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Went to a friend's place today to put the cat-back on my classic. Well, Greg and company were right on Saturday at the mini-meet, the bolts to the cat are rusted and won't move, BUT here's my dilemma:

The bolts go through the two flanges from the exhaust side, and there are NO NUTS on the cat side. Did these cars come from the factory with threads in the cat flanges? To compound my confusion, the bolts that are sticking through appear to have no threads, although at this point I am attributing this to rust.

I have bought new bolts/nuts/washers. I am thinking seriously about borrowing/buying a grinder and just cutting the bolts off, and then drilling the appropriate sized holes in the cat flange to accept the new exhaust system. Is this a good/bad idea? This will also apply to my upcoming header install, as the bolts on that end of the cat are even worse-looking than those at the back.

TIA
 

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Yes the stock cat is threaded. And yes you may have to cut them off. I got mine all off except for one. This in my 93 NX w/ 90K in NJ. I used Kroil penatrating oil (like liquid wrench but way better) and one of those small gas torches. The last one I had to cut off. The bolts on the cat are made with no threads that stick out from past the flang. I just got all new heardwear from the steelership and that is what the look like. If you end up cutting the bots and drilling the holes out you should be fine with some nots and bolts and some lock washers.
 

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i went to a hardware store and bought all stainless. It's a little more up front, but you'll never have a stuck bolt again;)

and yes, see if you can get that kroil stuff, that **** as amazing. thats what i used the first time to get all the rusted stuff out.
 

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rusted bolts

when i had the shop guys replace my exhaust cat all the way back due to complete rust out of the midpipe. All they used was an impact wrench and a acetlyne torch to heat up the bolts. I would suggest caution trying to thread the new bolts in. It may weaken the cat as far as the sides connecting to the mid pipe(?) try to get as close to oem size bolts.

good luck
 
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