UMI Performance 78-88 GM G-Body Weld-In Rear Rail Notch Kit, Bare Steel

Weld-In Rear Frame Notch Kit for the 1978-1988 GM G-Body, Advanced Fabrication Required

This kit narrows the rear upper frame rails of a G-Body so a wider rear tyre can fit, and it is fabrication work rather than an installation. UMI supplies six plates of 1/8 inch precision laser cut mild steel, profiled to follow the frame contour, and the installer cuts the rail, forms the end plates in a vise, and welds everything back into a boxed section. UMI states plainly that advanced fabrication skills are required.

The two large plates are deliberately oversized so that one kit covers the variation across every 1978-1988 G-body frame, and they are ground to a perfect seam on the car rather than arriving cut to a fixed dimension. Four smaller plates are the end enclosures that span from the kit back to the original frame, so the notch finishes boxed rather than open. The kit ships bare with no coating, no fasteners and no bushings.

Key Features

• Narrows the rear upper frame rails to make room for a wider rear tyre.
• 1/8 inch precision laser cut mild steel, profiled to follow the frame contour.
• Six plates in total: two large contour plates and four small end enclosure plates.
• End enclosures span from the kit back to the original frame so the notch finishes boxed.
• Deliberately oversized so the same kit fits every 1978-1988 G-body frame and grinds to a perfect fit.
• Easily weldable with a standard MIG welder.
• Ships bare, with no powder coat and no plating, ready for the installer's own finish.
• Designed, manufactured and raced by UMI in Philipsburg, Pennsylvania.

Fitment

UMI publishes this eight vehicle list on the 3061 page as the confirmed application. Fitment is manufacturer-confirmed even though installation is fabrication intensive.

This is not a bolt-in part. UMI records Direct Bolt-On as no and modifications as cutting and welding. Advanced fabrication skills, an angle grinder, a MIG welder and a hammer and vise are required, and the depth and length of the notch are chosen by the installer to suit the wheel being fitted.

The large plates arrive slightly oversize on purpose. UMI states the plate is slightly oversized to allow proper fit to all 1978-1988 G-body frames and instructs the installer to grind the large plate for a perfect fit. That is engineered coverage of frame variance, not a sign that the wrong part has been supplied.

A large retailer lists additional 1978-1988 G-body cars for this part number, including Buick Century, Buick Grand National, Oldsmobile Cutlass Calais, Cutlass Cruiser, Cutlass Salon and Cutlass Supreme, Pontiac Grand Am and Pontiac LeMans. Those come from the retailer's own catalogue rather than from UMI, so they are recorded here as supplier-listed applications and are deliberately not part of the manufacturer-confirmed fitment above or of this listing's fitment tags.

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

• Two large frame notch plates, UMI part number 3061A.
• Four small frame notch plates, UMI part number 3061B, which are the end enclosures.

That is UMI's complete box contents table reproduced exactly. Nothing else is supplied: no bolts, no weld-in nuts, no coating and no accessories. The printed instruction sheet accompanies the kit but is not listed as a separate contents line.

Because the kit ships bare and welding removes the protection from the surrounding frame, the finished notch has to be primed, painted or coated by the installer. UMI does not specify a coating, so no product recommendation is made here.

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. This part is the exception to UMI's tube bending and welding capabilities: the 3061 kit is laser cut flat plate only, with every weld performed by the installer, and it is the one part in the G-Body chassis range that ships with no coating at all.

FAQ

UMI publishes no figure, and this listing will not invent one. The reason is in UMI's own instructions: both the depth and the length of the notch are chosen by the installer based on the wheel being fitted. UMI's suggested starting point is to mark a section long enough to give your wheel proper clearance and to slice the frame flush with the inner fender, then cut conservatively and grind to the exact fit. Measure your intended wheel and tyre in place before any cutting.

No. UMI records direct bolt-on as no and modifications as cutting and welding. The kit is raw fabrication stock: flat laser cut plates that are trimmed, hammer formed in a vise, tacked and then welded into the frame. Anyone expecting to bolt something to existing holes is looking at the wrong part number.

UMI's own wording is that this kit does require major cutting, grinding and welding, and that advanced fabrication skills are required to install this product. The listed tools are a cutting and grinding tool such as an angle grinder, a welder, and a hammer and vise. If you are not comfortable cutting into a structural frame rail and welding it back up, this is a job for a fabricator.

Six. Two large plates, UMI part number 3061A, are the main contour plates that box the notched section, and four small plates, part number 3061B, are the end enclosures that get hammer formed to match the shape of the notch ends and span from the kit back to the original frame. Six plates cover both sides of the car.

Neither. There are no fasteners in the box because nothing bolts on, and the plates ship bare with no powder coat and no plating. The printed instruction sheet covers the full procedure. Plan on priming, painting or coating the finished notch yourself, since welding also strips whatever protection the surrounding frame had.

UMI's published starting point is to slice the frame flush with the inner fender, with the depth then adjusted to the wheel clearance you actually need. The instruction that matters most is the one about sequence: UMI says it is always best to cut less to begin with and grind to exact fit rather than trying to cut to exact dimensions. You can always remove more material and you cannot put it back.

UMI's design intent is that the notched section is re-boxed rather than left open, which is why the four end enclosure plates are included to span from the kit back to the original frame and why the sheet has you tack and weld the small plates first and the large plates second. UMI publishes no strength data for the finished repair, so no claim of structural equivalence is made here. Weld quality and preparation are what decide the outcome, and UMI is specific that the existing frame must be cleaned of dirt and rust to expose bare metal before any welding.

The kit is supplied with enough plate for both sides, which is what the two large and four small plates cover, and tyre clearance is normally a symmetrical problem. If only one side is being notched for a specific reason, the remaining plates simply stay in the box.

It is intentional. UMI states the plate is slightly oversized to allow proper fit to all 1978-1988 G-body frames, and instructs the installer to grind the large plate for a perfect fit. One frame rail is not identical to the next after forty years of production tolerance and repair history, so the kit covers the range and is dressed down to your particular car.

Yes, once the welding is finished. Nothing on the plates protects them, and the heat of welding removes the coating from the surrounding frame as well. UMI does not name a specific primer, paint or coating, so choose a system suitable for a structural exterior chassis area and apply it after the welds have been dressed.

UMI's procedure does not call for removing any of them, and the steps run from raising the car to locating the rear frame section, marking, cutting, forming, tacking and welding. That said, this is open flame and grinding sparks work in the same area of the car as the fuel tank and fuel lines, so protect or remove anything flammable in the work zone and follow UMI's instruction to use proper safety clothing and eye protection when grinding and welding.

Only while it is untouched. Once the plates have been trimmed, hammer formed or welded they cannot be returned, and damage caused by improper installation or fabrication is not a warranty matter either. Inspect the plates and test fit them against your frame before the grinder comes out, which is exactly why UMI's sheet opens by telling you to verify box contents and read through the instructions completely before installation.

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. Verify the box contents are correct and read the instructions through completely before starting.
2. Raise the car to a comfortable working height using the method of your choice and follow applicable safety procedures, using approved jack stands with a floor jack or proper technique on a drive-on lift, and use proper safety clothing and eye protection for grinding and welding.
3. Locate the existing rear frame section that will be sliced and re-boxed.
4. Mark the length of the cut based on the wheel you are trying to accommodate, allowing enough frame section for proper wheel clearance.
5. Decide the depth of the notch from the clearance you need. UMI's suggested starting point is to slice the frame flush with the inner fender, and it is always best to cut less to begin with and grind to exact fit rather than cutting to exact dimensions.
6. Use a vise and a hammer to bend the four smaller plates until they match the shape of the notch ends, then tack weld the small plates into place.
7. In preparation for welding, trim the large plates so they slightly overlap the small end plates.
8. Clamp the large plates into place and check for good seams to lay the weld bead into. The plate is oversized on purpose, so grind it for a perfect fit.
9. Clean the existing frame of dirt and rust to expose bare metal, weld the small end plates in place first, then weld the larger plates.
10. Dress the welds and protect the finished notch with a primer, paint or coating of your choice.

No torque value is published for this kit and none applies, because the kit contains no fasteners. The safety-critical guidance is UMI's own: advanced fabrication skills are required, clean the frame to bare metal before welding, tack the end plates first, and cut conservatively.