UMI Performance 78-88 GM G-Body Bolt-In Rear Shock Tower Brace - Black

Jig Built Bolt-In Rear Shock Tower Brace for the 1978-1988 GM G-Body, Gloss Black

Homemade rear braces on a G-body usually fail on one of two counts: they land on a slightly different hole pattern car to car, or they foul the exhaust. UMI builds this one in a jig from 1-1/4 inch USA tubing MIG welded to 3/16 inch CNC laser cut brackets, and designs it to clear all popular exhaust systems, so it goes in with the supplied Grade 8 hardware and the factory rear shock mounting points.

What it does is tie the two rear upper shock mounts into one load path instead of leaving each shock to work against its own patch of frame. It suits a stock spring and shock rear as readily as a coilover conversion, and UMI's own sheet gives the specific fastener routing for its 3048 and 3049 coilover kits. Gloss black keeps it visually quiet under a car where the underside is not the show piece.

Key Features

• Jig built, so every unit lands on the same hole pattern.
• 1-1/4 inch USA tubing MIG welded to 3/16 inch thick CNC laser cut brackets.
• Ties both rear upper shock mounts into a single load path to stiffen the chassis.
• Designed to clear all popular exhaust systems.
• Works with traditional spring and shock rear suspension and with coilover conversions.
• Grade 8 mounting hardware included, with a published tightening figure of approximately 25 ft-lbs.
• Installs with basic hand tools in the space between the fuel tank and floor pan and the chassis.
• Gloss black powder coat, made in Philipsburg, Pennsylvania.

Fitment

UMI publishes this eight vehicle list on the 3055 page as the confirmed application, and the page carries no fitment warning or exclusion of any kind.

Installation qualifications from UMI's sheet: depending on your frame and the shocks you are using, you may have to use a 3/8 inch drill bit to properly clearance the shock holes or the frame, and some models may require exhaust hanger relocation or modification. Those are sanctioned installation steps on the car rather than changes to the brace.

The brace mounts to the chassis and the upper shock mounts, so it is unaffected by which rear axle housing the car runs.

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

• One 3055 rear shock tower brace.
• Grade 8 mounting hardware, including the 3/8 inch fasteners, locking washers and nuts referenced in the installation sheet.

UMI publishes no itemised box contents table for this part number, unlike its 3053 front brace and 3061 notch kit, so no piece counts are stated here. What is documented is that Grade 8 hardware is included and that the sheet works with supplied 3/8 inch fasteners, locking washers and 3/8 inch nuts.

No shocks, coilovers or coilover support plates are supplied. If you are running UMI 3048 or 3049 coilovers, the support plate comes from that kit and the fastener passes through it.

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 3055 brace is jig built in Philipsburg so that the hole pattern repeats from unit to unit, which is the difference between a bolt-in brace and a fabricated one.

Related Parts

• UMI 3053-B front reinforcement brace in matching black, the front half of the same chassis stiffening job

FAQ

It ties the two rear upper shock mounts into a single load path so the shocks feed their loads into a structure rather than into two separate points of the frame. UMI's own description of the function is sharing the load and stiffening the chassis. On a street car the payoff shows up as a rear end that feels more settled over uneven surfaces and under power, rather than as a lap time.

It is a bolt-in part and it uses the factory rear shock mounting holes with the included Grade 8 hardware, but UMI's own sheet is honest about the variation: depending on your frame and the shocks you are using, you may have to use a 3/8 inch drill bit to properly clearance the shock holes or the frame, or fasten with 5/16 inch bolts instead. That is a long way from weld-in fabrication, but it is not a promise of zero drilling either.

UMI designed it to clear all popular exhaust systems, which is the usual failure point of homemade rear braces. The sheet still allows for the exception: some models may require exhaust hanger relocation or modification. If your car has custom pipework over the axle, check the route physically during the trial fit before final tightening.

Yes. UMI states the brace works on coilover setups as well as traditional spring and shock combinations, and the installation sheet gives a specific routing for UMI's 3048 and 3049 coilovers where the fastener passes through the support plate supplied with the coilover kit as well as through the brace, chassis and shock.

UMI's instruction is to final tighten to approximately 25 ft-lbs, and the word approximately is UMI's own rather than an editorial hedge. That figure applies to the 3/8 inch fasteners on this brace. Because the same fasteners also carry the rear shock upper mounts, check your shock manufacturer's upper mount instruction as well before you call the job finished.

UMI's procedure does not include removing the fuel tank. The brace slides into the opening between the fuel tank and floor pan and the chassis, which is why the sheet describes lining the slotted holes up with the driver's side of the frame as the first positioning step. Supporting the axle before the shock bolts come out matters far more.

It is a chassis-side part. It bolts to the frame and to the upper shock mounts, not to the axle housing, so a swapped rear end does not affect it. That is a genuine difference from UMI's axle mounted rear sway bars, which are designed for factory housings only.

UMI states Grade 8 hardware is included, and the installation sheet works with supplied 3/8 inch fasteners, locking washers and 3/8 inch nuts. UMI does not publish an itemised quantity table for this part number the way it does for its front brace, so no piece counts are claimed here. Count what arrives against the four shock mounting points before you start.

They are designed as the front and rear halves of the same chassis stiffening job, they share exactly the same eight vehicle G-Body application, and UMI produced a single video covering both. Each one works on its own, so there is no dependency, but the car feels more of a piece with both fitted.

Drilling the car's shock holes or frame to 3/8 inch is explicitly sanctioned by UMI's own sheet, and so is relocating an exhaust hanger. Cutting, re-drilling or re-coating the brace itself is a different matter: UMI's warranty excludes any product that has been altered, adjusted or tampered with, so modifying the part rather than the car is what puts coverage at risk.

It installs under the car in the space between the fuel tank and floor pan and the chassis, so it does not intrude into the boot or the passenger compartment. UMI publishes no dimensional drawing, so on a car with a fabricated floor, a relocated tank or a fuel cell, check the space physically before ordering.

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. Block the front wheels and jack the rear of the vehicle to a good working height, then place jack stands in a secure location on the chassis or the rear axle.
2. Support the rear axle with a jack or a jack stand if the vehicle is supported by the chassis.
3. Loosen all four bolts holding the shocks to the frame. If the axle is not supported at this step, removing the shock bolts will allow the axle to fall.
4. Remove the four shock bolts loosened in the previous step.
5. Slide the brace into the opening between the fuel tank and floor pan and the chassis, and line the slotted holes up with the driver's side of the frame.
6. Line the brace up with the chassis holes and the holes in the T-bar shock mount.
7. Slide the supplied 3/8 inch fasteners through the brace, the chassis and the shock in that order from the top. If you are using UMI 3048 or 3049 coilovers, the fastener also passes through the support plate included with that kit, so reference the coilover kit instructions as well.
8. Fit a locking washer and a 3/8 inch nut under the shock T-bar mount.
9. Final tighten to approximately 25 ft-lbs.

Approximately 25 ft-lbs is the only numeric torque UMI publishes for this part, and the word approximately is UMI's own. It is quoted here as written rather than rounded into a hard specification.

These fasteners also carry the upper mount of the rear shocks, so check your shock manufacturer's own upper mount instruction before deciding the final assembly is complete.

Depending on your frame and shocks you may have to open the shock holes or the frame to 3/8 inch with a drill bit, or fasten with 5/16 inch bolts, and some cars need an exhaust hanger relocated or modified.