Exhaust - safe to replace donut with flex pipe?

[wondercow2]

I've finally had to order a new set of catalytic converters for my '98 Legacy after an un-patchable failure. The problem is, I chopped off the end of the resonator pipe to deal with a broken flange at the donut gasket many years ago. For my most recent patch job I joined the resonator pipe to what was left of the rear cat with a spiral-coil flex pipe, but I think this was too rigid and helped accelerate the failure of the cat pipe further up in the exhaust.

 

I really don't want to replace the resonator pipe if I can avoid it (it's already got a patch at the failed flange to the muffler...). I'm not sure if I can find a donut gasket flange to weld or clamp on. Is it safe to join the resonator and rear cat with a higher-quality flex joint (the stainless braided type)?

 

I've replaced so many parts I'm not sure what's supposed to be down there anymore. As far as I can tell the cats are held rigid only by the y-pipe and the rigid hanger on the rear cat, and do not have a flexible mount. The resonator pipe and muffler are all on rubber hangar. Is this right?

[Rooster2]

On both my 98 and 99 Leggie Outbacks, I have replaced both resonators with a straight pipe, at a  On both cars, the pipe just rusted through and broke. Surprisingly, the replacement straight pipe does not make the exhaust any louder.

 

Over the years, on various cars, I have used the flex pipe approach. My experience is that the flex pipes don't last long. You may get a year or two out of a flex pipe before it rusts, or the metal gets brittle and cracks open.

 

Always best to use the rubber hangers that came with the car. I can't remember where the hangers are located, but keep using what you have.

[idosubaru]

Rusty exhaust is a pain and as much an art to repair as a science. Probably part of the reason I suck at it.

 

You can buy cheap flanges and pipe and make your own stuff. I've bought matching flanges and gaskets and welded those flanges to pipe to make your own exhaust. Tough getting it all to line up and be flush.

 

If you just need an OEM flange to marry to your current exhaust maybe someone in a western state can cut one off and mail it to you. Then you can attach it with pipe/clamps or weld. Or maybe even mail you the whole thing if you're lucky.

 

Www.car-part.com. Look up western state exhaust parts and call and ask if they'll cut off flanges for you?

 

They make some snazzy flanges you can bolt to a vehicle. But those can be pricey and hard to find.

[CNY_Dave]

I have used a piece of pipe that transitions from too small to too big them pulled the 2 pipes together with trampoline springs.

Was just like an old school 2-stroke dirt bike exhaust!

 

But that's a pretty crude fix.

[wondercow2]

Thanks for the replies. I haven't pulled the resonator pipe off yet but might go with a straight pipe if it's too far gone. I think I'm going to try the flex joint - local suppliers don't seem to have bolt-on or weld-on donut flanges? Do they have another name I should be looking for? In any case by the time I add on the cost of a donut and the spring bolt kit, I'm already up to what a short flex joint costs.

[Mike104]

Your local Mom and Pop (not chain owned) exhaust shop or a custom exhaust shop should have access to these types of repair flanges

 

https://theflangeman.com/cgi-bin/commerce.cgi?preadd=action&key=FX1748

[wondercow2]

Your local Mom and Pop (not chain owned) exhaust shop or a custom exhaust shop should have access to these types of repair flanges

 

https://theflangeman.com/cgi-bin/commerce.cgi?preadd=action&key=FX1748

perfect!!  Ordered from ebay for about the price of a spring bolt kit and a gasket.