An exhaust may look like a simple piece of metal with a tube running through it, but it is actually quite complex in terms of its function. Engineering one that works efficiently and soundlessly is all about overcoming a paradox: how to remove the combustion by-products while silencing the associated noise. Removal causes noise, but reducing noise lowers the efficiency of the removal -- and the overall performance of the car. Fit an exhaust which claims to deal effectively with both issues. Use high-quality tools and maintain a clean, tidy working environment.
Wear protective clothing. Clear a workspace around your car. Mount the car onto purpose-built ramps or drive it over a work pit. Put the car into first gear. Secure the handbrake. Switch off the engine. Leave to cool (if the engine is hot from a journey). Climb underneath the car, taking gloves, goggles, a hacksaw, hammer and angle grinder.
Wear the gloves and goggles. Remove the old exhaust using the hacksaw, large hammer and angle grinder. Spanners do not work to unscrew the bolts on old exhausts because usually the bolts are rusted over. Instead, angle grind the exhaust system into pieces. Grind off bolt heads and nuts. Knock chunks off using the hammer.
Collect the new exhaust system. Take it carefully under the car with you. Ask a friend to help lift the exhaust system into place. Unbolt the hanger from the car. Replace the exhaust rubbers on the hanger. Use heavy duty rubber for large bore exhausts. According to Matey Matey, heavy exhausts need two standard rubbers either side of the centre section, in front of the rear axle, and two chain rubbers on the rear muffler.
Re-bolt the hanger to the car. Bolt the exhaust loosely into place using large nuts and bolts, and a wrench. Add extra clamps of the correct size, if required. They measure between 2.8 and 5.9 cm (1 1/8 inch and 2 3/8 inches), as listed by Tube Clip. Apply exhaust assembly paste to the joints of mild steel exhausts and silicone sealant to the joints of shiny stainless steel exhausts. Do this regularly during the installation.
Drive the car onto a flat surface. Check the lie of each exhaust component. Make sure the tailpipe is flush with the rest of the car's underside. Mount twin pipes and letterbox tails extra carefully as they can be bulky and stick out. Trim the bumper aperture using the angle grinder if it means a better fit. Use extra bolts if necessary. Check round (and oval) tailpipes for signs of curvature. Check the pipe loop over the rear axle.
Align the exhaust clamps. Make the nuts accessible, but not protruding. Tighten all the bolts using the wrench. Increase the tightening gradually, ensuring that the nuts and bolts are not over-tightened and the metal they hold in place does not buckle or bend. Test the new exhaust.
- Hacksaws and particularly angle grinders are highly dangerous if used incorrectly or by inexperienced people. Do not let the angle grinder near the fuel tank. Wear protective clothing at all times. Read all the instructions for the devices. Ask a professional if you need to.
- Jacking the car up in your garage is not sufficient for a complete exhaust refit. Climbing underneath a car and trying to remove an old exhaust is very dangerous. You must take the car to a garage with a ramp or pit, unless you are only changing the rear section of the exhaust.