How to repack a non repackable silencer.
Posted: Wed Feb 24, 2016 2:56 pm
I have just finished this little project that I have been meaning to tackle for a while. I took photos while doing it so thought I would post on here in case anyone else wants to do the same.
My exhaust silencer was not silencing the exhaust much and I suspected all the baffling material had long been blown out of the tail pipe. The noise seemed to be being amplified rather than silenced. Some of the younger generation (as I was once) would maybe like this and celebrate it but I am a little more mature these days and although I obviously love the sound of the twink mine was just too grating especially when trying to drive sedately round town. I was sure replacing it would still give a nice, mellower sound at full throttle but be nicer to drive when not booting it. I have repacked the silencer a few times on my race car and I know this is the case. I hope it will be the same for the lotus and not make it too quiet.
The Silencer on my S3 DHC is the transverse oval box. It is easily removed from the car and can be seen here before I started on it.
I was not 100% certain on the internal structure of the silencer when I started but I guessed it was just the oval can with a straight through perforated pipe. So to get into it the only thing to do was to get the hack saw and saw it in half. First I marked a straight line around about 20 mm in from one side.
Then set to it with the hack saw.
This proved to be a little more difficult than I expected because as the cut went through, the tension in the metal, obviously in there during its construction, meant it started to distort and close up the gap I was sawing making the blade stick. It is also very difficult to hold the thing still without squashing it. I used various woodworking clamps to hold it onto the bench. Once through the outer can, I then continued sawing through the centre perforated pipe. Here is the result.
As expected it was a completely empty void with absolutely no wadding in there at all. Just horribly dirty carbon dust.
To put it back together, my plan was to make a strip of stainless steel the same thickness as the outer can and slide it into the end piece forming a joining face to which I can then pop rivet it together. Same for the perforated tube, so the original pipe will slide into the new outer sleeve. I started off by making some templates out of cardboard.
Luckily we have a fabrication shop at work who made the strips up for me and actually tack welded them in place. This meant I only had to have exposed pop rivits on one side of the join rather than on both as I originally planned.
Assembling it back together I found it was too tight a fit and I couldn?t slide it together. To achieve the required sliding fit, a small hack saw slit down the new strip made all the difference and meant the two halves could slide together. Holes were drilled for 6 pop rivets, 3 each side. I thought this was enough.
My exhaust silencer was not silencing the exhaust much and I suspected all the baffling material had long been blown out of the tail pipe. The noise seemed to be being amplified rather than silenced. Some of the younger generation (as I was once) would maybe like this and celebrate it but I am a little more mature these days and although I obviously love the sound of the twink mine was just too grating especially when trying to drive sedately round town. I was sure replacing it would still give a nice, mellower sound at full throttle but be nicer to drive when not booting it. I have repacked the silencer a few times on my race car and I know this is the case. I hope it will be the same for the lotus and not make it too quiet.
The Silencer on my S3 DHC is the transverse oval box. It is easily removed from the car and can be seen here before I started on it.
I was not 100% certain on the internal structure of the silencer when I started but I guessed it was just the oval can with a straight through perforated pipe. So to get into it the only thing to do was to get the hack saw and saw it in half. First I marked a straight line around about 20 mm in from one side.
Then set to it with the hack saw.
This proved to be a little more difficult than I expected because as the cut went through, the tension in the metal, obviously in there during its construction, meant it started to distort and close up the gap I was sawing making the blade stick. It is also very difficult to hold the thing still without squashing it. I used various woodworking clamps to hold it onto the bench. Once through the outer can, I then continued sawing through the centre perforated pipe. Here is the result.
As expected it was a completely empty void with absolutely no wadding in there at all. Just horribly dirty carbon dust.
To put it back together, my plan was to make a strip of stainless steel the same thickness as the outer can and slide it into the end piece forming a joining face to which I can then pop rivet it together. Same for the perforated tube, so the original pipe will slide into the new outer sleeve. I started off by making some templates out of cardboard.
Luckily we have a fabrication shop at work who made the strips up for me and actually tack welded them in place. This meant I only had to have exposed pop rivits on one side of the join rather than on both as I originally planned.
Assembling it back together I found it was too tight a fit and I couldn?t slide it together. To achieve the required sliding fit, a small hack saw slit down the new strip made all the difference and meant the two halves could slide together. Holes were drilled for 6 pop rivets, 3 each side. I thought this was enough.