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Tame Body Roll In Your Classic Fastback Or Coupe
Factory rear suspension geometry on classic Mustangs equipped with a 9 inch rear end was never built with modern cornering loads in mind. This Whiteline BFR1-KU4 rear sway bar bolts to your existing 9 inch axle housing and adds a full 18mm of heavy duty steel roll resistance, cutting down on the rear end wallow that shows up the moment you push into a corner with any speed.
Key Features
- 18mm solid steel bar diameter built specifically for 9 inch rear end axle housings
- Heavy duty non adjustable design for consistent, predictable roll control
- Silver powder coat finish resists corrosion for long service life
- Bolts directly to the factory 9 inch housing without axle modification
- Sharpens rear end response through fast sweepers and autocross corners
- BFR1-KU4 is purpose engineered for classic Mustang 9 inch rear end applications
Fitment
| Year Range | Make | Model | Trim |
|---|---|---|---|
| 1965-1973 | Ford | Mustang | GT |
| 1965-1973 | Ford | Mustang | Mach 1 |
| 1965-1973 | Ford | Mustang | Boss 302 |
| 1965-1973 | Ford | Mustang | Boss 429 |
Fitment applies to Mustangs equipped with a Ford 9 inch rear end axle housing. Verify your rear end type before ordering, as some six cylinder and small block cars from this era were built with a smaller 8 inch housing that this bar does not fit.
Specifications
| Detail | Value |
|---|---|
| Manufacturer | Whiteline |
| MPN | BFR1-KU4 |
| UPC | BFR1-KU4 |
| Position | Rear |
| Bar Diameter | 18mm |
| Material | Solid Steel |
| Finish | Silver Powder Coat |
| Adjustability | Non Adjustable Heavy Duty |
| Rear End Type Required | Ford 9 Inch |
What's Included
- 1 x Whiteline 18mm rear anti roll bar
- Mounting bushings
About Whiteline
Whiteline designs and manufactures suspension components engineered to sharpen handling while preserving daily drivability. Their sway bars, control arms, and bushing kits use proprietary synthetic elastomers and precision engineered geometry to correct factory suspension compliance and unlock more consistent, predictable handling, from classic muscle cars to modern platforms.
FAQ
What is the BFR1-KU4?The BFR1-KU4 is a Whiteline 18mm heavy duty rear anti roll bar built for classic Ford Mustangs equipped with a 9 inch rear end axle housing, designed to reduce rear body roll and sharpen cornering response.
How do I know if my classic Mustang has a 9 inch rear end?The 9 inch housing has a raised hump in the center section and a rounded shape, while the smaller 8 inch housing is flatter with a different bolt pattern, so it is worth confirming your axle type before ordering.
Is this sway bar adjustable?No, this is a fixed heavy duty bar rather than an adjustable unit, offering one consistent level of increased roll stiffness over the factory bar.
Will this bar work with my factory end links?Yes, this bar is designed to bolt up using standard mounting hardware and factory style end link locations on 9 inch equipped Mustangs.
Does installing this sway bar require welding?No, this is a bolt on installation that does not require any welding or permanent modification to your rear end housing.
Do I need an alignment after installing this sway bar?A sway bar swap does not change ride height or suspension geometry, so an alignment is not required, though checking alignment after any suspension work is good practice.
Can I install this sway bar in my home garage?Yes, most installers with basic hand tools and jack stands can complete this installation without specialty equipment.
Will this bar make my classic Mustang ride harsher on the street?This heavy duty bar increases roll stiffness over the factory setup but is tuned to remain comfortable for street driving while noticeably improving handling.
Install Instructions
- Raise and safely support the rear of the vehicle on jack stands
- Remove the factory rear sway bar end links and mounting bracket bolts
- Remove the factory rear sway bar and mounting bushings from the 9 inch housing
- Install the new mounting bushings onto the Whiteline bar
- Position the bar and torque the mounting brackets to factory specification
- Reconnect the end links and torque to spec
- Lower the vehicle and inspect all fasteners before test driving
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