Spring Rates Stock vs Aftermarket

[koche]

Hey - I have a new 2025 Tremor but I think the standard suspension sort sucks and is too soft - its like driving a boat around. But does anyone actually know the spring rates front and rear for OEM and then how much it changes from say an Bilstein, ICON or King set up?

 

[TexasTea]

Hey - I have a new 2025 Tremor but I think the standard suspension sort sucks and is too soft - its like driving a boat around. But does anyone actually know the spring rates front and rear for OEM and then how much it changes from say an Bilstein, ICON or King set up?

Gimme an hour and I'll tell you the butt-feel difference from OEM to Eibach Stage 2R

 

[CAMDENN]

Hey - I have a new 2025 Tremor but I think the standard suspension sort sucks and is too soft - it’s like driving a boat around. But does anyone actually know the spring rates front and rear for OEM and then how much it changes from say an Bilstein, ICON or King set up?

The springs aren’t the issue, it’s the shocks.

 

[koche]

The springs aren’t the issue, it’s the shocks.

Can't disagree but wonder if the springs are also contributing. Curious if the coil over kits use a different spring rate as well as better shocks.

 

[b-real]

You will notice more of a difference if you just swapped springs vs if you just swapped shocks, but pretty much no one does either of those options. Eibach is a good option. Bilstein has a lot of fans, but for me they are too stiff, but then again I like the stock spring rate. On my previous F150 I installed some Eibachs and used my stock springs and it stiffened it up a bit but not much.

 

[Yeti]

Front stock are silly low, like 450'ish. Icon goes with 550 which for an empty truck, is much better. If I remember right, I just replaced mine with 650 or 600 (I'll check tomorrow) but I'm constantly carrying about 1200 pounds and like my springs on the softer side. I don't remember what Halolifts ended up with. Likely 600 or 650. Elka starts at 700# but they get free dentistry and apparently kidneys..

Rear, I don't remember but I seemed to remember saying something about a wet noodle had more spring. I'm running the Icons and like them so far.

All that said, the shocks are the first failure. if you don't carry any weight in it, the springs aren't the issue.

 

[TexasTea]

Hey - I have a new 2025 Tremor but I think the standard suspension sort sucks and is too soft - its like driving a boat around. But does anyone actually know the spring rates front and rear for OEM and then how much it changes from say an Bilstein, ICON or King set up?

Eibach 2R setup at max lift - really only very very minor difference from OEM. Call it "OEM Plus". Very very slightly more firm but in no way harsh or rattle-y. Back end doesn't step out over rough asphalt. Damping is still soft and kinda wobbly if you go over a speed bump diagonal. At higher speeds it does soak bumps better. Imperfections in the road hidden/cope better than OEM toasted shocks.

So an upgrade, but really gotta be hunting for differences. Not huge changes, which is good.

Regarding spring rate I see a lot of anecdotal claims the Eibach 2R uses 450lb spring, so that's why it feels a lot like OEM as well.

 

[NickJ28]

Eibach 2R setup at max lift - really only very very minor difference from OEM. Call it "OEM Plus". Very very slightly more firm but in no way harsh or rattle-y. Back end doesn't step out over rough asphalt. Damping is still soft and kinda wobbly if you go over a speed bump diagonal. At higher speeds it does soak bumps better. Imperfections in the road hidden/cope better than OEM toasted shocks.

So an upgrade, but really gotta be hunting for differences. Not huge changes, which is good.

Regarding spring rate I see a lot of anecdotal claims the Eibach 2R uses 450lb spring, so that's why it feels a lot like OEM as well.

It’s not anecdotal. It’s printed right on the spring. Eibach is definitely 450.

Lowering the Eibach off the max height makes a huge difference in ride quality.

 

[TexasTea]

It’s not anecdotal. It’s printed right on the spring. Eibach is definitely 450.

Lowering the Eibach off the max height makes a huge difference in ride quality.

Yeah. I need a spacer lift. And then lowering it off the factory setting.

 

[NickJ28]

I’ve been there. Don’t do it. 1-1.5” higher than stock Tremor height is the sweet spot for drivability. I finally broke down and lowered mine after Accutune said they wouldn’t actually sell me a set of shocks to run the front 2” over stock Tremor.

I lowered the rear to standard FX4 height with 2WD Eibach 1.5” rear blocks

The truck has never handled this good. It is so much more composed over bumps.

 

[Escape Hatch]

I’ve been there. Don’t do it. 1-1.5” higher than stock Tremor height is the sweet spot for drivability. I finally broke down and lowered mine after Accutune said they wouldn’t actually sell me a set of shocks to run the front 2” over stock Tremor.

I lowered the rear to standard FX4 height with 2WD Eibach 1.5” rear blocks

The truck has never handled this good. It is so much more composed over bumps.

I find this response very interesting. Care to elaborate on the driveability issues when exceeding 1.5 inch front end lift? Did Accutune specify why they wouldn't sell you 2+ inch shocks on the front end? I find it curious when many manufacturers have options exceeding 1.5 inches without a known impact to driveability, case in point my 2.5 inch Icon coilovers.

 

[TexasTea]

I’ve been there. Don’t do it. 1-1.5” higher than stock Tremor height is the sweet spot for drivability. I finally broke down and lowered mine after Accutune said they wouldn’t actually sell me a set of shocks to run the front 2” over stock Tremor.

I lowered the rear to standard FX4 height with 2WD Eibach 1.5” rear blocks

The truck has never handled this good. It is so much more composed over bumps.

Disagree. A strut top spacer just moves the entire assembly downward. It doesn't stretch or load the spring any differently. The cv angle is worse and may wear more, yes. You may run out of down travel, limited by the geometry of the control arms yes. But the feel of the shock and rebound and damping should remain the same until you limit out on down travel.

 

[NickJ28]

You can do whatever you want, but I've done all these:

Stock with 2.5" spacer
6112 with 1.5" spacer (1" lift circlip on the 6112)
Eibach maxed
Eibach 1.5" lift


And the last one is hands down the absolute best.

6112 with spacer runs out of travel via the control arm (and yes I have aftermarket arms).
Eibach maxed runs out of droop travel almost immediately. It tops out over the smallest bumps in the road.


The CV angles really aren't a problem. I think that's blown out of proportion for anyone who has the Tremor CVs. It's the poor dynamic suspension geometry with the vehicle operating way out of it's designed operating window. This was Accutune's feedback and I can confirm with first hand experience. At 2-2.5" lift my truck wandered all over the road, steering feedback was light and numb, and it bump steered like crazy.

 

[TexasTea]

You can do whatever you want, but I've done all these:

Stock with 2.5" spacer
6112 with 1.5" spacer (1" lift circlip on the 6112)
Eibach maxed
Eibach 1.5" lift


And the last one is hands down the absolute best.

6112 with spacer runs out of travel via the control arm (and yes I have aftermarket arms).
Eibach maxed runs out of droop travel almost immediately. It tops out over the smallest bumps in the road.


The CV angles really aren't a problem. I think that's blown out of proportion for anyone who has the Tremor CVs. It's the poor dynamic suspension geometry with the vehicle operating way out of it's designed operating window. This was Accutune's feedback and I can confirm with first hand experience. At 2-2.5" lift my truck wandered all over the road, steering feedback was light and numb, and it bump steered like crazy.

Well chances are I'm gonna add another data point with the eibachs + spacer + control arms it seems. I'm just not happy with sitting so nose down even with the eibachs maxed, though I don't find their ride to be much different from oem. There's gotta be a balance point. Add spacers and control arms, and dial down the eibachs is my next stop.

Funny enough I liked the stance better with whatever this solid 1 inch puck was wherever it was sandwiched in the OEM parts .... Just a solid puck with 3 holes. Ride was fine except for the shocks being blown and floaty. And the stance was 40/42 which was good enough for me.... 40.5 or 41 would be ideal

 

[Escape Hatch]

I have zero issues with steering feel, truck wandering, etc. on my setup. I am still intrigued as it is illogical to me based upon myl experince.

 

[TexasTea]

I have zero issues with steering feel, truck wandering, etc. on my setup. I am still intrigued as it is illogical to me based upon myl experince.

In my own experience, wandering, and twitchy or light steering is almost entirely a product of alignment. One can find loads of documents and explanations from the car racing world about how toe, camber, caster all affect steering response in various ways. I've felt it myself. Bad toe out feels horrible. Toe in feels "tight". Doubting it has anything to do with lift itself so long as the alignment could still be brought into shape.

 

[TexasTea]

Just so anyone from the future finds it.

Eibach Pro Truck 2R left it nose low at 39.5F and 42R
adding a basic bitch solid spacer, a 1/2 inch puck, adds 1 inch of height

Now it rides 40.5F and 42R, definitely has a "visual lift" because of the wheel arch space and higher hood line. It's a good look.

The ride quality of the Eibach Pro Truck 2R is very similar to OEM but less floaty over rough pavement. Back end doesn't step out. Ride is not harsh.

Adding the 1 inch level spacer made no change to the ride quality and left the ball joints and angles all in a reasonable position. The truck was able to be aligned without any extra bolts or parts. The control arm has plenty of space and won't hit the Eibach because the eibach is smaller circumference springs than OEM.

So all and all, the eibachs plus a 1 inch level spacer works well and I don't foresee any huge issues.

Final ride height 40.5 F / 42 R.

Note I am running OEM tire size but on a +12 Vortek rim. No rubbing.

 

[Escape Hatch]

Pic?