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Discussion Starter #1
Sorry, but I do not see a suspension section.

Son’s 2001 GT Convertible. Can anybody tell me what factory (stock) ride height is measured from floor to center of fender arch?

Seems it was 28.5” all around. Then we put in Eibach Pro-line for a COUPE (used CraigsList; advertised as suitable for Coupe or Convertible). Installed new Koni adjustable on from and near new Bilstein’s at rear. Dropped to 27” front and 28” rear. Have 2016 GT 18” wheels all around. Left front tire hits center/top of wheel well even under light braking. Had to adjust Koni’s to full firm in attempt to alleviate the rubbing (does not rub lip. Rubs top of wheel well). Car was not stable at higher speed if road has any irregularities; I would describe it as porpoising.

Called Eibach and they found it odd they way the car was handling but did advise I had the wrong springs. So I bought the right springs from them. Just installed the fronts springs (kid is getting good at it!). Now working on rear tonight. The front is now at 28.25” using Prothane isolator top and bottom. Does this seem about right?

Thanks!
 

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Discussion Starter #2
All 4 springs now installed with 28.5” ride height. Have not driven it yet as intake is broke. Bullitt system going on next!
 

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Measurements from the floor to the fender opening are only valid when the tire size is known and the OE size also known. Unfortunately, I'm not all that familiar with SN95 details, and my best guess without looking it up is that your new tire size is 235/50-18. 1.5" lower by your measurement plus half the difference in diameter could have put the actual suspension change beyond 2" with much increased risk of frequent bump stop contact (bump stop rates being beyond your shocks' ability to properly control).

Porpoising is a matter of having springs with front vs rear rates that are mismatched for the car's weight distribution. Sprung weight distribution actually, not including wheels/tires/brakes/axle/about half of suspension/etc. Shocks with weak or soft rebound damping due to age/mileage/internal breakage allow this to be at its worst. Either search on or google 'flat ride' as it applies to cars.


Norm
 

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He said he's running the '16 GT wheels, but I'd be surprised if he's running 235/50-18. I would assume the stock '16 tires have been replaced with a more suitable size.

Anyway, as Norm said, you don't want to measure from the floor. Instead, measure from the center of the wheels to the fender lip; that way the wheel and tire size don't affect the result. With that said, I don't know what an SN95's ride height is supposed to be, so hopefully someone in the know can chime in.
 

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He said he's running the '16 GT wheels, but I'd be surprised if he's running 235/50-18. I would assume the stock '16 tires have been replaced with a more suitable size.
That could contribute to part of the problem. The tires on the '16 wheels are larger in overall diameter than what came on the Sn95. Really need to swap to Sn95 specific tire sizes.
 

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I keep hoping that OP will stop by this thread and clear up this tire size matter. Otherwise it's as good an assumption as any to think that the wheels and tires were bought (by somebody, doesn't matter who) as a new-take-off set. Mounted and all.

Near as I've been able to find out, the 18x8 S550 wheel runs a +40 mm offset, which ought to have helped an outside shoulder rub (at the expense of strut-side clearance, which wasn't identified as a problem).


Norm
 

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I keep hoping that OP will stop by this thread and clear up this tire size matter. Otherwise it's as good an assumption as any to think that the wheels and tires were bought (by somebody, doesn't matter who) as a new-take-off set. Mounted and all.

Near as I've been able to find out, the 18x8 S550 wheel runs a +40 mm offset, which ought to have helped an outside shoulder rub (at the expense of strut-side clearance, which wasn't identified as a problem).


Norm

That's what I'm thinking. Higher offset of the wheel and possibility of still running stock S550 size.

OP: My car was lowered on Sportlines with stock ISOS.

I ran 255/40's on 99 GT 17" starfish wheels no issues (also had a spacer can't remember how wide, maybe an inch) I don't think there is any difference in the specs but also has the spacers and same tires on stock 94-95 3 spokes and no rubbing as well.

Currently on 17x9 and 17x10 Saleen SC reps with 245/45 and 275/40 never rubbed.
 

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Discussion Starter #8
These are P235/50/18 new car take-offs 2016 Mustang GT with 40mm offset. Measured from centerline of wheel center to center of wheel opening is about 15.75”.
I had looked up previously the OD difference between a factory 17” wheel / tire and our factory 18” wheel / tire and it was only .75”.
There is about 2” between the top of the tread to the fender arc. I would have thought this would have been a little tighter with the Eibach Pro kit.
The front wheels seemed OK but we added 1.5” spacer's to the rear. Looks pretty good now.

At this point we have new wheels & tires, new Koni’s up front and new Bilstein rear & quad shocks. New Eibach springs and Energy Suspension (not Prothane as I originally wrote) isolators top & bottom on all four corners. Plus the rear spacers. I’m not usually a fan of spacers but after taking a more serious look, decided it was ok. All lug & nuts (spacer and wheels) are 100# installed.

So basically, we dropped about .25” from stock GT springs but those had 165,000 miles on them so who knows how saked out they were? And when we bought the car it had some 21” or 22” “bling” wheels so we never had a reference to factory 17” wheel (couldn’t get rid of the bling wheels fast enough!).That’s why I was asking OEM spec.
We liked the look of the 2016 wheel and it was $700 for the new take-off set. It was cheaper than most sets of good used OEM Bullitt’s and tires and I’m not a fan of most aftermarket wheels; prefer OEM.

At this point, we have the suspension done and tomorrow we can start putting the engine back together. I believe the left front tire rubbing the center of the wheel well will be a problem of the past.
 
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