Diesel coil spring rates

[ZoneArc]

Anyone know of a 4.5-5" lift coil for the rear that has a spring rate designed for the diesel and heavier rigs with lots of equipment? The Evo 4.5" HD coil sags so much I had to add a 1.5" spacer to compensate so that one is out. Heck, I had to add stacked airbags because the 1.5" spacer only got me level with the front and now I need to fill air bags if I load the rear up with lots of wood or the tongue weight from a trailer.

I called them and they won't tell me the spring rate of the coil, so I'm flying blind.

Current gear is an overlanding rack, tools/recovery gear in the swing toolboxes, and the JCR Vanguard tire carrier with a 40 on it. Ballpark ... 500lbs additional sprung weight from stock.

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[AjMac]

Sucks to see no one has replied to you, so hopefully this bump helps.

I am also interested in hearing about this, as I am about to buy a lift, and am considering getting different springs than what comes with the kits. Rock Krawler seems to use quad rate coils for their "diesel" kit, so I am eyeballing those by default.

 

[ZoneArc]

I've fixed it now. We had to go with 6.5" rear springs from Evo so they sagged down to ~5" so I have a slight rake to the back with my fronts.

 

[AjMac]

I've fixed it now. We had to go with 6.5" rear springs from Evo so they sagged down to ~5" so I have a slight rake to the back with my fronts.

So I am about to purchase my lift, and am going with the Metal Cloak 3.5 Gamechanger. They are gonna include the Evo 4.5 HD's...

I keep seeing people talk about the sag...so Im hoping it does well for me until I pick up some Rock Krawler 4.5's. I dont have additional weight (besides the diesel) so fingers crossed.

 

[ZoneArc]

It's about the weight/gear you put on it. If your bed is empty, and you don't run a spare, no issue.
If you have toolboxes, larger spare tire, bed rack, etc then it'll sag. Since the MC Gamechanger uses springs and not coilovers, you can't lower the front ride height to compensate.
So, your options (if it sags) will be:

1. Add a 1-2" rear spacer and keep the Evo 4.5 springs. (My first approach)
2. Get the Evo 6.5 HD springs. (that's what I ended up with)

With #2, I ended up with .75" positive rake. I like a slight rake and also appreciate it for when I put a trailer behind it with some tongue weight.

 

[rharr]

Rk 3" lift jtdr front springs VS oem

 

[ZoneArc]

Rk 3" lift jtdr front springs VS oem

It's less about the height, and more about the spring rate.

 

[rharr]

Well they are a stiffer springs for sure, and it seems some of these mfrs are compensating short stiff springs with softer longer springs to give some preload. Different solutions for the same end result. I rather have some preload to keep everything in place on full droop

 

[Rubiko]

Anyone know of a 4.5-5" lift coil for the rear that has a spring rate designed for the diesel and heavier rigs with lots of equipment? The Evo 4.5" HD coil sags so much I had to add a 1.5" spacer to compensate so that one is out. Heck, I had to add stacked airbags because the 1.5" spacer only got me level with the front and now I need to fill air bags if I load the rear up with lots of wood or the tongue weight from a trailer.

I called them and they won't tell me the spring rate of the coil, so I'm flying blind.

Current gear is an overlanding rack, tools/recovery gear in the swing toolboxes, and the JCR Vanguard tire carrier with a 40 on it. Ballpark ... 500lbs additional sprung weight from stock.

Hey! I'm in the exact same position as you. Currently running the 4.5" Teraflex long arm lift, same rear bumper, rack, and everything lol, and my rear is sagging significantly.

1. How are you finding the ride on these springs?

2. Did you have to replace sway bar links or adjust track bar/control arms?

3. Do you know of any other options out there at the moment for a HD springs for 4.5"+ lift?

 

[Jeepasaurus_Rex]

Following. My JT is a thick booty Judy, too

 

[ZoneArc]

The fix is simple ... if you're on 4.5" lift height, get 6.5" rear coil springs. You'll need the additional compression to counter the additional weight in the back. I can only speak to the quality of the Evo springs and not other brands. Evo's spring rate seems to be lighter than you would want for a traditional truck that tows/hauls, and meant for flex and faster rebound/compression. As a result, they compress more once you load up the truck. The additional 2" will counter that.
The good thing is that you won't run in to an issue with reduced compression as your bumps, diff, etc will hit things long before the 6.5" springs will compress fully, so there are no issues other than that you may sit at a slight rake when installed.

I've been going this way for about 6-8 months now and i'm happy with the results. However, I'm likely changing it up again soon I'm looking at switching the rear to coilovers. I want more fine tuned control over lift height and with dual rate springs I can get the exact action I want out of that rear.

 

[Rubiko]

The fix is simple ... if you're on 4.5" lift height, get 6.5" rear coil springs. You'll need the additional compression to counter the additional weight in the back. I can only speak to the quality of the Evo springs and not other brands. Evo's spring rate seems to be lighter than you would want for a traditional truck that tows/hauls, and meant for flex and faster rebound/compression. As a result, they compress more once you load up the truck. The additional 2" will counter that.
The good thing is that you won't run in to an issue with reduced compression as your bumps, diff, etc will hit things long before the 6.5" springs will compress fully, so there are no issues other than that you may sit at a slight rake when installed.

I've been going this way for about 6-8 months now and i'm happy with the results. However, I'm likely changing it up again soon I'm looking at switching the rear to coilovers. I want more fine tuned control over lift height and with dual rate springs I can get the exact action I want out of that rear.

Gotcha! Thanks for the quick reply.

Would you go with the longer springs up front as well? And did you have to make any other changes beyond just swapping in the springs and doing ana alignment?

 

[@californiajeeping]

I would look at going coil overs on the rear. RK makes a kit.

 

[CrazyCooter]

This is why I'm hooked on @Clayton Off Road parts! The ONLY Jeep suspension builder I have come across who openly shares their spring rates........ This kind of transparency allows technical guys to make an educated decision. The rest of them I have dealt with know inside they don't have what you need, so they lie and decieve you into buying their product. I'd love to name them out, but trying to stay classy.

The answer is never as simple as "Just get a taller spring to compensate". Yes, that may get you the height you desire, but if the laden weight is the issue......this really requires a heavier rate to control it?

I know you need more published lift than Clayton offers as standard, but i'd be inclined to buy a 3.5" spring and run a small spacer to do the job than blindly buy spring till you get it right?

 

[rharr]

just a fyi, i ended up with 4.5" RK rear springs (from 3" RK rear springs) to get rid of a minor droopy butt with my cap and tools in the back. Rides the same just more lift in the back.

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