Have just bought some heater boxes with the intention of opening up the seam to remove the pipe inside so I can then use stainless steel J pipes in their place with a larger internal daimeter than the stock pipes.
Anyone done this successfully and if so what method did you use to open the heater box outer shell then reassemble it afterwards. The seams appear to be just folded howeevr opening and closing them neatly seems a challenge
Cheers..................Wayne

Yes i did this about 2 months ago to fit a Vintage Speed exhaust and muffler with large J pipes and make the heater work

you need the later type heater boxes with no alloy surronds on the tubes they open up much easier

use a oxy flame to heat he seam and open with a flat blade screw driver

when the tube is fitted they can be panel beated back into place 2 person job for sure

I am just to lazy, as I bought larger diameter heater boxes and fitted them

Kev

they make heater boxes in 1 1/2 inch 38mm standard
1 5/8 42mm
1 3/4 45mm
1 7/8 48mm

not sure what sizes are sold in Australia..

If You are opening standard boxes make sure they are the later pipe only type and not the finned alloy types...


LEE

Please enlighten me vw54 and 68Autobug. Why not use the finned alloy types?
Cheeers...........Wayne

I honestly don't think it would make any difference, I have a bunch of them sitting in the shed and the outer shell looks identical on both.

I think the housing on the alloy ones has larger openings as the alloy sheath adds to the diameter of the exhaust pipe. Not really an issue as the casing is normally needing repair in that area anyway and will probably need changing for the new pipe.

inside the alloy ones, if you cut the actual pipe open too, isn't even a round pipe, its actually cast iron with fins on the inside then that has alloy fins cast to the outside. I imagine this to be fairly restrictive compared to a round exhaust pipe.

I thought that too till someone did a cross section comparison on the samba and calclated the pipe area of the two.
The wavey shaped ones have larger inside pipe surface area than stock 1 3/8" round ones but whether the shape of the walls makes them flow worse is anyones guess till someone tests them.

I don't know if they are all like it, I;ve got some de-shelled 72 bug ones which was the last year of the finned ones in aus I feel like cutting right open.


Edit...

Can't find the thread but heres the pics,

Thanks guys for all your input. Joel and vlad01, I had no idea that the inside of the pipe wasn't round. Seeing that section and all the effort that VW put in to make them makes me wonder how well straight pipes will actually give off heat. It gets fairly cold in Melbourne. I may be better off sacrificing a tiny bit of performance for the sake of a good heater and keep using the stock alloy ones
Cheers.....Wayne

The 73 and later heaterboxes are just J tubes with the heaterbox shell.

I still had them in a couple of my bugs, whilst they don't get as hot it;s not that noticable and I'd bet stainless steel generates a bit more heat and quicker than the stock metal ones.