New Flexible Heat Tubes (and resonating sound)

[DougB]

Hello all,

I replaced the flexible heater tubes (from the flapper boxes to the inlet pipes on the underside of the car) this past weekend (one of the originals had a hole in it) with some new replacements from CIP1. However, there were some differences between the originals and the replacements:

- the new ones don't use the rubber rings (the ones that replace the original asbestos ones)...the tube mouth is just big enough to fit over the pipe ODs)
- the new ones had to be cut to size
- inside the new ones (which are 2-piece shells like the originals, just with a smaller diameter) is fiberglass held to the edges with a steel coil spring
- There is a little less flex to the new ones compared with the originals

So I get these things installed, and when driving the bus this morning I'm not getting some engine noise seemingly resinating through the heater ducts to the dash. Could the rubber ring-less mounting of the new tubes, and the less flexible nature of them, really be resonating engine noise/vibration right up to the dash through the heater ducts?

Does anyone have a good source (other than the Classifieds or eBay) for OEM-style flexible heater tubes that use the rubber rings (which I assume dampen any engine noise or resonating vibration from coming through the ducts)?

Thanks in advance!

- Doug
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'75 Campmobile (tin-top to SpaceRoof)
'73 Fastback
'52 BMW R67/2
'41 Zundapp KS600
'55 Puch SGS250
A very, very understanding wife

[tommu]

I bought one NOS one from eBay. The longer one. Still looking for the shorter tube.

I had precisely the same issue with the meticulously insulated heater tubes Jon put together before I bought his Bus:
https://www.thesamba.com/vw/forum/viewtopic.php?p=7911566&highlight=heater#7911566

I had a very odd resonance that, when visiting in the summer, Colin suggested might be due to the heater tubes. It turns out the original baffles isolate the engine noise / vibration from the cabin. I don't know if they dissipate sound waves or just dampen the vibrations. I took them off and used very fine wire mesh around which I rolled weed barrier and then insulation. (Weed barrier to stop insulation fibers being blown into the cabin). I made sure not to let the wire mesh reach the caps on the heater tube. Resonation disappeared. It was a real shame to take apart those tubes.

Is there anyway you can modify yours to isolate the baffles from the tube ends?
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[DougB]

Thanks! I may have made matters worse thinking the fiberglass was only in there to insulate the hot air from the cold...Instead of the coil spring to keep the fiberglass out of the air flow, I used a section of the flexible aluminum heater hose...which would be good for airflow, but probably allows the noise to resonate more. I think I'm going to try to repair my originals (one has a hole in it) and put those back on. Bummer that who ever reproduced the design didn't just do it like the originals. That explains why the heat tube boxes under the rear seat in my '73 Fastback are so huge as well - never thought that they muffled/dampened the sound as well.
_________________
'75 Campmobile (tin-top to SpaceRoof)
'73 Fastback
'52 BMW R67/2
'41 Zundapp KS600
'55 Puch SGS250
A very, very understanding wife

[Wildthings]

Every Transporter came with a pair of these, there are going to be lots and lots out there.

[Tram]

[DougB]

I just patched the hole in the old one and put the originals back on. We’ll see how much longer they last.

- Doug
_________________
'75 Campmobile (tin-top to SpaceRoof)
'73 Fastback
'52 BMW R67/2
'41 Zundapp KS600
'55 Puch SGS250
A very, very understanding wife

[DougB]

Old tubes reinstalled last night and driving to work this morning was much quieter. Now to find at least one replacement hose for the one I was to patch.
Thanks for the input, all!

- Doug
_________________
'75 Campmobile (tin-top to SpaceRoof)
'73 Fastback
'52 BMW R67/2
'41 Zundapp KS600
'55 Puch SGS250
A very, very understanding wife

[Brian]

http://www.thebusco.com/

Got mine from Ken. Robbie had some shitty SS ones that were loud as shit. I traded him before I sold the truck, and it really turned down the noise in the cabin. Don't fall for the aftermarket crap!
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Wash your hands

'69 Bug
'68 Baja Truck
'71 Bug
'68 Camper

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