66 rear leaf springs

[Soell66]

Not sure if my 66 rear leaf springs have ever been replaced. There is a ford stamp and C6TA 5560.. how much arch should they have .

 

[DirtDonk]

Not sure if we've ever posted a chart showing the arch, whether installed or loose, but we have a measurement you can make as long as the vehicle is still on the ground and at full weight.
Measure the distance between the top of the axle tube and the bottom of the frame rail. The rear is approx. 6" stock (front is 7" if you're going to check that too) so anything more than a half-inch above or below that is your lift or sag.
If you do not have any lift (there would be no block under the spring from the factory on Early Broncos) then anything below 6" is the amount of sag.
I mention half an inch, but really it should be within about a quarter inch I would think. It's just that there are variations even from the factory.
A roadster vs a half cab might sit differently, but a roadster vs a full hard top and rear tire carrier with larger tire and a roll cage and other additions certainly would.

But it gets you close.

Paul

 

[DirtDonk]

Oh, and yes I would imagine that there should be a Ford number and logo stamped somewhere. Probably on the main leaf.
But I've heard of people not finding the numbers. Never looked for them on my originals...

Original orientation of certain things might help too. Other than just looking like they're original.
The shackle's open end faces the rear.
The "Berlin eye" of the leaf pack is attached at the front/frame end. The standard eye is at the rear/shackle. (Berlin eye has a slight curve to the leaf before the round eye. Putting the leaf almost directly into the middle of the eye rather than below it)
Original u-bolts are about 1/2" max and often break when you try to remove them. Anything newer looking or larger than that, and at least the u-bolts have been replaced.
Original bushings are rubber vulcanized to a metal sleeve with serrated ends. They're most likely trashed.

And finally, if either of the rear spring or shackle bolts will not come out, they're likely original!

Paul

 

[Soell66]

Not sure if we've ever posted a chart showing the arch, whether installed or loose, but we have a measurement you can make as long as the vehicle is still on the ground and at full weight.
Measure the distance between the top of the axle tube and the bottom of the frame rail. The rear is approx. 6" stock (front is 7" if you're going to check that too) so anything more than a half-inch above or below that is your lift or sag.
If you do not have any lift (there would be no block under the spring from the factory on Early Broncos) then anything below 6" is the amount of sag.
I mention half an inch, but really it should be within about a quarter inch I would think. It's just that there are variations even from the factory.
A roadster vs a half cab might sit differently, but a roadster vs a full hard top and rear tire carrier with larger tire and a roll cage and other additions certainly would.

But it gets you close.

Paul

Ok so all my measurements are longer than that. My rear leaf springs have 6 springs. 3 have the band around them. The total width of the springs are 2 inches at the axle where they attach with u bolts. I would send pics but can’t just attach them like an email.

 

[DirtDonk]

Right, to upload them directly to this discussion, you need to become a contributor for $12 a year.
However, you can upload them to your “garage“ or “gallery“ functions, and we can still view them if we navigate to those locations.
You can also send them to me at my paulb@wildhorses4x4.Com work email address and I can post them up here for you.

 

[DirtDonk]

Does your count of six leaves include the thick lower leaf that is usually slightly separated at the end? The bottom leaf is an “overload” so to speak.
Factory leaf springs were available in five or six leaf packs, depending upon which suspension option you got.
The heavy duty had five leaves plus an overload, and the light duty had four leaves plus an overload.
Usually if the main pack is sagging it will touch the bottom overload leaf. Makes the ride real stiff, but also indicates a bit of sag.

 

[Soell66]

Right, to upload them directly to this discussion, you need to become a contributor for $12 a year.
However, you can upload them to your “garage“ or “gallery“ functions, and we can still view them if we navigate to those locations.
You can also send them to me at my paulb@wildhorses4x4.Com work email address and I can post them up here for you.

Sent you an email with pics.

 

[Soell66]

Does your count of six leaves include the thick lower leaf that is usually slightly separated at the end? The bottom leaf is an “overload” so to speak.
Factory leaf springs were available in five or six leaf packs, depending upon which suspension option you got.
The heavy duty had five leaves plus an overload, and the light duty had four leaves plus an overload.
Usually if the main pack is sagging it will touch the bottom overload leaf. Makes the ride real stiff, but also indicates a bit of sag.

6 total 5 regular and 1 overload.

 

[DirtDonk]

Thanks. I was going to message you earlier, but didn’t get the chance. I got a notification that an email had failed, so maybe our system is giving us a little trouble with pictures.
I’ll see if I can get that dealt with, and in the meantime, when I get back to my computer, I will private message you my Email directly, so you can just send them straight to me without going through our server/system.

 

[Soell66]

Thanks. I was going to message you earlier, but didn’t get the chance. I got a notification that an email had failed, so maybe our system is giving us a little trouble with pictures.
I’ll see if I can get that dealt with, and in the meantime, when I get back to my computer, I will private message you my Email directly, so you can just send them straight to me without going through our server/system.

Sounds good. Mine aren’t bottoming on overload spring. Haven’t had a bronco before but have a 60 model f-100. Bronco just seems really stiff

 

[DirtDonk]

That's common, especially with the old leaves. Leaf packs often "take a set" where they tend to stay where they have sat for the last 60 years or so almost.
In some cases it's just stiction, while in other cases the tips of the leaves have each actually worn a groove into the leaf above them. This makes the initial movement difficult until they break free, so to speak. Making the ride particularly harsh.
I found this on my '71 and when I wanted a little cheap lift I used add-a-leaves even though I knew (incorrectly as it turns out) that they would make the ride even stiffer.
The result was that, moving each leaf out of it's pocket slightly actually improved the ride! An added leaf must by design make the spring "stiffer" but what went away was the initial harshness of the ride around town. Bonus!

But two other things greatly effect the ride. Along with springs, the shocks and especially the tires have a great effect on perceived stiffness and ride harshness.
So don't automatically spend a bundle on springs and use old shocks and old tires.
Speaking of which... What type, brand and size tire, and what air pressure are you running?

Paul

 

[DirtDonk]

Sent you a PM (private message) now called a "Conversation" in our newer system.

Paul

 

[Soell66]

That's common, especially with the old leaves. Leaf packs often "take a set" where they tend to stay where they have sat for the last 60 years or so almost.
In some cases it's just stiction, while in other cases the tips of the leaves have each actually worn a groove into the leaf above them. This makes the initial movement difficult until they break free, so to speak. Making the ride particularly harsh.
I found this on my '71 and when I wanted a little cheap lift I used add-a-leaves even though I knew (incorrectly as it turns out) that they would make the ride even stiffer.
The result was that, moving each leaf out of it's pocket slightly actually improved the ride! An added leaf must by design make the spring "stiffer" but what went away was the initial harshness of the ride around town. Bonus!

But two other things greatly effect the ride. Along with springs, the shocks and especially the tires have a great effect on perceived stiffness and ride harshness.
So don't automatically spend a bundle on springs and use old shocks and old tires.
Speaking of which... What type, brand and size tire, and what air pressure are you running?

Paul

I have 285/70 R17 Cooper discovery and they run at 28-29lbs

 

[DirtDonk]

Nice tires. But if they are load range E then even with low air pressure they probably still have a little bit of inherent ride harshness that you will feel.
I got the pictures you sent and will post them up as soon as I get home.
Looks like you have Monroe Magnums on there too. Maybe Gas Magnums.
They might’ve been painted over so there’s no telling how old they are. But given the fact that they are Monroe magnums probably means they’re pretty old.
And stiff…

 

[DirtDonk]

Sorry for the delay in getting the pics posted up. Not very efficient this method!
But here they are finally:

1. Looks like a 5-leaf pack with an add-a-leaf.

2. You can see where the spring has barely moved during use, but clearly it wipes the spring above it as mentioned before. Rusting where the paint is rubbed off.

3. Looks like a Gas-Magnum to me. But were there other shocks labeled as "Magnum" back in the day? The Monroe was the most well known at least.

 

[Soell66]

So springs are good? I plan on changing our front and rear shocks

 

[DirtDonk]

Well, “good“ is a relative term with near 60 year old springs.
They’re still holding the vehicle up, they are all in one piece, and they’re not gonna leave you stranded. However, they are going to ride like crap as all old truck springs did and do, and you may need to replace the bushings.
However, they are perfectly usable in their current condition.

 

[Soell66]

Well, “good“ is a relative term with near 60 year old springs.
They’re still holding the vehicle up, they are all in one piece, and they’re not gonna leave you stranded. However, they are going to ride like crap as all old truck springs did and do, and you may need to replace the bushings.
However, they are perfectly usable in their current condition.

So my next question would it be worth replacing them since I am changing out shocks and if so are those a normal set up or is the add a leaf different

 

[DirtDonk]

There are a lot of better, more modern designs available now. Including from us.
Fitment should be no problem, because even with the presence of an add-a-leaf, that doesn’t change the overall dimensions of the spring itself. Just the ride height.
The thickness of the pack, and the number of leaves will be different, but that is part of the new design strategy.
They would still be the same width and roughly the same length as your current spring packs.

Which ones you choose as far as lift height is concerned will depend on what your measurements were the other day.
Maybe a one and a half inch lift would put you right where you are now and match the front springs.
Add a leaf kits were typically designed around the 1 1/2 inch to 2 inch height change.
If you are doing just a street truck and not going to carry any heavy loads or full weekend camping gear and passenger type stuff, you could go with a slightly higher lift spring and remove some leaves to bring the height down a little and for an even softer ride still.

So still a few questions, and decisions to be made before you decide to change, or if so, which way to go.
Hopefully others will get in on the discussion and give you some good ideas as well.