FAQs & Tech Tips


MM News

NASA Racers! MM will support NASA road racers with $1,000 contingency prizes for the American Iron, American Iron Extreme, and Spec Iron at the 2019 National Champions. You must register to be eligible.

New! Read the article Maximum Motorsports Tames Fox & SN95 Mustang Rear Suspensions on FordMuscle.com.

MRT Exhaust! MM now offers premium MRT cat-back exhaust systems for 1996-2004 Mustangs.

New! for Street & Strip Mustangs! Big-bore rear wheel cylinders for 1979-1993 Mustang with 9" drum brakes. Improves braking when running big rear tires and front skinnies, and/or different OEM front brakes.

New! Swapping a Coyote into a Fox Mustang? MM's Hydroboost Conversion Kits allow easy installation of a 1996-2004 Mustang Hydroboost power brake assist unit into a 1979-1993 Mustang.

New! Swapping an IRS into your Fox Mustang? MM makes it easier with a brake line kit made just for this conversion. Bolts-in, with no cutting or flaring of brake lines. Designed to fit standard IRS brake hoses.

New! MM's billet aluminum Pedal Box Spacer for Fox Mustangs. Replace the breakage-prone OEM plastic spacer when converting to manual brakes or Hydroboost.

Canadians! Please read the latest about ordering from Canada/shipping to Canada.

We've posted the parts list and link to the video of MM's Mustang in /DRIVE Tuner car Shootout

Big-bore rear wheel cylinders, 1979-1993 Mustang with 9" drum brakes (pair)
Actual product may differ from photo.


  • Item # MMBK-16


Drag racing?
Big-bore rear wheel cylinders shift brake bias toward the rear, improving braking when running big rear tires and front skinnies and/or different OEM front brakes.

The typical Mustang has more braking power up front than the rear-typically 70-75% front bias. That's way too much for a drag race tire setup with skinny front tires and fat sticky meats out back! The front tires will lock much sooner than the rears in that situation. Braking more lightly to avoid front lockup will lead to longer stopping distances. The solution? Improve braking by taking advantage of the fantastic grip provided by those big rear tires.

The easy way to shift braking force from the front to the rear with drum brakes is to install these wheel cylinders having a larger bore diameter. When coupled with stock Fox front brakes (excluding SVO) or 1999-2004 GT/V6 front brakes, the rear brake bias will increase 17%. Stopping ability goes up because the front tires will no longer prematurely lock, and the big sticky rear tires can support a large increase in braking effort.

Swapping Calipers?
For Fox Mustangs equipped with these big-bore rear wheel cylinders, there will be varying effects, depending on the exact combination of front brake parts and tire sizes used.

Recommendation table for MMBK-16
This table lists typical combinations of front brake and tire configurations. All tire and front brake combinations assume installation of the MMBK-16 big-bore wheel cylinders. "Yes" means the combination works well and is recommended; "No" means the combination should be avoided.

    Tire Configuration
    Bigs and Littles F/R Same Width
Front Brake Configuration 1979-93 GT/LX Yes No
1994-98 GT/V6 See Note Below* Yes
1999-2004 GT/V6 Yes No
1984-86 SVO No No


*This combination of brake parts will have too much front brake bias for use with bigs and littles. While installing the MMBK-16 will make the brake bias better, we still do not recommend this combination.

If your brake system isn't listed...
The brake setups most likely to have poor bias are those put together by DIYers. These systems are often done following dubious Internet directions, or simply because the parts were readily available and easily bolted up. Good DIY mechanical skills don't always coincide with good brake system engineering. MM can help you by evaluating your brake system and recommending how to improve it. Go to the Technical Services page, select the Master Cylinder option, and we'll run the numbers for you.

Related parts
  • Improves braking on Mustangs fitted with front skinnies.
  • Easily shifts brake bias rearward by 17%.
  • Provides improved braking while retaining rear drum brakes.
  • Includes 2 rear wheel cylinders with larger bore diameter.
  • New, not rebuilt

1979-1993 Mustang equipped with:

  • Stock front calipers, stock 9" rear drum brakes, and stock master cylinder
  • 1999-2004 GT/V6 front brakes, stock 9" rear drum brakes, and stock master cylinder
  • 1994-1998 GT/V6 front brakes, stock 9" rear drum brakes, and matching master cylinder BMC-4
  • Direct bolt on. No modifications to brake lines needed.

We're working on FAQs for this product. If you have a question, please use our Contact Us page to email your question. We'll answer your question by return email, and also consider it for possible addition to this FAQ section.