DIY: Cat-back Exhaust Install

[domino]

I recently got a new cat-back exhaust, and after a lot of searching and finding no real help on how to install one I thought I'd give it a go and do a write up to help others.

Tools for the job:

Trolley Jack
Jack Stands - Safety First
10mm Socket - For the earthing wire
12mm Socket - For the 2x hanger bolts
14mm Socket - For the 4x exhaust bolts
Breaker Bar
PB Blaster or WD-40
Permatex Copper high temp exhaust silicon
Torque Wrench if available

Step 1: Jack the front of the car up and place jack stands under the frame rails, then do the same for the rear of the car. I left the jack under the diff as well just in case.


Step 2: Give the two nuts holding the exhaust onto the cat a good squirt of PB blaster to loosen them up, leave it to soak in for a couple of minutes so it can work it's magic.


Step 3: While the PB blaster is working, you will need to undo the two hanger's that are held on by a bolt. There is one before and after the diff, they should be easy to see. They take the 12mm socket. Then it should be only the 2 hangers left at the muffler end.

Step 4 : By now the PB blaster will have done it's job. Grab a breaker bar with the 14mm socket attached
then crack both the nuts and undo them but leave them attached still because you will need to remove the earthing wire before you pull the exhaust off. Once you have removed the earthing wire completely, reattach it at the other end of the cat.


Step 5 : Now that you have moved the earthing wire you can pull the exhaust away from the cat, then go to the back of the car and slip the last remaining hangers of the car. WD-40 will make this a lot easier. Then you have fully removed the old exhaust.


Step 6: Take the rubber hangers off the old exhaust and transfer them to the new exhaust, it will be easier to attach the two hangers with bolts onto the body of the car first.


Step 7: With the old exhaust off, you will need to bend the protective shielding on the cat a little to accommodate for the larger exhaust piping.


Step 8: Inspect the gasket from the cat to see if it's re-usable. Mine was in pretty good condition so I just cleaned it up and wiped away the remaining carbon from the gasket. I wasn't sure if the multi-layer gasket needed silicon but I used some anyway. Put a continuous ring of silicon onto the gasket then place it onto the cat, grab the middle section of the new exhaust and attach the hanger that has been bolted back onto the body. Then put another ring of silicon on to the other side of the gasket thats already on the cat and fit the new exhaust up to the cat. Put the two nuts back on finger tight.



Step 9: Now for the rear section of the exhaust, attach the hangers to the muffler and to the hanger that is up behind the diff. For the next bit it will make it easier if you can have some pull the muffler back a little, so you can concentrate on putting a ring of silicon onto both sides of the new gasket and to give you a bit of gap to put the gasket into place. Once again tighten the bolts up finger tight. Now leave the silicon to dry for about an hour.


Step 10: I couldn't find a definite answer for the next bit. Now that you've given the silicon some time to dry, torque the bolts up nice and tight. I tried searching quite a bit for an answer to how tight they should be but I couldn't find an answer so I tightened them up to 30lb which should be enough.


Then your all done


The shitty little jack I had didn't go very high so I didn't have much room under the car, But I had it all done in a couple of hours.

[andrew600]

1)cool stuff. but there isnt a write up because how simple it is.
2)you dont need silicone, the multilayer gasket forms to your mounts, and the heat makes it expand and fills the holes.

cool beans, nice camera.

[SLiDe_WaYz]

Couple hours damn bro it literally takes like 30minutes to remove and install.


I guess good write up for young ones just now getting in the game, or the ricers moving from Honda to here.

[xErniexChaosx]

Originally Posted by SLiDe_WaYz

Couple hours damn bro it literally takes like 30minutes to remove and install.


I guess good write up for young ones just now getting in the game, or the ricers moving from Honda to here.

lol

[domino]

Ease up, not everyone is mechanically minded and would give it a go.

[Edwin562]

Good job on write up. simple and straight forward.

[outtamyway]

as simple as it may be, some people may be too timid on trying something like this. Good right up man.

[Kom3t]

That pretty good!! Dont forget to mention the size of the exhaust matters, cause bigger exhaust won't fit on the stock catalytic, what sizes are just perfect to put on stock piping?

[91cupcake240]

nice job!

[S-Nation S13]

Word straight to the point..i did mine exactly like you did except on a s13...my question is ..what gasket do I need to use if the ones that came with my exhaust goes out?

[codyace]

Where exactly do you live? I can't believe I've ever seen such a 'rust' free exhaust

And I don't mind the idea of copper high temp sillicone...it may be redundant to some, but with the crappy gaskets that many of the lower quality exhausts have, it's a great idea to make double sure it won't leak.

[domino]

Originally Posted by Kom3t

That pretty good!! Dont forget to mention the size of the exhaust matters, cause bigger exhaust won't fit on the stock catalytic, what sizes are just perfect to put on stock piping?

The new exhaust is 80mm, I assume the stock cat has a 2.25" outlet.

Originally Posted by S-Nation S13

Word straight to the point..i did mine exactly like you did except on a s13...my question is ..what gasket do I need to use if the ones that came with my exhaust goes out?

I bought some spare 3" 7 layer metal gaskets in case the others fail. From a company called Frushlife on eBay.

Originally Posted by codyace

Where exactly do you live? I can't believe I've ever seen such a 'rust' free exhaust

And I don't mind the idea of copper high temp sillicone...it may be redundant to some, but with the crappy gaskets that many of the lower quality exhausts have, it's a great idea to make double sure it won't leak.

I live in Sydney, Australia

[dorrifto]

its a little unreal how clean it was under your car!

[s15xacee]

How many inches is your Exhaust piping ? I was planning to get a 3'' Catback Exhaust , and i was wondering if i still can use the stock Cat?

[domino]

The exhaust is 80mm, which is about 3.15", it fit pretty easy.

[vipa]

i got a question,help!
so i got a 3 inch high flow cat and i got my stock down pipe..
is this possible??

[vipa]

^^^ oh and its on my ka24de s13

[iBlaze240]

Nice write-up and great photos. We need more DIY's like this with details and good images like you provided. Keep up the good work!

[domino]

^^^^Thanks

re: vipa

I'm not sure to be honest, I have no experience with KA's. Is the cat you have meant as a direct replacement for your model car? meaning, does it already have the flanges attached or do they need to be welded on?

[vipa]

yes its got the flanges, its a bolt on/
my down pipe inlet is around 2.25 like yours as well , do you got any leaks?

[laurentj23]

I did my exhaust and now trying to install the header. I found out that nuts/bolts that are attached to the cat are rusted out. Will PB blaster help to take it off or do I need to use a blow torch and heat it up like they did for my exhaust.

What size nuts/bolts are those anyway?

[andrew600]

depends on how rusty, they will most likely just break. i would just torch them off. and whatever grade8 hardware from ace or other hardware stores that will fit.

[Frank_Jaeger]

Originally Posted by andrew600

1)cool stuff. but there isnt a write up because how simple it is.

I wouldn't have known it was this simple if I didn't read this write-up. I'm sure I would've found out when it came to it, but this was a nice resource.

[domino]

Originally Posted by vipa

yes its got the flanges, its a bolt on/
my down pipe inlet is around 2.25 like yours as well , do you got any leaks?

I don't get any leaks at all. I didn't really need to use the gasket silicon on cat either but it's just a little extra assurance.

Just give it a go, you only have to undo 4 bolts or torch them, then get 4 new bolts with lock tight nuts. I think the bolts are M14 in size but not sure

[johnnysombrero]

Nice Writeup. I didn't use liquid gasket on my 300zx exhaust, and it developed a minor leak even with a new gasket. Won't make that mistake again.

One minor note otherwise, FSM claims 38-48 ft-lb torque on exhaust bolts. Page FE-7.