questions about rear springs on '70 Fury convertible

[saforwardlook]

The 215 whitewalls I bought are Hankook H724s. I did a lot of online research, and they get pretty good reviews. I ordered mine at Walmart, but I see that Amazon carries the 235 version of this tire, also whitewall, online for 82 bucks.
When you want whitewall "modern" tires, the universe is pretty limited out there. I think these Hankooks will be fine for my purpose.

The Hankooks that I am aware of in whitewall 235s are the Optimo - is that the same as the H724 designation? I really hated the look of the sidewall on the Optimos and eliminated them as an option for that reason. But don't know how wide the tread is either compared to what Dave is showing on his Polara.

 

[PM27G0D]

The Hankooks that I am aware of in whitewall 235s are the Optimo - is that the same as the H724 designation? I really hated the look of the sidewall on the Optimos and eliminated them as an option for that reason. But don't know how wide the tread is either compared to what Dave is showing on his Polara.

Yes, they are called Optimo H724s. I haven't really analyzed the sidewalls as they are still in the back of my Suburban, but, looks are somewhat secondary to me, except for the whitewalls...once I stray off the reservation of OE type tires.

 

[bluefury361]

I disagree with Will on this one. .... The springs have plenty to do with stability.

It's true Dave. Springs are designed to support vehicle weight, and only that. Of course a new set of springs will improve vehicle stability over a 45 year old set. And a new set of springs not engineered to the vehicle will adversely effect handling without additional modifications. Springs that raise a vehicle over its OEM ride heighth increases center of gravity, That effects handling to a negative degree. That's apples to oranges.

Springs do not effect axle joust, shocks do. Springs have no effect on body sway A sway bar and shocks do.

A little research will bring this to light.

 

[polara71]

The spring metal can flex and roll, it all works together....shocks, sway bar, springs.....putting a great set of shocks on a car with bad springs will do very little

 

[1970cat]

springs are up and down movement. the only way i could see them twisting is extreme force such as drag racing (axle wrap). any side to side movement should be limited to the the play in the shackles and bushings. if the springs themselves flexed then it would pull the bands apart. new shocks will mask the signs of bad springs but not for long. they aren't designed to support the weight of the car.

 

[bluefury361]

The spring metal can flex and roll, it all works together....shocks, sway bar, springs.....putting a great set of shocks on a car with bad springs will do very little

Damm kids...... just won't listen.
If the metal in your springs is "flexing/twisting" as your suggesting then you've got a real problem.

 

[polara71]

I need more....

So you're telling me the springs give absolutely no control over side to side movement, down to the millimeter? The car is sitting on them for Christ sakes......


So I'm watching the movie Bullet and that Charger and Mustang are relying completely on shocks and a sway bar to keep those cars from going side to side?

 

[commando1]

 

[bluefury361]

So I'm watching the movie Bullet and that Charger and Mustang are relying completely on shocks and a sway bar to keep those cars from going side to side?

YES....!!! :yes:
I'm a standard measure kind of guy. I don't use millimeters. But it sounds a little nit picky.
I'm sure the OEM bushings will allow for "inches" of side thrust movement on a huge C body.

 

[68plymouth383]

I can agree with a handling aspect that good shocks, and front sway bar will at least make the car more stable. But 90 percent of how the rear end of the car responce is in the springs. Shocks dampen. Shocks help control. If you've ever seen the movie uncle buck john candy car needed shocks 20 years ago. Shocks control travel when you hit a bump. Shocks in, and of themselves won't make your car handle like it's on rails. Shocks won't take the marshmallow ride out. New springs will get that taken care of. My 2 cents, and a penny more for good measure.

 

[1970cat]

yes, but that was up and down, not side to side as in cornering. there are rubber bushings in the shackles. they along with the shackles themselves are the side to side flex.

 

[bluefury361]

I need more....

So you're telling me the springs give absolutely no control over side to side movement, QUOTE]

Actually they do, to a degree. In addition to supporting the vehicles weight the leaf springs also locate the axle so as to maintain wheelbase and alignment, in addition to transferring forces from acceleration and braking to the vehicle in a controlled manner.

Body roll is limited by the length of travel of each leaf spring during hard cornering, which would be too extreme to maintain vehicle control. The rubber bushing in the springs front "eye" would need to absorb all the energy and it would not be long before it would fail. Solid, non energy absorbing mounts are sometimes used in racing applications, but are not condusive to smooth street operation.
This energy is absorbed with an anti sway bar. For general use, street driving vehicles, a bar in the front will usually suffice. For the more aggressive driver the addition of a rear sway bar will diminish body roll.

Lastly are the shock absorbers. They maintain joust and rebound control of the springs.

There are hundreds of combinations of springs, shocks and sway control devices. To obtain optimum performance for your driving demands a well planned combination will be rewarding.

 

[Fury440]

I have a 70 Fury convertible with a factory 440 and the springs are just like your picture. They are flat with zero bow. I do have a factory front sway bar which makes a difference. I found tire pressure front to rear is critical. Start with 30 psi all round and then test drive. Once the tires cool, reduce the fronts by 1 psi and retest. If I remember I ended up with 26psi front 30psi rear. When you get it right, a 70 Fury convertible with it's lower center of gravity corners like it's on rails.

BTW full size radials handle much better that the low profile "rubber band" tires.

 

[commando1]

 

[PM27G0D]

I have a 70 Fury convertible with a factory 440 and the springs are just like your picture. They are flat with zero bow. I do have a factory front sway bar which makes a difference. I found tire pressure front to rear is critical. Start with 30 psi all round and then test drive. Once the tires cool, reduce the fronts by 1 psi and retest. If I remember I ended up with 26psi front 30psi rear. When you get it right, a 70 Fury convertible with it's lower center of gravity corners like it's on rails.

BTW full size radials handle much better that the low profile "rubber band" tires.

Hi Bill
thanks for that info. Do your springs have just 5 leaves as well? If you have your broadcast sheet, I'd be interested in what numbers it shows under springs.

 

[bluefury361]

Good point. Proper tire size and inflation will play an additional and important role in handling. Tire pressure will increase or decrease joust in conjuction with shock absorbers.

 

[polara71]

And the springs

 

[saforwardlook]

I find this thread confusing relative to the terms/context being used. Spring rates affect stability of a car. When making turns and loading one side of the car due to inertial forces, a stiffer spring rate will resist sway or body roll on the side being loaded more than a weaker spring rate. And yes, sway bars, properly set up will also enhance the stability or resistance to sway. I am not sure what all the other gobbledygook is about? Maybe maximum cornering ability?

Steve

 

[PM27G0D]

Yeah, I'm not looking to road race or autocross this thing. I just want a little more confidence that if I have to do any sort of avoidance manuever at highway speed, that I won't end up upside down in the median...or worse. It's that scary now.

 

[polara71]

I find this thread confusing relative to the terms/context being used. Spring rates affect stability of a car. When making turns and loading one side of the car due to inertial forces, a stiffer spring rate will resist sway or body roll on the side being loaded more than a weaker spring rate. And yes, sway bars, properly set up will also enhance the stability or resistance to sway. I am not sure what all the other gobbledygook is about? Maybe maximum cornering ability?

Steve

Thats all im sayin'