New exhaust very close to rubber bellows ?

[Qldelsie]

This morning I received my new exhaust (ooooh - Shiny VS stainless ! ) and was doing a trial fit while the engine is on the stand. All goes together very well, but when I fitted the rubber bellows, the bottom is only about 1 inch away from the muffler. Surely this is going to get a bit warm down there, and will eventually cause the rubber to deteriorate quite badly ?
So I thought maybe I could take a piece of light heatshield material and form up a small plate that would be held in place by the big clamps that hold the bellows on, and would then deflect a lot of the direct heat away from the rubber. In the 4th & 5th photos I show a mock up just using a piece of carboard.
I have used this heatshield material to insulate heat from exhausts before - it is a ceramic filler sandwiched between two 0.15mm aluminium steel sheets and is designed for use near turbochargers, catalytic converters, exhaust systems, manifolds & other hot spots and has a maximum temperature range 850 to 900 degrees Celsius, so it is up to the task.

Do these rubber bellows suffer from the exhaust heat ? Has anyone else got a a better solution to the issue ? Or is it all totally unnecessary ?

Thanks,
G

[KTPhil]

VW thought something was needed for the stock muffler:

It was a sandwich of sheet metal and what I hope was not asbestos plate.

The plate mounting you suggest may act as a reflector, but may also act as a heat sink and then conduct that heat to the lip of the seal where it is clamped. You might consider making the edge that you clamp shaped with fingers, rather than a continuous edge, to minimize the heat transfer.

Uglier, but probably more effective would be such a plate clamped to, and a slight distance away from, the muffler body.

[Qldelsie]

Yes, good point about original muffler. And agree it might be better clamped to muffler than to bellows - with spacers, of course. Easier too as it can just be fitted while muffler is off car.
You would hardly be able to see it from underneath if it is only on the top side of the muffler, so not too ugly, especially if fabricated nicely with turned edges, which is real easy with this stuff. I have used it to make battery boxes for cars which have under hood batteries, and it can look really nice.
Good input, thanks.
Giles

[Chupa7hingy]

While I am very new here, I have lurked for some time and my father-in-law who was a factory VW mechanic in his early years is helping with my Notch project. I got the same style muffler, and we found it's not just the bellow, but the actual tailpipe is too close to the rear skirt. We had to make spacers for the top tubes to tilt the whole muffler down to clear the skirt. Now we did put new trans mounts which likely raised the engine up a smidge, but the muffler needed to be massaged to fit and clear.

Hope this helps.

[Qldelsie]

I will watch out for it when I put the engine back in.
What year is your notch, Chupa7hingy ?
G

[W1K1]

I have the same exhaust, I bought some of this for my heat exchangers off amazon,and I think I'll order some more to wrap the muffler as well https://www.designengineering.com/floor-tunnel-shield-ii-non-adhesive/
they also have this, it looks to be the same thing with a couple clamps https://www.designengineering.com/muffler-shield-kit/

it's a pretty solid layer of aluminum, as you can see I replaced the fiberglass that was on the short tubes, it was disintegrating after a few years in use on the car.

_________________
http://www.thesamba.com/vw/archives/manuals/jim_martin_engine_build.php

1973 super
1965 squareback 1500E
1971 bay window westy- subi swap

[Qldelsie]

Yes, W1K1, that is very similar to the stuff we get down here. I have used in on various cars and it is very effective. However for best results you need a little bit of clearance between the hot surface and the shield, so air can pass through, so I am looking at ways to just put some kind of spacer in between so they are not quite touching. There isn't much room up to the bellows, and I don't want ithe heat shield touching them, I I can't get the recommended 1" clearance. Which is why I am still considering fixing the heatsheld to the bellows themselves so how - either with the existing long hose clamps, or some other way. I am aware of KTPhil's comment that the heat shield could transfer heat to the bellows if it is in direct contact with them at the strap.
Interesting puzzle !!
Another oddity with my car - Although lots of bits were falling apart, all the packing around my heater pipes was in perfect condition !! Go figure !!!
G

[ataraxia]

The VS exhaust looks nice and has a good tone to it - I was not able to get it to fit my car properly. I owned two Type 3s at the time and had two VS exhausts - one positive thing about them - they're made very consistently - neither fit correctly.

I felt like the tip was too short compared to a stock exhaust. The exhaust itself gets very hot - I would either wrap it in a fiberglass mat or something similar to what W1K1 uses on his heat exchangers (DEI makes a larger version specifically for wrapping mufflers).

Heat will definitely affect the lifespan of a rubber boot - the less heat, the longer that boot will survive.

I will be using something very similar on my current exhaust once it's all fitted/sorted and installed.

[Qldelsie]

When you say "wrap it in" fibreglass mat or similar, I am not sure I see the value. My (limited) understanding is that if you put the heat shield material (whether it is fibreglass or metal) in direct contact with the hot surface, in this case the muffler, all you will do is transfer the heat to the heat shield material because it is radiant heat. OK, it might be a couple of degrees lower than the muffler, but not much.
However, if you leave a slight air gap between the muffler and the heat shield so that air is able to pass through there, then the effect of the heat shield is dramatically increased.
On the manifold (or headers or whatever you call them on a normal car) it is slightly different as you are trying to keep the heat in the manifold. And anyway, there is a big school of thought that wrapping of exhausts causes premature rusting - But thats a different subject, especially since this muffler is stainless.
Also, wrapping the heater tubes is fine because, again you are trying to keep the heat inside the tube so it can keep your toes toasty !!
I am looking at leaving at least a little space between my heat shield and my muffler - Just trying to work out best way to do it !!
G

[pitargue]

The CSP exhaust has a heat shield between the muffler and the rubber boot which is mounted off the muffler. Or that's what it looks like.

https://www.csp-shop.com/en/exhaust-heating/python-exhaust-system-251-303-038-23835b.html

Perhaps something like that could be fabbed and attached to the VS muffler in some way...

[Clatter]

[Qldelsie]

Yes, that sure is a lovely exhaust ! Love your analogies, Clatter Always hated anyone who farted in church
$$$ make it a bit out of reach. Thats more than twice the price of the VS, before shipping and duty.
Heater pipe connections lead on to a separate post which I will title "How to connect heater pipes", which is my next issue.
In the meantime, I have a few ideas for my heat shield !! More later...........
G

[Bobnotch]

[W1K1]

I did have a plate with tabs on top of my OTT , I can't weld stainless, so it didn't happen on the VS

the CSP stuff is always nice, if you can justify the cost, its always a jump above everyone else
_________________
http://www.thesamba.com/vw/archives/manuals/jim_martin_engine_build.php

1973 super
1965 squareback 1500E
1971 bay window westy- subi swap

[Bobnotch]

[ataraxia]

[ataraxia]

[Qldelsie]

[Bobnotch]

[KTPhil]

I found the photos in another thread, so here you go: