Independent Front Suspension in a 32 Ford

There are multiple manufacturers of independent suspensions, and I have been looking at them closely. I ended up purchasing a TCI set up from Pete and Jakes. I selected this unit because it had several more desirable features and was actually less costly than some of its competitors. I know they have been around a long time and even market complete chassis set ups. In looking at the suspensions, I noticed that on many/most of them, the upper A arm is not parallel to the ground......yet some are parallel to the ground. Is this just a difference in adjustments or designs?
I would like to know how this positioning affects driveability and what the pros and cons are. Here are some pictures to illustrate what I'm saying.

Heidts



Here is the Pete and Jakes Display set up











Another Heidts notice that the top arm is angled more than the one in the first picture.

 

The length and angle of the arms in relation to each other dictate what the tyre (tire) does when the suspension moves, particularly under compression.
To best se it in action you need to visualise (or draw it up) what each arm does when the suspension rises or falls.
You want the top arm to move in a tighter circle or shorter arc than the bottom to promote the top of the wheel to move inwards more than the bottom.
By moving the top of the wheel inwards, promoting negative camber, you improve cornering.
Do so searching in Goggle and you will find enough reading material to last the rest of you life.
Suspension geometry is fascinating and actually quite complex.

 

Lower control arms that are level or at an upward angle(bj higher than pivot), tend to have bad roll centers and will not handle well.

Also note that the P&Js frame is unloaded , put a body and drivetrain in it the control arms will probably be similarly angled as the completed cars.

It puts the roll center in the ground, making for a teeter totter of a ride.
Some pure race cars do have near horizontal lower control arms however these cars are so low and have low mass as well as low center of gravity, that it won't affect them as badly as a street vehicle. F1 cars have some extreme funk when it comes to geometry but they operate in a different world.

Ideally if you want a lowered ride, the inner pivot points would be moved up, leaving the BJ at the desired height while maintaining a decent roll center.

On the 32 it can get away with a bit, engine is behind axle centerline, car is relatively small and light~2500lbs.

All in all I don't think there will be any difference looking at the angles.

 

The tie rods should be level with the ground as well as lower arm , swing in same arc . Correct ?

 

@Kerrynzl

I'm fairly sure the top arm should be angled down towards the frame. Kerry will know....

 

Spindle height and control arm mounting height can be different per how these are designed.

Taller spindles or lowering the upper arm mounting position was used to improve handling on older cars. The upper arm angling upward towards the spindle

 

^^^. See articles on the “Shelby drop” for early Mustangs and Cougars.

 

Both upper and lower pointing downward is ideal.
If the upper only is lower it can shorten the instant centre which raises the roll centre.
But the benefit of this is ^^^ is camber gain which is more desirable.

Low roll centre increases bodyroll [overturning moment] but this can be controlled with roll stiffness.

Understand all these "quirks" are only a problem at the limit of tyre adhesion.
If lateral acceleration loads [weight transfer] exceed the vertical weight of the vehicle you can get "jacking" on a corner.

This ^^^^ is very similar to Anti-Squat / Squat at the CG on a drag car [which most people confuse for overturning moment]

The rules aren't "set in concrete"
They raised the lower inner pivot on F1 cars to gat the same camber gain [this method was needed for the High Nose Venturi Aerodynamics]
this was in 2001


But these cars also have massive down force that would exceed any "jacking" and very limited suspension movement.

Generally all these changes are engineering "integrity" [ the taller spindle will spread /dissipate the loads through a wider area.]
It is all about force over resistance [with leverage in between]
The force is applied at the CGH, and the resistance is applied at the tyre contact patch

Modern race cars [open wheelers] are trending towards raising the lower A-Arm for Aero purposes, but this creates an increased cantilever effect between the tyre contact patch and upper A-Arm [but carbon fibre and Titanium is now the normal materials]

The old Shelby drop was used purely for camber gain, If a car had zero bodyroll no camber gain is needed at all
Back then the cars were quite softly sprung.
They needed to be [because they were all understeering pigs]

 

I have 91 corvette c4 on the front of my truck. The lower a arms are parallel to the ground at ride height.

 

There is a library of books on suspension design and tuning. Since you brought up a very specific application, you should try to find good information on that exact case. That's going to be the hard part!

But in general, you want in order (guessing here), that it all fits to '32 frame rails and under 32 fenders, good ride over public roads, good handling, good tire wear/looks and is easily serviced and repaired.

So what works on a vehicle that has different weight, center of gravity, built for race track or off road, has components that won't fit, etc. may point in different directions.
Since you already bought a quality setup from a known source, there may be tricks and tips to get the most out of it, but their tech line probably has the most data to work with. Only a high volume specialty car dealer is going to have near the same breadth of experience. Polling a bunch of forum people who for the most part only have a couple cars isn't going to provide specs that get the best for you.

Just looking at the recent 1932 Ford thread (with trad suspension) shows the vast differences on ride height and wheel/tire selection. That will make a big difference in how the suspension is set up and adjusted.
https://www.jalopyjournal.com/forum/threads/best-32-ford-of-all-time-lets-see-em.1339400/

 

I have read each of the responses and appreciate the input from everyone. One of the things that concerns me is that when the upper A arm is on an angle while at its normal roadside weight, The range of motion for the upper ball joint seems to be much smaller on several of these assemblies. Is there a way to insure that there is sufficient travel and does the one in the picture look wrong (to much angle) to any of you ? Again, thanks for the inputs.

 

Are you making your own A-Arm??
You mount/tilt the ball-joint "cup" vertical [blue vertical lines] at ride height, it doesn't matter if the actual A-Arm is at an angle.
The A-Arm geometry is a straight line between 2 pivot points [the actual shape of the Arm doesn't matter]


The "Shelby drop" was 1" which was the most that Shelby's crew could get without the ball-joints binding.
But now you can buy wedge sandwich plates to correct this.
On my old racer we dropped the uppers 2" and also tilted them back for some "Anti-Dive"

The distinct advantage of dropping the A-Arm is more induced camber [dynamic camber] so on a road car you can have 0° camber for cruising around/tyre wear. But lean on it and there is Neg.

 

Also you can move the A-Arm inner pivots rearward [or change the shape of the "A"] to get caster.
This leans the spindle/knuckle rearward. at the top.

If you tilt the rear pivot down 10° + it indices "Anti-Dive".
As the front suspension compresses, there is dynamic caster [which fights brake torque reaction in the spindle]
Brake torque reaction tries to "plant" the front wheels into the pavement.

The downside of too much anti-dive is the front end, it feels unstable braking hard on uneven surfaces.

Here is my old Corvette racer [showing the Guldstrand mod/Shelby drop]
4 mods were done at the same time by cutting welding the frame horns.

They were moved inboard [Camber]
Moved rearward [Caster]
Tilted [Anti-Dive]
Lowered [Induced Camber]

It was a "Very thin" interpretation of the rules.
The rules said we must maintain the original mounting points which we did [we simply moved them]

 

Imagine equal-length, parallel A-arms, parallel to the ground at rest. Because the lines of the upper and lower arms never cross, the effective swing-arm length on each side of the car is infinite. In this respect it'd behave like a VW Bug trailing-arm setup, i.e. camber gain equals the roll angle.

Like the VW system, the roll centre is on the ground at ride height, but unlike the VW system, the roll centre moves below the road during bump motion and above the road during heave/droop.

If we make the upper arms shorter than the lower arms, the effective swing arm length is still infinite when the suspension is at rest. As soon as anything moves, however, the angle of the upper arms changes more rapidly than that of the lower arms. That causes the effective swing arm length to be less than infinite. During bump, the effective swing arm centre is somewhere on the opposite side of the car, and it moves closer the more the suspension moves. The roll centre stays somewhere around road level, which is good.

During heave/droop, however, the effective swing arm centre goes and sits out on the same side of the car. That most certainly puts the roll centre below the ground. A roll centre below the ground isn't necessarily a bad thing in itself, but a roll centre whose migration suddenly changes halfway through suspension cycling can be. And it gets more complex in roll, when you have both effective swing arm centres on the inside of the curve!

It's probably splitting hairs, though.

Moving the upper arm inner pivots down shortens the effective swing arm length at ride height, and creates a situation where the effective swing arm length will never go to infinite anywhere during any suspension motion. Generally, this means smaller and more linear changes in geometry through the various suspension motions.

Moving the lower arm inner pivots down as well allows you to get the roll centre closer to the ground.

Relatively short effective swing arms are good for camber recovery, but they have a practical limit. I mentioned that equal/parallel A-arms and trailing arms produce camber gain equal to the roll angle. Unequal-length A-arms produce camber gain less than the roll angle, especially if the arms are angled intelligently. This reduction in camber gain is called camber recovery.

In the days when the handling ill foremost in designers' minds was vicious oversteer — due to wide rear spring bases and way too much rear roll stiffness — the advantage of IFS was precisely camber gain. That is why pure trailing systems like the Dubonnet/GM Knee Action were taken seriously, even in competition contexts. As suspension improved overall, 100% camber gain became a net liability, and camber recovery became more important.

Within the geometric variables of SLA suspension, 100% camber recovery requires an effective swing arm length of half the track width. As effective swing arm lengths can change a lot with suspension motion, this can easily result in weird wheel movements at extremes of bump and droop — or even simply in the range you'd expect during ordinary driving. No SLA setup you're likely to meet comes close to 100% camber recovery. Even extreme racing suspension only approaches 100% camber recovery by having very limited travel, and the possibility of placing the roll centre below the ground to counteract jacking effects.

Anyone claiming to have a streetable SLA suspension with 100% camber recovery is either lying or doesn't understand camber recovery.

 

No, I'm using the ones that came with the TCI kit. In the picture above it just seems to me that the inner mounting point should be a little higher for the A arm. I will mock up mine and check this clearance before welding it solid. Right now I have not removed things from the boxes yet, so maybe I won't have a problem (hopefully), but it just seemed odd to me that there was so much variation from kit to kit. There does seem to be room for the inner pivot to be higher. Anyway I'm appreciative of all the help everyone is giving me.

 

Thanks for the explanation. I have to take my wife to a doctors appt and don't have the time to digest this thoroughly right now. Looks like I'm going to have to study these responses and read them a few times to try to absorb what you guys are telling me. Thanks again, gotta go.

 

hope you don't plan to have the front low

 

the only thing you can lower on a fendered 32 with Ifs is the value...

 

here's what happens.... the 32 doesn't have much wheel well...so you need to run the front up about 3'' more than a traditional axel.... if you look at all the pics you post, about 1'' travel... if you run a soft enough spring to make the ride good.... the tire will knock the fender off and at full compression the cross member is below the scrub line.. if you set it up to have suspension... it'll have the gasser , low rider, front too high look... nothing rides as good as set up proper traditional front end... aat least thats what mitch told me....

 

No.
I've seen this stated many times, it's wrong.
This will start the suspension on a camber losing curve.
When a straight line can be drawn from BJ to BJ while intersecting the lower control arm pivots, that is the maximum amount of camber that the LCA can gain. Rotating up or down is positive camber. Immediately handicapping yourself.
An upper control arm can only do so much, especially in a constrained space.
But worse...
Roll center will be in the middle of the front cross member at best. Lower it and roll center starts going into the ground. It also limits useful suspension travel.

Steering links and lower control arm should allow LBJ and outer tierod BJ to sweep in congruent arcs through useful suspension travel. This will reduce bump/roll steer. Depending on desireable outcome, a little bumpsteer can be an aid during certain cornering conditions. But in a straight line you want 0.

 

listen to this.... spot on....and the problem for lowered hot rods...they'll do some weird shit in wash board situations...by design... they work... but not lowered...the fix is to install the cross member up higher...so there is suspension travel...but what happens again is the no wheel travel because of fenders..soooo. look at all the premium hot rod builders.. anotice... none of them use IFS on pre 36 cars....and like said... when done it will lower the value of the car... that and you have to listen to... who the fuc put that suspension on a 32... I had a roadster with tci....and a sedan with heidts...nether performed well and for sure a down grade...but your car... do what you want...thats what I do... but also... you asked.....so I stepped up hoping before you jumped in the swamp... there is probley more than a 100 to one that think that you should not do this.... but don't post

 

very good info.... this is why I cycle the suspension with out the coil over...then you can see the happy spot and spring for that...some times to get a quality ride... you have to fake wheel travel and in stall bump stops... this gives you a somewhat nice ride... but keeps you from blowing through the suspension on a pot hole or big bump...also keeps you from blocking out the coil spring

 

Look, without being offensive, I don't build anything to satisfy other people. I build it to suit what I think is best for my vision and my needs. I don't let others set parameters that I have to adhere to so that I can be accepted in their circle of friends.

I think that a straight axle looks great on early street rods. Personally I think that a well done independent suspension looks good too. Virtually everyone that builds a traditional street rod employs many things into their builds that weren't used or even available in "pick an era" years. Even picking an era or time period is a matter of personal preference. The Hamb defines it as anything prior to 1966. Other sites define it as prior to 1950, or some other arbitrary date.

I posted this in the "OFF TOPIC" section, so more broadminded people could provide me with some help and the benefit of their knowledge. I appreciate what they have provided for me to digest and hopefully grasp.

If I wanted a straight axle, that's what I would have bought, but the decision to use independent suspension was not done with out a lot of thought about how I want my car to be. Build your car your way and I'll do the same on mine. If you have any technical info that would help me, I'll be glad to get it. I think you will see lots more people doing this swap as old dinosaurs like myself continue to become extinct. There will always be some among us that like to place limits on whats acceptable for others. I have certain things that I dislike in many more modern builds, but I just avoid those vehicles and try to find others that appeal to me..........


I met a guy at the Nationals a few years ago and he bought a Model A from me. He had this Rat Rod with a turbocharged 4 Cyl honda in it. No widows or unnecessary weight. Took me for a ride in it and it was a white knuckle experience. He had torn out second gear and I couldn't even tell it. Scared the crap out of me. He was a nice guy and I enjoyed meeting him and his family when I towed the Model A to his house. It was a great experience, I learned a lot, and it was memorable day for me. If I had closed my mind to him because he had a Rat Rod I'd never have had that memory.




Enjoy.................

 

I haven't noticed that they have a problem obtaining a low enough front end or getting the stance that I want. Here is an example that looks just fine to me.

 

Used to be you could get a 30 day trial for Performance Trends suspension software.
This is what I did with my 65 Chevelle.
If you have all the pickup points, arm length,BJ locations, etc. etc., you can plug them in and see what effects what.
And you can move them around to see what mods would benefit being moved.
Worth a look see. If nothing else you may get a visual of how things play together or not together.

 

That 'looks' good. However, in my limited understanding of the double wishbone Short/Long Arm suspension system, the normal set up is that both upper and lower control arms are attached to the frame ABOVE the respective ball joint ends at ride height. This allows the arc they move through to swing thru the middle of their arcs under compression.
The lower arm is parallel to the ground, not angled down from frame to spindle. The upper is probably level or pointing UP from the frame to spindle. This is a design choice and is a compromise.
I tried to find a basic design site or video, but it seems AI and India have clogged up the results.

Are you old enough to remember the old suspension displays in repair shops? They had one that showed why you needed to replace your worn springs. The suspension would droop, lowering your car. This caused tire wear and less stable handling. The top of the tire would lean in under compression.
All the guys that wanted to lower their cars would ignore these!

 

There was 32 with IFS done before 60,
I think I have seen afew pic's here before
40 , Not for sure , may be 50 right after
WWII , roadster
This 32 if I remember correct was Originally built west coast before 60 , maybe 55 , sold went East , the son of father located purchased back a few years ago , & drove back from
NJ to Ca ,
If this Not the 32 , one like it ,

 

look a little closer AT THE PIC.... THE SPRING IS ALMOST BLOCKED OUT SETTING THERE... SO NO UP TRAVEL... PERFECT TRAILER QUEEN... DO WHAT EVER YOU WANT... if want you want is some support that what you are doing is good... can't help.... but... when the people that sell the stuff won't put it on their car... there's a reason...to me... I don't really care what you do... just wanted to post the other side of the result...

 

It’s got plenty of travel.
These light weight rides don’t need a lot
The straight axle stuff has minimal movement.

Kugel runs his stuff on his rides. Maybe the experts should call him. He might appreciate the advice

scrub isn’t any different than any dropped axle cruising around.
2 cars. One with IFS the other with a straight axle running the same front diameter tire can sit at the same height and have the same travel.
And both rub the fender.