Rob Walker Posted October 11, 2006 Share Posted October 11, 2006 Hi, I have an SLR silencer box on my car that has become too noisy. The plan was to cut off the outer skin and make the box repackable by installing a nice aluminium outer sleeve in place of the stainless steel sleeve. I cut off the old sleeve using metal cutting discs in my angle grinder, no problem. When opened up I was surprised at the construction of the box and hence my query. The outer skin was made up of two layers of 2mm thick rolled stainless steel sheet spot welded together. The ends of the box were of a double skin design with a 10mm gap between and the box was filled with rolled stainless steel wire wool. Now I am puzzled why Cheesmans who make the exhaust systems for caterham went to all that trouble constructing the box in this way? it would seem they wanted to make it as heavy as possible. Why double up on materials and why have an 10mm void between the double skin on the ends of the box. BTW the box had abviously become noisy due to the build up of carbon within the stainless wool in the silencer as non of this packing had burnt away or deterorated. The carbon had reduced the sound absorption properties of the ss wool. Rob. Link to comment Share on other sites More sharing options...
WILL FLY Posted October 11, 2006 Share Posted October 11, 2006 maybe they dd it for strength although 2mm is hugely thick for an exhaust. My powerspeed one is nowhere near that thick. Did the cheesman one have the perforated tube down the middle ? Roy See willfly.net for more info. If you don't spin you ain't trying Happiness is knowing you have just a tad too much power DVA 1.8K R345 Link to comment Share on other sites More sharing options...
Rob Walker Posted October 11, 2006 Author Share Posted October 11, 2006 Roy. Yes there is a perforated tube roughly central, the offset being to increase ground clearance allow the silencer box to run parrallel with the side of the car. It is a massively strong construction and certainly made with durability in mind. The removal/replacement of the outerskin has reduced the overall weight of the silencer by 3KG. Rob Link to comment Share on other sites More sharing options...
Bozz Posted October 11, 2006 Share Posted October 11, 2006 Rob Maybe it needs the strength because the only support is at back of the silencer whereas the Powerspeed can is supported front and rear. Bozz McLaren Orange and Black 1.6SS 6 Speed here Link to comment Share on other sites More sharing options...
Paul McKenzie Posted October 11, 2006 Share Posted October 11, 2006 "The carbon had reduced the sound absorption properties of the ss wool". Rob, this sounds a little strange ...how do you come to this conclusion? I can't quite get my head around the construction from your description , but could it be possible that fouling of the stainless wool with carbon is forcing the gases (and the noise) to bypass the wool and travel straight along the centre perforated tube? Paul Link to comment Share on other sites More sharing options...
Rob Walker Posted October 11, 2006 Author Share Posted October 11, 2006 Paul, You got it . The carbon build up is preventing the sound waves from penitrating the s steel wool and passing straight out of the perforated tube and tailpipe. It would be an interesting experiment to see if its possible to wash out and restore an old noisy silencer using solvents or even hot water. Rob Edited by - Rob Walker on 11 Oct 2006 14:28:23 Link to comment Share on other sites More sharing options...
Paul McKenzie Posted October 11, 2006 Share Posted October 11, 2006 You won't be able to solubilise the carbon with any solvent, but you might well be able to displace it with a water jet if it's physically possible to direct the jet at the fouled wire wool. My VX silencer is suffering from the same condition ☹️ and I was considering the practicality of having it butchered and rebuilt as a repackable, but I'd convinced myself it must have lost all the packing, but it doesn't seem to be the case from what you've found. Paul Link to comment Share on other sites More sharing options...
Rob Walker Posted October 11, 2006 Author Share Posted October 11, 2006 Paul If its of the same construction I would say its almost indestructable. I would remove the outer skin to be replaced with one made from ali or titanium. It should be possible to carefully unravel the s steel wool wrapped around the perforated center tube. If this was then held out flat on a board with nails it should be possible to powerwash the carbon out and blast with compressed air/ allow to dry and re-wrap . I have reused a small amount of the s steel wool around the perforated tube the remainder of the box I have filled with e-glass wool. I have not noise tested the box yet but it sounds quiet. Rob Link to comment Share on other sites More sharing options...
Jason Plato Posted October 11, 2006 Share Posted October 11, 2006 so you doin Dony sunday Rob ? 😬 Paul - if you need a skin rolling - I can do these here , like I did for Robs here is C7 TOP South Wales AO Link to comment Share on other sites More sharing options...
Mark Durrant Posted October 11, 2006 Share Posted October 11, 2006 Why not replace the packing material Mark D Comp Sec Link to comment Share on other sites More sharing options...
Rob Walker Posted October 11, 2006 Author Share Posted October 11, 2006 Mark, Just being tight I guess the s steel wool is £32 per Kg plus carriage. It also outlasts other types of packing. Rob Edited by - Rob Walker on 11 Oct 2006 15:45:28 Link to comment Share on other sites More sharing options...
k.russell Posted October 11, 2006 Share Posted October 11, 2006 Rob i have cut up a couple of OE exhausts and they have been double skinned but not 2mm thick, probably 1mm twice, your exhause must weigh a ton , the double ends give the pipe support, like holding a tube with two hands is stronger than with one, when i made my exhaust i did this also to provide strength. kevin R black-ali HPC Link to comment Share on other sites More sharing options...
Sheds Moderator Posted October 11, 2006 Share Posted October 11, 2006 The double skinned ends are to absorb sound, I would have thought. Double skinned outer skin, I don't know. Speaking as a chemist, oily carbon residues will generally *suspend* (note I don't say dissolve) in a 5% solution of sodium hydroxide (caustic soda). The stuff costs nothing so it's worth a shot. Finally, £32 a kilo wire wool? What is it, gold plated? DIY wire wool of all grades/gauges is in French DIY shops for pennies. It's spun steel for Christ's sake, how expensive can it be? Link to comment Share on other sites More sharing options...
Rob Walker Posted October 12, 2006 Author Share Posted October 12, 2006 Boss, Steel wool will not do the job. Firstly you can set it on fire with a blow torch , try it. Secondly it will rust away in a matter of days. Rob Link to comment Share on other sites More sharing options...
Sheds Moderator Posted October 12, 2006 Share Posted October 12, 2006 Aah, live and learn. Is it stainless then? Link to comment Share on other sites More sharing options...
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