolled Electrically Welded. The material is heated to above the "transformation temperature" before forming, which leads to the formation of an oxide scale during cooling. This typically requires pickling (an acid wash, mainly) to remove before finishing or welding. Scale may be removed locally using a wire wheel or cup brush.

FlyingLow

How much would dom run me. I think I'm gonna go with some 2" 1/4 wall.

PingPong

If you want to build it once... and want something pretty cool get some Heat treated aluminum links.


As for what DOM costs, that depends on location and how much you buy. If you buy a whole stick.. you can go to the supplier, but if you try and cheap ou and buy less you pay more.

FlyingLow

I'd do aluminum, but don't have the cash for pre fabricted stuff, and no access to a aluminum welder. So dom it is.

nick_n_ii

aluminum control arms are just plan scary...

Go DOM

RDK_YJ88

What makes you say that?

claygrassmann

i kno strength comes from design as well as material but i dont see alluminum holding up as well as steel

5-90

Depends on stresses and environment.

For LCAs, I'd not want to use it - it tends to gouge when drug over something, instead of scrape. This compromises the strength of the part rather quickly.

For UCAs, it's doable - although you'd want a thicker wall than you'd want for steel to preserve column strength.

For steering linkage, there's not a lot of reason it couldn't work - as long as the steering is up out of the way (Over-The-Knuckle comes to mind.) Same complication as for LCAs.

And, for any use undercar, the aluminum gets a good hard anno (clear or coloured) after machining, so be sure to allow for the thickness of the anno job in your machining and fabrication (anno grows "half in and half out" - a .010" thick anodise will make the part .005" larger on the relevant dimensions. So, if you use a .010" thick anno inside a hole, the hole will come out to be .010" smaller - .005" on each side.)

For anything wanting extreme strength, I'd probably go with 41xx or 43xx gas-welded using a carburising flame (which is what those alloys were originally formulated for anyhow - it allows gas-welding with minimal post-heat-treatment and preserves strength in the HAZ.) For parts where aluminum is doable, 6061-T4 is a good general-purpose alloy, then you can go up to -T6, 7075-Tx, or some of the 2xxx-series alloys (which tend to approach mild steel in strength. A good structural aluminum alloy can be as strong as 12xx or 13xx steel, with less weight!)

Before you think mild steel is useless, bear in mind that most OEM axle halfshafts are 1541 steel...