A Guide to the Disc Brake Caliper on Your 1995-2001 Mack MS300P Mid-Liner
Keep your medium-duty truck's stopping power reliable by understanding its disc brake calipers.
- The MS300P uses hydraulic disc brake calipers, and aftermarket replacements are typically remanufactured.
- Symptoms of failure include pulling, fluid leaks, a spongy pedal, or dragging brakes; these are serious safety issues.
- Always replace calipers in pairs (left and right) to ensure balanced braking.
- The brake system must be professionally bled after installation to remove air and restore stopping power.
Is Your Mack's Brake Caliper Failing?
A brake caliper works under high pressure and heat. Over many years and miles, its internal seals can wear out or the piston can seize from corrosion. Because parts for the Mack Mid-Liner can be hard to find, it's important to recognize the signs of failure early. Ignoring a bad caliper is a major safety risk.
Common Symptoms of a Bad Caliper
- Truck Pulls to One Side: When you brake, a seized caliper on one side will cause the truck to pull towards the opposite, working brake.
- Brakes Dragging: A caliper that doesn't release properly will feel like the brakes are always slightly on. This can cause overheating and a burning smell.
- Brake Fluid Leaks: Puddles of fluid near the wheel are a clear sign of a failed caliper seal.
- Spongy or Soft Brake Pedal: If a seal fails, air can get into the hydraulic lines, making the pedal feel soft and reducing stopping power.
- Loud Noises: Squealing or grinding when you brake can point to a variety of brake issues, including a stuck caliper.
Choosing a New Aftermarket Caliper
For a vehicle like the 1995-2001 MS300P, finding original equipment (OEM) new parts is nearly impossible. The market primarily consists of aftermarket parts, which are mostly remanufactured. A remanufactured caliper is an original part that has been taken apart, cleaned, and rebuilt with new seals, boots, and bleeder screws to meet or exceed original performance.
Available Brands: Cardone
Cardone is a widely available brand for this truck. They are one of the largest producers of remanufactured parts. While they offer a cost-effective solution, owner feedback on quality can be mixed. Some users have reported issues with the quality of reused components or assembly. However, for an older commercial vehicle where parts are scarce, a readily available remanufactured caliper from a known brand is often the most practical choice.
Cost of Replacing a Disc Brake Caliper
The cost involves the part itself and the labor to install it. Labor for a medium-duty truck like the MS300P will be higher than for a standard car.
| Part Type | Estimated Part Cost |
|---|---|
| New OEM | Not Generally Available |
| New Aftermarket (Remanufactured) | $70 - $125 |
| Shop Labor | $150 - $300 |
Frequently Asked Questions
Should I replace calipers in pairs?
Yes. It is highly recommended to replace both the left and right calipers on an axle at the same time. This ensures even braking force and prevents the truck from pulling to one side, which can happen if you have one new caliper and one old one.
Do I need to bleed the brakes after replacing a caliper?
Absolutely. Any time you open a hydraulic brake line, air enters the system. You must bleed the brakes to remove all the air. Air in the lines will cause a spongy pedal and severely reduce your stopping ability. This is a critical safety step.
Are there any recalls on the MS300P brake calipers?
No. Searches of the National Highway Traffic Safety Administration (NHTSA) database show no specific recalls for the disc brake calipers on the 1995-2001 Mack MS300P Mid-Liner.
What is a core charge?
Since most aftermarket calipers are remanufactured, you will often see a "core charge" on your bill. This is a deposit that you get back when you return your old, worn-out caliper to the parts store. This allows the manufacturer to rebuild it for the next customer.
Technical Specifications
This vehicle is equipped with a hydraulic disc brake system, likely as part of an air-over-hydraulic setup. Calipers are typically two-piston designs with phenolic pistons. Most replacements are sold as 'friction-ready,' meaning they do not include brake pads.
The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
- Mack MS300P Mid-Liner: