A: There are several situations where vacuum-assisted power brakes may cause a problem that can be solved by converting to manual brakes.
- Mustangs with low vacuum due to a big camshaft may lose power assist at the worst possible time, greatly lengthening the stopping distance.
- Some engine conversions, such as a 4.6L swap, may not allow enough room for the vacuum booster.
- Pedal feel when road racing or open-tracking may be very inconsistent due to the vacuum level fluctuating from extended periods of wide-open throttle. Brake modulation and control can be improved by converting to manual brakes.
- Turbocharged and supercharged engines may not have enough vacuum available for consistent braking with vacuum-assisted brakes.
Q: Besides the Manual Brake Conversion Kit to mount the master cylinder, is there anything else I should do to my brake system when I convert to manual brakes?
A: Yes. You should improve the rest of your brake system as much as your circumstances allow. Without power-assist, everything else in the brake system needs to work as well as possible. Among the things to consider:
- High performance brake pads, matched to how you use your car, should be installed. A street-driven Mustang needs pads with a high coefficient of friction when cold. Road-raced Mustangs need friction material suited for the temperatures encountered on the track.
- Any axle endplay will contribute to increased rear pad knockback. That will cause an intermittent low pedal that is much more noticeable with manual brakes than with power brakes. The stock Traction-Lock differential should have the clutches shimmed tightly to minimize axle endplay.
- Stainless steel braided brake hoses will reduce hose expansion, and provide a firmer pedal feel. The soft pedal feel from hose expansion is more noticeable with manual brakes than with power brakes.
- Swapping to larger front discs will greatly improve the stopping ability. For example, swapping GT rotors to larger diameter 13" Cobra-sized front brake rotors will provide a significant reduction in stopping distance.
- An adjustable brake-proportioning valve will allow adjusting the rear brake pressure for the best front to rear bias on your particular Mustang.
- Properly sizing the front and rear rotors, as well as the front and rear caliper piston areas, to be close to a front/rear bias of 70%/30% will provide the best braking performance.
- In the end, braking ability is determined by tire grip. Sticky tires have more grip, and will provide more stopping ability.
- Optimize your combination. For example, a drag race car with big sticky rear tires and skinnies up front will need a brake system with a rear brake bias much higher than 30%. Designing the brake system to have more rear bias will avoid prematurely locking the skinny front tires, and take advantage of the greater amount of rear grip.
- Choose a master cylinder size that properly matches up to the front and rear brakes on your Mustang.
A: It is the best because each component was carefully designed to do the task required. The MM Engineering Team does not take shortcuts; others lack the attention to detail required to create a safe design.
The MM aluminum firewall adapter block
- Locates the master cylinder at the correct angle to properly align with the pushrod. Excessive angularity between the pushrod and the master cylinder will cause premature master cyclinder seal failure from increased piston side loading.
- The vertical position of the master cylinder is placed to match a pedal having the proper leverage ratio for manual brakes.
- The aluminum block is machined from thick billet instead of cut from thin plate. The block reinforces the firewall, reducing flex when braking.
- The aluminum is anodized for best appearance and corrosion resistance.
- Rather than reusing the power brake pedal, or requiring you to modify your power brake pedal arm to correct the mechanical leverage ratio, MM designed a pedal arm with the proper ratio for manual brakes. This is the key to avoiding excessive pedal effort.
- The MM arm is much stiffer than the OEM Ford pedal arms. Having less flex in the pedal arm provides a firmer pedal feel, and easier modulation when threshold braking.
- The pedal pad is separate from the pedal arm. The bolt-on attachment allows adjusting the pedal pad location to suit your needs.
- The pedal arm is designed for a pushrod with a spherical rod end attachment rather than a stock pushrod. This design eliminates excessive play, as described below.
- Mounts to the pedal arm with a spherical rod end. That eliminates the excessive pedal play allowed by the stock pushrod, a unique Ford design used for brake switch activation. Less play in the system means quicker brake response and improved modulation.
- Stiffer than OEM Ford pushrods to prevent flexing under the higher pedal loads typically encountered with manual brakes.
- Is adjustable in length to accommodate variances in master cylinders, and allow fine-tuning the pedal pad height (distance from the firewall).
- A new switch replaces the stock switch because the MM pushrod design (to reduce slack in the system) is not compatible with the stock switch's method of activation.
- Mounts to an included laser-cut bracket that bolts to the Mustang pedal box.
- Included is an adjustable upper pedal stop.
- This pedal stop is used along with the adjustable pushrod to fine tune the pedal pad height.
A: While it takes a bit of time, it is within the skill set of most Mustang DIY's.
- We include illustrated instructions: MMBAK-10, and MMBAK-13
- For easier installation, we also offer installation kits of prebent hardlines to connect the most popular Mustang master cylinders to your Mustang.
- New hardlines for the master cylinder are required because a manual brake conversion relocates the master cylinder about 6.5" closer to the firewall, beyond the reach of the stock power brake hardlines.
A: The SN95 Mustang ratio is different from the Fox chassis ratio because of differences in the unibody chassis.
- The MMBAK-10 kit for 1979-93 Mustangs has a ratio of 6.15:1.
- The MMBAK-13 kit for 1994-95 Mustangs has a ratio of 5.32:1.
- These are the ratios when the MM pedal pad is in the stock position on the pedal arm. The ratio can be increased or decreased slightly by changing the pedal's position on the arm.
A: While some aftermarket master cylinders will work, we recommend using one of the several Mustang master cylinders because:
- Direct replacement Mustang master cylinders are readily available at most auto parts stores. In the event of a failure, a replacement master cylinder can be located without much difficulty.
- Aftermarket master cylinders all have the outlet ports on the opposite side from the stock master cylinder. That makes bending the brake lines to fit to the ports much more difficult, as there is very little room between the master cylinder and the chassis.
- MM makes installation kits that greatly simplify installing a stock Mustang master cylinder. We do not make such kits for aftermarket master cylinders; you will be on your own to create lines with the proper tube nuts.