UMI Performance 78-88 GM G-Body Solid Front & Rear Sway Bar Kit - Black

Matched Front and Rear Solid Sway Bar Kit for the 1978-1988 GM G-Body, Gloss Black

Buying the front and rear bars as one part number is how you change a G-Body's roll stiffness at both ends at once instead of chasing balance one bar at a time. This kit is UMI's 1.250 inch solid front bar rated at 428 lb/in together with its 1 inch solid rear bar, both in 4140 chrome moly, both formed as single pieces, and both finished in the same gloss black so the underside looks deliberate.

The two bars are made differently on purpose. The front bar is CNC bent cold, which is what keeps its 44 11/16 inch centre to centre geometry repeatable. The rear bar is heat treated and hot formed, which UMI says holds its memory longer and gives roughly double the tensile and yield strength of a cold bent bar, at the cost of a slightly textured surface that is normal rather than a coating fault.

Key Features

• Complete two position kit: 1.250 inch solid front bar and 1 inch solid rear bar under one part number.
• Both bars formed from 4140 chrome moly as single pieces, with no splices or welded arms.
• Front bar rated by UMI at 428 lb/in of deflection with a published 44 11/16 inch centre to centre.
• Rear bar heat treated and hot formed for roughly twice the tensile and yield strength of a cold bent bar.
• Front bar supplied with new high quality end links and greaseable bushings in zinc plated clamshells.
• Rear bar supplied with new Grade 8 M10 mounting hardware and a published 45 ft-lbs torque figure.
• Matching gloss black powder coat on both bars.
• Non-adjustable at both ends, so the balance is set by the pairing rather than by fiddling with holes.

Fitment

UMI publishes this eight vehicle list on the 303534 kit page as the confirmed application, so the fitment above is manufacturer-confirmed rather than inferred.

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.

The rear bar half of this kit is designed for factory rear end housings only. UMI states plainly that it does not fit a Ford 9 inch rear, and that a car with an aftermarket rear end needs a chassis mounted rear sway bar instead. That is a fitment limitation, not a warranty condition, and it is the single most likely reason for a return on this part number, so check the housing under your car before ordering.

The kit page lists Hardware as included and Modifications as none. Both are true of the rear bar's Grade 8 hardware. They do not mean the front bar's clamshell bolts are supplied: UMI requires the small diameter GM specific factory bolts to be reused on the front bar.

Specifications

What's Included

• One 1.250 inch solid front sway bar.
• Two front end link assemblies.
• Two front sway bar bushings with clamshells.
• One 1 inch solid rear sway bar.
• Four M10 bolts, eight M10 washers and four M10 locknuts for the rear bar.

This kit is documented by UMI as a combination of two part numbers, 3035 front and 3034 rear, and the contents above are assembled from the box contents lists on those two installation sheets. No kit-level contents table exists, and nothing beyond those documented items is claimed here.

The front bar's clamshell mounting bolts are not supplied. UMI requires the factory bolts to be reused with the UMI clamshells because they are GM specific and small in diameter.

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. The 303534 kit is UMI's own pairing of its 3035 front bar and 3034 rear bar, sold as one part number rather than as a separate design.

Related Parts

• UMI 3068 front sway bar mount spacer, offered by UMI as an add-on for this kit
• UMI 3008 Super Lube synthetic grease for the greaseable front bushings

FAQ

It is the same two parts. UMI's own kit page carries a kit items block listing the 3035 front bar and the 3034 rear bar, so the kit is those two part numbers under one number, with their own bushings, end links and rear hardware. The advantage is that it is cheaper than the two individually and the colours are guaranteed to match, and the kit is not a separate design with different construction.

No. UMI states the rear bar does not fit a Ford 9 inch rear, and on its Stage 3 package page it explains that its axle mounted rear bars are designed to fit factory rear end housings only, with aftermarket rear ends requiring a chassis mounted sway bar instead. Treat that as a fitment restriction on the car, not as a warranty term. If your car has a swapped housing, the front bar alone is still usable but this kit is the wrong purchase.

45 ft-lbs on the M10 fasteners, which UMI describes as moderately tight with hand tools, with the final tightening carried out with the suspension at its operating position. That figure is specific to the rear bar. UMI publishes no ft-lb value for the front bar, so use the factory service specification there instead of reusing 45.

For the rear bar, yes: four M10 bolts, eight M10 washers and four M10 locknuts, described by UMI as new Grade 8 hardware. For the front bar, no. The factory clamshell bolts are reused because they are GM specific and small in diameter, and UMI requires them to be used with its clamshells. The kit page's blanket hardware included attribute covers the rear bar only.

They are not. UMI describes the front bar as CNC bent and formed as one piece, a cold forming process, and the rear bar as heat treated and formed as one piece, a hot forming process that UMI says holds its memory longer than a cold bent bar and gives roughly double the tensile and yield strength. Both bars are 4140 chrome moly and both are one piece, but the two processes are genuinely different and should not be described interchangeably.

No. UMI raises this itself: as a hot formed part the rear bar is expected to show some surface texture, and that texture comes with roughly twice the tensile and yield strength of a cold bent bar. It is a consequence of the forming process, not a powder coat fault.

Downward, so the bar clears the differential. UMI also specifies that the mounting bolts go from the outside to the inside. Both details are in the 3034 installation sheet that covers the rear half of this kit.

Yes, the two bars install independently and each has its own procedure. Bear in mind that until both are fitted the car is running a front-biased setup, which will feel like more understeer at the limit than the finished kit gives. If you are doing it in stages, drive it gently until the pair is in.

UMI publishes no clearance dimension for the rear bar and no exhaust compatibility statement for this kit, so no promise is made here. What is published is the front bar's 44 11/16 inch centre to centre dimension and the rear bar's downward bow for differential clearance. On a car with custom exhaust routing or a fabricated loop, check physically during the trial fit before final tightening.

Yes. The colour option on this part number applies to the kit as a whole, so both bars arrive in the same powder coat and the underbody looks intentional rather than mismatched.

Both are offered by UMI as add-ons on this kit's own page. The 0.600 inch sway bar mount spacer is there for cases where the front bar needs to sit further from the frame, and the synthetic grease is a genuine consumable for the greaseable front bushings rather than an upsell.

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. Read both installation sheets before starting. This kit is covered by the 3035 front bar sheet and the 3034 rear bar sheet rather than by a single kit document.
2. Front bar: raise the car under the front crossmember, set stands behind the front tyres on the frame, and remove the old end links, which may need an impact wrench or cutting off.
3. Front bar: fit the new end links finger tight one side at a time, attach the bar to both links, then mount the clamshells to the existing factory holes using the factory bolts.
4. Front bar: centre the bar for equal side to side clearance, lower the car so its weight is on the bar, then tighten the end links with a 9/16 inch wrench until the bushings start to bulge slightly, with the washers cupping toward the bushings and no grease on the links.
5. Rear bar: fit the bar with its bow facing downward so it clears the differential.
6. Rear bar: run the bolts from the outside to the inside as UMI specifies.
7. Rear bar: tighten the M10 fasteners to 45 ft-lbs, with the final tightening done with the suspension at its operating position.
8. Turn the wheels through a full sweep and check clearance around the brake lines, tie rods, control arms, exhaust and driveshaft before the car is driven.

45 ft-lbs is the only numeric torque UMI publishes for this kit and it applies to the rear bar's M10 fasteners. No ft-lb figure exists for the front bar, so use the factory service specification for the front clamshell bolts on your year and model rather than borrowing the rear bar number.