Coilovers - changing springs to effect ride height.

[c_walters]

I took from this thread for the Peak coilovers I installed on mine. They come with 400/250 f/r rates, I put 200lb in the rear and they ride awesome.

I think if I could may even go to a 180ish rate out back then add some preload with the adjusters and see just how soft it can be.

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[GreyZ]

I took from this thread for the Peak coilovers I installed on mine. They come with 400/250 f/r rates, I put 200lb in the rear and they ride awesome.

I think if I could may even go to a 180ish rate out back then add some preload with the adjusters and see just how soft it can be.

Interesting I had not seen or heard of those before, but they are pretty pricy compared to some of the other quality options with more data and pedigree. What made you go with those? 400/250 is also a crazy front rear split based on @87-Z28 roll stiffness calcs. At 400 on the front I would be a bit concerned that you would run into spring bind at even SAS stock heights but would need more details on the spring lengths and damper stroke details.

 

[c_walters]

Interesting I had not seen or heard of those before, but they are pretty pricy compared to some of the other quality options with more data and pedigree. What made you go with those? 400/250 is also a crazy front rear split based on @87-Z28 roll stiffness calcs. At 400 on the front I would be a bit concerned that you would run into spring bind at even SAS stock heights but would need more details on the spring lengths and damper stroke details.

I talked with the owner a good bit, he also has a 2 door he runs them on and they worked with Elka for over two years developing them for the bronco. I liked the fact they had a low rate upfront. With the adjusters backed all the way down I got about 2.25/1” (18” 200lb in the rear). Ride is awesome, we will see how it flexes soon. With the spring they send in the rear I wasn’t able to drop it as low as I wanted without the spring being loose so that’s what drove me to the 18”.

They wouldn’t give me collapsed/extended lengths but I measured extended, 23 5/8” (F) 26 3/4” (R).

Spring:
16” (F/R)
406lb/250lb linear rate
Travel numbers:
5.5” (F) 7.9” (R)

I’ve run kings, fox, and icon in the past on different platforms so I wanted to try something different. Was also interested in the ride shocks and may still pull the trigger on those for my wife’s Bronco.

 

[87-Z28]

Eibach 3”x16” 400 lbs/in spring has 9.4” of available travel. Shocks have 5.5” stroke. Assuming 0.5” of hard bump stop at jounce end then conservatively, 9.4 - 5 =4.4 inches of preload max. Call it 4” to be safe. Carrying 1500 lbs on corner in front (stockish) that is 1500*1.6=2,400 lbs to react. So then 2400/400=6 inches of spring compression for equilibrium. To be near shock mid stroke, 2.5 inches of travel, that is roughly 6-2.5=3.5 inches of preload. Should be good as long as preload stays in the 3ish range. You will be eating up most of your available preload just to get near mid stroke. Not a bad thing, lower cg for sure without excessive lift. Shock extended length seems to be similar to OEM.

It does seem that 400/250 is a bit much in the rear. 200 seems a much better balance. Are you sure about the spring rate numbers? There is not a lot of travel on those in the rear <8”. So it doesn’t seem like you could run out of spring travel in the rear. 16” spring in the rear is a different. I don’t think that would be possible with 9+ inches is shock travel.

You should flex pretty well with 400/200 spring rates. Curious how it works out for you.

How is the feel on the road when getting after it? Around twisty corners? Small whoops?

 

[c_walters]

Eibach 3”x16” 400 lbs/in spring has 9.4” of available travel. Shocks have 5.5” stroke. Assuming 0.5” of hard bump stop at jounce end then conservatively, 9.4 - 5 =4.4 inches of preload max. Call it 4” to be safe. Carrying 1500 lbs on corner in front (stockish) that is 1500*1.6=2,400 lbs to react. So then 2400/400=6 inches of spring compression for equilibrium. To be near shock mid stroke, 2.5 inches of travel, that is roughly 6-2.5=3.5 inches of preload. Should be good as long as preload stays in the 3ish range. You will be eating up most of your available preload just to get near mid stroke. Not a bad thing, lower cg for sure without excessive lift. Shock extended length seems to be similar to OEM.

It does seem that 400/250 is a bit much in the rear. 200 seems a much better balance. Are you sure about the spring rate numbers? There is not a lot of travel on those in the rear <8”. So it doesn’t seem like you could run out of spring travel in the rear. 16” spring in the rear is a different. I don’t think that would be possible with 9+ inches is shock travel.

You should flex pretty well with 400/200 spring rates. Curious how it works out for you.

How is the feel on the road when getting after it? Around twisty corners? Small whoops?

If I remember from the last time I was measuring I have about 3.5”up in the front before I’m in the bumpstop, with the collars backed all the way to the top. This gave me around 2.25-2.5” lift over sas (Flair height is 41” on stock sas tires) up front. Rear with the 18” 200 spring, collars backed all the way up gives 1-1.5” of preload on the spring and about 2” up before I’m in the bump. With the 16” 250lb spring just enough preload to keep the spring from coming loose at extension it had me 1.5-.75” over sas in the rear. I was afraid to take more out and have the spring come loose while flexing. Also rear end felt “springy” when going over bumps forcing the rear up quickly. Now with the 18” 200lb that’s still faintly there but feels much more controlled.

Out of the box they had a ton of preload on the springs F/R and it lifted close to 4.5” (was very stiff as well).

On road you feel the road more then the factory bilsteins but feels much more controlled, and planted. It’s not stiff but you do feel more of the small bumps. Corners feel like it’s on rails (as much as you can with a lifted bronco). Dialing up the adjusters you can really firm them up, I’d say they got the valving pretty spot on but I’m sure there’s room for improvement. As far as actual spring rates, just going off of what they told me. Rear definitely was softer switching to the 18” 200lb springs.

 

[87-Z28]

Also rear end felt “springy” when going over bumps forcing the rear up quickly. Now with the 18” 200lb that’s still faintly there but feels much more controlled.

Yeah the front/rear balance is kinda off with 400/250 combo. 400/200 should be much better. The 500/200 combo seems ideal and it is pretty easy to adjust preload and get ride height near shock mid stroke. Also keep cg down a bit. Not ideal for 37s tho. Great for 35s.

It seems that you are riding a tiny bit extended in the front, 3.5” available jounce (mid-stroke is 2.5) and compressed in the rear, 2”available jounce (mid-stroke is 4). What kinda weight are you carrying in the back? Heavy?

Let us know how it works out when you hit the trails.

 

[c_walters]

Yeah the front/rear balance is kinda off with 400/250 combo. 400/200 should be much better. The 500/200 combo seems ideal and it is pretty easy to adjust preload and get ride height near shock mid stroke. Also keep cg down a bit. Not ideal for 37s tho. Great for 35s.

It seems that you are riding a tiny bit extended in the front, 3.5” available jounce (mid-stroke is 2.5) and compressed in the rear, 2”available jounce (mid-stroke is 4). What kinda weight are you carrying in the back? Heavy?

Let us know how it works out when you hit the trails.

Light weight 2 door, metal rear bumper/factory modular front bumper, factory rock rails, full size spare, full metal skids

 

[c_walters]

I’m also awaiting a buddy at the tire shop to get me a take off set of 37’s (so I don’t have to purchase them) to test clearances. I’m thinking with the limited bump travel it’ll keep 37’s out of the fenders.

 

[Snacktime]

Ordered some rear 1800.300.200 Eibachs, not sure I need lighter springs on the front with all the steel I have added.

 

[Snacktime]

So the springs dropped my rear 1.5" with slightly more preload. Eibach springs needed an extra few turns as they are maybe 1/4" shorter. Going to drive around a while and see if I want to do the front. The 40, 60 & 80mph Speed bump test was two middle fingers from the spectators at church. After the 3rd pass I am pretty sure they called the cops.

 

[popo_patty]

So the springs dropped my rear 1.5" with slightly more preload. Eibach springs needed an extra few turns as they are maybe 1/4" shorter. Going to drive around a while and see if I want to do the front. The 40, 60 & 80mph Speed bump test was two middle fingers from the spectators at church. After the 3rd pass I am pretty sure they called the cops.

If it was my church, you would have been spiked

 

[Snacktime]

If it was my Starbucks, you would have been spiked

No doubt!

 

[popo_patty]

No doubt!

I see what you did

 

[Snacktime]

Got to do a little more testing yesterday and going to stick it out with the 600lb fronts and 200lb rears.

For me the swap to 200lbs rear springs got me a solid 2 1/2" of drop after a week of settling. After cranking them back up to a total of 1 1/2" drop the ride got substantially better. Its like the pre load in the rear giving the rear more downward force near full extension. Was noticeably better through the whoops with the rear end feeling more planted when not pushing the limit. When you hit the rears limit it got sketchy instantly. Note that the point of becoming sketchy was at faster speeds than before, hence the instant bad harmonics are substantial. I did relocate my rear shocks up 2" years ago for slow speed crawling and these springs take me back into 5" up & 5" down travel.

The 600lb fronts seem to balance out the rears with similar downward force at full extension. I feel if I went to a lower spring rate I would have to crank the tension higher and have more force when the shock is completely extended. Right now it transitions from 3 wheels while crawling back down very softly and controlled. I have a lot of extra weight in the front and it clearly factors into this decision.

 

[GreyZ]

Got to do a little more testing yesterday and going to stick it out with the 600lb fronts and 200lb rears.

For me the swap to 200lbs rear springs got me a solid 2 1/2" of drop after a week of settling. After cranking them back up to a total of 1 1/2" drop the ride got substantially better. Its like the pre load in the rear giving the rear more downward force near full extension. Was noticeably better through the whoops with the rear end feeling more planted when not pushing the limit. When you hit the rears limit it got sketchy instantly. Note that the point of becoming sketchy was at faster speeds than before, hence the instant bad harmonics are substantial. I did relocate my rear shocks up 2" years ago for slow speed crawling and these springs take me back into 5" up & 5" down travel.

The 600lb fronts seem to balance out the rears with similar downward force at full extension. I feel if I went to a lower spring rate I would have to crank the tension higher and have more force when the shock is completely extended. Right now it transitions from 3 wheels while crawling back down very softly and controlled. I have a lot of extra weight in the front and it clearly factors into this decision.

Remind me if you have a rear sway bar?

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