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View Full Version : CJ8 (or CJ7) heavy duty suspension question.



Joe West
12-23-2009, 06:24 PM
Hi Gang,

I had the factory springs on my Scrambler re-arched, pads and centering bolts replaced and then painted and it reminded me of a question I had for the experts here.

The original owner that I bought it from said she ordered it with limited slip and heavy duty suspension. I have verified the limited slip but I never verified it had heavy duty suspension.

If I look at my springs... the front springs have 4 leafs and the rear springs have 6 leafs... does anyone know how many leafs a standard suspension has? Perhaps someone who still has factory springs could examine the number of leafs front and rear and let me know what they find on their rig. I'd be curious to know whether the heavy duty suspension has additional leaf springs in the rear.... or perhaps someone knows the difference between standard duty suspension and heavy duty suspension off the top of their head.

Thanks in advance.

Joe

85LAREDOCJ7
12-23-2009, 06:41 PM
Joe....my stock CJ is sitting in Doc's shop. Maybe he can take a look at it for ya??

85LAREDOCJ7
12-23-2009, 06:46 PM
Maybe the scramblers came with a heavier leaf because of the payload capacity for the bed??

Doc in AZ
12-23-2009, 06:52 PM
Joe....my stock CJ is sitting in Doc's shop. Maybe he can take a look at it for ya??

lol... i was going to look in the morning and post up... but...


Maybe the scramblers came with a heavier leaf because of the payload capacity for the bed??

yeah

Joe West
12-23-2009, 06:53 PM
By the way... I have a bunch of miscellaneous pictures of Scramblers that I've captured from the web (I use them for restoration references) and every picture I can find of an original rear leaf spring setup on a Scrambler has 4 leafs on it. I hypothesize that the standard suspension had 4 leafs front and rear and the heavy duty suspension had 4 leafs front and 6 leafs rear.

ob1jeeper
12-23-2009, 07:36 PM
By the way... I have a bunch of miscellaneous pictures of Scramblers that I've captured from the web (I use them for restoration references) and every picture I can find of an original rear leaf spring setup on a Scrambler has 4 leafs on it. I hypothesize that the standard suspension had 4 leafs front and rear and the heavy duty suspension had 4 leafs front and 6 leafs rear.
Joe,
There were several suspension spring offerings and combinations for CJ8's destined for various markets and uses.

Front springs ranged from a "soft-ride" 4-leaf, to a "severe use" 7-leaf for export markets, with both a 5 & 6 leaf between the 4 & 7 leaf options.

Rear springs ranged from a "soft-ride" 4-leaf, to a "severe use" 9-leaf for export markets, with a 5, 6, & 7 leaf option inbetween the 4 & 9.

Ditto for the shocks... There were multiple shock packages to fit the varety of spring options that could be ordered...;)

HTH...;)

Joe West
12-23-2009, 07:43 PM
Thanks Steve. 4 up front and 4 in the rear must be the common US configuration... out of the 10 or so pictures I have of the undercarriages of various scramblers, all of them have 4 leafs front and rear.

I can't imagine what 7 springs front and rear must ride like... oh... wait... yes I can... it would ride like a Willys MB.

HAHAHAHAHAHAHA




Joe,
There were several suspension spring offerings and combinations for CJ8's destined for various markets and uses.

Front springs ranged from a "soft-ride" 4-leaf, to a "severe use" 7-leaf for export markets, with both a 5 & 6 leaf between the 4 & 7 leaf options.

Rear springs ranged from a "soft-ride" 4-leaf, to a "severe use" 9-leaf for export markets, with a 5, 6, & 7 leaf option inbetween the 4 & 9.

Ditto for the shocks... There were multiple shock packages to fit the varety of spring options that could be ordered...;)

HTH...;)

djui5
12-23-2009, 07:45 PM
Steve,
My CJ-6 has 9 leafs in the front and 5 in the back, was that factory??

ob1jeeper
12-23-2009, 07:59 PM
Steve,
My CJ-6 has 9 leafs in the front and 5 in the back, was that factory??
Randy,
For the '74 CJ6, the fronts were either a 7, 9, or 10 leaf, with 7 the std suspension for the 6-cyl, and the 9-leaf std susp. for the V-8, and the 10 leaf the "HD" susp frt spring option. Your 9-leaf front is correct and is PN 5352848.

The standard rear spring for both 6 & 8 cyls should be a 5-leaf, with a PN of 5352845. The HD rear optional suspension spring was a 10 leaf.

;)

ob1jeeper
12-23-2009, 08:34 PM
Thanks Steve. 4 up front and 4 in the rear must be the common US configuration... out of the 10 or so pictures I have of the undercarriages of various scramblers, all of them have 4 leafs front and rear.

I can't imagine what 7 springs front and rear must ride like... oh... wait... yes I can... it would ride like a Willys MB.

HAHAHAHAHAHAHA
Not to confuse th issue, but the number of the leaves in each spring pack alone will not give you a true insight into the spring rate (stiffness) of a given spring pack.

Just look @ the front 9-leaf packs on Randy's CJ6, which were the "std" suspension set up, to see that the individual leaf thickness also has a great deal to do with leaf spring rates...;)

Joe West
12-23-2009, 09:04 PM
Hi Steve,

I assumed for any specific application, the thickness of the leafs were the same no matter how many leafs there were.

For instance... if standard duty on my CJ8 was 4 leafs... I assume the 5 leaf added 1 more leaf of the same thickness as each of the original 4 and the 6 leaf added 2 more leafs of the same thickness of each of the original 4 and so on.

I assumed that each application may use different leaf dimensions but in any given application, all the leafs were the same dimension and the factory just added more leafs to get the spring rate for the different options.

Do you know if this is correct for Jeeps? Would the leaf dimensions in a 4 leaf Scrambler spring have the same dimensions as a leaf in a 6 leaf Scrambler spring?





Not to confuse th issue, but the number of the leaves in each spring pack alone will not give you a true insight into the spring rate (stiffness) of a given spring pack.

Just look @ the front 9-leaf packs on Randy's CJ6, which were the "std" suspension set up, to see that the individual leaf thickness also has a great deal to do with leaf spring rates...;)

ob1jeeper
12-23-2009, 09:15 PM
Hi Steve,

I assumed for any specific application, the thickness of the leafs were the same no matter how many leafs there were.

For instance... if standard duty on my CJ8 was 4 leafs... I assume the 5 leaf added 1 more leaf of the same thickness as each of the original 4 and the 6 leaf added 2 more leafs of the same thickness of each of the original 4 and so on.

I assumed that each application may use different leaf dimensions but in any given application, all the leafs were the same dimension and the factory just added more leafs to get the spring rate for the different options.

Do you know if this is correct for Jeeps? Would the leaf dimensions in a 4 leaf Scrambler spring have the same dimensions as a leaf in a 6 leaf Scrambler spring? First, I assume you are speaking ONLY of the thickness of the leaf's... IF the leaf's are common in thickness between various applications and options, that is the result of the manufacturing $'s that are saved by using common or "std sized" materials, rather than because of a design desire/need... ;)

Overall length dimensions are defined by the vehicle envelope package, and will be common (except in RARE instances)...

djui5
12-23-2009, 09:40 PM
Just look @ the front 9-leaf packs on Randy's CJ6,

I was gonna say the individual springs up front were really thin, and the rear springs were quite a bit thicker.

Joe West
12-23-2009, 09:44 PM
You are correct... I'm speaking only of thickness. I assumed that width would not vary between leafs in the same pack and that length of the spring is dependent on vehicle and pack design.

I originally thought that the factory simply added leafs of the same thickness to increase the spring rate "one leaf at a time" for various applications (soft ride, heavy duty, rural export, etc).

I never considered the possibility that the factory would design spring packs with leafs of different dimensions for each application. So for instance, soft ride would have 4 springs of 3/16 thickness while heavy duty would have 6 springs of 5/32.






First, I assume you are speaking ONLY of the thickness of the leaf's... IF the leaf's are common in thickness between various applications and options, that is the result of the manufacturing $'s that are saved by using common or "std sized" materials, rather than because of a design desire/need... ;)

Overall length dimensions are defined by the vehicle envelope package, and will be common (except in RARE instances)...

ob1jeeper
12-23-2009, 09:47 PM
I was gonna say the individual springs up front were really thin, and the rear springs were quite a bit thicker.True Dat...;)

ob1jeeper
12-23-2009, 09:51 PM
You are correct... I'm speaking only of thickness. I assumed that width would not vary between leafs in the same pack and that length of the spring is dependent on vehicle and pack design.

I originally thought that the factory simply added leafs of the same thickness to increase the spring rate "one leaf at a time" for various applications (soft ride, heavy duty, rural export, etc).

I never considered the possibility that the factory would design spring packs with leafs of different dimensions for each application. So for instance, soft ride would have 4 springs of 3/16 thickness while heavy duty would have 6 springs of 5/32.
Leaf thickness and numbers of leaves are determined by settling on a desired spring rate, then finding the closest "common" material that will allow that spring rate to be achieved.

Thus is is not out of the realm of possibility for the spring leaves on each end of the vehicle to be of differing thicknesses, nor for "HD-vs-STD" ot be of differing thicknesses ... In fact it is rare that you are able to get both to use the same material thicknesses and still acheive the desired spring rate...;)

Desertdawg
12-23-2009, 10:14 PM
=I can't imagine what 7 springs front and rear must ride like... oh... wait... yes I can... it would ride like a Willys MB.

HAHAHAHAHAHAHA

Okay, I see how you are, make fun of the MB guy.

Be careful I know where you live. :policeman:

Joe West
12-23-2009, 10:45 PM
I didn't expect you to be up this late... thought I could sneak it in while you weren't looking :D


Okay, I see how you are, make fun of the MB guy.

Be careful I know where you live. :policeman:

mysunnshine
12-24-2009, 07:51 AM
I can't imagine what 7 springs front and rear must ride like... oh... wait... yes I can... it would ride like a Willys MB.

HAHAHAHAHAHAHA

My 9 leaf packs ride like coil springs-

CaptainMorgan
12-24-2009, 07:39 PM
I have a Scout80 with 10 leaf pack f/r and it rides really nice and smooth on the dirt. They are custom and did not come on the Scout.

Desertdawg
12-26-2009, 11:33 PM
Hey Joe I found this website that may answer some of your questions regarding springs.

http://www.generalspringkc.com/index.php?p=catalog&parent=147&pg=1

Joe West
12-27-2009, 02:02 PM
Thanks Mike... that's an excellent link. I've bookmarked it in case I need to ever replace my factory springs.


Hey Joe I found this website that may answer some of your questions regarding springs.

http://www.generalspringkc.com/index.php?p=catalog&parent=147&pg=1