In this guide I will show you how to change the back box on your exhaust.
Its not really complicated, just time consuming as most parts will be rusted.
I had to change the back box on my daily run around as the box imploded and broke the welds, due to every day use.
You can use the same principles as in this guide to replace your standard back box to a performance box for more power and sound!
Right we will start with the tools needed as always:
Tools Needed:
Trolley Jack
Axle Stands
Wheel Chocks
Socket set or
Spanners
Screwdriver or Chisel
Dermal or Grinding/Cutting Tool.
Rubber Hammer.
Stanley Knife.
Wire Brush.
Parts Needed:
Back Box.
Exhaust pipe Clamp.
Exhaust rubber hanger if old are perished.
Exhaust sealer if needed.
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Back Box
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A Pipe ! Not Big is it?
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Right, lets get started,
Get the car on a level surface then chock the front wheels so the car will go nowhere
as you will need the back end off the floor, the handbrake is useless, and because
the front wheels do not lock with the handbrake you need the chocks to stop the car rolling onto you.
Place the jack under the rear beam in the middle with a block of wood in the groove and lift the car up, both sides will life.
Place the axle stands under the chassis legs, not the floor. The chassis legs are the boxy sections under the car.
Then lower the jack down so that the weight of the car is supported by the axle stands but as a safety measure, pump up the jack so it rests just under the beam.
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Now look at the back box and spray the clamp with WD40 and leave it for a while,
then undo the nuts with a socket or spanner. Remove and discard the clamp.
Give the joint a good whack with a rubber hammer or something hard to break the rust.
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The old exhaust will be held up to the car by a rubber hanger near the rear valance,
in most cases this will be perished, brittle, ripped or just saggy. Simply cut this off with a knife and discard.
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If you are lucky you should just be able to twist the back box while pulling it and it should
come away but in most cases you will need to use either a screwdriver or chisel to separate
the overlapped joint on the two pipes.
Once you have done this, give it another go and if that fails, get out the dermal or grinder
and cut the pipe off, making sure that you don't cut into the inner pipe.
Pull the pipe debris off the rest of the exhaust system and use a wire brush to clean
the end of the existing and remaining pipe, this is to remove the excess build up of rust
and grime that would prevent the new pipe making a good contact.
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Shown below is my old back box along side its replacement, as you can see it is very damaged.
The entire honeycomb within the old exhaust had imploded as the welds broke.
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Now to the refitting, you first need to test fit the new pipe to the remaining system to ensure it fits correctly.
If it does then remove it and put a new exhaust hanger onto the bracket on the top of the exhaust pipe.
Next push the clamp onto the existing part of the system and push it out of the way for the time being.
It's entirely up to you if you use exhaust sealant in the next step, but I didn't as it created a decent joint.
Push the new back box onto the existing system and direct the rubber hanger over the mount on the underside of the car.
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Now the back box is roughly in place you need to jack up the middle section of the
exhaust as this has a tendency to sag. One you have got the middle in the correct position
you need to twist the back box so it is level and the exit pipe is facing down towards the floor.
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Move the clamp over the new pipe, making sure that it will clamp top and bottom of the slits and not side to side,
as this will not seal the join correctly.
Tighten up the nuts on the clamp evenly making sure that they are tight,
lastly give them a coat of crease to stop them rusting.
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Lower the jack from the middle of the exhaust and the pipe should stay up in the channel under the car.
Put the jack back under the rear beam and jack it up enough to remove the axle stands,
then lower the car back to the floor, and remember to remove the wheel chocks.
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The End
And that's it, done,
Hope this guide is of some use to somebody out there.
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Guide Written and © On 10 Dec 2005 by Andrew Whiteman (AW3K)
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