Front spring comparison; ATR, UMI & stock.

1986 Buick GX1

GX1 #001 [The One and Only]
I bought my GN new in '86, took delivery 7-10-86 and put '86 Vette wheels (16x8.5 w/ 1.5" adapters/ spacers) and 255/50-16 tires on the car in April of '88 and replaced the stock springs with ATR performance springs on the front and Moog cargo coils on the rear because the front tires rubbed the top outer part of the fender a little on large dips.
Even with Bilstein shocks i have always wanted the front to be a little stiffer and am installing UMI Performance 1" lowering springs.
I thought I'd compare the three front springs while I had everything apart.

Front springs
Stock springs w/ approx. 10k miles of use. (sitting for 28 yrs) ---------- .650" wire dia 14 1/4" free height. (420#)

ATR springs (just removed w/ 28 yrs & 60k mi of use) ----------.735" wire dia 12 7/8" free height. (Unknown spring rate, I'm guessing by wire size. 540 - 550#)

UMI Performance 1" drop springs (new) --------.755" wire dia 13 1/4" free height. (600#)

From left to right.

ATR (??? 540 - 550#???)UMI (600)Stock (420#)

Edited for spring rates.
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Well-Known Member
Neat to see them all lined up side by side. Thanks for taking the time to do that!
Hit me up on those ATR springs if you want rid of them. Been wanting mine to sit a bit lower in the front.


Active Member
I'd like to know about the ride difference with the UMI's. I would'nt mind a bit more of a sportscar ride with my bilstiens.