Bottoming out at highway speeds

FOX87STANG

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I bought a 04 vert last year and it has a Stifflers fit system. It only has 2.75" of clearance. It's lowered on Eibach springs and has the stock Bilstein shocks. At speeds over ~40 mph it often bottoms out due to the force of the car pushing downward if that makes any sense. It doesn't have to be a rough road either. I can simply be at the bottom of two smalls hills and it will scrape the fit system. I checked the shocks and they retract and extend as they should. What are some of my options to keep this from happening? I attached a picture of the car so you can get an idea of how low it is. It doesn't seem too low in my opinion but maybe that's the root cause.
 

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Zemedici

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Springs more than likely the culprit, eibachs hammer them.

Could change to different springs to raise her up a bit.
 

me32

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Its the vert struts/shocks. They are softer the coupe. I would look at getting some stiffer struts/shocks.
 

shurur

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If you don't have a FLSF like stifflers, you should get that before fooling around with springs.

The verts, like all verts, come with softer springs than the coupes. This is so the stiffer springs don't shake the car apart.

Full length subframes are the first mod on a vert..actual all mustangs up to 2004, but especially verts.

Edit...you mentioned the fit system.
Then I would look at what strut/shocks you have matched to the Eibachs first...as others have said, those stock strut/shocks may be all pissed out...this would give you the raw spring experience you are getting.

I would get something that you could upgrade to a higher spring rate should the strut/spring not fix your problem with the eibachs.
 
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HudsonFalcon

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I had the Eibach springs and while they lowered the car to the perfect height I would scrape a lot.

Switched to H&R Race with Bilstein HD’s and I never scrape. Plus, the car handles much better and feels stiffer/flatter in corners.
 

DSG2003Mach1

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If you’re gonna do springs and shocks/struts might not be much more to get MM coil overs, can stiffen it up without killing the ride and adjustable on the height

And I had bilstein HD with H&M’s springs and were a little harsh at times
 

shurur

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If you’re gonna do springs and shocks/struts might not be much more to get MM coil overs, can stiffen it up without killing the ride and adjustable on the height

And I had bilstein HD with H&M’s springs and were a little harsh at times
Can't lie..my H&R race springs are a rough ride...the word visceral comes to mind.
 

DSG2003Mach1

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Can't lie..my H&R race springs are a rough ride...the word visceral comes to mind.

My main issue was like hitting the transition from asphalt to concrete when going over a bridge and stuff like that, it was like getting smacked. Definitely notice shit like that more as you get older
 

68gtscode

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Interesting feedback in this tread. I had H&R Race springs with MM isolators (one removed in the back for a more level stance) and don’t recall the ride being too harsh.
 
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01yellercobra

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I've experienced Eibach springs on three cars. Two 98 GT's and an 06 GT vert. They all had the good stance, but the issue is the Eibachs are soft springs. They're made that way because a lot of people want the stock ride while being 2" lower. Can't have both. Even with good shocks/struts the ride is meh at best IMO. I put Koni's on the 06 and it did make it less skittish, but it still didn't ride as well as my 04 with Bilsteins and H&R race springs.

As mentioned a good coil over is the best of both worlds IMO. I'm a little lower than I was with the H&R's, but it rides just as good and handles really well. I would say if you're going to invest in coilovers to put the money into Vikings. I installed a set on a buddies car and they're really nice. It has me thinking about ditching my MM set up.
 

AnarchyVA

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My main issue was like hitting the transition from asphalt to concrete when going over a bridge and stuff like that, it was like getting smacked. Definitely notice shit like that more as you get older

Thats my problem right now. I can handle the speed bumps and the occasional pothole. But those transitions are just terrifying! It sounds like the car is being dropped onto the road surface from a crane.....BAM!!! Makes your butt cheeks sweat. My fiancé always yells at me. But sometimes you just don't see those transitions coming. Its time to do something about it....I just don't know what yet...
 

Rambro

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I have an 03 cobra with H&R race springs, and a 15 gt with eibach sportlines. Both will bottom out hard on these transitions on the highway, so it’s not the brand of springs necessarily. Couple years ago I was driving on the highway and had 2 people in the back seat of the cobra, I hit one of those transitions and it ripped one of my tailpipes off. I shudder to think what would happen to a car with an aftermarket K member, and an aftermarket oil pan if it hits one of these dips in the highway. Be careful out there.
 

Rambro

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And yes it’s scary when you don’t see it, and you hit one doing 70 mph, BOOM! Maybe new shocks and struts will help, but to keep it from bottoming out I’m afraid you would have to put taller springs in to totally eliminate it.
 

Roush6018

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most of the weight is in the engine and transmission. they are in the front half of the car. its the front suspension doing most of the work.

the front lower control arms are bolted in tight to the k-member in 2 spots, on each side. inside of the arms are 2 rubber bushings with the top and bottom of the rubber missing and the left side and right side are connected with rubber. when the control arm is installed the 2 bolts are tightened to 148 foot LB. when the bolts are tight the lower control arm can only move up and down about 1-2". the rubber bushings will flex some. if these bushings are torn or broken the lower control arm will move free up and down.

i recommend replace both of the front lower control arms (complete with bushings and ball joint) if these bushings have failed.

i did put poly bushings in my front lower control arms and they do move free when the bolts are tight, i am running H&R sport with (aftermarket ) upper and lower ISO in the front. i dont scrape too much, mostly steep driveways, but my front suspension is pretty bouncy over the rough roads. my conclusion is they are for drag racing to get the front to lift as much as possible to get a better weight transfer to the rear when you launch from a complete stop ( DIG ) .
 

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