Hot Rods Spring in front of front axle ???

Thanks gimpyshotrods. Your second last paragraph is where I am at. Not wanting to totally re-invent the wheel. Ford obviously went to "spring in front" for valid reasons and I was only contemplating whether the gains would justify the effort of a simple (relatively) upgrade to the later setup in a model A. Frame will be a custom build and as rigid as possible, a custom made spring will not be a problem if required, and shocks will be chosen on merit (NOT price). I have put a lot of time into understanding basic suspension principles, but am by no means an expert in any of this.

I guess you are right, it is a try & see proposition. I do enjoy a challenge, and nothing is irreversable.

 

Thanks Pist-n-Broke. I thought that not recessing the firewall would have been part of the overall design.

 

It will help. Doubly so, if you use new, modern movable parts.

You can take it farther than Ford ever did!

 

More info please (modern movable parts) ?
Hope I haven't just set myself up to look like a total moron.

 

The only morons are the ones who don't bother to ask.

New, modern spring, with buttons or sliders, with more, thinner leaves (allows it to be tuned by adding/subtracting leaves). New, modern, adjustable shocks. Every other moving part (tie rod ends, etc. replaced, or renewed). Steering box properly mounted, and in perfect working order (new, if necessary).

If running a Panhard bar, make sure it is exactly the same length, and exactly the same working slope as the drag link. You'd be surprised how many cars that I have had to fix this on.

 

I feel better now. All of this is a given. If this goes ahead it will be a ground up build with everything new or totally rebuilt, and set up as it should be. Half measures are not an option.

 

Putting the spring in front of the axle alters the motion ratio slightly ,making the wheel rate stiffer.
But because the spring is now hanging off the front of a V shaped bone, the spring is now longer therefore softer. [without using mathematics, they almost cancel each other out]

With parallel leaf springs , you can increase "roll stiffness" without increasing ride quality by widening the spring base [at the expense of steering lock]

With a crossleaf there is 2 methods to increase roll stiffness! 1: Either an anti-roll bar or 2: increasing the base of the spring perch [Corvette style]
The Corvette style spring perches cause the spring to "S" shape during body roll but bend like a Bow in straight line compression.
I am surprised that nobody has bothered to do this method here


The spring in front method gives the builder the ability to move the wheelbase by using a T bucket type crossmember and spring perch.
A Corvette type spring could hide the perches under or near the frame rails

 

In talking about Panhard bar and cross steer link and equal length. Think about a proper 4 bar going sideways. I'm assuming your talking about the swing arc being equal to each other. That's difficult to achieve if you go to the right side steering arm with the steering link. I have used the Bronco tie rod end and that has helped a good bit. I actually built a Tie Rod with the receiver eye inboard more but now the two rods are quite short ending up with a rapid arc. Can you keep going with things you've done to make things better?
The Wizzard

 

Hi Kerrynzl. Have been waiting to hear from you. We had a very helpful discussion some time ago regarding wishbone 3-link stuff (Lotus Cortina style).

Thanks heaps for adding another option in to keep me thinking - Corvette front spring.
Would the wider double spring perch work the same with a multi-leaf steel spring? Would it be able to be "tuned" for roll stiffness by making the two perch positions adjustable inwards and outwards?

 

Correct ^^^ except for a very minor amount that is irrelevant here.

All telescopic shocks require a compressible gas in them to take up the displacement of the shock shaft, or they would burst.[or hydro lock]
If the shock is sealed correctly this gas tries to push the shaft back out

Twin tube shocks ["Koni"] have a 1-way piston valve on the shaft [for compression] and a 1-way foot valve at the bottom of the cylinder [for extension]
The up down movement recirculates the oil and aerates it [it loses the ability to dampen] A lot of shock fade is also due to heat expansion causing leaking past the pistons.
On twin tube shocks, the outer tube is purely an oil reservoir, so they can be dented

Monotube shocks ["Billys"] have a 2-way piston valves [for compression and extension] and a floating piston/chamber that is gas pressurized to take up the displacement of the shock shaft.
Monotube shocks have less fade due to a larger piston area because the outer wall is the cylinderbag . If they get a dent in them , they are trashed.

I have built Twin tube shocks with a inflated plastic bag inside the reservoir to take up the displacement, they can be mounted at any angle and make a very good steering damper. They don't aerate the oil, but can still fade due to heat. [the bag can't burst as it is surrounded by oil]

 

Yes, it will work the same in theory .but A multi leaf is progressive and a mono leaf linear.
So a multi will be stiffer on the outside during bodyroll, and softer on the inside.

You could probably fold up a "lipped channel" cross member with multiple holes on the lips to tune the spring base as long as you have another type of lateral control [the centerbolt won't locate laterally]
The arch of the spring will tuck up inside the channel in the centre

 

Is this an advantage or a disadvantage, and why?

 

I am talking cross steering, and a parallelogram formed by the Panhard bar, and drag link, when viewed from the front. That's not hard to do. I have managed it on every single so-equipped vehicle.

They need not be on the same plane. That is often impossible. They just need to have the same length, and slope angle. The arc can be short sometimes, but the idea is to have the arc of the Panhard bar, and the arc of the drag link be equal, when the steering is centered. The more that the arcs diverge, the more straight-line bump steer will occur.

I used to build a whole lot of 4x4 stuff, from gigantic components. I used a right-side tie rod end, with a eyelet for the drag link, in many cases. An equal length and slope Panhand bar and drag link, even when at a 12-15º angle prevented most straight-line bump steer, save for what was induced by the radical slope shifting the axle over.

 

Better for ride quality! less so for bodyroll [but still better than a single perch]

Also the arch between the two perches needs to be reasonably flat, as the perches will try to spread apart during compression.

If you removed the top leaf [as most do] then widened the two perches outwards to just catch the ends of the 2nd leaf, it would be a very good starting point.

 

So a simple modification like this would be a definite improvement? Maybe lots of test and tune necessary, but if the setup was designed as fully adjustable (spring perch width), it should be able to be dialed in AND reasonably conceilable.

 

I'm not. Every time I mention doing something that has not already been done 10,000 times, I get a full ration of shit for not being traditional.

 

I guess in the true sense of "traditional", it means we should just accept sub-standard performance and safety.
I'm all for traditional to a point. The trick, IMO, is to ahceive a better and safer outcome while not straying too far from "the look". A balancing act for sure, but can be done.

 

I have been told that hot rods are supposed to ride and handle like crap, and that is traditional.

That's why I don't build to that tradition.

 

Agreed, but lets not get ouselves in the shit here. We are all here because we are inspired by the traditional look, and some take it further to include the whole experience. That's great, I get it. It's just my opinion that some improvement in the areas of suspension/braking/safety is not a bad thing. We put our asses, and the collective asses of all other road users, on the line every time we drive out the driveway. Responsibility is not a dirty word.

 

Yes,
This is not a hidden secret. I've seen this on old speedway midgets [they also used a weight jacker on the RF]

Have a good look at the photo I posted. The 2 perches are able to swivel ,and there are multiple holes to tune it.
Note that particular Corvette leaf is progressive [it is tapered]
On a multiple leaf spring I would weld the "rebound clips" so they wouldn't open up [I do this myself, on the front of trailer springs for brake torque]
You would need some way of locating the spring as the centerbolt no longer locates it in the perch [the Corvette spring also uses the taper for this purpose

If somebody has to crawl underneath to find it, I would consider it reasonably concealed.

Just say that "Ak Miller" tried it once and you'll be all good mate!!

I get the same shit from the rule-makers ,Apparently I have a thinner interpretation of the rules than what the rule-makers intended [Including HAMB rules ]

The reality is we are trying to build Traditional Hot Rods in a modern world, So Radial Tyres and T5 gearboxes are creeping in.
A simple wishbone or 4 bar front end with a dropped axle and cross-leaf would always be considered traditional. The fact that you spread the four perch bolts further apart [or used 8 bolts] should be considered innovative engineering.

 

Was already thinking along that line. Sort of a double shackle (for want of a better word) arrangement to allow the centre section to float/flex. The side to side location restriction would seem to be the major hurdle.

 

Swap the centrebolt for a longer hex head bolt , and attach a small heim joint to the top of the spring.
This heim can be used to make a small panhard bar to control lateral movement.
All hidden under a cross-member of course

OR if you want it to be less "creative" , make the top helper leaf small enough to fit just inside the perches [you'll need to get the widths determined first or have a different helper leaf for each setting.

Remember.........Cheating is traditional

 

What about a vertical locating rod off the centrebolt that runs up and down in a guide (roller bearing)? I would think that the centre of the spring pack would not see much vertical deflection.

 

That would work OK.

I was doing a bit of thinking before about how to "cheat" the top helper leaf.
Drill a bunch of holes in the top leaf to line-up with a hole drilled in the perches [holes at the different width settings in the spring]
In the hole in the perches , use locating dowels and spot weld it

You can move the perches over to the next set of locating holes etc

and best of all NO MOVING PARTS to fail

 

I don't know if that bunch of little east coast rod mags that I had are salvageable anymore after being in the shed for too many years but in the late 50's that seemed to be the norm rather than the exception for East Coast cars.

 

Brilliant. I knew I liked you for a reason.
Mini reverse spring pad/ swing shackle arrangement X 2.

 

Simple engineering,is not always as simple as it looks,yet often better at doing the job when known. "Simple is king"

If there are any buddy's near you,that have hot rods with set up you like,get them to take you for a ride . Real world feel beats just talk.

 

Here's mine. this car was first built in the early 50's and I kept all of the front end and steering the same. It seems to work pretty good but I agree from the side it shoves the front wheel back a little too far.

 

Good advice Dana, as we have come to expect from you.

I should probably point out that the methods being talked about in the recent posts are things I will NOT be using in my build. I do, however, think that discussing such things can be helpful in understanding the dynamics of leaf springs and the workings of suspension systems in general. If a little knowledge is then applied back to our "traditional" setups during construction, it makes for a better basic setup.

Granted, some of us stray off topic a little at times. Some are just cursed/blessed with minds that are a little too inquisitive. Are we learning? Yes, and that is a good thing. Would we use some of the wierd shit we sometimes talk about in our build? Definately not.

 

Yeah jimgoetz, I see it, but I had to look hard. As a package deal, that car is very appealing to the eye. It's a bit like a freckle on a super-model's elbow. It's there, but I'm having trouble keeping my mind on looking for a freckle.
And besides, if it was used in the build for a valid/beneficial reason, it justifies itself.