Confirmed: Rubicon Front Springs 340/ 343 are 1" Taller than Sport S Max Tow

[ShadowsPapa]

Really? I don't have a micrometer, but visually they look consistent. That's interesting if the wire diameter does change. The coil wrap (diameter) is definitely smaller (the progressive part), giving the spring the beehive look. I didn't think springs changed wire diameter, that's now how it's done on "How It's Made" that I've seen.

No problem, I have more micrometers than I'll ever wear out..........
I knew the Rubicon were different from top to bottom just by looking in my pics, but to clarify just how much, and to show it's not just Rubicon, I got my ladder off the hooks, pulled a bunch of stuff down and unboxed my springs......... I measured both Overland original rears and Rubicon rears.
Here's what I got (and I ignored the first coil since that's the base or top and doesn't "move" or "spring") I concentrated at least 2 or 3 coils from each end.

Overland rears -
top 4 coils were .658"
Bottom 2 1/2 coils were ~ .536"

Rubicon rears -
4th coil and up .650"
3rd coil and down - . ~.587"

Those are appreciable differences and obviously for a purpose. We're talking over .1" in some cases, close to that in others.

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[MPMB]

No problem, I have more micrometers than I'll ever wear out..........
I knew the Rubicon were different from top to bottom just by looking in my pics, but to clarify just how much, and to show it's not just Rubicon, I got my ladder off the hooks, pulled a bunch of stuff down and unboxed my springs......... I measured both Overland original rears and Rubicon rears.
Here's what I got (and I ignored the first coil since that's the base or top and doesn't "move" or "spring") I concentrated at least 2 or 3 coils from each end.

Overland rears -
top 4 coils were .658"
Bottom 2 1/2 coils were ~ .536"

Rubicon rears -
4th coil and up .650"
3rd coil and down - . ~.587"

Those are appreciable differences and obviously for a purpose. We're talking over .1" in some cases, close to that in others.

Well hot-diggity-dog. That's pretty cool.

I tried running the numbers as two separate springs. Doesn't work out. Oh well. Guess we'll have to trust the internet on spring rates. :D

Progressive springs are pretty cool and useful. They weren't allowed in our racing division, so pretty much my experience with springs has been linear ones. At one track we used a light (150# I think) short spring on top of a heavier one because there was a nasty dip in the track. This combo allowed the car to not get upset from the dip.

 

[rickrogan]

Well now that I have a STEEL bumper and WINCH and SKID PLATE I need to find a 343 Rubicon spring. I'll move my 340 to the left and put the 343 on the right.

Anyone got a spring for sale?

So, that's kinda what I am thinking also... but my mental model of how the 26 different variants of the 2020 JT Front Coil Springs would play out started with a Driver-vs-Passenger split. That is half of them would be lefties and the other half righties.

This approach (move the 340 to the left) takes that model and blows it to pieces.

Not saying that it isn't (or can't be true)... just that it is a whole new level of complexity.

 

[ShadowsPapa]

So, that's kinda what I am thinking also... but my mental model of how the 26 different variants of the 2020 JT Front Coil Springs would play out started with a Driver-vs-Passenger split. That is half of them would be lefties and the other half righties.

This approach (move the 340 to the left) takes that model and blows it to pieces.

Not saying that it isn't (or can't be true)... just that it is a whole new level of complexity.

Ignore the left vs. right spring. There is no "this is a left spring" and "this is a right spring".
It's "of any given pair of springs, the higher number goes on the right".

This gives them a whole lot more possible variations of spring pairs than strictly using certain numbers on the left and only certain numbers on the right. They can get a lot more spring pairs if they are universal and applied based on the pair and not the side.

I should scan the AMC parts books I have - pages of springs....... depending on the options. Go-pack, AC or not, PS or not, V8 or I6, etc.

The last three digits of the part number are large/bold......... reminds me of Jeep springs.

 

[Free2roam]

So I've got a Ecodiesel Sport S. Non max tow. 3:73 gearing if I put Mohave springs in it. Will I need the shocks from it too?

 

[Mr._Bill]

So I've got a Ecodiesel Sport S. Non max tow. 3:73 gearing if I put Mohave springs in it. Will I need the shocks from it too?

You don't 'need' the shocks, but take them if you can get them. The diesel engine is much heavier, so changing springs could possibly have a negative impact.

 

[ShadowsPapa]

You don't 'need' the shocks, but take them if you can get them. The diesel engine is much heavier, so changing springs could possibly have a negative impact.

I'm not so sure I'd take diesel springs out and put non-diesel springs in. How will they carry the weight?

 

[Rockabillyroy]

Ignore the left vs. right spring. There is no "this is a left spring" and "this is a right spring".
It's "of any given pair of springs, the higher number goes on the right".

Just to be clear, the parts are listed as front left and front right in the parts catalog.

Just use them as you please. Heh

 

[ShadowsPapa]

Just to be clear, the parts are listed as front left and front right in the parts catalog.

Just use them as you please. Heh

Don't take that literally - they would literally need the VIN to get the exact correct spring as the factory used.
As has been proven, some will have the 340 spring on the right while heavier trucks will have it on the left.
Whether or not a given number is a left or a right spring depends on the truck. A 340 isn't a right in all trucks. It's a left on a Rubicon with steel bumper and matching skid plate.
Parts "books" as shown online generalize, and as happens quite a bit, replacement springs may be generic. Not sure if Jeep is doing that, but normally you find "use xxx" in the notes section.
What happens in the replacement market isn't the same as what the factory does in all cases.
We have absolutely proven that a left spring under one truck could be a right spring under another.
(I know about parts books and listings..... ... have used them for many years. )

 

[FutureOdin]

Now, what about Rubicon springs for the diesel? Part no. on the spring that I have for the front (not sure if left or right) is 68506377AA. The other spring doesn't have the part no. tag on it

Are rears the same? Or do those have certain sides?

 

[basicGlad]

1C6JJTBG1LL117934
LE takeoffs and the front springs were 340/343. I messaged him about this and he confirmed.

Yeah I've seen Rubicons come with 339/340
Or 340/343 in the front.

Highest number goes passenger side

 

[Aonarch]

Now, what about Rubicon springs for the diesel? Part no. on the spring that I have for the front (not sure if left or right) is 68506377AA. The other spring doesn't have the part no. tag on it

Are rears the same? Or do those have certain sides?

Ignore this entire thread for the Diesel, completely different.

And as a non-diesel owner, I've done exactly ZERO research on Diesel suspension options.

 

[MPMB]

Don't take that literally - they would literally need the VIN to get the exact correct spring as the factory used.
As has been proven, some will have the 340 spring on the right while heavier trucks will have it on the left.
Whether or not a given number is a left or a right spring depends on the truck. A 340 isn't a right in all trucks. It's a left on a Rubicon with steel bumper and matching skid plate.
Parts "books" as shown online generalize, and as happens quite a bit, replacement springs may be generic. Not sure if Jeep is doing that, but normally you find "use xxx" in the notes section.
What happens in the replacement market isn't the same as what the factory does in all cases.
We have absolutely proven that a left spring under one truck could be a right spring under another.
(I know about parts books and listings..... ... have used them for many years. )

Has anyone done a weight test on the springs? Like put it into a rate checker, squished it down 1" and see what the load is between the pairs? Then coilbind the soft section of the spring and then test the progressive rate?

I'm thinking that there are "pairs" of springs with different part numbers, but the same spring rate. Because everything is codified, tracked, numbered, etc. Each part needs it's own identifiable part number.

It would make sense that the Rubicon gets special springs for off-road use. Same with Mojave. Sport/Sport S/Willys get general springs. Max tow gets springs for heavy loads. Overland a spring that focuses on road ride. So those combinations would eventually add up, but it's not like each individual spring has a different rate.

The Quadratec page for JT springs list 26 springs. That's 13 pairs to divvy amongst 10 trims and 2 engine choices over 2 model years.

And my spring part #s aren't even listed yet. 68506362AA (L) & 68506363AA (R).

 

[MPMB]

Now, what about Rubicon springs for the diesel? Part no. on the spring that I have for the front (not sure if left or right) is 68506377AA. The other spring doesn't have the part no. tag on it

Are rears the same? Or do those have certain sides?

Front driver side = Front Left
Front passenger side = Front Right

We drive left-hand drive vehicles, versus right-hand drive like in Asia and Europe

 

[Mr._Bill]

Now, what about Rubicon springs for the diesel? Part no. on the spring that I have for the front (not sure if left or right) is 68506377AA. The other spring doesn't have the part no. tag on it

Are rears the same? Or do those have certain sides?

None of the springs, front or rear, are side specific. Each spring has a specific part number that correlates to its weight handling capability (and other features). The springs are paired up in certain combinations, based on the weight and features of the vehicle they are being installed on. The diesel engine adds about 400 pounds to the front end, so the springs for those models will be different than those used on the gas engine models.

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