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Fox Body 4 Cyl. To V8 Brake Line Conversion Guide | 1979-93 Mustang

Created by Taylor Ward
Last Updated 7/6/2021

One of the most overlooked steps on a 4 cylinder to V8 engine conversion is the brake lines. Check out LMR's Fox Body Mustang Brake Line Conversion Guide!

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FOLLOW: 79 93 mustang , brakes , tech guide

Fox Body 4 Cyl. To V8 Brake Line Conversion | 79-93 Mustang - Fox Body 4 Cyl. To V8 Brake Line Conversion | 79-93 Mustang

Often one of the most overlooked steps on a 4 cylinder to V8 engine conversion is the brake lines. 4 cylinder Mustangs have the main rear supply line routed towards the passenger side of the rear. When converting to a V8 engine with dual exhaust, this brake line gets in the way of the new tailpipe assembly on the passenger side. 5.0 Resto's V8 brake line conversion kit provides V8 specific brake components to route your lines exactly as they did from the factory!

5.0 Resto includes all of the main conversion components needed to properly convert your brake lines. These components are designed for owners swapping an 8.8" rear end along with the V8. Starting with the rear axle hard lines, we offer 2 different kits (LRS-2073DISC & LRS-2073DRUM) that are designed to either disc or drum rear brakes. These pre-bent lines are constructed with OE-style steel and include the correct fittings for a quick and easy installation. An 8.8" specific rear center brake hose is included to replace the 7.5" hose. The hose features a factory rubber construction and correct fittings to the new brake lines. The center hose connects to the included V8 upper brake hose bracket. This bracket was found on 86-95 factory V8 Mustangs and routes the brake lines away from the exhaust. Finally, an intermediate brake line is included to connect the center brake hose all the way up front to the proportioning valve/distribution block at the firewall!


Brake Line Conversion Steps

  1. When converting the four-cylinder Fox Body Mustang to a V-8. You will also need to add the dual exhaust system and upgrade to the 8.8 rear end. The original four-cylinder brake line that goes to the 7.5 rear axle, is located where the new exhaust system needs to be routed.
  2. Fox Body 4 Cyl. To V8 Brake Line Conversion | 79-93 Mustang - Fox Body 4 Cyl. To V8 Brake Line Conversion | 79-93 Mustang
    At the rear of the 4 cyl. brake line there is a bracket that bolts to the body on the passenger side. This is where the muffler hanger is mounted on the V8 cars. This area is the reason that this must be replaced with the V8 brake line setup.

  3. Converting the brake line and bracket to the 8.8 requires removal of the original four-cylinder brake line and replacing it with the V8 Brake lines and bracket. You can start by removing the right front tire and the inner fender liner to gain access to the brake line where it enters the right rear corner of the engine compartment. Please Note: The intermediate line that we sell doesn't include the brass union that is shown in the first image below. We do sell an alternative option for all 1979-93 Mustang models (LRS-785437).
  4. Fox Body 4 Cyl. To V8 Brake Line Conversion | 79-93 Mustang - Fox Body 4 Cyl. To V8 Brake Line Conversion | 79-93 Mustang
    The splice at the right rear corner of the engine bay is the beginning of the brake line that ends at the rear of the drive shaft tunnel.

  5. The clamps holding the brake line to the body are secured with pop rivets or screws.
  6. Fox Body 4 Cyl. To V8 Brake Line Conversion | 79-93 Mustang - Fox Body 4 Cyl. To V8 Brake Line Conversion | 79-93 Mustang
    Under the car the brake line comes from behind the passenger side inner fender splash shield.

  7. These pop rivets must be drilled in order to release the clamps from the body.
  8. Fox Body 4 Cyl. To V8 Brake Line Conversion | 79-93 Mustang - Fox Body 4 Cyl. To V8 Brake Line Conversion | 79-93 Mustang
    The line is routed along the passenger side frame rail with riveted clamps
    Fox Body 4 Cyl. To V8 Brake Line Conversion | 79-93 Mustang - Fox Body 4 Cyl. To V8 Brake Line Conversion | 79-93 Mustang
    Transitioning from the frame rail to the pinch weld and shares a riveted clamp position with the fuel vapor line.
    Fox Body 4 Cyl. To V8 Brake Line Conversion | 79-93 Mustang - Fox Body 4 Cyl. To V8 Brake Line Conversion | 79-93 Mustang
    At the rear of the pinch weld, the brake and vapor line again share a rivet clamping the two lines to the body.
    Fox Body 4 Cyl. To V8 Brake Line Conversion | 79-93 Mustang - Fox Body 4 Cyl. To V8 Brake Line Conversion | 79-93 Mustang
    The two lines turn back to the rear frame rail and have a plate that clamps and protects these lines at the vulnerable area under the frame rail.
    Fox Body 4 Cyl. To V8 Brake Line Conversion | 79-93 Mustang - Fox Body 4 Cyl. To V8 Brake Line Conversion | 79-93 Mustang
    At the rear of the 4 cyl. brake line there is a bracket that bolts to the body on the passenger side. This is were the muffler hanger is mounted on the V8 cars. This area is the reason that this must be replaced with the V8 brake line setup.

  9. The two brake lines are routed identically until you get to the rear area where the line is directed to the driveshaft tunnel and a bracket mounted just to the left of the tunnel. You will need to install the new rear attaching bracket.
  10. Fox Body 4 Cyl. To V8 Brake Line Conversion | 79-93 Mustang - Fox Body 4 Cyl. To V8 Brake Line Conversion | 79-93 Mustang

  11. The replacement brake line has a shipping bend that must be straightened before installing.
  12. Fox Body 4 Cyl. To V8 Brake Line Conversion | 79-93 Mustang - Fox Body 4 Cyl. To V8 Brake Line Conversion | 79-93 Mustang
    Fox Body 4 Cyl. To V8 Brake Line Conversion | 79-93 Mustang - Fox Body 4 Cyl. To V8 Brake Line Conversion | 79-93 Mustang


You have now successfully completed the 4 Cyl. To V8 Brake Line Conversion! Check out 5.0 Resto's rear disc or rear drum conversion kits below to get started.