Question about exhaust flange bolts and Magnaflow replacement. What bolts do I need? (1 Viewer)

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My Y pipe has bit the dust, as well as showing symptoms of bad cats. I ordered The Magnaflow 23120 and the matching second cat and I'm hoping to install them later this week.

Here's my question: What bolts do I need for the cats? Does the kit come with the ones that I need? Can I cut the heads off of the bolts and punch them out or are they threaded all the way through?

This is my first exhaust job, but I'm working with a buddy who has done a few before. Wish me luck, I guess. Any tips or tricks are appreciated!
 

NLXTACY

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Only gaskets came with mine. You are removing the nuts from the exhaust manifold flange. The studs are part of the exhaust manifold. I'm in SoCal so I didn't have rust issues so the entire affair was eventless and took just a touch under an hour.
 
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If you're lucky enough to loosen the stock bolts without having to cut them out due to rust, you can just re-use them. If not, quick trip to the hardware store for anything that will fit through the hole (and matching nuts/washers). I don't remember the magnaflow cats coming with the bolts, but it was a couple years ago, so I might be mistaken.
 
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Thanks guys. I'm sure I'll end up cutting the bolts, this cruiser has lived in Utah its whole life and hasn't ever had the exhaust worked on :clap:
 
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Thanks guys. I'm sure I'll end up cutting the bolts, this cruiser has lived in Utah its whole life and hasn't ever had the exhaust worked on :clap:
Mine was from Utah also, and I recently replaced my gaskets. I soaked the studs with blaster and they came off reasonably easily. I did the gasket replacement on my lunch hour.

I now need to do my cats too, and Im also looking to use the magnaflow part.
 

NLXTACY

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FWIW I just used a bunch of long extensions to get to the flange nuts and just laid on my back. Easy in and out.

Oh, one thing to keep in mind, the overall length of my new cats/pipe was 3/8" shorter than stock. This put added torque on the exhaust bushings. YMMV
 
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FWIW I just used a bunch of long extensions to get to the flange nuts and just laid on my back. Easy in and out.
This right here for sure. I ended up using like two long extensions, and a flex joint to get to them all. Much easier if you pull the airbox, and move the throttle cable and intake tube out of the way. The heat shields were kind of a pain to remove, but use PB Blaster (or =) and make sure you use anti seize when you put it back together.

I think I put some pics up in the "what did you do with your 80 today" thread.

These probably arent hugely helpful, I thought I had some better ones, but at least you can see the real estate.
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Thanks again for thr input. The heatshields and manifold bolts were removed recently, I did have my flange gaskets replaced up there last summer. I'll be sure to use some anti seize when I put it all back together. I'm more worried about the rear cat bolts, but I'll soak them in on blaster for a few days so hopefully they come out a bit easier. I'm super lucky, my friend has a lift in his garage so we won't have to he flat on our backs for the whole time.
 
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All of the gaskets are just donuts, correct? I won't be needing any springs for the bolts or anything like that?
 
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Just did this last weekend with the same parts. I ended up using an impact with a few extensions to take the Y pipe off the manifold, made life a lot easier. One of the studs backed out with the nut, but they all went back in just fine with a standard 1/2" socket and extensions. If you have the time, take your front drive shaft out and you'll have a lot more room to work with. I didn't remove mine as I was lazy, but it would have been helpful. As far as hardware, the rest of mine were rusted beyond salvage. Simply went to the local parts store and grabbed some, M10 is what I used I believe. The only issue I have is that the flange on the tail pipe behind the second cat is a little warped from over the years. I can't get a good seal on that and will need to visit a local exhaust shop to have that cut off and a new one welded on. Other than that it was a pretty straight forward process. Oh, the new set up will smell funny for a few days as it heats up the first few times.
 
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when I did mine, I used Brass nuts when I connected the two cats, sourced at napa I believe, I just bought stainless bolts and washers and used the same thread brass nuts to combat corrosion [east coast here]
 

RWD

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Is this a job that you can do using jack stands or will I need a lift? In other words, how high off the ground does the 80 need to be in order to snake all of the pipes around ? I'm thinking about changing all of the cats and pipes and muffler myself if no lift is required.
 
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Is this a job that you can do using jack stands or will I need a lift? In other words, how high off the ground does the 80 need to be in order to snake all of the pipes around ? I'm thinking about changing all of the cats and pipes and muffler myself if no lift is required.
Good question, I would like to know that too, as I am starting to think about re-doing everything except a muffler and a tail pipe, as those were done by the PO recently. I may keep the O2 sensors too, if they are OK. Mine is a '94, so I think it has a different set up than the 95-97.

If it's not easy-ish to do at home, what do people see from shops as far as labor goes? I would rather buy the parts I want installed, and I want them to use stainless hardware as much as possible. Sorry to hijack the thread, but this seems like as good a place to talk exhaust as anywhere.
 

NLXTACY

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All of it done on the ground. If you can get your beer belly under the cats you're good to go :flipoff2: :beer:
 

RWD

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Just an update. I finally got around to changing the exhaust from the cat back with a Borla system I bought a while back. It was a new-old-stock system off of Ebay that was probably sitting around for 10 years. Anyway, I was able to change out the exhaust using jack stands and a creeper all by myself. Lots of rust but not too bad. Took about 2 hours to cut the old system off and replace.
 

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