Brembo GP4-RS Caliper vs Brembo Radial Monoblock Caliper Kit M4 34/34 108mm Left/Right Set
The GP4-RS is the sharper track tool: a single finned monoblock caliper, 10% lighter than the M4, with 30% more air-exposed fin area. The M4 kit is the value pick when you need both front calipers: it is a left/right pair with 34mm pistons and a 310-330mm disc range. Prices differ sharply: the GP4-RS is $716.38 at 2WheelHQ as of November 1, 2026, while no price was given for the M4 kit.
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Brembo GP4-RS Caliper
Choose the GP4-RS if you run one front caliper on a 108mm-mount sportbike and want MotoGP-derived cooling and lower weight for track days.
- Finned monoblock body sheds heat better than the M4
- 10% lighter than the M4 One-Piece
- Rigid one-piece casting resists deformation under hard braking
- Comes with sintered pads and temperature strips
- Accepts Brembo Racing Z04 pads
- One caliper only, so a twin-disc bike needs two kits
- 30mm pistons give less fluid displacement than 34mm
- Track-focused; overkill for casual street riding
What separates them
| Brembo GP4-RS Caliper | Brembo Radial Monoblock Caliper Kit M4 34/34 108mm Left/Right Set | |
|---|---|---|
| Quantity in kit | 1 caliper | 2 calipers (left and right) |
| Piston diameter | 30mm, four pistons | 34mm, four pistons |
| Construction | Cast monoblock, machined from one workpiece | Monoblock radial mount |
| Weight | 10% lighter than the M4 One-Piece | Heavier M4 body |
| Cooling | MotoGP-derived fins, 30% more air-exposed surface | No finned body |
| Disc diameter fitment | Not stated; 32-34mm disc height | 310-330mm discs |
| Finish | Anodized titanium color | Black hard anodized |
Price history
- Brembo GP4-RS Caliper: lowest $716.38 on Nov 1 at Amazon; $716.38 on Nov 2.
- Brembo Radial Monoblock Caliper Kit M4 34/34 108mm Left/Right Set: lowest $750.95 on Nov 2 at Bobleisure.
Prices at every store
Brembo GP4-RS Caliper
- AmazonCheck price at Amazon
- BobleisureCheck price at Bobleisure
- eBayCheck price at eBay
Brembo Radial Monoblock Caliper Kit M4 34/34 108mm Left/Right Set
- BobleisureCheck price at Bobleisure
Specs compared
| Spec | Brembo GP4-RS Caliper | Brembo Radial Monoblock Caliper Kit M4 34/34 108mm Left/Right Set |
|---|---|---|
| Piston diameter | 30mm (same diameter 4-pot) | 34 mm |
| Vehicle Compatibility | sportbikes | Street Motorcycle |
| Application | Brake | Sports driving, High-performance road use |
| Type | Caliper | Caliper |
| Kit Contents | Brembo sintered brake pads, MotoGP-tested adhes… | Pads |
| Subtype | monoblock caliper | Brake Caliper |
| Quantity | 1 (kit) | 2 (Units per box) |
| Braking Power | counteract caliper deformation during heavy bra… | Performance, High-performance |
| Friction Material Type | sintered brake pads | New brake pad compounds |
What reviewers say
Brembo GP4-RS Caliper
Reviewers describe it as a genuine Brembo caliper with strong, precise braking, and several report good fitment and clearance on their bikes. Complaints are thin, mostly about one seller's slow chat replies.
- Genuine, verified-original Brembo caliper
- Strong braking performance
- Precise build quality
- Good fitment and clearance on listed bikes
- One seller's chat replies were slow
Brembo Radial Monoblock Caliper Kit M4 34/34 108mm Left/Right Set
Brembo M4 calipers are widely regarded among sport riders as a strong, fade-resistant upgrade with excellent lever feel. Owners often note the cost and the need for proper setup, and some find the initial bite aggressive for street use.
- Noticeably firmer lever and less fade on repeated hard stops
Questions and answers
- Which is better for track days?
- The GP4-RS. Its finned monoblock body exposes 30% more surface area to air and weighs 10% less than the M4 One-Piece, which matters over repeated hard stops.
- Which gives stronger braking?
- The M4 kit's 34mm pistons move more fluid and suit 310-330mm discs, giving more leverage. The GP4-RS uses 30mm pistons but a stiffer one-piece body for consistent feel.
- Do I need one caliper or two?
- The GP4-RS is sold as a single caliper, so a twin-disc front end needs two kits. The M4 kit ships as a left/right pair.
- Is the GP4-RS worth the extra?
- At $716.38 at 2WheelHQ as of November 1, 2026, it buys lower weight and better cooling. If you only ride the street, the M4 pair covers it for less.
- Will either fit my bike?
- Both use 108mm radial mount spacing and 32-34mm disc height. The M4 kit is listed for 310-330mm discs; the GP4-RS has no stated disc range, so check your rotor size.
- Can I run race pads in them?
- Yes. The GP4-RS is compatible with Brembo Racing Z04 pads. The M4 kit ships with pads and accepts new compound pads.