wishbones- OD & ID?

[Pauly]

all,

we are currently finalising dimensions for wishbones(using chromo) and have done all the worst case loads, buckling etc and are thinking of using 14mm OD and 1mm wall thickness.

what are other people running?

cheers

[ben]

We always used 16mm od and 1mm wall.

Ben

[GTmule]

We use .635" OD by .035" wall (just SLIGHTLY smaller than ben uses)

[CrazyDave]

We used .625" dia .028" wall. I would be scared to go to .5" personally. Dont forget about the "orange cone" loading factor

[Faterooski]

We used 1/2" OD with a .125 Wall thickness. Maybe a little overkill, but we have never bent any, and we don't have to worry about bending them when we put the car up on jackstands. I'll take plenty of peace of mind about our factor of safety over 8 ounces anyday.

[rjwoods77]

We are using 1" od x .035" wall thickness. It is really for cosmetic reasons. All of the baja cars I ever built have had a-arm material being the same diameter as the chassis tubing. It makes for a real bold and tough look. It looks like an extension of the spaceframe, like arms, which I feel is the most beautifull parts of the car. Adds overall less than a pound to the car but man it looks really cool. One of a bunch of little comsmetic things that will add to look of our car. People dont think about looks sometimes and that really bothers me. I hold the "all that matters is fast" opinion but at the same time you have to roll in style. Substance without style is a mark of a boring engineer. I hate spindly little tubing for suspenion. Gives the car a frail look.

[jack]

1" OD?! holly crap, how did you get that to fit in 10" wheels? aren't you running 0 scrub too? i barely got .625" to fit with 2" of scrub.

by the way we are using .065 wall because our welder is a pussy. oh well, it will take a good smack from a cone..

[rjwoods77]

Originally posted by jack:
1" OD?! holly crap, how did you get that to fit in 10" wheels? aren't you running 0 scrub too? i barely got .625" to fit with 2" of scrub.

by the way we are using .065 wall because our welder is a pussy. oh well, it will take a good smack from a cone..

No. 2" scrub. With 8" balljoint centers. It will be close but it fits. The a-arms are a little different in design but are stronger and more rigid than any other designs that I have seen. The a-arm members have some bending moment in them but that is due to the fact of where my mounting points on the frame are located (15" spread). Comprimises about, but I like them, they will work nice and they look cool.

[Frank]

15.875 * .889

5/8 * .035

a crash we had made me think smaller wasn't a good idea

[Z]

Originally posted by Frank:
a crash we had made me think smaller wasn't a good idea
Smashing things up is probably the best structural analysis you can do. http://fsae.com/groupee_common/emoticons/icon_wink.gif

Z

[Storbeck]

Unfortunately it's also the most expensive...

[Frank]

agreed...

we made chassis changes as well (other than the repairs)

[TG]

I'm working on a composite a-arm project for our car. I would like to do some empirical tests using a cone to do a failiure analysis of a worst cas senario of a cone getting stuck under the a-arm and putting a repeated amoount of bending forces into them. I was wondering if anyone could give me an idea of what type of cones are used at comp? I just want to know how high, thickness and such so I can find something that suitably represents what we'll be racing with. I am thinking I could go to Bondurant to borrow a cone of theirs, but they probably have the most durable cones out their to withstand ths student drivers in the mustangs and CTS's running over them. Thanks in advance.

[Denny Trimble]

I think the 12" cones are pretty standard. New cones are more supple than old cones. You local SCCA chapter may have an old cone or two to loan you. Also, the colder the temperature, the stiffer the cone. We've bent 4130 a-arms hitting cones at 40F before.

[TG]

Originally posted by Denny Trimble:
I think the 12" cones are pretty standard. New cones are more supple than old cones. You local SCCA chapter may have an old cone or two to loan you. Also, the colder the temperature, the stiffer the cone. We've bent 4130 a-arms hitting cones at 40F before.

Thanks. We're going to the FSAE West competition so hopefully the temps will be at least what they are here in Phoenix now.

[Dan B]

Originally posted by Pauly:
all,

we are currently finalising dimensions for wishbones(using chromo) and have done all the worst case loads, buckling etc and are thinking of using 14mm OD and 1mm wall thickness.

what are other people running?

cheers

After much calculation I found that the largest load was in bending from someone picking the car up by the A-arm right in the center. No matter how hard you try something stupid will happen. I ended up with .75"x.035wall.

[RacingManiac]

5/8" .035 for lowers and 5/8" .028 for tops..

[mario_rbr]

I made my study and it depends on your fsae gross weight after all, and of course your FS,seeing the dimensions you guys use I was wondering if anyone of you have done heat treatments on your wishbones tubes?
what about welding?...

[Jersey Tom]

06 car, .625 OD x .035 wall. TIG welded, 70S-2 filler, post-weld flame normalize, mostly to get rid of warping.

[Kenny T Cornett]

Originally posted by Jersey Tom:
06 car, .625 OD x .035 wall. TIG welded, 70S-2 filler, post-weld flame normalize, mostly to get rid of warping.

it makes me cry a little inside to hear you already have that figured out and we haven't had our first FSAE meeting http://fsae.com/groupee_common/emoticons/icon_frown.gif haha

[Jersey Tom]

Well thats how we rolled last year and its an easy backup plan. We used to use .065 wall.. why is beyond me.

This year, our former team captain is investigating some different construction possibilities. Got one that looks very slick, strong, and light. Will be badass if this new fabrication method works.

[KU_Racing]

we used 1/2" .040 6al-4v. retarded light, not very stiff.

New fabrication method Tom?? you probably wont share, which is understandable, but you got my fabricator brain hummin trying to figure out something other than the usual style...

[Jersey Tom]

I don't want to talk it up if it doesnt work out, haha. You'll see it at competition!

[KU_Racing]

argh.. no fun tom. well good luck with it! hope it works so we can all get drool all over your sexy new control arms.

[Mike Claffey]

We run thinner ones on the upper a-arms.

[Jersey Tom]

Yea. That new manufacturing process works.. and its one of the coolest damn things I've ever seen.

[Peter]

any pictures? http://fsae.com/groupee_common/emoticons/icon_wink.gif

Peter
Delft

[Jersey Tom]

No pics till what we're building with it (a-arms and probably as many other things as we can) is done.