Tackling the demon bolt...
 

2 hours and still haven't even budged them... 24" worth of extension with a breaker bar, 14 mm socket and PB blast. Still couldn't even move it. Going to buy some bolt extractors tomorrow and try again.

Ended up spending the last hour trying to get the easier bolts out. Even though they are easier, the space is so tight that it make's it hard to do much.

:mad:

Could you not get off the other 4 bolts? You didn't round off the nut on any of them did you?

here's what i did:

jack up car. spray bolts with PB Blaster. drive car around to heat up exhaust again. jack up car. spray bolt before using a 6 point deep impact socket and breaker bar. tighten bolt first to get it moving. go the other way and losen/remove bolt.

for the two bolts that had to be removed through the engine bay I used a breaker bar and only impact extensions, most of them were swivel extensions. didn't have to remove the Z1 post MAF tubes. for these bolts i placed the impact socket on the bolt first and from under the car and then had someone feed me the extensions so i knew it was flush and wouldn't strip and pressed into the breaker bar with one hand so it stayed flush as i was turning the breaker bar.

used so much force on the top two bolts that i fell once they loosened and wasn't sure what happened at first.

What Critical said. Impact sockets, impact swivel, 1/2 inch extensions and a big big breaker. I wasn't sure if I'd snapped them or loosened them either when they broke loose.

I was able to get the 4 easy bolts moving and out. They weren't a problem at all.

The two demon bolts from the engine is killer though. Will try again after I wake up in the morning. I PB blasted them before I left it alone.

I used a 15" breaker bar with a pipe extension to try and get the demon bolts moving. Still no luck.

As for driving the car to warm it up, that is not an option as the injects have been changed and intake manifold is off right now.

I will update tomorrow if I even get them moving.

Thanks guys

IMPACT swivels are key. They don't bind like normal swivels do. Chances are, if you're using ~20-30" of total breaker bar length, and you aren't getting any movement, it's because your swivels are binding and you're just putting torque on them instead of the nuts.

This is what I have, super cheap and get the job done. 2 Piece Universal Impact Joint Set

1/2" drive is key here! i tried with a 3/8 and just BARELY got it off.

OP, so I just fought with these bolts last week. It took me 3 days to get those demon bolts off trying everything. I tried tons of options ($$$). This is what worked for me.
- 6 sided 14mm socket, 3/8" as otherwise it won't fit
- 1/2" to 3/8" adaptor
- 1/2 ft 1/2" extension + another 1/2" extension to be able to reach out of the engine bay. The key here is to have as few extensions as possible 2x1/2ft would be ideal I guess
- 27" 1/2" breaker bar (the one you can find at harbor freight)
- gallons of pb blaster, wd40 whatever you have
- 3 days
The driver side was what took me longer as it seemed it did not want to come out. Finally it loudly snapped and came off. The passenger side didn't snap, it literally "broke in half" from the torque I applied to it luckily it broke towards the end of the nut stud so I was able to get the cat off.

Side note: the Service manual says those nuts have a torque of 43lb/ft, those demon bolts are NOT like that on this planet.

If you use all impact-rated parts, you can get away with a 3/8th size socket, but good luck finding 3/8ths inch impact rated tools.

I did them all with 1/2 inch drive stuff and didn't have any issue fitting a socket on.

I could literally give you a list of tools I used, as they all came from harbor freight, and you can order all the same stuff.


And the FSM is right about the torque rating... It's the heat that causes corrosion that makes these nuts difficult to get off.

If you drove a car home from the dealer and immediately went to take them off, they'd come right off, no big deal.

I am not even using a swivel. It is a straight shot with the intake manifold off. Does it matter if i use a deep socket or not? Or is that bolt too tall for a regular socket?

Hmm. I'd probably use a deep impact socket anyway, just to be sure.

If you have a straight shot (meaning the socket/extensions are exactly perpendicular to the nut's install plane) and you're using all half inch tools with an impact socket and 24+ inches of breaker and you aren't moving anything...

Man up, eat some wheaties, something.

:bowrofl:

(I'm just teasing. Just put more PB on them and keep trying.)

use a deep impact socket. there's no way you're staying flush with the bolt not having swivel extensions, nor having a deep impact socket.

I have bolt extractors and deep impact sockets. I think the bolts are stripped because the deep impacm sockets won't lock on. If I turn the wrench it slips.

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You rounded them off because you didn't use a deep impact or swivels sounds like

oh the threading is stripped? you're using this?

Sears.com

idk man...

If the threads are stripped, you gotta cut the nut. Usually you can cut it through on one side and then you can get the nut to grip the threads again.

Had to do this the other day on one of my front sway bar studs.

I have defeated the demon bolt and the world is saved. Now we can all live peacefully...

I ended up asking my neighbor for help. He presented a torch and helped me out. Torched the b!tch a$$ and it came loose. The passenger side snapped in two but that doesn't matter because it came out. The driver side made a loud crack sound and started to spin. I swear I put something like 1000 ft lbs into that thing to get it turning. I was shooting sweat out of all my pores using so much force.

I used the bolt extractors. When we heated the bolts up, it was easier to hammer the bolt extractor in to get a better bite. This way it turned. I feel so good accomplishing this lol.

:tup::icon17:

http://oi43.tinypic.com/2f055wg.jpg

So what are these cats worth if I were to sell them?

We hit the bolt with PB blaster, heated it with a blow torch, and accessed it from the engine bay, removing the air box. Then, we broke a 12" extension. Replaced it, then we snapped the bolt, leaving the stud in the cat.

EDIT: good job OP

For those that are going to remove there cats, here are the things I recommend.

Torch
1/2 inch everything (wrench, sockets, bolt extractors, 24-30" worth of extensions)
lots of strength
Another person to help
PB blast
patience

Big thing like everyone else said was that you need to have the socket seated correctly and have it bite onto the bolt. If you don't you will strip it.

6 hours total to get 6 bolts out. At least 5 of the hours were just for the demon bolts.

The problem is every car is different. Some had no issues at all and others, like you and me went thru hell. LOL Sucks but you just never know what you will get when you tackle the infamous 370Z demon bolt. :)

The bolt was stuck on so tight that the craftsman bolt extractor actually stripped. It wasn't until we torched the bolt that the craftsman bolt extractor sat into the bolt a lot better.

thats crazy lol. i think im just gonna let a shop do mine when i get tp/hfc.

Save like 200 bucks if you do it yourself and you learn something new.

It really isn't that bad just time consuming. Even aa shop can give up on it.

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A LOT of shops charge upwards of $400+ for this job.

I guess its 400 then. Lol

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Yeah with all that u slayed mine in what about 3hrs ...start to finish!

I tried doing this myself, but gave up. ended up getting my shop do it for $150

Good job!

I had one that was a b%$ch and ended up snapping. Then I started stressing about how bad the other side would be but it came out easily. Looks like it is different on every car.

This was one of the most difficult things that I have ever tackled on a car. I did end up going in through the engine compartment with about 30" of extensions and a breaker bar. The "demon bolt" finally broke after about 15 minutes of pulling.

I did try bringing it to a few places to get an estimate (even two NISSAN dealers) and they basically said :gtfo2: . With some persistence, PB Blaster and long extensions, it can be done. But be prepared for a few WTF moments.

I’m glad u had it easier then me I managed to break 2 impact extensions and a universal join at that point I just borrowed my neighbors 1700 ft pound torque impact gun and let the bolts have it
Those bolts are no joke man

I just broke these SOBs loose last night, after about a 3 week project trying to get them off. Being in PA and dealing with salt, I knew it wasn't going to be fun, but luckily the Z has become my project car so I had nothing but time over the winter. For those planning to tackle this, here are the lessons I learned:

- soak them in PB Blaster (and I mean, soak them) over an extended period and let it do some of the work for you. I doused them pretty much every night for about 2 weeks. My wife is pissed because the entire garage now reeks of PB Blaster, but oh well.
- use a joint to make sure you're sitting flush on the bolts. I started off going straight in on the passenger side thinking it was flush, and ended up rounding the bolt almost completely off when the deep socket slipped off. Which brings me to...
- skip the deep sockets and go right for bolt extractors, at least for the demon bolts. I picked up a set from Harbor Freight for $20 and they saved me. Not only did it grip the rounded off passenger bolt, but with the low profile I was able to slip it behind the steering column on the drivers side, then attach a joint to it, and not worry about moving the column around. The caveat: since I'm replacing the bolts anyways I wasn't worried about destroying them, but using an extractor from the start on the drivers side bolt popped it off with no damage.

I'm not going to lie - I wish I had recorded the sound it made when they broke loose because I would listen to it every day... such a satisfying metallic "CRACK" followed by the bolt finally turning. Planning on framing the rounded off, partially destroyed passenger side bolt for the garage as a trophy.

Oh, and I also had 2 glasses of bourbon while taking them off, to which I primarily attribute my success.

I know this thread is old AF, but guys living in the northeast definitely get my respect for taking this on yourselves. I feel kinda bad sweating it on a Florida car.

That said, money notwithstanding, how many of you feel like installing headers (and fighting the hardware at the heads rather than cats) would be the same or maybe even easier?

I’m asking about comparing just the labor, not the power difference, which is a different conversation.

Maybe? I think I saw that the install times are similar for both headers and HFCs (~6 hours for a mechanic) which makes me think it's about the same labor-wise. You'll still be dealing with the cramped engine bay/weird angles trying to get the headers loose. I never seriously looked into replacing the headers, though, so YMMV.

Being in FL you won't have to deal with the salt issues but will likely have some heat corrosion on the bolts depending on overall mileage... I wouldn't let that deter you from doing it. Looking back, I bet if I had started with a swivel joint/extractors for the demon bolts I could have knocked the whole HFC install out in one weekend. Once those bolts are off, it's smooth sailing.

Thanks for the tip about the bold extractors. It wouldn't have occurred to me to buy them ahead of time, but it makes sense.

I'll just have to post my results when I get to this stage, and decide on headers vs. HFCs only.

Having done both, I can tell you headers take longer.

Test pipe labor is about 80% of the header labor. Have to remove a few extra parts like the exhaust manifold for the headers. Not significantly different in time (most of it is for the demon bolt), but definitely longer because of the extra steps.

The easiest way of getting the demon bolt out is, let someone else do it. :rofl2:

LTH's. Once I dropped the CBE. It took me about 45 minutes to do the right side cat and manifold as one piece. The left side took me about 5 hours. Mostly because of the manifold heat shield and the steering shaft. And all of the little screw and bolt ends sticking out to tear your hands to pieces.

Before you start with either the LTH's or test pipes. REMOVE all of your O2 sensors to keep from destroying them from the vibrations. :tup:

This. The drivers side is a torturous tunnel, designed to shred your hands and claim your will to live.

Nah.........I just felt like I went 15 rounds with a pissed off alley cat and lost.