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Center the Rear Axle and Eliminate Rear-End Wander on Your 1975-1980 GM H-Body with the UMI 5021-B Adjustable Panhard Bar
The UMI Performance 5021-B is a single adjustable panhard bar with a precision rod end for the 1975-1980 GM H-Body platform, covering the Chevrolet Monza, Chevrolet Vega, and Pontiac Astre. The factory H-Body panhard bar is a non-adjustable rubber bushing design that allows the rear axle to shift laterally under load and over time loses its ability to keep the axle properly centered in the chassis. This lateral movement results in a wandering rear end, inconsistent corner handling, and excessive body roll.
The UMI 5021-B replaces the factory unit with an adjustable tubular steel bar featuring a polyurethane bushing on one end and a precision rod end bearing on the other, allowing the rear axle to be precisely centered in the chassis. The rod end bearing eliminates the deflection and compliance inherent in rubber bushing designs, providing a more precise lateral location of the rear axle under all driving conditions. Finished in black powder coat and manufactured in the USA at UMI Performance's Philipsburg, Pennsylvania facility.
Key Features
- Single adjustable panhard bar allows precise rear axle centering in the 1975-1980 GM H-Body chassis
- Precision rod end bearing eliminates lateral compliance of factory rubber bushing design
- Adjustable length corrects axle offset from lowering springs, drop spindles, or suspension modifications
- Tubular steel construction for rigidity and durability
- Black powder coat finish for corrosion resistance
- Fits 1975-1980 Chevrolet Monza, Vega, and Pontiac Astre
- Manufactured in the USA by UMI Performance in Philipsburg, Pennsylvania
Vehicle Fitment
| Year Range | Make | Model |
|---|---|---|
| 1975-1980 | Chevrolet | Monza |
| 1975-1980 | Chevrolet | Vega |
| 1975-1980 | Pontiac | Astre |
Specifications
| Detail | Value |
|---|---|
| Part Number | 5021-B |
| Brand | UMI Performance |
| Type | Single adjustable panhard bar |
| End Fittings | Polyurethane bushing one end, rod end bearing other end |
| Material | Tubular steel |
| Finish | Black powder coat |
| Application | 1975-1980 GM H-Body |
| Country of Manufacture | USA |
| UPC | N/A |
What's Included
- 1x UMI Performance 5021-B adjustable panhard bar
- Hardware for installation
About UMI Performance
UMI Performance is an American suspension and chassis manufacturer based in Philipsburg, Pennsylvania, specializing in GM F-Body, G-Body, H-Body, A-Body, and CTS-V performance components. All UMI products are engineered and manufactured in-house for precision fitment in street, autocross, and road race applications.
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Frequently Asked Questions
What is the UMI Performance 5021-B?
The UMI 5021-B is a single adjustable panhard bar with a rod end for the 1975-1980 GM H-Body Chevrolet Monza, Vega, and Pontiac Astre. It replaces the factory non-adjustable rubber bushing panhard bar to precisely center the rear axle in the chassis, eliminating axle wander and improving rear suspension consistency under cornering loads.
Why do I need an adjustable panhard bar on my H-Body?
The factory H-Body panhard bar is fixed length and uses rubber bushings that allow compliance and lateral movement of the rear axle. If the vehicle has been lowered, has worn bushings, or the rear axle has shifted off-center from the factory position, an adjustable panhard bar like the UMI 5021-B allows the bar length to be set so the axle sits perfectly centered in the chassis. This directly improves rear end stability and cornering balance.
What is the difference between a single adjustable and double adjustable panhard bar?
A single adjustable panhard bar adjusts at one end only, allowing the overall length to be set to center the axle but not providing independent control of each end. A double adjustable bar allows both ends to be adjusted, giving more precise control over the bar angle and axle position. For most street and autocross H-Body builds, a single adjustable panhard bar provides adequate adjustment range to center the axle properly.
Will the 5021-B fit my H-Body if I have lowering springs installed?
Yes. The adjustability of the UMI 5021-B is specifically valuable on lowered H-Body vehicles, where the change in suspension geometry from lowering springs can shift the rear axle off-center from the factory position. Set the bar length after installation with the vehicle at ride height and the axle visually centered in the chassis and wheel wells.
Does the rod end require maintenance?
Rod end bearings used in adjustable suspension links benefit from periodic inspection for wear, corrosion, and smooth operation. Inspect the rod end annually or after any hard off-road or track use. Replace the rod end if any lateral play or binding is detected. UMI designs the 5021-B with an appropriately sized rod end for the load demands of the H-Body rear suspension.
Does the 5021-B fit the 1971-1977 GM H-Body Vega?
The UMI 5021-B is listed for the 1975-1980 GM H-Body. Confirm fitment for 1971-1974 Vega models with UMI Performance directly, as the earlier H-Body variants may have different rear suspension mounting dimensions.
Is the 5021-B street legal?
Yes. The UMI 5021-B is a direct replacement for the factory panhard bar and is fully street legal. No emissions-related modifications are involved. The rod end design is appropriate for street driving loads and does not require additional reinforcement for street use.
Where is the UMI 5021-B manufactured?
The UMI 5021-B is manufactured in the USA at UMI Performance's facility in Philipsburg, Pennsylvania.
Installation Instructions
- Safely lift and support the vehicle on jack stands with the rear suspension hanging freely to allow access to the rear axle and panhard bar mounting points.
- Locate the factory panhard bar. Note the mounting point on the frame on one end and the rear axle bracket on the other.
- Remove the factory panhard bar hardware and set the factory bar aside for reference.
- Thread the UMI 5021-B to approximately the same length as the factory bar as a starting point.
- Install the rod end end of the 5021-B to the appropriate mounting point (axle or frame per the factory orientation) and the bushing end to the other. Install hardware loosely.
- Lower the vehicle to ride height with the weight of the vehicle on the suspension.
- Visually check the rear axle centering in the wheel wells by measuring from the axle to the wheel well lip on each side. Adjust bar length to center the axle if needed.
- Once centered, torque the mounting hardware to the factory specification for your application. Torque jam nuts on the rod end body.
- Recheck centering after torquing. Drive the vehicle and recheck after the first 100 miles as the new bar settles.
WARNING: This product can expose you to chemicals including lead and phthalates, which are known to the State of California to cause cancer and reproductive harm. For more information go to www.P65Warnings.ca.gov.
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