Spring lift calculations
- Thread starter UKTJ
- Start date
I picked them up from this site, as I believed these were the stock springs. But I am now not so sure as they quote an installed height of 11" for the front spring and you and others say it is 12".
https://www.shockwarehouse.com/inde...ed_model=4144&selected_year=2004&mode=results
The 3227 rear matches the Rubicon figures in the table in the Resources post and the 3229 matches the non Rubicon. The maths also works using the spring rates and corner loads they provide for the rear springs (e.g 11.28"-(653/200)=8.02"). So s that seemed to tie up I accepted the fronts must be correct as well, but they are not in your table to check. I take the non-Rubicon 4.0L to be the 3224 with a load of 719lb and the Rubicon to be the 3226 with a load of 826lb. That maths works to get back from the quoted free heights to the quoted install height using those weights and the sprung rates. But both the quoted install and the confirmatory maths gets you to 11", not 12".
I took those sprung weights for what I took to be a stock non-Rubicon and simply added half the additional weight I am adding to front and rear to get the weights I used.
Math checks out to me, assuming your spring rates and weights are all correct. Might get some variation in application, but I would say you would definitely get close to the 2.5" front, 3" back.
What would be good to understand is why the link I gave shows an install height of 11" (rather than 12"). The maths work out, so that means for the install height to be wrong either the quoted corner load, spring rate or free height must be wrong, or this is not the stock spring.
I note that in the table you gave to Chris the front stock spring is not listed in terms of free height or spring rate, but do you knwo the part number of the stock front springs (Rubicon and non-Rubicon)?
Edit: Summit Racing sells the 3224 and quote the same free height (16.4") and spring rate (134lb per inch). If the install height is a known 12" that gives an implied stock front corner load of 589lb.
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There is a lot a bad information out there as evidenced by my terrible mistake on the Metalcloak springs in the other thread.
I didn't pay much attention to stock springs after I got rid of them. Plus there are multiple rates and lengths that came out of the factory. I didn't care to make sense of it all.
@Chris! More spring info for the big list.
I’ll update it shortlyThere is a lot a bad information out there as evidenced by my terrible mistake on the Metalcloak springs in the other thread.
I didn't pay much attention to stock springs after I got rid of them. Plus there are multiple rates and lengths that came out of the factory. I didn't care to make sense of it all.
@Chris! More spring info for the big list.
You're not wrong there, I have now found Moog's own online parts catalogue shows the install height for those springs as 11". Which is most likely the source of the info being provided by the various suppliers. Given the manufacture should know the spring rate and free height, the corner load has to be the top candidate for the error.There is a lot a bad information out there as evidenced by my terrible mistake on the Metalcloak springs in the other thread.
I have my stock springs in the pile somewhere. I can't give them away so they'll eventually be scrap. I could make them useful and measure. Or someone could set them up and run a load/deflection study. Maybe I'll use everything for an art project.
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