UMI Performance 78-02 GM Rear Control Arm Bolt Upgrade Kit, 12 mm Class 10.9

Twelve Millimetre Class 10.9 Rear Control Arm Bolt Upgrade Kit for 1978-1988 G-Body and 1982-2002 F-Body Cars

GM used a smaller diameter bolt in the rear control arm mounts than the holes really allow, and after decades of load the fit gets sloppy. This kit steps the fasteners up to 12 mm class 10.9 with nylon insert lock nuts and washers, and it covers one pair of arms, either the upper or the lower set. UMI plates the hardware bright zinc so it survives underneath the car.

Key Features

• Upgrades the rear control arm fasteners to 12 mm diameter class 10.9 bolts.
• Four bolts, four nylon insert lock nuts and washers in the kit, enough for one pair of arms.
• Covers either the upper or the lower rear control arms, buyer's choice.
• Bright zinc plated finish for corrosion resistance.
• Fits both the 1978-1988 GM G-Body and the 1982-2002 GM F-Body rear suspension.
• Listed by UMI as a direct bolt-on upgrade.
• Made in the USA by UMI Performance.

Fitment

UMI publishes both platforms for this kit, the 1978-1988 G-Body and the 1982-2002 F-Body, which is why the title carries the combined 78-02 span rather than one platform's years.

The Oldsmobile Cutlass range on this part number's page starts in 1981 rather than 1978. That is UMI's own list for this kit and it is reproduced here as published, even though UMI's related bolt kits show 1978 for the same car.

One automated fitment feed lists a single 1998 model year for this kit. It contradicts UMI's published platform coverage and is not used here.

Specifications

What's Included

• Four 12 mm class 10.9 bolts
• Four 12 mm nylon insert lock nuts
• Washers, quantity not published by UMI

About UMI Performance

UMI Performance designs and manufactures chassis and suspension parts at 509 Hemlock Street in Philipsburg, Pennsylvania, using North American raw material, in-house laser cutting, CNC bending and fixture welding. UMI's rear control arm bolt kits sit alongside its G-body and F-body rear suspension range, where the 3001 pair kit and the 3002 complete kit cover one pair of arms and all four arms respectively.

Related Parts

• UMI Performance 78-88 GM Complete Rear Control Arm Bolt Upgrade Kit, 12 mm

FAQ

No. It contains four bolts and four nuts, which is one pair of arms, upper or lower. UMI's complete kit, part 3002, carries eight bolts and eight nuts for all four arms on a G-body.

Either. UMI publishes the kit as suiting the upper or the lower rear control arms, so the pair you choose is up to you. Some dealer titles say lower only, which understates UMI's own description.

Diameter and grade. The kit moves the joint to a 12 mm class 10.9 fastener, which is a larger and higher strength bolt than the original in these mounts, and it comes with fresh nylon insert lock nuts rather than reusing decades old ones.

Yes. UMI lists this kit for the 1982-2002 F-Body alongside the 1978-1988 G-Body, which is why the part is titled 78-02. It is the same rear control arm bolt size across both platforms in UMI's listing.

Not published. UMI gives the diameter as 12 mm and the grade as class 10.9 but publishes no length or thread pitch, and no dealer record itemises them either. Measure your existing fasteners if length matters to your build.

Because that is what UMI's page for this part number says. UMI's other G-body bolt kits list the Cutlass from 1978. Rather than smooth the two lists together, this listing publishes the range from the page for this exact kit and flags the difference.

UMI publishes none for this part number and no UMI installation sheet exists for it, so this listing does not print one. Use the applicable General Motors factory service information for your model year and the specific joint you are fastening. Torque figures printed on UMI sheets for other part numbers apply to those parts, not to this kit.

UMI lists washers as part of the kit but does not publish how many. Expect them, but if your build needs an exact count, ask us to confirm against the current pack before ordering.

A thin sacrificial zinc coating with a bright finish, applied for corrosion resistance on exposed chassis fasteners. UMI publishes the finish but no salt spray rating, so treat it as normal plated hardware rather than stainless.

They are two different documents. UMI's policies page publishes a two year limited warranty to the original purchaser against defects in materials and workmanship, with exclusions for normal wear on bushings and bearings, improper installation, alteration and exceeding the design limits of the part. The disclaimer printed on UMI's installation sheets is narrower and says parts are warranted to be free of defect at the time of purchase, with remedy limited to replacement. Read the policies page as the customer facing warranty and the sheet as the in-box legal notice. Neither one is a Black Ops Auto Works warranty.

Installation Instructions

1. Support the rear of the vehicle safely with the axle supported so the control arms stay near their normal position.
2. Work on one fastener at a time so the arm never loses its location in the mount.
3. Remove the original bolt, clean the mount and the bushing sleeve, and check the mount for elongation before fitting new hardware.
4. Fit the 12 mm class 10.9 bolt with a washer and a new nylon insert lock nut, leaving it finger tight.
5. Repeat on the second arm of the pair, then lower the car to ride height so the bushings are clamped at their normal loaded position.
6. Tighten to the figure in the applicable General Motors factory service information for your model year, because UMI publishes no torque value and no installation sheet for this kit.
7. Recheck the fasteners after the first drive and again after the first few hundred miles.

UMI publishes no installation sheet for part 3001. The steps above are a safe fitting sequence for replacement hardware, not a UMI procedure, and they do not replace GM factory service information or the instructions supplied with any aftermarket control arms you are fitting.