UMI Performance 78-88 GM G-Body Front & Rear 2in Lowering Spring Kit

Matched Front and Rear 2 Inch Lowering Spring Kit for the 1978-1988 GM G-Body

One part number drops the whole car and keeps the two ends in proportion. UMI pairs a linear 600 lb/in front spring in 5160 chrome silicon with a linear 130 lb/in rear spring in 9254 chrome silicon, which is a deliberate choice of two alloys for two different jobs rather than one wire used everywhere. Buying the set is also cheaper than the front-only and rear-only part numbers bought separately.

UMI is specific about what the kit fixes, and it is not only ride height: the company names the floating feeling common to G-body cars as the thing these rates are meant to remove, along with the body roll that goes with it. The nominal 2 inch drop is quoted for standard small block and LS power, with a full weight Big Block instead producing roughly a quarter inch of nose down rake.

Key Features

• Complete front and rear spring set for a nominal 2 inch drop under standard small block or LS power.
• Linear 600 lb/in front rate in 5160 chrome silicon premium wire.
• Linear 130 lb/in rear rate in 9254 chrome silicon premium wire.
• Two alloys chosen for their respective jobs rather than one wire used at both ends.
• Aimed at removing the floating feeling and body roll G-body owners describe, not only at stance.
• Black powder coat on all four springs.
• Developed with a top Sprint Cup chassis engineer and made in the USA.

Fitment

UMI publishes this eight vehicle list on the 3051 page as the confirmed application. There is no F-Body coverage on this part number: it is the pure G-Body kit.

The 2 inch figure is conditional, and UMI conditions it three ways: it is quoted for standard small block and LS power, a full weight Big Block car is instead told to expect roughly a quarter inch nose down rake, and a V6 Turbo Grand National may require spring trimming because of its lower engine weight. UMI's spring tips sheet adds that ride height is approximate and cannot be guaranteed because of the weight of the car, engine and accessories.

UMI publishes year, make and model only for this part number, with no submodel, trim, engine or drivetrain breakdown, so the fitment tags on this listing stop at model rather than inventing a trim.

Specifications

What's Included

• Front lowering springs.
• Rear lowering springs.

UMI describes this part number as a front and rear kit but publishes no explicit piece count on the product page or on the installation sheet, so no number of springs is asserted here. Check the contents against your car's requirement on receipt.

No shocks, isolators, bump stops or hardware are documented as being supplied.

About UMI Performance

UMI Performance builds chassis and suspension parts at 509 Hemlock Street in Philipsburg, Pennsylvania, from North American raw material supplied by leading USA steel suppliers, with machine-guided precision bent DOM tubing, precision laser cut components, Tiger Dry Lac powder coat and welds laid by skilled and robotic welders. UMI groups its G-Body springs into families by drop, with this kit sitting at the 2 inch end alongside the front-only and rear-only part numbers, and links the kit to its own G-Body spring height guide.

Related Parts

• UMI 3051F front only 2 inch lowering springs from the same family
• UMI 4051R rear only 2 inch lowering springs from the same family

FAQ

Yes. This is the front and rear kit, which is what separates it from the front-only part number in the same family. UMI does not print an explicit piece count on the page or the sheet, so the listing does not claim one, but the kit is sold and described as covering both ends of the car.

It depends on what is under the bonnet and what else has been done to the car. UMI quotes the 2 inch figure for standard small block and LS power. A full weight Big Block car is told to expect roughly a quarter inch of nose down rake instead, a light V6 Turbo Grand National may need trimming, and UMI states that ride height is approximate and cannot be guaranteed because of the weight of the car, engine and accessories. Treat 2 inches as the design target, not a promise.

They are doing different jobs at very different rates. The front carries the engine and runs at 600 lb/in in 5160 chrome silicon wire; the rear runs at 130 lb/in in 9254 chrome silicon. Both alloys are chrome silicon spring steels chosen for fatigue resistance, and UMI specifies each for the end it serves rather than using one wire everywhere.

It is the vague, slow, disconnected sensation a soft-sprung G-body gives over crests and through long corners, where the body keeps moving after the road has stopped asking it to. UMI names it directly and points at the combination of higher linear rates front and rear as the fix: the body stops rolling and pitching as far, and the car settles instead of continuing to move.

Yes. UMI prices the front and rear kit below the sum of its front-only and rear-only part numbers in the same 2 inch family, which is the main reason to buy the pair together if you are doing both ends anyway. The listing does not quote figures, but the kit is the cheaper route.

Flat end up, open coil end down into the lower A-arm. On UMI control arms the open end is clocked against the ramp in the arm; on stock GM arms it goes between the weep holes. UMI adds one more instruction that saves a lot of second-guessing: disregard the orientation of the UMI sticker, since it is applied for identification and carries no installation meaning.

No, and it is worth knowing before you start. The installation sheet UMI serves for this kit is titled for the front coil spring and covers front orientation, clocking and the too-high troubleshooting list. There is no rear spring procedure in it, so follow the factory service procedure for rear coil replacement on your year and model.

UMI's own troubleshooting list for its front springs: confirm the upper spring bucket is clean, confirm the spring is fully seated, and confirm the frame fingers are inside the spring rather than outside it. UMI's tech tip for the last case is to bend the perch fingers inward with a crowbar. UMI also states outright that ride height is approximate and cannot be guaranteed because of the weight of the car, the engine and the accessories, so a small deviation from the nominal figure is expected rather than a fault.

UMI sanctions trimming. Its spring tips sheet states that trimming is permissible and sometimes required, and that front springs can be trimmed a quarter coil at a time using a slicing wheel. That is a genuine tuning step rather than a bodge. The trade-off has to be said plainly: UMI's warranty excludes any product that has been altered, adjusted or tampered with, and the returns policy only accepts new, unopened product in sealed packaging within 30 days, so a trimmed spring is neither returnable nor a realistic warranty claim. Fit the springs first, measure the car, and only trim once you know how far off target you are.

Both numbers come from UMI. The product page for this part number states a linear 600 lb/in front rate, and UMI's platform level G-Body spring height and lowering guides state 530 lb/in. The 600 figure is published on this listing because the part number page is the document UMI maintains per SKU, while the same 530 wording also appears verbatim on UMI's A-Body guide, which suggests reused platform copy rather than a measurement of this spring. The rear figure of 130 lb/in agrees across all of those pages. If the exact rate matters for a shock or bar calculation, confirm it with UMI before you commit to a valving choice.

Yes, a proper spring compressor is mandatory. A loaded coil in a GM short-and-long arm front suspension stores enough energy to be lethal if it is released uncontrolled. On torque, UMI publishes no ft-lb figure for these springs in any of its documents, so none is printed here. Use the factory service specification for your year and model on the lower control arm, shock and spindle fasteners, and tighten suspension pivots with the car at ride height.

Two inches is a meaningful change on a G-body: it uses up bump travel, changes the front geometry and can bring wide tyres closer to the lip and the inner arch. UMI publishes no clearance figures for this kit, so nothing is promised here. Plan on an alignment afterwards, check tyre clearance through full lock and full bump before driving, and if the car is already running wide rear rubber, check clearance at the rear as well.

UMI publishes a two year warranty from the original date of purchase against defects in materials and workmanship, to the original purchaser only, and it is not transferable. The same policy excludes misuse, use beyond the design limits of the part, improper installation, acts of God, shipping damage, any product that has been altered, adjusted or tampered with, components not made by UMI, incidental costs such as towing and labour, and normal wear items including bearings and bushings. UMI also states it cannot guarantee compatibility with other manufacturers' components. The printed sheet in the box still carries an older disclaimer that predates the current two year term, and the live policy page is the document that governs. Neither is a Black Ops Auto Works warranty.

Installation Instructions

1. Support the car safely on stands and remove the wheels at the end you are working on.
2. Front: fit a proper spring compressor and remove the factory coil following the factory service procedure for your year and model.
3. Front: clean the upper spring bucket, then fit the new spring flat end up with the open coil end down into the lower A-arm.
4. Front: clock the open end against the ramp on UMI control arms or between the weep holes on stock GM arms, and disregard the orientation of the UMI sticker.
5. Front: confirm the spring is fully seated and the frame fingers sit inside the spring.
6. Rear: replace the rear coils following the factory service procedure for your year and model, since UMI's sheet for this kit covers the front spring only.
7. Refit the wheels, lower the car and let the suspension settle before measuring anything.
8. Measure ride height at all four corners and only then decide whether any front trimming is needed.
9. Have the car aligned.

UMI publishes no fastener torque figure for these springs in either the item sheet or the general spring tips sheet, so no number is printed here. Use the factory service specification for your year and model, and tighten suspension pivot fasteners with the car at ride height.

A spring compressor is required for the front springs. Do not attempt the job by levering a loaded coil out of the pocket.