UMI Performance 78-88 GM G-Body Adjustable Rear Upper & Lower Control Arm Kit - Red

Adjustable Rear Four-Link Control Arm Kit for the 1978-1988 GM G-Body, in Red Powder Coat

This is a rear axle kit, not a front A-arm kit. UMI's own name for it is Rear Control Arm Kit, Adjustable, and it replaces all four arms of the G-Body's rear four-link: two single-adjustable tubular lower arms and two on-car adjustable upper arms with rod ends. Anyone who has watched a stock G-Body wrap its rear suspension up on a launch knows why the factory rubber-bushed arms are the first thing to go.

The kit is built from UMI's 3014 lower arms and 3017 upper arms. The lowers use a QA1 rod end at the housing and a greaseable fluted polyurethane bushing at the chassis; the uppers use a solid one inch heat-treated chrome moly adjuster so pinion angle can be dialled in with the car on the ground. This listing is the red powder coated version.

Key Features

• Complete rear four-link replacement: two adjustable lower arms and two adjustable upper arms.
• Lower arms use 1.500 inch by 0.120 inch wall DOM mild steel tube with TIG welded 4140 chrome moly tube adaptors.
• Upper arms are 4140 chrome moly, TIG welded, with CNC machined 0.250 inch mild steel mounting points.
• Upper arm length adjuster is a 1.000 inch solid 4140 heat-treated chrome moly bar, so pinion angle can be set with the suspension loaded.
• QA1 three quarter inch hard chrome plated rod ends with a Teflon and Kevlar lined self-lubricating race at the axle end of each lower arm and on the uppers.
• Energy Suspension fluted polyurethane chassis bushing with a grease fitting on each lower arm.
• CNC machined 6061 aluminum step bushings locate the lower rod ends.
• Arms ship preset to factory length so the car can be driven before pinion angle is fine-tuned.
• Red powder coat over the full set.

Fitment

UMI publishes this kit for the 1978-1988 GM G-Body, including the wagons and the El Camino and Caballero, which share the same rear four-link geometry. UMI publishes year, make and model only for this part number and lists no submodel or trim breakdown, so the fitment tags on this listing stop at model rather than inventing a trim.

A retailer additionally names Buick Grand National and Pontiac LeMans for this kit. Grand National is a Regal trim already covered by the Regal listing, and LeMans is not on UMI's published vehicle list, so neither is tagged here.

No exhaust, transmission or rear-axle exclusion is published for this kit. Do not confuse the part with UMI's 401417 A-Body kit or the double-adjustable 302717, which are different platforms and different parts.

Specifications

What's Included

• Two adjustable tubular rear lower control arms, part 3014, with polyurethane chassis bushings and QA1 rod ends installed
• Two adjustable rear upper control arms, part 3017, with rod ends and the solid chrome moly adjuster
• Two CNC machined aluminum step bushings for the lower rod ends
• Installation instruction sheets for both the lower and the upper arms

Mounting bolts are not included: UMI publishes hardware as Not Included for this kit and the factory rear control arm bolts are reused. Note also that no grease packet ships with 301417, unlike UMI's non-adjustable 301516 kit, which does include one. A retailer bullet list claiming replacement installation hardware contradicts UMI's own page and is not correct.

About UMI Performance

UMI Performance builds chassis and suspension parts at 509 Hemlock Street in Philipsburg, Pennsylvania, using North American raw material from USA steel suppliers, machine-guided precision DOM tube bending, laser-cut plating and welds laid by skilled and robotic welders. Rear suspension is where the company started for these platforms, and the adjustable G-Body four-link is its most configurable version: on-car pinion angle at the uppers, single adjustment at the lowers and QA1 rod ends where the housing needs to be located precisely.

Related Parts

• UMI 3028-B rear control arm reinforcement braces for 1978-1988 GM G-Body
• UMI 3008 Super Lube synthetic grease for the greaseable polyurethane bushings

FAQ

Rear. UMI's official name for the part is Rear Control Arm Kit, Adjustable, and the four arms in the box are the G-Body's rear four-link: two lowers from the chassis to the axle housing and two uppers that set pinion angle. It has nothing to do with the front A-arms, and a retailer index that files it under A-arms is using its own taxonomy rather than UMI's.

The lower arms have one adjustment, used to square the axle housing in the chassis and set wheelbase. The upper arms carry a solid one inch heat-treated chrome moly adjuster that can be turned with the car on its wheels, which is how pinion angle is set. The uppers are the ones you will touch again after the first drive.

UMI's procedure is to measure the driveshaft angle and the rear end or yoke angle with an angle finder and add them together. Its published guidance is that the best settings for a street driven car are 1 to 2 degrees downward. Adjust both upper arms equally with a one inch wrench, with the suspension loaded and the vehicle level, and check the jam nuts often afterwards.

No. UMI publishes hardware as Not Included and the design reuses the factory rear control arm bolts, which are 18 mm on the head. If your original bolts are stretched, rusted or previously over-torqued, source correct replacements before installation.

UMI publishes 72 ft-lb for both the lower and the upper control arm bolts, and specifies that the fasteners are torqued with the weight of the vehicle on the rear axle. Tightening at full droop preloads the polyurethane bushing in a twisted position and is the most common installation error on this kind of kit.

UMI calls for 1 to 1.5 pumps of grease per fitting, using a marine type grease, two to three times per year, and warns specifically against over-greasing. The zerk on each lower arm should be angled toward the ground so a grease gun can reach it with the car on stands.

The kit is published for the factory G-Body rear suspension, and the sway bar has to be disconnected from the lower arms during installation and refitted afterwards. If the car has an aftermarket rear end housing, verify the control arm mount spacing on that housing before ordering, because housing swaps are where four-link geometry most often changes.

They transmit more than a rubber bushing does. The lower arms use a QA1 rod end at the housing with a Teflon and Kevlar lined self-lubricating race, which is quieter than a bare metal spherical joint, and the chassis end keeps a polyurethane bushing. If your priority is a silent street car, UMI's non-adjustable 301516 kit uses polyurethane at every point instead.

This one adjusts. It uses rod ends and threaded adjusters so pinion angle and axle position can be set on the car, and it is built around the 3014 and 3017 arms. The 301516 kit is built from the 3015 and 3016 arms, uses greaseable polyurethane bushings at every mounting point, has no adjusters at all, and is the quieter street-first option.

A rear four-link swap does not require a conventional alignment, but pinion angle must be checked and set, and the axle needs to be square in the chassis. Driveshaft length is unchanged if the lower arms are left at their preset factory length; if you move the axle with the lower adjusters, check driveshaft engagement at the transmission.

Yes. The R suffix denotes red powder coat and the B suffix black. The tubing, machining, rod ends, bushings and adjusters are the same. Choose on appearance.

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, exceeding the design limits of the product, improper installation, altered product, non-UMI components, 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. Note that the printed sheet in the box still carries an older, narrower disclaimer that predates the current two year term. The policy page is the current document. Neither is a Black Ops Auto Works warranty.

Installation Instructions

1. Raise the rear of the car and support it so the axle stays located, then disconnect the rear sway bar from the lower control arms.
2. Work one side at a time and replace one arm at a time so the axle housing never loses its location. The factory control arm fasteners are 18 mm.
3. Install the two CNC machined aluminum step bushings into the lower arm rod end before offering the arm up to the car.
4. Fit each lower arm with the rod end at the rear axle housing and the polyurethane bushing at the chassis, with the grease fitting angled toward the ground.
5. Fit the upper arms, which arrive preset to factory length, using the original hardware.
6. Refit the rear sway bar to the lower arms.
7. Lower the vehicle so the weight of the car is on the rear axle, then torque both the lower and the upper control arm bolts to UMI's published 72 ft-lb.
8. Set pinion angle by measuring the driveshaft angle and the rear end angle with an angle finder and adding them, adjusting both upper arms equally with a one inch wrench, with the suspension loaded and the vehicle level. UMI's street recommendation is 1 to 2 degrees downward.
9. Tighten the jam nuts, then grease each fitting with 1 to 1.5 pumps of marine type grease.
10. Recheck the jam nuts and the control arm torque after the first drive, and re-grease two to three times per year thereafter.

The 72 ft-lb figure and the 1 to 2 degree street pinion angle are UMI's own published values for this kit's arms. Any fastener not covered by UMI's sheets should be torqued to the General Motors factory service value for your year and model.