Repacking a standard Duratec silencer.

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Nigel B
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Repacking a standard Duratec silencer.

I've recently noticed I'm getting a little resonance from the exhaust, generally when the throttle is lifted during gear changes.

Taking the silencer off & shaking it from side to side, I can feel the packing material sliding about. There clearly isn't as much in there as there used to be!

I believe the silencer on my 2017 420 isn't repackable, but having Googled it, I have found a few references to people modifying them in order to make them repackable.

From what I can make out, if the rivets at the forward end of the can are drilled out & the internal perforated pipe is cut with a dremel & cutting disc, the end cap can be removed. 

I'm assuming a modification to the end cap would then be required to keep the perforated pipe in place after the silencer has been repacked?

Has anyone successfully managed to do this? I'm struggling a little to visualise exactly what is involved & whether I'd actually have the skills to tackle the job!

Any advice (or ideally photos!) would be very much appreciated!

ScottR400D
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Hi Nigel. Don't know how to do this but interested for obvious reasons!

How many miles have you done now?  

L7C
colindavies56
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If you drill out the rivets, you shouldn't be able to pull the end off as it has a mandrell groove around it. Try sticking a thin blade in the gap and it won't go through..if you do somehow separate them you can get repacking stuff from a motorcycle accessories shop. 

Nigel B
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Hi Peter! I think the mileage is at about 20,500 right now. I've only recently noticed the resonance. I hope your R400 is running well.
 

Colin, that's an interesting observation. I presume the groove is there to stop the end caps moving, in relation to the sleeve? Perhaps it won't be possible then? I might take it to a local exhaust fabricator next week & ask their opinion. 
 

Thanks for the input! Thumb Up

aerobod
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On the version of the silencer (without a catalytic converter) that has bolts to hold it together to allow easy repacking, the groove acts as an end-stop for the end caps, as opposed to being swagged into the end cap itself.

James

Nigel B
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Hi James, 

Yes, I think that may well be the case. Having done a bit more Googling, I came across this thread from 2016. I think the silencer in question is from a Sigma car, but it does look very similar to mine. It's an encouraging thread!

https://www.caterhamlotus7.club/forum/techtalk/can-standard-silencer-be-repacked-yes-it-can-see-post-8

Cheers!

Nigel.

ScottR400D
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You've done a fair few miles more than I have, Nigel so maybe I'm a little way behind you in exhaust terms. I didn't notice anything untoward when it was last off this year and it gets through TD noise tests OK. 

That's an interesting thread about how to make the non-repackable repackable, though a fair bit of work. when the time comes I might just buy a new one then hack away at the old one out of interest. 

A pity that it's not designed properly in the first place though, it could easily have been. At least ours don't have the built in cat....... 

L7C
Nigel B
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Hi Peter, 

Yes, it's annoying that they're not repackable as standard, but I suppose from Caterham's perspective, they get to save a few pennies on each silencer they make & it encourages owners to simply buy another when the packing material blows out.

There are a few custom exhaust businesses locally, so I think I'll take it to one of them next week & see if they're willing to modify it. It looks like it should be possible.

Fingers crossed anyway.

paul_w
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I repacked my 2010 Sigma exhaust that looks similar, I had a buzzy resonance that I worked out was the rivets at the front having worked loose. Was a pretty easy process except that the replacement rivets I bought needed an industrial strength rivet gun, not the normal handheld one I had, so see if you can borrow one if you're going to give it a go.

paul_w
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(duplicate post)

Nigel B
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Thanks for your post Paul!

Was the process the same as the one described in the post I linked to above? Essentially, drill out the rivets & cut the end of the perforated internal pipe to remove the end cap?

If so, how did you modify the end cap, to keep the perforated pipe in place after cutting?

It hadn't occurred to me that I might need a heavy duty rivet gun, so thanks for that tip!