Hot Rods Split wishbones, hairpins or 4 bar front end?

I’m into a new project and am using a model a style frame with a 4” drop axle . I have a set of wishbones but I don’t know if I can use them on a drop axle. What is the best configuration for this kind of set up . Or is it just preface ? I don’t have any steering box yet so I’m sure that will come into play. I used slit wishbones on my last car but that was a Henry Ford straight axle . I may drill my wishbones out for speed holes if I use them. Any thoughts please

 

The drop effectively puts the stub axle and wheels higher, so the perch bolts are still in same position relative to everything chassis related. Steering arm is different position.
The speed holes won’t make it go any faster, just weaken it, and if you ‘box’ them you will lessen their ability to twist correctly, (although most everyone else will probably disagree with my last comment about boxing/twisting them).

 

i won’t disagree

 

Is the 4” axle a tube or I beam?

 

I beam axle

 

I'd go 4 bar, if I wanted a better suspension set up.

 

^^^^^^ yes, - and wishbones if you’re going for looks or an earlier more traditional car…….

 

A dropped axle or original axle makes no difference on any of those choices, as long as caster and engineering is correct. A tube axle would not be ideal with split wishbones. Drilled and sleeved split wishbones won’t flex/twist as they should with a I beam axle. Don’t use a 4 link on a traditional build, even though shortly several of you will post pics of said setup.

 

Hairpins are traditional....

 

I've got a '29 A Roadster and it had 4 bar front and rear. It has a 4" dropped A I beam axle.
Boxed frame and open driveline rear end
I wanted a more traditional look and removed the front 4 bar set up for a hairpin. Left the 4 bar set up on the rear
Used the same batwings that were used with the 4 bar. It has a panhard bar
I actually believe I like the handling of the hairpin set up better. I am believing by leaving the 4 bar on the rear that only the front end is steering the car.

 

If it’s out in the open on a fenderless car, I prefer hairpins. Split wishbones are traditional, but I like them as much. A four bar is probably better, engineering wise, but IMHO kinda ugly to look at.

 

Just did a 32 chassis with bones but most of the customer chassis I have done over the past 10 years have had hairpins. Haven't done a 4 bar in at least 7 years.

 

This is a great question and you answered it correctly, never us split bones with a tube axle, I learned the hard way.

4 bars work great but to me they are not aesthetically pleasing to the eye, like the hair pins or split bones. HRP

 

To my eyes, they are the most hideous on the rear of an A hiboy (Model A chassis).

 

I'd go with split wishbone - easy, cheap, traditional, and time-tested.

 

I-beam is the correct answer wrt hairpins or split wisbones...but I would go one step deeper in the question...is your I-beam cast or forged? If cast, I suggest replacing it with a forged unit before subjecting it to any of the torsional stresses inherent with either the hairpin or split bone set-ups.

 

Obviously different set-ups will transfer forces differently. While I understand that purists don't like them, I always found the 4 bar to look the best, and it definitely works the best. The question is whether you are building your car to suit your tastes or building it to suit others and gain their approval? Myself, I think the best engineered one is the four bar and I think its the best looking as well. You have to decide what is important to you though.

 

How do I tell if I have a cast or forged axle?

 

Post a close up photo of the axle, front and top. There might be some clues we can see. Where did you get the axle?

 

Obviously this is a crank but the information still applies, castings have a knife edge parting line

 

As others have said, post a few pictures. Also, you can hang the axle on a wire and strike it lightly with a hammer. If it rings (tttiiiinnngggg) like a bell it's forged, if it thuds (tink) it's cast. Henry's axles were forged, some of the less scrupulous after market suppliers made cast axles (and there has been much documentation and discussions about them failing).

 

I beg to differ, 100 lbs equals a 1/10 of a second the best way to save 100 lbs is to save 1,600 ounces

 

Four bar works the best but would not have them on anything I own!
Wishbones are my first choice and hairpins next.

 

I stand by my original comment:
he was going to box the cutouts, so unlikely to have any weight savings.
Remember to include the weight of your welding wire/rods when you do your calculations…….
More surface area = more head wind type resistance also.
(I can’t believe the effects of lockdown has driven me to even respond to this…….).

 

Turns out to be a cast axle , how bad is it to use this?

 

Anybody?!

 

If it is a cast axle from any of the Hoffman brands; I would ditch it.

Super Bell axles seem pretty tough; at least the one on Adam's car turned into a pretzel with coming apart when he was hit.

Of course a dropped '33-'36 axle with '40 bones looks about the best.

 

Just my personal preference but I’d pass although there is at least one good cast axle out there. Can you post some good, clear pictures of your axle that show some detail?
There are cast axles and then there are crap cast axles, we need to see what you have. Hoffman was mentioned, one of their axles might be safe under a trailer behind your lawn tractor but that’s about it.

 

I have a ductile cast axle and I believe that it is probably strong enough because I also have a chrome ductile cast axle which is basically a wall hanger from a buddy who ran his car into a pole. That thing has a nice bend in it but it didn't break. Nice conversation piece however.

 

I have two questions I hope I can get answered...

First, why do people split bones when running a flathead? I just don't get it as it was engineered that way by the factory.

Second, I have a dropped and filled Henry axle. How much of a negativity is the filled part? Am I going to die daddy? LOL