Front Coil Springs & Suspension (de)Codes?

[Gojira94]

In looking for ride height, I found THIS thread, in which a member asked "This may be a stupid question but why is does one say front : 7.75   rear : 9.2 and the second answer say front: 6.75 and rear: 6" . Does anyone know or know how to find out what the 2-letter codes translate to? I ask because I'm setting wheelbase at what will be on a 6" lift and wondered what the difference is that makes the 4WD ride height 1" higher than 2WD. These differences, according to what @Eagle shared as "...M.R. 277 for the Comanche, I.S. Notes. Specifically, it's in I.S. 14E, which addresses spring identification and selection."

 

Mainly, I'd like to know if it's just coil and leaf spring differences (taller/ more) and just explains how much more spring is needed to make that 1" difference in all the combinations of engine/ transmission/ transfer case, rear axle, short vs long wheelbase, etc.

 

Parts Catalog list (38 different coil springs):

 

8
52001107
SPRING, Front
Light Duty, Coded EF
Require Quantity:
2
8
52001108
SPRING, Front
Light Duty, Coded EG
Require Quantity:
2
8
52001109
SPRING, Front
Light Duty, Coded EH
Require Quantity:
2
8
52001110
SPRING, Front
Light Duty, Coded EJ
Require Quantity:
2
8
52001111
SPRING, Front
Light Duty, Coded EK
Require Quantity:
2
8
Jeep 52001114
52001114
SPRING, Front
Standard Duty, Coded FE
Require Quantity:
2
Package Quantity:
1
8
Jeep 52001115
52001115
SPRING, Front
Standard Duty, Coded FF
Require Quantity:
2
8
Jeep 52001116
52001116
SPRING, Front
Standard Duty, Coded FG
Require Quantity:
2
Package Quantity:
1
8
Jeep 52001117
52001117
SPRING, Front
Standard Duty, Coded FH
Require Quantity:
2
8
Jeep 52001118
52001118
SPRING, Front
Standard Duty, Coded FJ
Require Quantity:
2
8
Jeep 52001119
52001119
SPRING, Front
Standard Duty, Coded FK
Require Quantity:
2
8
Jeep 52001122
52001122
SPRING, Front
Heavy Duty, Coded GF
Require Quantity:
2
Package Quantity:
1
8
Jeep 52001123
52001123
SPRING, Front
Heavy Duty, Coded GG
Require Quantity:
2
Package Quantity:
1
8
Jeep 52001124
52001124
SPRING, Front
Heavy Duty, Coded GH
Require Quantity:
2
8
Jeep 52001125
52001125
SPRING, Front
Heavy Duty, Coded GJ
Require Quantity:
2
8
52001784
SPRING, Front
Light Duty, Coded EL
Require Quantity:
2
8
52001785
SPRING, Front
Light Duty, Coded EM
Require Quantity:
2
8
52001786
SPRING, Front
Light Duty, Coded EN
Require Quantity:
2
8
52001787
SPRING, Front
Light Duty, Coded EP
Require Quantity:
2
8
52001788
SPRING, Front
Light Duty, Coded ER
Require Quantity:
2
8
52001789
SPRING, Front
Standard Duty, Coded FL
Require Quantity:
2
8
52001790
SPRING, Front
Standard Duty, Coded FM
Require Quantity:
2
8
Jeep 52001791
52001791
SPRING, Front
Standard Duty, Coded FN
Require Quantity:
2
Package Quantity:
1
8
Jeep 52001792
52001792
SPRING, Front
Standard Duty, Coded FP
Require Quantity:
2
8
Jeep 52001793
52001793
SPRING, Front
Heavy Duty, Coded GK
Require Quantity:
2
8
Jeep 52001794
52001794
SPRING, Front
Heavy Duty, Coded GL
Require Quantity:
2
8
52001795
SPRING, Front
Heavy Duty, Coded GM
Require Quantity:
2
8
52001796
SPRING, Front
Heavy Duty, Coded GN
Require Quantity:
2

Edited June 27 by Gojira94

[eaglescout526]

Oh hey! Welcome to the mystery I’ve been trying to understand since ‘19. 

[Gojira94]

2 minutes ago, eaglescout526 said:

Oh hey! Welcome to the mystery I’ve been trying to understand since ‘19. 

 

Crap. This from a guy who had access to all the old tomes in the Chrysler dealership network for a long time... I'm screwed lol. Wish I knew C++ or C# better, I could generate the number of combos of wheelbase, drivetrain and 2WD/4WD. I bet it'd be around 35-40. More modern XJs and probably the 90-92 MJs build sheets list things like SDA, SDU, etc. for standard/ heavy duty suspension options. I bet the 2-letter codes from the AMC era are equivalent, but nobody we know has the decoder ring.

 

Suffice it to say I suppose it was arbitrarily decided by AMC/ Chrysler design engineers that 4WD offerings should have an additional 1" of ride height/ ground clearance. And I also suppose that's all I need to know to set my ride height and wheelbase on my project, based on the amount of lift I'm adding.

[eaglescout526]

lol. Yeah I scoured alllllll over ever piece of media I could get my hands on to find this info. Got nothin. 
 

If I had to say there’s probably two sections for the springs. One set is 2wd, the other is 4wd. Divided up by both wheel base and duty and engine probably into the mix. Chances are they could also be ratings too. So say from the manufacture and AMC put together a specific set of ratings of pounds for each spring for each code. It is without a doubt a great question as to why so many codes for something simple as three categories of light, standard and heavy duty springs. 

[Eagle]

On 6/24/2024 at 2:39 PM, Gojira94 said:

Suffice it to say I suppose it was arbitrarily decided by AMC/ Chrysler design engineers that 4WD offerings should have an additional 1" of ride height/ ground clearance. And I also suppose that's all I need to know to set my ride height and wheelbase on my project, based on the amount of lift I'm adding.

 

No. It isn't purely 2WD vs. 4WD.  And it may be different for XJs vs. MJs.

 

My first Jeep in this type was an '88 XJ Pioneer. I special ordered it, with 4WD and a "heavy duty" suspension, but no off-road package. Ride height, even with the stiffer springs, is the standard XJ height, not the +1 inch that in later years became known as the "Up Country" package.

 

In the MJ, however, I think it may be correct that 4WD models ride higher than 2WD models. Unfortunately, I have never bought a new MJ, so I don't really have any valid frame of reference other than the technical bulletin I cited and which was quoted above.

[Gojira94]

12 hours ago, Eagle said:

 

In the MJ, however, I think it may be correct that 4WD models ride higher than 2WD models. Unfortunately, I have never bought a new MJ, so I don't really have any valid frame of reference other than the technical bulletin I cited and which was quoted above.

 

Fair enough, as good information as I could ask for. I think what I need to do is double check my shock travel numbers, bumpstop distances and decide on front height of 12.75", 13.75" or in between for my 6"-ish lift. Thank you for chiming in.

[Eagle]

One of the early members of NAXJA, Ed Stevens, came up with some data on Ranco shocks. It's for the XJ, not the MJ, but the fronts are the same.

 

 

Here's some data from Bilstein: