Hot Rods Tranverse Springs Tech Info.

The beauty with the last type of transverse spring mounting point is that it does offer lots of opportunity to adjust a desired ride height by changing the final position of the plate/tongue with not much trouble involved and while doing so castor can easily be set.

The down side is that at some point by raising the plate height unless compensating in other ways the tie rod generally begins to have clearance problems with the chassis.
I know guys put their tie rod out front in a reversed manner to the norm and it has been done that way many times, but rarely with much geometrically success.

 

At the other end of a transverse front spring, it can connect to the front axle by 3 main positioning methods;

1. Over the top of the axle - similar to Model A & T Fords.
2. Ahead of the axle - similar to 1935 on wards.
3. Behind the axle, as per many modified hot rods.

 

The spring spreader is a handy tool that has been around forever and be of great assistance when installing springs.
It is obviously a safe way to install springs, although other methods have been around as well.
I don't own one and have never done enough of this kind of work to justify owning one.
However, I have seen springs let go and there is a lot of energy released when one does.
You don't want you hands or any other body parts in the way of a spring letting go.

 

This is a great thread on transverse springs and traditional builds.
What is your thoughts of the best way to measure caster and where do you measure it if your car has a rubber rake ?

 

Thanks for your kind thoughts.
You would think a transverse spring is such a simple unassuming item, but when you start looking into it there is way more there to know about.
Mostly, as hot rodders we are learning new stuff all the time and I don't pretend to know it all, but talking about stuff usually brings a whole lot of information together from numerous sources and helps spread the knowledge and the word.

Honestly, it is funny what stuff get drawn to the surface in talking about topics like this, as I am still unsure whether to spell the word as "caster" or "castor". I'll go with your spelling for now...

I've chosen to measure caster by using a digital angle reader that I place vertically against my kingpin boss on the axle and see what it reads and then I do a confirmation check at the center of my I beam axle.

Really it is about homing in on the correct numbers you need to make your car as drivable as possible.
I remember in the early days everybody seemed to think 5 degrees for front caster was good, but now we seem to shooting for about 7 degrees which seems to have stuck these days.

The trick is building this caster number into your chassis ahead of time.
To do think it is worth considering what rake and what a choice of rubber will use early into a build.
If you have a level stock chassis (say a Model A) with say a 5 degree caster set in the front cross member from the factory and you decide to hot rod or modify it in such away that the level chassis for what ever reason is now not so level and lowered at the front.
If the front caster has not been adjusted as part of these modifications, then your caster will be diminished to a point where any self centering characteristics in what is expected in normal steering will be lost and other scary shakes and shudders can start to be felt at various speeds.

In most builds caster can be difficult to adjust once your chassis is setup initially and welding is done.
We note guys using split radius rods generally try to wait until all the weight etc is on their chassis before choosing the exact final chassis attachment point for the radius rod ends, but still where the spring attaches to the chassis needs to be close to what is workable.

That is also the beauty in my view of the round pipe suicide front spring mount as it can be tacked welded together with caster set, but can easily be adjusted late into a build with few issues.
Four link suspensions offer a degree of adjustment, but who knows if the stance is severe enough, there may not be enough adjustment in threaded ends to get it where you really need it.
One of the greatest innovations in this regard is the swivel spring perches that offer an extra degree of compensation and adjustment.

What I am hoping to do is influence folks to think ahead of time when setting up the position and angle of their transverse spring attachment point on their chassis.
I don't like seeing springs twisted and distorted and forced into a unnatural shape as a means to achieve the caster angle that works.

Why caster angle is used?
The purpose of this is to provide a degree of self-centring for the steering — the wheel casters around in order to trail behind the axis of steering. ... Caster angles over 7 degrees with radial tyres are common. Power steering is usually necessary to overcome the jacking effect from the high caster angle.

What is the purpose of a caster?
The pivot points of the steering are angled in a way that a line drawn through them intersects the road surface slightly ahead of the contact point of the wheel. The purpose of this is to provide a degree of self-centering for the steering - the wheel casters around so as to trail behind the axis of steering.

Which way does caster pull?
Improper camber will wear our tires, but it will also affect handling. With other factors equal, a vehicle will pull in the direction that has the most positive camber. For instance, with a camber of zero degrees on the left wheel and one degree positive camber on the right wheel, produces a pull to the right.

 

The amount of caster you need depends on the weight on the front end. Stock specs range from -2° for a heavy, front-wheel-drive '66 Olds Toronado to +9° for a light, rear-engined Fiat 850 Spyder. An early Ford hot rod will generally have less weight on the front axle than a later, conventional car of comparable weight.

Caster and trail are interdependent. I'm not aware of any automobile manufacturers who use a significant offset of the stub axle on the spindle, though in theory it's possible. Conventionally, therefore, trail depends on caster in a definite proportion. All kinds of interesting possibilities emerge once you introduce "swivel lead", e.g. combining positive caster angle with negative trail might make the elusive but rather academic possibility of rear-wheel steering practical.

Significantly, the shopping trolley is really a bad illustration of caster flutter. The single wayward wheel on a shopping trolley is invariably due to a slight bend in the trolley frame. It certainly does not illustrate that caster flutter is caused by too much caster (swivel lead, or trail). It isn't. In fact manufacturers of casters recommend an increase in swivel lead as a cure for caster flutter. So, please stop trying to explain caster by reference to shopping trolleys!

 

A little something I found during some of my research, probably qualifies to be here.
Just goes to show what a transverse spring can do when called upon.
Boy, look at that front transverse spring working out...

 

Those old cars were made to twist and bend. You have seen the original Ford I beam axle twisted like a
screw. Henry Ford use alloy steel in critical parts. Other OEMs not so much.

 

Yes: the spring deflections are quite visible in the pic. But there's less twisting and bending than you might think. Simple pivoting on the shackles probably allows for the first 3½° of roll displacement.

 

Note the front wheel bottomed out on the front fender.

 

This is a perfect visaual explation of the correct preload tension.
Notice how the spring is actually pulling on the shackles into a nearly horizontal position. The weight of the chassis alone is not enough to get the spring to move much.
That is how Henry designed it


This next one is an aftermarket spring and after market axle.
It's pretty close to correct but the spring is just a touch too long- probably because of the revered eyes



These are great examples of springs that are too long,
Notice how the shackles are far away from horizontal
Both aftermarket, both will ride too high, both will ride hard,
Both will have the shackles crashing into the perches.
Seeing this condition at either stage is a great place to stop the
build and get the right spring.
These two are great examples of exactly what you do not want.


Be cautious about the bogus springs out there. The first clue is that you can install it without spreading or fighting it too much,,, there should be quite a bit of preload tension upon install

 

Never truer words spoken on this topic.
Thanks Buddy.

 

Greetings Ned!...been a few weeks since I checked this thread, I have heard of " suspension frequency in regards to oval track racing chassis's but don't have an adequate explanation, ..care to elaborate?...would I be even remotely correct in thinking the correct number has some correlation to sprung vs unsprung mass?...Love many of your comments, sometimes THEY keep me awake at night....I also agree wholeheartedly with 31 Vicky on the reason for a wider spacing on the U bolts as opposed to on in the center bolt location as I saw a whole lot of spring leaves that split through the U bolt hole due to loose U bolts and thus flexing in an undesirable location.

 

Caster is relational to the ground.

Crossmember angle is relational to the arc of the suspended swing.

The two are not necessarily directly related.

This is one of the most persistent misconceptions in transverse leaf suspension construction.

 

Someone finally mentioned having an extended 2nd leaf not interfere with a reverse-rolled eye. I remember one rodder snapping the entire reversed eye off the main leaf because the 2nd leaf was just too long.

 

I've explained it, or parts of it, before. Try:
https://www.jalopyjournal.com/forum/threads/check-my-math-please.986403/#post-11109944
https://www.jalopyjournal.com/forum...-in-hot-rods-school-me.1112128/#post-12619443

 

Here is a little something that has a place here.
Although no explanation regarding status of what weight or preload is being applied as mentioned earlier by 31Vicky.





Picture and diagrams always make things more interesting.

 

The pictures I referenced are just chassis weight, clearly.
The drawings are correct at full weight of a completed vehicle

It's confusing because the free arch height and loaded arch height are different, and as the arch height gets loaded with weight the spring length changes.

That 45* shackle angle results only when all the following are correct.
1 spring length
2 spring rate and vehicle weight match
3 preload tension is correct.
Bonus points if the loaded arch height is giving you the ride height you want.
If one of those 3 are off you'll not have the 45* angle.
The angle isn't the target per see it's the result of getting it right.

 

Was going to pose this question as a new post. Decided the transverse spring experts are already in attendance here. Folks seem to agree that in the stock configuration the 1932 Ford rear wheel sits 3/4" forward in the fender opening. See the pictures for my proposal. Has anyone done this? What are the ramifications? Will the banjo clear the rear crossmember? If not can crossmember be modified for clearance? Ron

 

Depending on what stage of a build you are at, it maybe easier to move the cross member back 3/4".
What account are you taking with respect to torque tube and drive train, will that all be moved back 3/4" as well???

The 1932 Ford has an interesting rear spring...
Must have been designed by Australians with that boomerang shape.

 

Speaking of rear springs, maybe it is time in this thread to discuss rear transverse springs.
That is not to say if anybody has more front spring stuff they whish to discuss, please have your say...

 

First we have the stock over the top of the diff setup mostly used in Model A's & T's.
The rear spring used in these models was of am unusually but practical shape and is still favoured by many hot rodders today.
Of course, as times have changed many of a our brethren have chosen to employed later model diffs and weld on kits were derived.

 

Except that shackles for springs (in a correct configuration) have NO or very little impact loading. Since a typical factor of safety for shock or impact loads is at least 2, the lack of shock loads allows these to safely be smaller than might be initially thought.

 

That’s my “Hot Rod” spring pictured above. It’s a 26/27 T -Spring made to 2.25” wide for a direct fit into a Model A xmember. The idea was to create a bolt in application for lowering a hot rod without major alterations to the spring,perches or xmember.


Sent from my iPhone using The H.A.M.B. mobile app

 

Matt, thanks for the opportunity to use it here in this thread.
When researching the internet one never knows whose pic's they are so now I can give you credit for that example.

 

Sticking with the same Model A & T rear spring, we find that this same odd looking spring was not only deployed over the diff, but also located behind the diff.
Cleverly done by some folks to lower the rear of the car in the first instance, but also to fit quite nicely over a quick change diff center which in actual fact looked as if it was made for it.
It would seem that generally the matching cross member was used.

 

FWIW
caster on my ‘32 sedan is 10 degrees
As it would have come from the factory.

 

Now we are talking about the spring behind diff setup, the 1932 Ford also had an interesting rear transverse spring with both arch in the spring leaves as well as a curvature in the horizontal.
I am not that familiar with all Ford models so don't recall if years after 1932 had similar or they lost the curvature and straightened themselves out.

 

33 and 34 Fords also had the curved rear spring, and the width is the same as a 32 Ford.

 

Running a behind the diff spring generally requires that the spring at the shackles is supported by spring hangers extended out from the radius rods as per stock or innovated or by welding on an extension from the diff tubes.
Either way seems to work fine, but there is still a little science in it when it comes to attaching original radius rod or weld attachments to a non stock diff.
Thought needs to be given to center to center spacing and matching the correct spring to that distance.
Having the wrong spring out back can see a car running with either a too hard or too soft ride and without enough preload quite sloppy in the handling department.