32/30 Ford front suspension options?

[Jantrix]

I suspect, like a lot of you, I'm already planning my 30 Model A coupe build. One thing I'm planning on is to lower the front end (I do like a rake) and push the front axle out in front of the grill a bit. So lets talk about the ways that might be accomplished. And what would be better, more PERIOD correct. What I really want to know is how a serious hotrodder, who does quality work, (looking at you Bill) who wants to really drive the car and be safe would accomplish this modification. There's lot of options. As I'm just a plastic hot rodder, I just don't know which option(s) were conceived by a deranged man with a welder. Any help or insight would be appreciated.

1st. Keep the stock spring location, just move the spring mounting points backward. This is what I'm leaning towards. Assuming you are a competent welder it seems the safest. 

2nd. Remove the frame horns and add a suicide perch. I like this also. It screams period hot rod. However the "suicide" moniker is not lost on me.

3rd. Quarter elipticals. I'm told this is a very unstable setup. It does look great though.

4th. Then there's this set up. Hmm.......

Edited April 23, 2016 by Jantrix

[wayne swayze]

Glad you asked this question Rob. Like you, I have only worked with styrene, and I love a good rake and extended front suspension. This is an area I'm weak in. I'll be following this for the experts suggestions .

[oldnslow]

since it's just a model and won't be out on the road, which ever set up gets you the look you're after is probably the way to go. The first 2 would be period correct, the 1/4 eliptics need a panhard bar to keep them from oscillating side to side, not to mention some shocks, it would be like driving a boat, the last pic with the coils , yuck , but that's just me.

Edited April 24, 2016 by oldnslow

[Jantrix]

 the last pic looks like it's an in progress, the shocks are collapsed and there is no spring set up installed , but that's just me.

You are correct sir. After further research of the page the pic came from that is the case. I've replaced that pic with another option.

[Ace-Garageguy]

 The first two ways are what you'd really see on a period rod most often. I've seen the 1/4 elliptic setup on some old '40s-'50s lakes racers too, but to make it work at all, it NEEDS a cross link (Panhard bar) to keep the axle from squirming around relative to the chassis.

Relocating the front crossmember, or swapping it in for another one, is/was frequently seen. The relationship between the front axle centerline and the grille shell is tricky to get right. There's a 'sweet spot' that usually looks best, so do a lot of mockups and measuring to determine stance and proportions (trying to keep in mind what's possible with what there is to work with) and then build your suspension to give you the stance you're after.

One old practice on the real ones was to swap in a model-A front crossmember; it didn't have as much height, so would lower the car (I think about an inch or 2). You can achieve much the same thing by filing what's there, or fabbing something out of styrene . I turned the existing one upside down for this build on the same chassis you're asking about, but lower flanges need to be made for it (and the upper ones need to be cut off) and as you see, the frame needs to be notched to clear the axle (this is the dropped unit from the OLD-TOOL Revell model-A kits). I also had to notch the bottom of the grille-shell to get it visually right (to me) relative to the axle.

Same basic idea, but this time I used an Ala Kart front crossmember. Same effect, still had to notch the frame (which you'll see on many real ones.

Speaking of notching frames...today, you don't see it as often as you did in the old days, simply because NEW axles dropped as much as 4" or more are available, so you can go pretty low with just the axle.The old dropped-axles were reworked from original parts, and a 2" drop was about the limit available, so to get lower, you had to bring the axle closer to the frame rails...hence clearance notches.

Suicide front-end mounts are fine in the real world as long as they're thought-out well and welded correctly, made from the right stuff. They pose additional problems relative to grille and radiator mountings and as no two builds are going to be the same, each one requires fiddling to get things looking right and being close to something that would actually work in reality. Best engineering practice is to use a round tube front crossmember, which resists twisting under load better than a square or rectangular one (the well-built period cars had round tubes). For the perch, I usually use styrene channel.

 

[Ace-Garageguy]

PS. Some guys in the wayback also used torsion bars. Done right, they look a lot better than coils and work well. I'm on the way out the door to the real shop, but I'll see if I can find any period shots of a good torsion-bar setup later.

Just keep in mind you can pretty much put a front crossmember anywhere you want it in realty, and you can fabricate something to fit your needs exactly from steel stock, so whatever proportions and stance you envision for your model can be made to work, within reason.

Also remember that relocating the crossmember and axle always opens up other issues like clearance between the rad shell and the axle, height and placement of the radiator itself, etc. etc. 

 

[Skip]

http://www.honestcharley.com/hot-rod-parts/28-31-model-a-ford/complete-front-ends/full-frt-end-w-tube-axle-28-31-4-5bc.html

Something like this is infinitely more streetable versus the welded spring eye onto the radius rods.  The drop, proper geometry, ride are all a part of this suspension system.   Ask yourself this question, nothing has changed since Henry Ford's Engineers designed their suspension system why didn't they go with a variation of the one shown?  Likely because there are geometry issues with it, I've seen this setup but never ridden or driven a car with it.  My question however is while this is likely as strong as the original design placing the axle that far ahead of the spring with a set of disc brakes will make the axle want to roll under during normal braking.  I know this front suspension has been around and in magazines for a while, I'm just a tad bit leery of it, one concern with the frame horns above the axle it could bottom the axle on the frame horn and not have bump but bang steer!  Second, I hope there is more airspace between that axle and the brake line /fitting or it might get snapped off when the radius rod hits it.

The issue associated with semi-elliptical suspension systems is when you put efficient modern brakes on the axle which may or may not have the spring rate calculated. On a soft spring the brakes will cause the front axle to ocellate which is why you see it on a lot of light roadsters without front brakes.  Semi-elliptical front suspensions were production suspension systems with brakes and without a pan hard bar.  Obviously someone felt they were a stable front end, not to mention a whole lot of board track and early oval track roadsters.  I have ridden and driven a properly setup semi-elliptical suspended roadster, with brakes I didn't feel any of the skittishness mentioned, it's all in the spring rate.

With  the dropped original Ford designed suspension, the lowering is done first by the reversed spring eye, softer spring and or the additional load of the larger engine.  Second the dropped axle itself will bring the front end down accordingly.

[Ace-Garageguy]

http://www.honestcharley.com/hot-rod-parts/28-31-model-a-ford/complete-front-ends/full-frt-end-w-tube-axle-28-31-4-5bc.html

Something like this is infinitely more streetable versus the welded spring eye onto the radius rods.  The drop, proper geometry, ride are all a part of this suspension system.   Ask yourself this question, nothing has changed since Henry Ford's Engineers designed their suspension system why didn't they go with a variation of the one shown?  Likely because there are geometry issues with it, I've seen this setup but never ridden or driven a car with it.  My question however is while this is likely as strong as the original design placing the axle that far ahead of the spring with a set of disc brakes will make the axle want to roll under during normal braking.  I know this front suspension has been around and in magazines for a while, I'm just a tad bit leery of it, one concern with the frame horns above the axle it could bottom the axle on the frame horn and not have bump but bang steer!  Second, I hope there is more airspace between that axle and the brake line /fitting or it might get snapped off when the radius rod hits it.

The issue associated with semi-elliptical suspension systems is when you put efficient modern brakes on the axle which may or may not have the spring rate calculated. On a soft spring the brakes will cause the front axle to ocellate which is why you see it on a lot of light roadsters without front brakes.  Semi-elliptical front suspensions were production suspension systems with brakes and without a pan hard bar.  Obviously someone felt they were a stable front end, not to mention a whole lot of board track and early oval track roadsters.  I have ridden and driven a properly setup semi-elliptical suspended roadster, with brakes I didn't feel any of the skittishness mentioned, it's all in the spring rate.

With  the dropped original Ford designed suspension, the lowering is done first by the reversed spring eye, softer spring and or the additional load of the larger engine.  Second the dropped axle itself will bring the front end down accordingly.

1/4 elliptics as shown above and SEMI-elliptics are two entirely different animals. Semi-elliptics don't need a Panhard bar, as both end of the springs are located to the chassis to resist sway.

By the way...I know a little more than the average internet cruiser about suspension design.

If you recall, I build REAL cars with this stuff under them, and it HAS to work.

There ARE serious geometry issues with any dropped solid-axle setup that involves "splitting the wishbones" and all that entails on older cars, and most other mods bring in undesirable secondary issues too...but they're manageable.

None of these old setups are going to handle and stop as cleanly and predictably as an old 911 Porsche, but most of them HAVE been used under real race-cars, driven hard and fast, and will function pretty well if engineered and set-up correctly.

Edited April 23, 2016 by Ace-Garageguy

[Jantrix]

PS. Some guys in the wayback also used torsion bars. Done right, they look a lot better than coils and work well.

That seems like a very cool option. Take out the stock spring perch add some channel with some rods running through it, and some lever arms outside the frame, and you can call it a torsion system all day long. And you can still mount the radiator above it. I like it.

[Jantrix]

1/4 elliptics as shown above and SEMI-elliptics are two entirely different animals. Semi-elliptics don't need a Panhard bar, as both end of the springs are located to the chassis to resist sway.

 

Here's a semi-eliptical. This guy went the extra mile and added a panhard anyway. Seems like some shocks would be useful too.

[Ace-Garageguy]

That seems like a very cool option. Take out the stock spring perch add some channel with some rods running through it, and some lever arms outside the frame, and you can call it a torsion system all day long. And you can still mount the radiator above it. I like it.

 

 

Exactly. Just notice the end of the link from the T-bar sits ON the axle, free to slide. If it's attached to the axle, even with a rod-end bearing or balljoint, it will bind as the differing lengths of the hairpins and the t-bar links swing-radii fight each other.

The setup shown also needs a Panhard bar (visible in your lower photo) as there's nothing else to positively locate the axle side-to-side.

Edited April 23, 2016 by Ace-Garageguy

[Ace-Garageguy]

There are multiple variations of transverse torsion-bar setups, like the trailing-arm version below, and there are longitudinal torsion-bar setups as well.

[Ace-Garageguy]

Here's a semi-eliptical. This guy went the extra mile and added a panhard anyway. Seems like some shocks would be useful too.

Nope. Those are 1/4 elliptics. The reference pix on the internet are wrong. Imagine that. SEMI means half. A semi-elleptic setup looks like this...

BOTH ENDS of the half-of-an-ellipse spring are ATTACHED TO THE CHASSIS.  

This is a 1/4 setup. ONLY ONE END  of the 1/4-of-an-ellipse spring is attached to the chassis...    

 

 

 

Edited April 23, 2016 by Ace-Garageguy

[Jantrix]

Gotcha. And boy does that semi-elliptical setup look squirrely.

[Ace-Garageguy]

Gotcha. And boy does that semi-elliptical setup look squirrely.

The "semi-elliptical" setup is under the rear ends of the vast majority of cars and trucks with solid axles on leaf springs. It was under the front of quite a few production cars and trucks as well.  It's also the common setup under the front ends of "gassers". It's simple, cheap, works predictably. You WILL see some gassers running semi-elliptical springs in front also running Panhard bars for better predictability and stability at high speed.

the 1/4 ellipric setup CAN be made to work pretty well, and sometimes its great. The Stone-Woods-Cook Willys used 1/4 elliptics in the rear, with LONG ladder bars, and the resulting geometry let the car hook up a lot better than many of it's stiffer-sprung competitors.

In general, 1/4-elliptical in the front has a lot of links and pivots moving in a lot of hard-to-predict paths, and the axle moving around on all those pivot points usually makes a car squirrely indeed. Again, it CAN be made to work, but few rod-builders bother with the necessary math to get it right.

[Ace-Garageguy]

PS. The Chebby-engined rat you posted above at least has all the necessary links to control axle movement, so it would be perfectly acceptable for a model, where you don't need to know the exact geometry, but want to look like something that could at least be driven with some confidence. 

 

Edited April 23, 2016 by Ace-Garageguy

[Snake45]

Fabulous thread! I've had some of these same questions myself! Thanks guys for all the wonderful info and ideas!

[Skip]

Ace, you hit on pretty much what I was trying to get across at 04:00 Hrs.  The problem being most of the garage assembled / built setups lack any engineering to make them function correctly.  There are always trade offs when you modify a stock based suspension like the dropped forged Henry Ford and Super Bell front axle shown.  They were originally designed with the axle on one plane then it gets dropped to another.  Posies, Bell, and a host of others have put the math and engineering into their products and it shows in the way they function.  It really goes back to just because something looks cool doesn't mean it works, or works safely.

You nailed it on the Semi and Quarter elliptical, which I nearly always get confused in the first place which is which, I was referring to Quarter Elipticalls in my comment, didn't Chevrolet use Quarter Elliptical suspended front axles, I know there were a few others who did.  Point is when they are well thought out they work as they were engineered to do in the first place.  Probably should have waited until the coffee kicked in to make a statement on anything requiring thinking.

As an Engineer, my point is you just don't go and weld things up to look cool and expect them to perform like something that was engineered on proven principals to work a specific way.  The front suspension set up which got me on the rant is the split wishbone with the "spring eye" welded to the wishbone, can't imagine how that one handles.  I don't want to see either.  Ford and others built their suspension systems on hard gained, tested and proven knowledge which they changed things a little bit at a time, not making huge jumps in theory and practice.  That set up just reminds me of some of the stuff seen under rat rods, probably why I have issue with it in the first place.  That set up could work, it's built stout enough, just the more distance between axle and spring tends to act as a lever to introduce torsional twist into the spring as well as up and down.  There are so any ways to get a buggy sprung front axle in the weeds which use sound time proven methods and parts to get the job done without trying to reinvent the wheel too!

[Ace-Garageguy]

Skip, I agree with every word you wrote.   

[afx]

The front drive Miller Indy car used 1/4 elliptical front suspension.

[Longbox55]

 

You nailed it on the Semi and Quarter elliptical, which I nearly always get confused in the first place which is which, I was referring to Quarter Elipticalls in my comment, didn't Chevrolet use Quarter Elliptical suspended front axles, I know there were a few others who did.  

Yes, Chevrolet did use quarter elliptical springs, front and rear, on the 490. Most of the other early Chevrolet cars (which includes the Little and Mason) used semi elliptical  on the front, and 3/4 elliptical on the rear.

[Ace-Garageguy]

Man, that Miller is a beautiful thing. It may be old, but it sure is pretty.

It looks to me like the drive-axles do the job of limiting side-to-side movement that a Panhard bar would normally be called on to perform when running quarter-elliptics.

I sure would like to see inside that drive-housing, to find out how the gears were able to move with suspension travel.

Harry Miller was a staggeringly gifted and prolific innovator and engineer. You can bet the front suspension he built worked very well indeed.

Still, you have to remember this was a purpose-built racing car, intended to run on a relatively smooth surface, and turn (not too sharply) in mostly one direction. Not easy to get right, but not as difficult an environment to have to cope with as a vehicle on the streets and roads.

[Ace-Garageguy]

In the case of the Miller shown above, it DOES look like the upper and lower spring leaf packs themselves also provide the side-to-side limits for axle movement.

Of course there's an outer universal joint to allow for steering, but in the photo below, it appears there's also an inner UJ to allow for the drive axles to 'flex' relative to the gear case. This would necessitate some kind of sliding joint on the drive-axle itself, to avoid binding...and it appears that the 'step' visible on the drive axle may be the sliding, splined joint.

And of course, having a sliding splined joint on the drive axles would make them incapable of limiting side-to-side movement.

So...it must be the spring-packs themselves preventing lateral movement in this case, and they must have been very carefully designed to do this job as well as suspending the car's weight.

[Spex84]

I might have missed a post or 2, but there is also the "spring-behind" setup, as seen on the Doane Spence roadster and the Rolling Bones cars.

In this setup, the spring is moved off the top of the axle and set behind it, with the shackles on either end mounted to the radius rods (or the batwings on the hairpins, if it has those). Generally the frame horns have to be cut off for this to work, and often the front crossmember is flattened/cut down with notched frame rails for spring clearance. It's a bit like a suicide front-end, and I guess if the frame rails were cut off completely, if one of the spring shackles failed, the car would nose-dive into the road, so it can carry similar risks.

[Ace-Garageguy]

I might have missed a post or 2, but there is also the "spring-behind" setup, as seen on the Doane Spence roadster ...

Excellent example of a perfect older rod...the Doane Spencer car, built in 1947, is an icon for sure. The perfect relationship of all of the major front end masses to each other, made possible with the suspension setup you mentioned (without resorting to a deeply-dropped axle) is apparent in this shot. (In Spex84's photo above, notice the notches in the frame rails necessary to clear the spring, similar to the notches on my model shots farther up. Same idea.) 

    

The "spring behind" setup can also be achieved with hairpins on a tubular axle like this...   

This "spring behind" setup for a beam-axle uses hairpins like the Spencer car too, and the spring hangers are part of the batwings that bolt to the axle, rather than being welded to the modified original radius rods. 

      A "batwing"...    

You can use a spring-behind setup with a suicide-style frame perch too if you want to go REALLY low and long.

There are an almost infinite number of variations possible , and once you understand what works in the real world, you have a lot more options available to yourself to build realistic models that look right.   

Want more info on dropped axles for hot-rods? Read this...   http://www.hotrod.com/how-to/additional-how-to/0808rci-beam-tube-axles/

 

Edited April 24, 2016 by Ace-Garageguy