Resonator

Remove and replace the exhaust resonator on a 1970 AMC Rebel Machine, reducing backpressure and improving exhaust flow.

Warnings

Tools required

Parts

• Exhaust resonator assembly × 1 — Use OEM specification or aftermarket equivalent for 390ci V8
• Exhaust clamps × 2 — 2.5 inch diameter band clamps
• Rubber exhaust hangers × 2 — Replace if deteriorated

Preparation

1. Ensure engine and exhaust system are completely cold to the touch
2. Park vehicle on level, solid ground and apply parking brake
3. Place wheel chocks behind rear wheels
4. Raise vehicle using floor jack at frame rails and support with jack stands under manufacturer-specified jacking points
5. Spray all exhaust clamps and hangers with penetrating oil and allow 15-20 minutes soak time

Procedure

1. 1

   Locate the resonator
   Position yourself under the vehicle midway between the mufflers and the catalytic converter. The resonator on the 1970 Rebel Machine is typically located in the mid-section of the dual exhaust system, between the H-pipe and rear mufflers. Identify the inlet and outlet connections and note the routing of exhaust hangers.
2. 2

   Remove exhaust hangers
   Locate the rubber exhaust hangers supporting the resonator. Using an exhaust hanger removal tool or large flat-blade screwdriver, carefully pry the rubber hangers off their mounting hooks. Work the hanger free from the exhaust pipe bracket first, then from the frame-mounted hook. If hangers are cracked or deteriorated, plan to replace them during reassembly.
3. 3

   Loosen inlet clamp
   Locate the band clamp or U-bolt clamp connecting the resonator inlet to the pipe coming from the H-pipe or intermediate pipe. Using a 1/2 inch ratchet and appropriate socket (typically 15mm), loosen the clamp nuts or bolts. Do not remove completely yet. If clamp is severely rusted, apply additional penetrating oil and attempt to work it back and forth to break corrosion free.
4. 4

   Loosen outlet clamp
   Move to the rear connection where the resonator connects to the tailpipe or muffler inlet pipe. Loosen the band clamp or U-bolt clamp in the same manner as the inlet clamp. Again, loosen but do not fully remove the fasteners yet to maintain alignment while separating the joint.
5. 5

   Separate inlet connection
   With clamp loosened, attempt to twist and pull the resonator away from the inlet pipe. The connection may be seized due to carbon buildup and corrosion. If stuck, use a wire brush to clean around the joint, apply more penetrating oil, and use gentle twisting motion. If connection will not separate and pipe is being replaced, carefully cut the pipe with a pipe cutter or reciprocating saw.
6. 6

   Separate outlet connection
   Repeat the separation process for the outlet connection. Work the resonator free from the downstream pipe using twisting and pulling motions. Once both connections are free, maneuver the resonator out from under the vehicle, being careful not to damage brake lines or fuel lines in the vicinity.
7. 7

   Clean pipe ends
   Using a wire brush, thoroughly clean the ends of both the inlet and outlet pipes that will mate with the new resonator. Remove all carbon deposits, rust, and old gasket material to ensure a proper seal. Inspect pipe ends for damage, excessive rust, or collapse that might prevent proper sealing.
8. 8

   Install new resonator
   Position the new resonator under the vehicle in the correct orientation, ensuring directional flow arrows (if marked) point toward the rear of the vehicle. Slide the inlet end over the front pipe approximately 2-3 inches for proper overlap. Do not fully seat yet to allow for alignment adjustment.
9. 9

   Connect outlet end
   With inlet loosely connected, slide the outlet end of the resonator over the rear pipe, again allowing 2-3 inches of overlap. Adjust the resonator position to achieve proper clearance from the frame, fuel tank, and brake lines. Ensure minimum 1 inch clearance from all components to prevent heat damage and rattles.
10. 10

    Install exhaust clamps
    Slide new band clamps or U-bolt clamps over both connections. Position clamps at the center of the overlap area for maximum holding strength. Hand-tighten the clamp hardware while maintaining proper resonator alignment and clearances. Verify all clearances once more before final tightening.
11. 11

    Tighten clamps
    Using the 1/2 inch ratchet and socket, tighten both exhaust clamps firmly. For band clamps, tighten until the band begins to deform slightly and the connection is secure. For U-bolt clamps, tighten evenly in a cross pattern. Do not overtighten as this can crush the pipe or crack the clamp.
12. 12

    Reinstall exhaust hangers
    Install the rubber exhaust hangers by first attaching them to the frame-mounted hooks, then stretching them to engage the exhaust pipe brackets. Use the exhaust hanger tool or screwdriver to help guide the hanger into place. Ensure hangers are fully seated and the exhaust system is properly supported without excessive stress or binding.

Reassembly

1. Double-check all clamp tightness and exhaust hanger engagement
2. Verify minimum 1 inch clearance between resonator and all chassis components, fuel lines, and brake lines
3. Inspect entire visible exhaust system for damage or loose connections while under vehicle

Verification

• Lower vehicle from jack stands carefully
• Start engine and listen for exhaust leaks at resonator connections while engine is at idle
• Have an assistant rev engine to 2000-2500 RPM while you listen from outside for leaks or unusual sounds
• Check for visible exhaust smoke or fumes escaping from clamp connections
• After test drive, re-inspect all connections and clearances with engine cool
• Verify no contact marks, soot patterns, or heat discoloration on nearby components

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