metal question (springer legs)

[hellbilly1932]

Ok so I need to make new legs for the springer on my chop. Gonna make them longer to get rid of the crazy rockers I had to put on it to get it level. The springer is a bolt together design and will require very little machine work to replace the legs. The current ones are solid steel, and my thoughts are to stay that way with the new legs since this is a heavy bike and lots of stretch.

Now the question..... What grade steel should I be looking for? And would chromoly be the best bet? Looking for some real world expirence here from anyone who has built springers, or has a good working knowledge of this stuff.

[Tman]

DOM tubing would have more strength than solid rod.

[Nitropathic]

Originally Posted by Tman

DOM tubing would have more strength than solid rod.

That would depend on what wall thickness the tubing was and material as well as the material of the solid rod. If all were equal, say 4130N tubing vs. 4130N solid bar both same O.D. the solid bar would be stronger every time. There would be a point in bending strength where the tube would be more efficient in weight vs. total load carrying ability than the solid bar, but it would never be stronger or stiffer if all other factors are the same. If they were already solid I would just put solid back in. It's not a race bike so a few extra pounds does not matter, but saftey does. I would use 4130N solid bar it's the strongest and toughest steel that you can get easily. www.aircraftspruce.com has it and they are in Corona, CA. Make sure to get "n" normalized bar not "A" annealed.

[bigassbike]

nice post. ive seen a few 1-1/2" frame backbones broken in two. dont think 1-1/2" solid would do the same. its more complicated than one is better than the other.

[jahluv]

A post from Sugar Bear on the subject from over at chopperweb.net

I've seen so many broken springers over the years that I can't count that high! there's so much info out there, that it's hard to know what's real w/o some experience. Chrome Moly - hard stuff, but if not welded or relieved correctly, can break very easily - becomes brittle. I use 1018 cold roll steel - strong but is soft enough to bend before it breaks. I've had clients centerpunch cars and the forks stayed together (they bent and were twisted -never broke!).

The entire thread is here: http://www.chopperweb.info/forum/sho...threadid=11283

[BLACK13]

More ......More !!!!

[Tman]

Maybe thats why airplanes and automobiles and HDs are all bilt with solid rod.................not.

[Pearson Customs]

I use 1.500 dom with a .156 wall on the ear legsOf our springers and they have never bent or broke. If I was to use a solid rod I would use 1018 cold rolled, I would never use chromeolly for the fact of it breaking before it bends.
Chad
www.pearsoncustoms.com

[Nitropathic]

The other thread was an interesting read. I sure hope this doesn’t turn out like that one. Some people get real touchy about this stuff for some reason. Obviously there is no simple answer to the question of how to build a part. There are limitless things that can go wrong and even pro’s mess up sometimes. I think a lot of what you hear about proper procedures for welding and material properties are just plain old wives tales. >>
There is no reason to be afraid of CM tubing or solid. I’m thinking they specify only 4130N material in top fuel and funny car for a reason. Some say that CM will just shatter or bend before it breaks, BS! Check the properties of both 1018 CRS and 4130N materials. Onlinemetals.com has some specs.
>>
Notice that 4130N has over 13 percent higher elongation at the breaking point than 1018. That says 4130 will bend more than 1018CRS before it gives up! Now in all fairness welding will change the properties of the steel. But unless you give it an ice water shower as soon as your done laying the bead the metal will be on the softer side meaning more elongation. I would also never use stainless filler on CM or mild steel, makes pretty welds, pretty weak!

[Nitropathic]

Here’s another point to ponder, lets say a crack forms in your forks. You have a set of solids and a set of tubes of the same everything, and the crack is half way through the round tube or bar. Which one can provide more strength? The one with more area to bear a load. Tubing would be fine for a fork but the design has to take the tubing into account. If the round section is limited to a small diameter by existing forks I’d use solid. If you can make the diameter big enough, tubing works great too, it just depends.
Bottom line is if you really want to know, read a book and don’t just trust a message board. Building a front-end is no joke and maybe better left to a pro.
>>
Tman: Comparing a springer front end to an airplane is like apples and elephants. Only older and very cheap planes (very cheap plane is relative) use CM tubing for primary structures. The obvious reason is weight. Last time I checked the landing gear on a 747 wasn’t made from 1018 mild steel tube it was a heat-treated 300M steel solid forging. I would guess HD might have a hard time forming frames from solid bar. But in this specific case the front end lends itself to the easy use of solid bar or tubing.
>>
Not trying to piss in anyone’s cornflakes I’m just sharing.

[Tman]

Lighten up francis, you read too much.

[Nitropathic]

Haha, no problems here. I get that "you read too much" shit a lot, but I still don't listen. Seriously, I do think that a lot of bad info gets spread just because people don't really investigate things themselves.

[bigassbike]

every material has a work method. a place i worked built alot of springers out of what most folks would call the wrong material. to date(bout 40 years) i have never heard of that brand's units having issues everyone says they should be having. but around these forums when metal pops up...they may as well been built out of balsa. so i tend to say bullshit. if you are gonna weld structural material together...you should learn how. regardless of the material.

[Tman]

Which reminds me.........this is good info that popped up on a thread on the HAMB last week. It seems some racecar manufacturers as well as aerospace guys have been seeing issues with Chinese steel and Fastners. Tubing that is labeled as 4130, Assumed Grade 8 fastners........both have been found to be of inferior quality.Slpil tubing, sheared off bolts etc. Ask your metal supplier if they know what they are selling you!

[hellbilly1932]

all very good points. Remember I'm not building a all new springer here, and it's a bolt together design. I'm not here looking for the specs of this metal Vs. that one, just looking for some insight from people who may have done this before, like the sugarbear post.

Thanks guys.

[jinx13]

Originally Posted by jahluv

A post from Sugar Bear on the subject from over at chopperweb.net The entire thread is here: http://www.chopperweb.info/forum/sho...threadid=11283

thanks for the link. I was thinking of building a springer sometime in the future as I have a few ideas for one, but now after reading that entire thread it sounds like more of a headache than it's worth. I'm not the biggest fan of them anyway.

[Unkl Ian]

4130 is prone to cracking if not welded correctly.

Mild steel DOM is a better choice.

[Tman]

Hmm, lots of good info,and GOBS of opinion on that thread. Decided to read all of it. Suffice to say, most of us here, on either side of the argument, just hit the high points of each method.

Keith Bontragers quote should make everyone happy "light,strong,cheap, pick any two."