Need advice from spring, shock and control arm gurus

[JMT]

Do what @Mike_H said in post #8. Save yourself a ton of time and money.

 

[jjvw]

Who sells TJ springs that won't compress?

It's a mystery.

 

[Mike_H]

The manufactures also make the shocks. Following your line.... shocks don't matter. Any shock that correctly fits your Jeep is made to work properly. Ergo shocks don't matter.

Yet they do. They all vary in their valving the same way springs vary in their travel rates. THEY BOTH MATTER. Irregardless how soft a spring, a shock with too stiff valving will restrict it from moving. Irregardless how soft a shock valving, a spring with too high a rate (for YOUR application) won't compress.

The difference is that I can use two different shocks, properly sized in length for the application and commonly available (say a rancho 5000x and a bilstein 5100) and they will ride MUCH differently. Certainly it will be something someone will notice.

The same cannot be said for common, off the shelf springs designed for the TJ platform. If you want to go find some junkyard application that has a dump truck like spring rate, go for it. I'm not using those springs.

Oh, and the word is regardless, not IRregardless

https://www.merriam-webster.com/dictionary/irregardless

 

[freebo86]

So I had time and measured some things. Little background on the actual springs and shocks installed below. I also removed the lower bolt on one of the rear shocks to see down travel and it matches up to the calcs, the shock travel is 8".

Front:
OME 2934 Springs
Measure on vehicle 13-1/2" to 13-3/4"
Shocks RS55239, Listed Travel Length 9.14", Exposed Shaft 4.75". So nearly 50/50 split and the front does not seem to be a issue.
Starting Height with 33s stock was 33-1/2" now I'm at 36". Gained 2.5" basically.

Rear:
OME 2949 Springs
Measure on vehicle 10-1/2"-10-3/4" - Hard to measure exactly.
Shocks RS55241, Listed Travel Length 8", Exposed Shaft 5-7/8". Approximately ~2-1/4" down travel left.
Starting Height with 33s stock was 35" now I'm at 37.5". Gained 2.5".

The front doesn't appear to be an issue, the rear does. My rear has a DIY Bumper with Swingout, full size 33" spare. Gas tank at time of measuring is approx. 1/4 full. Currently soft top is on the Jeep.

So why is my rear end like this and the travel bias so far off? Is in fact the 2949 spring rated to high with a constant that is preventing the rear to sit lower? I also tied a zip tie around the rear shaft to see where it moves to on the next drive.

Really looking to see what your guy's thoughts are.

 

[Lou]

I think the springs are fine if you are happy with the ride height. You just need the next size up shocks for the rear.

 

[freebo86]

I think the springs are fine if you are happy with the ride height. You just need the next size up shocks for the rear.

Ride height is perfect. It’s a street Jeep and it’s level without the use of any spacers etc. which is what I wanted.

So going with the next size up shock lists travel at 9.66 so based on my numbers I’d have 3.785 left for down travel.

Is the 2.xxx down travel an actual concern with the current setup?

 

[Goatman]

Who sells TJ springs that won't compress?

Won't compress (AS MUCH)
Thanks for the catch.

 

[jjvw]

Won't compress (AS MUCH)
Thanks for the catch.

Name one

 

[freebo86]

So just checked the shock since I tied a zip tie to it looks like the up travel used is basically just over 2”. What does this tell me? That the 2” down is barely cutting it? It’s properly setup?

I’m at a total loss and just scratch this entire lift setup, lol?

 

[bobthetj03]

Assuming you have functioning jounce bumpers (the spongy cushion thingy in the top of the steel cup), measure how much up you have until the lower spring pad hits the jounce bumper. Keep in mind, the jounce bumper compresses almost to the steel cup under hard events. If you have added more bump stop extension, this will decrease the amount of up you have under normal driving conditions. You need a symbiotic relationship between the amount of up your shocks will give you and the amount of up you can get under free spring compression before hitting the jounces.

 

[freebo86]

Assuming you have functioning jounce bumpers (the spongy cushion thingy in the top of the steel cup), measure how much up you have until the lower spring pad hits the jounce bumper. Keep in mind, the jounce bumper compresses almost to the steel cup under hard events. If you have added more bump stop extension, this will decrease the amount of up you have under normal driving conditions. You need a symbiotic relationship between the amount of up your shocks will give you and the amount of up you can get under free spring compression before hitting the jounces.

They are in there and intact. I did add bump stops at the rear and cycled the suspension during the lift install. Took a quick measurement now, to the bottom of the jounce and the coil pad its ~4". From the coil pad to the metal cup lip/opening (where jounce slides into) ~6". The rear bump stop extension was approx. 2" I used round aluminum stock.

 

[Lou]

You could always buy rear shocks that will put you close to 50/50 travel at ride height and call it good.

 

[jjvw]

They are in there and intact. I did add bump stops at the rear and cycled the suspension during the lift install. Took a quick measurement now, to the bottom of the jounce and the coil pad its ~4". From the coil pad to the metal cup lip/opening (where jounce slides into) ~6". The rear bump stop extension was approx. 2" I used round aluminum stock.

The bottom of the jounce is irrelevant. Measure between the cup and pad.

 

[bobthetj03]

The bottom of the jounce is irrelevant. Measure between the cup and pad.

I wouldn't say it's totally irrelevant, as it does compress under load, but it does effect the overall feel.

 

[freebo86]

The bottom of the jounce is irrelevant. Measure between the cup and pad.

6” as originally indicated.