Cat flanges?

Huw Powell human747 at
Sun Nov 3 23:15:06 EST 2002

> We stock replacement flanges in two sizes that fit most VW/Audi
> application and they are a Split flange which means not cutting and welding.

Those are the slip, or loose, flanges, that depend on a flare
(chamfer...) on the end of the pipe on which they are captive to mate
with the donut gasket.  Because they are captive, when they rust apart
or get cut off due to trashed fasteners, etc., they must be replaced
with the two part gizmos, which are pretty cool when you need them.

Mike needs the "other half," the fixed flange that usually goes on one
or both ends of the cat and has the chamfer built in.

I'd recommend cutting the old ones off your cat or a spare hunk of
exhaustage and welding them to your new cat, btdt a few times, most
recently in using a 20v cat back acquired piece by piece on my 10v 90Q,
the 20v cat has a four bolt front flange, the 10v down pipe is a three
bolt flange outlet.  Had to use a hack saw blade as a spacer (!), but it
all welded up ok and doesn't leak.

> >After some investigating, it seems that the cat from the turbo syncro has a
> >melted core. I guess that 10:1 air/fuel ratio during the EFI tuning finally
> >caught up with me! Anyway, I need a new cat, no problem, I can get a nice
> >universal that's the right length for about 60 bucks.
> >The problem I'm having, is finding some of the 3 bolt flanges that have the
> >chamfer for the metal doughnut. Does anybody know where I can find these
> >flanges or am I going to have to cut them off my old cat?

Huw Powell

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