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On-Car Adjustable Rear Upper Control Arms for the 1978-1996 GM B-Body
These rear upper control arms let a 1978-1996 GM B-Body owner set pinion angle with the car assembled. They ship preset 5/8 inch longer than the factory arm, and the 4140 chrome-moly adjuster allows another half inch of length in either direction from there.
The bodies are DOM tubing with CNC machined mounting points, greaseable polyurethane bushings and a glossy powder coat. UMI designs them to work with extended length lower control arms, so they are the natural pairing for a B-Body rear end that has already been lengthened at the bottom links.
Key Features
- Preset 5/8 inch longer than factory, with a further half inch of lengthening or shortening available
- On-car pinion angle adjustment using a 1 inch wrench
- DOM tubing with CNC machined mounting points
- 4140 chrome-moly tube adaptors and a 4140 chrome-moly heat treated solid adjuster
- Greaseable polyurethane bushings
- Glossy powder coat finish, black on this part number
- Direct bolt-on with no modifications required
Fitment
| Vehicle | Years |
|---|---|
| Buick Roadmaster | 1991-1996 |
| Buick LeSabre | 1978-1985 |
| Chevrolet Caprice | 1978-1996 |
| Chevrolet Impala SS | 1994-1996 |
| Pontiac Bonneville | 1977-1981 |
| Pontiac Catalina | 1977-1981 |
The packaged instruction sheet is headed 1991-1996 GM Impala SS, and older catalogue copy repeats that range. UMI's live application table lists the Impala SS itself as 1994-1996 within a 1978-1996 B-Body platform, so the 1991-1996 wording is B-Body generation shorthand rather than an Impala SS fitment range. The years published here follow the manufacturer application table.
UMI publishes year, make and model for this part number without a submodel, trim, engine or drivetrain breakdown, so the fitment tags on this listing stop at model level rather than inventing a trim. The one exception is the Impala SS, which UMI names directly.
This part number is the polyurethane bushed upper arm. UMI's rod end style B-Body upper arm is a separate part number and is not what is sold here.
Specifications
| Detail | Value |
|---|---|
| Position | Rear upper, sold as a set of two arms |
| Length as shipped | Preset 5/8 inch longer than the factory arm |
| Adjustment range | A further half inch longer or shorter than the preset length. This is a different range from the B-Body lower arms, which offer 1/4 inch |
| Tubing and machining | DOM tubing with CNC machined mounting points |
| Adjuster | 4140 chrome-moly tube adaptors with a 4140 chrome-moly heat treated solid adjuster |
| Bushings | Greaseable polyurethane |
| Material and style | Mild steel, tubular |
| Finish | Glossy powder coat, black on this part number |
| Function | On-car pinion angle adjustment, designed to work with extended length lower control arms |
| Mounting hardware | Not included |
| Modifications required | None. Direct bolt-on |
| Recommended torque | 72 ft-lb on the upper control arms, with the jam nuts checked often for tightness |
| Recommended pinion angle | One to two degrees downward for a street driven car, measured with the vehicle level and the suspension loaded |
| Tools | 18 mm socket and wrenches for the mounting bolts, a 1 inch wrench for the adjusters, and an angle finder |
| Shipping weight and boxed dimensions | Recorded by UMI as not available |
| Country of manufacture | United States. UMI manufactures in Philipsburg, Pennsylvania |
| Manufacturer warranty | Two years from the original date of purchase against defects in materials and workmanship, to the original purchaser only and not transferable |
| Warranty exclusions | Misuse, abuse, neglect or accident, use beyond the design limits of the product, improper installation, acts of God, handling and shipping damage, any product altered, adjusted, tampered with or defaced, non-UMI components, incidental costs such as towing and labour, and normal wear items including bearings and bushings |
| Warranty document conflict | The packaged instruction sheet still carries an older all-caps disclaimer limiting coverage to freedom from defect at the time of purchase. UMI's live policies page publishes the current two year term and is the document summarised here. Neither is a Black Ops Auto Works warranty |
| Third-party component compatibility | UMI states it cannot guarantee compatibility or performance of its products with other components used alongside them, so confirm dimensions before mixing brands |
| Suitability versus warranty | UMI builds this arm to correct and hold pinion angle on lowered or extended-length B-Body rear suspensions. That describes what the part is built to do. Warranty eligibility is separate: UMI covers defects in materials and workmanship for two years and excludes damage from exceeding the design limits of the part, improper installation, and normal wear on bushings and bearings |
What's Included
- Two adjustable extended length rear upper control arms with greaseable polyurethane bushings
- One installation instruction sheet
Neither the product page nor the instruction sheet publishes an itemised box contents list for this part number, so nothing beyond the arms and the sheet is claimed.
About UMI Performance
UMI Performance builds chassis and suspension parts at 509 Hemlock Street in Philipsburg, Pennsylvania, using precision bent DOM tubing, laser cut steel, TIG and robotic welding and durable powder coat finishes. The B-Body upper arms carry UMI's chrome-moly adjuster design, which is what allows pinion angle to be dialled in without dropping the rear end.
Related Parts
- UMI Performance adjustable extended length rear lower control arms for the same 1978-1996 GM B-Body application
- UMI Performance rod end adjustable extended length rear lower control arms for the same 1978-1996 GM B-Body application
FAQ
Do these set pinion angle?Yes. They adjust on the car, and UMI's sheet recommends one to two degrees downward for a street driven car with the vehicle level and the suspension loaded.
How much adjustment do I get?They arrive preset 5/8 inch longer than stock and adjust a further half inch longer or shorter from that point.
What wrenches do I need?A 1 inch wrench turns the adjuster, and an 18 mm socket or wrench fits the mounting bolts. An angle finder is needed to measure pinion angle.
What torque do the upper arm bolts get?72 ft-lb, and UMI adds a specific instruction to check the jam nuts often for tightness.
Do I need matching lower arms?UMI designs these uppers to work with extended length lower control arms, so pairing them with a matching lower set keeps the rear geometry consistent.
Will I need a longer driveshaft?UMI notes that a longer driveshaft may be necessary once ride height and axle position are final. Check slip yoke engagement before driving the car.
Are these rod end arms?No. This part number uses greaseable polyurethane bushings. UMI's rod end style B-Body upper arm is a separate product.
Is mounting hardware included?No. The factory upper arm bolts are reused.
Does adjusting them void the warranty?No. Using the designed adjuster within its range is the intended function of the part. The warranty language about altered or tampered products refers to modifying the part itself, and bushing wear remains excluded as normal wear.
Should the car be on the ground when I set the angle?Yes. Measure with the vehicle level and the suspension loaded, then turn each adjuster equally and retighten the jam nuts.
What warranty applies, and what is excluded from it?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, handling and shipping damage, any product that has been altered, adjusted, tampered with or defaced, 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 sheet packed 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
- Note that the arms arrive preset 5/8 inch longer than the factory length.
- Place jack stands under the frame and support the centre of the rear end with a jack applying slight upward tension.
- Work one side at a time using 18 mm wrenches and a socket, removing the front and rear bolts of that arm only.
- If the rear end housing bushings are being replaced at the same time, follow the note in UMI's sheet, which recommends a torch for removal.
- Fit the new arm and leave the bolts loose until the suspension is loaded.
- Repeat on the opposite side, then lower the car so the rear suspension carries its weight.
- Tighten the upper control arm bolts to 72 ft-lb and check the jam nuts for tightness.
- Set pinion angle with the car level and the suspension loaded, using an angle finder and a 1 inch wrench, turning each adjuster equally toward one to two degrees downward for street use.
- Retighten the jam nuts and recheck them after the first few drives.
UMI's installation sheet for this part number is published at https://static.speedwaymotors.com/pdf/1853620B.pdf.
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