Spring rate questions

XLR8 · Post by **XLR8** » Wed May 08, 2019 11:44 am

So i'm a newbie to Broncos having bought my wife one last year. It's been a learning experience ever since.

I recently ordered some 2.5 Kings for the front using the Threat coilover mounts and stock length TTBs. I won't name the vendor yet but since i didn't have corner weights they used a calculator to come up with the rates. They sent me 12" 3.0 300 lbs springs for the top and 14" 3.0 400 lbs for the bottom with a 1" pre load. Does that sound right?
Also they sent Eibach springs and not the normal King ones i've gotten for other vehicles. Frankly i don't care but seemed odd.

I was thinking of ordering a few more sets to have them here when i'm doing the install and send back what i don't use.

The truck will be used on road a lot with some trails and a bit of fast offroad stuff but nothing like you SoCal guys do. I'll probably take it to Utah and Colorado once a year as well.

Thoughts?

Thanks

BDKW1 · Post by **BDKW1** » Wed May 08, 2019 2:50 pm

That will get you in the ballpark. It will have more than an inch of preload though. Valving will be the important part.

King gets springs from at least 3 different vendors, one of them being Eibach.

mobil1syn · Post by **mobil1syn** » Thu May 09, 2019 9:08 am

sounds about right.

i am using a 275/400 on a 12" shock with 6" of shock shaft about around an 1.5" of preload.

mobil1syn · Post by **mobil1syn** » Thu May 09, 2019 9:11 am

i also a firm believer that corner weights are not the proper way to select springs. you need to get a spring on there, do some math and select accordingly.

XLR8 · Post by **XLR8** » Fri May 10, 2019 11:32 am

got it, thanks everyone. who knew this was more complicated than a race car? It is!

mobil1syn · Post by **mobil1syn** » Fri May 10, 2019 2:56 pm

who did you buy your stuff from?

Andy Jones · Post by **Andy Jones** » Fri May 10, 2019 4:10 pm

I’m running a 14” 3.0 up front. Spring rate is 300/400. Valving is key.

Sent from my iPhone using Tapatalk

XLR8 · Post by **XLR8** » Sat May 11, 2019 11:57 am

mobil1syn wrote:who did you buy your stuff from?

Accutune

mobil1syn · Post by **mobil1syn** » Mon May 13, 2019 8:47 am

XLR8 wrote:Accutune

good people over there who have a solid handle on making vehicles work.

4lowLance · Post by **4lowLance** » Fri Sep 18, 2020 10:01 pm

Can anyone offer up some wisdom?
2.5x12 kings ordered from desolate, they supplied 400/450 springs. This is with 2.5” of preload, still seems too low to me but from my searching, my spring rate is spot on.

Wrightracing.net · Post by **Wrightracing.net** » Sun Jan 14, 2024 8:04 am

I have not tuned my Fox 2.5x16 coilover's with 2.5x16 bypass yet, but I have 400x16, 450x16 and 500x16 springs to choose from. On Chris Wilson's Class 3 Early Bronco with a 1990 chassis under it, Glen ran 500 over 500 with 14 inch shocks and the spring length was 14 inches each, upper and lower.

I am running the 16's because I already have the Fox 2.5x16 and Glen said with 3 inch wider beams and no AC box to worry about the 16s would kick back a little and work fine. A benefit will be more oil and a bit more cooling with them. On the Wilson Bronco he only widened it by 1.5" to stay within the Class 3 rules.

My question is why some people run shorter coilover's and leave the threaded body unused. What are the Pros and cons

?

David