My winter project.

Need help from a fellow owner, something to air - discuss away!

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DJ.
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My winter project.

Postby DJ. » Sat Dec 21, 2019 1:01 pm

Back in 2016 my Caterham silencer needed repacking. I wrongly thought it was designed to be repacked, as most kit silencers are, and at £460 it isn’t cheap to replace. Some of you may remember that I had some fun doing it, but to cut a long story short, I repacked it successfully.

At the time, I had two problems: 1) I didn’t have any way to weld stainless and 2) I had to cut the centre tube to get the end plate off. I got around these by riveting some stainless onto the front face to secure the centre tube:

114_exhaust_repacking_7.jpg


114_exhaust_repacking_6.jpg


At the end of this summer, I noticed a crack had developed in the front cap, so as a temporary measure I welded it and riveted on some external reinforcement that looked terrible, but got me through until winter.

I took the end cap off in November, you may remember me posting a photo of the Acousta-fil packing that had lasted really well. And since then I’ve been trying to figure out how to repair it. Here is the cap:

117_end_cap_repair_01.jpg


117_end_cap_repair_02.jpg

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DJ.
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Re: My winter project.

Postby DJ. » Sat Dec 21, 2019 1:33 pm

I didn’t want to bin all that Acousta-fil, although at times I have seriously considered buying a new silencer from CBS as theirs look good and are half Caterhams price.

To stop the end cap cracking again, I decided I needed to :
1. Transfer more load directly into the central perforated tube
2. Make the end cap much more rigid so loads could be transfered into the outer skin without the end cap flexing

I tried one solution that didn’t work, and in the end decided I need to separate the front pipe from the end cap. This was a pain, but I managed it with lots of angle grinding and hack sawing.

I bought some stainless tube with 60mm internal diameter the same as the external of the front and perforated tubes. I welded 3” of this onto the front tube, so the connection between front and perforated tubes was much more secure.

I tried to buy a new front cap but couldn’t get one and I decided I couldn’t make one that would look good enough. I managed to weld up all the holes in the cap, and decided to make up a reinforcing frame that would be welded to the centre tube and fixed to the cap and outer skin with the 8 rivets Caterham had used.

Here is the extended tube and support frame:

117_end_cap_repair_07.jpg


117_end_cap_repair_08.jpg


Here is how it fits inside the end cap:

117_end_cap_repair_03.jpg


Here is a photo of the tube trial fitted into the end of the silencer:

117_end_cap_repair_09.jpg


In theory the centre tube and welded pieces should transfer all the load, and the end cap is now just to seal the silencer and make it look ok. There is no weld between the centre tube and cap, so you can see an exhaust gasket I fitted here with some exhaust putty. I suspect this is the weakest part of the design, but time will tell.

And this is it sealed and riveted.

117_end_cap_repair_10.jpg


The front plate looks rather second hand, but it tends to be covered in mud most of the year, so I’m hoping it won’t be too obvious :D

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Wingco
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Re: My winter project.

Postby Wingco » Sat Dec 21, 2019 3:37 pm

What a great job Duncan, well thought out, love the extra welded brackets inside the tube, good thinking. Just need to try it out now but I think that will do the job very nicely.
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DJ.
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Re: My winter project.

Postby DJ. » Sat Dec 21, 2019 6:07 pm

Wingco wrote:What a great job Duncan, well thought out, love the extra welded brackets inside the tube, good thinking. Just need to try it out now but I think that will do the job very nicely.

Fingers crossed! Thanks :)

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locost220
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Re: My winter project.

Postby locost220 » Sat Dec 21, 2019 6:32 pm

Looks really good Duncan
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Tony C
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Re: My winter project.

Postby Tony C » Sat Dec 21, 2019 7:36 pm

Very neat, shout if you need some stainless steel rivets, I've got a box of them knocking around somewhere, but they are a bu##er to compress, turns out stainless is tougher the aluminium :shock:
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DJ.
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Re: My winter project.

Postby DJ. » Sat Dec 21, 2019 7:51 pm

Tony C wrote:Very neat, shout if you need some stainless steel rivets, I've got a box of them knocking around somewhere, but they are a bu##er to compress, turns out stainless is tougher the aluminium :shock:


Thanks Tony, but I've just bought plenty. I had to buy a huge pop rivet tool with 24" arms too, when they go it makes quite a noise!

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Nash
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Re: My winter project.

Postby Nash » Sat Dec 21, 2019 10:06 pm

Nicely done Duncan. Great job
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Re: My winter project.

Postby greenwoo » Sun Dec 22, 2019 8:53 am

Good effort Duncan.....and as you say, most silencers are covered in a degree of crud anyway!!

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Crunchie Gears
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Re: My winter project.

Postby Crunchie Gears » Sun Dec 22, 2019 11:29 pm

Like that solution Duncan :D


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