Cat-Back Exhaust Installation on an E36 BMW


There is nothing about this installation that is truly difficult, but it is definitely awkward.
Wear old clothes and safety goggles (you'll be on your back with dirt falling in your eyes!), and take your time.
(I can do a complete swap in 10 minutes. Expect your first time to take at least 30. If you get in a jam feel free to call me at 303-898-9871.)

Tools needed:
- ramps (preferred) or floor jack and jack stands
- 13mm box end wrench
- 12mm box end wrench
- 13mm deep socket
- 3/8" ratchet
- 3/8" extension (anything longer than 2")
- safety goggles

Optional tools:
- 12mm socket
- 13mm socket
- steel wool or wire brush
- WD40 or similar lubricant
- rags


Removal...

1. Drive the rear of the car onto ramps -- OR -- jack up the rear of the car and put on jackstands (as high as possible).

2. Loosen, but do not remove, the two 13mm nuts on the brackets holding the muffler to the chassis. (ratchet & 13mm deep socket w/extension) The bracket and nut closest to the fender may be somewhat hidden behind the fender panel. If so, just pry the muffler toward the center of the car to get at the nut.

3. Loosen and remove the four bolts that connects the twin tail pipe section to the cat section. (Use a 13mm socket or box end wrench on the bolt and a 12mm box end wrench on the nut -- or -- vice versa, depending on how yours was oriented at the factory.)

The two pipes have two separate types of connections. The shorter of the two pipes coming from the muffler joins with the pipe coming from the cat in a butt joint. Take care to retrieve the donut gasket from between the joint so as not to drop and break it. (It's reusable provided you don't break it.)

The longer of the two pipes coming from the muffler slips approx. 3" over the pipe from the cat (the donut gasket will stay on the pipe) and will support the muffler section after the bolts are removed.

4. Prepare yourself to support the weight (nearly 50lbs) of the muffler section and maneuver the muffler out of the two hanging brackets that you loosened earlier. Once you have released the muffler from the brackets, slide the entire muffler section toward the rear of the car. Once it has moved rearward approx. 3" the pipe that had been slipped over the pipe from the cat will drop free and the entire section can be removed from beneath the car.


Re-installation...

5. Before you actually raise the muffler unit into place, do two things; a) clean the rearmost portion (from the donut gasket to the flared end of the pipe) of the "longer pipe" coming from the cat and lubricate it with a small amount of WD40 to ensure smooth reassembly, and b) remove the nuts and lower halves of the muffler hanging brackets (leaving the threaded portion hanging down) and save for reinstallation.

6. Slide the muffler under the car and, holding the unit parallel to its final installed position, slip the longer of the pipe connections together so that the conjoined pipes supports the weight of the unit in the front.

7. Raise the muffler so that the threaded portion of the muffler hangers can now be bolted to the tabs on the muffler using the lower half of the clamp brackets (rotated 180 degrees if needed to fit) and nuts. Leave nuts finger tight for now.

8. Slide the muffler unit as far toward the cats as possible, or until the "shorter pipes" butt together. Be sure the donut gasket is in place. Fasten the flange bracket with two bolts and tighten until the pipes are firmly joined together, but do not perform final tightening yet. (This step can be used to "pull" the muffler section to the cat section if necessary.)

9. Assemble the remaining flange bracket using the remaining two bolts and nuts.

10. Go back and tighten all nuts and bolts firmly. (I recommend re-tightening all nuts and bolts after the first 100 miles or so.)

Enjoy your new exhaust! ....(And weight savings of more than 20 pounds if you installed one of my units.<g>)

 


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