My exhaust was leaking at the coupling in front of the muffler (ball and socket joint, requires no gasket).
One of the bolts was corroded through. Or what I thought was a bolt. Turns out mine had studs.
Studs in the flange on the catalytic converter pipe, and they had to have been factory.
Every diagram I see, factory and aftermarket shows through holes for bolts in that flange, which is how it should be.
Does anyone else's D2 have studs there?
I tried cutting, grinding, drilling, and broke 2 carbide bits trying to get them out, to no avail.
My Dad is a retired engineer, and said he's never seen studs that hard. Long story short, cut off the old flange, and he made me a new bolt on one.
It'll last the remaining life of the 122k mile cats.
Easy bolt on and works great.

 

New flange
Bolts aren't tight in pictures

 

Sixpack, that was one of the hardest part I did. The rust welded the bolts in place. It was very hard to drill that part and I dulled a couple of bits and gave up. No PB Blaster soaking will do as well. At the end I bought somewhere about 7 inches of 5/8 bolt, torched the flange and hammer it out with the bolt I bought. Took few minutes to get it out.

Well, that was a good idea how your clamp was made I guess you just have to use a lot of anti seize or that will be more difficult to remove. But it will take another 10 years to replace those. cheers

 

So, yours had bolts in the cat flange then?
Not studs?

 

No studs, only 2 larger bolts to compress both.

 

In over 35 years I've never owned a RRC, DI, or DII that didn't have studs with the OE Y-pipe CATs. And have been there, done that trying to get those ba$tards out.
Most of the time I would have to use an Exhaust Flange Repair Kit (like what your Dad made....& your DAD KICKS A$$!!).
These "kits" come in many sizes and types/styles. The one in the pic is from NAPA, but you can get them at most auto parts stores or online (Summit Racing etc). WALKER makes a few different designs like > WALKER® EXHAUST SYSTEMS :: E-Catalog Lookup

 

Thank you sir!
The old man has helped me out of many a jam over the years. It's great having free engineering/machining services, lol!
I'm also happy to know that they did come with studs on that flange. And that I didn't get a Disco built on friday afternoon...at least not for that reason. So far so good everywhere else.
I have been working on bikes and cars since he started teaching me at 12, so 28 years. I worked for a couple dealerships after school before I realized I did not want to do that for a living!
In all that time, I have never seen the bolt on flanges like you posted. Hence, he made one.
How have I missed that all these years?!?!
Makes me wonder what else I'm missing. lol!

 

Can confirm, that flange had press-in studs. Took me half a day to remove mine and replace with bolts, but I'm still left with a flange thats in ****ty condition. Thanks for the tip on aftermarket flanges

I think the key for me was grinding the heads off the stud, drilling out some of the stud to create a relief, and then tapping it out with a hammer. Torching did not work

 

After the failed effort of removing the studs from the threaded side, grinding the heads of the studs and hammering them through from the other side was next.
My Dad offered to make the new flange, and save me the trouble. I was quick to agree.
One stud was completely rusted through, causing a leak.
They looked like rotted bolt heads.
But, after Dad pointed out what should have been obvious to me, I realized they were studs.
Strange that all the diagrams I have found show flanges with holes for bolts. Oh well.
I appreciate everyone's input, and confirming that they are studs.
I also apollogize for the thread jack, I didn't mean to stray from the OP's topic.

 

FYI, text and illustrations in D2 WM indicates studs/nuts.


......