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Discussion Starter · #1 ·
I'm in the process of buying a new exhaust off another member, and I think I can probably have a crack at changing it myself on the driveway. Seems to me that if I'm just doing a catback replacement, there's only two joints to undo (second cat/centre section, centre section/backbox), then it's a case of wrestling them off the hangers with plenty of WD40 and leverage. My only real concern is access, but I should be able to at least get the back of the car high enough to get under it nicely.

I just wanted a quick sanity check on a couple of things though:
- Ancillary parts: I assume I need two new gaskets for each joint. Where can I get these? Had a quick search on ebay, but all I can find are manifold gaskets.
- As far as I know, each joint is attached with a pair or sprung bolts. Do these need to be replaced, or can they be reused (assuming they aren't destroyed during removal)?

Anything else I should know? Hoping it's not too difficult for someone like me. After all, it's just plumbing really, and plumbing's just lego, innit? Water lego. </SuperHans>
 

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If you arent changing the manifold you dont need gaskets for em. You just need 2.5" exhaust gaskets; how many depends on what catback you get.

And itd be a good idea to get a new donut gasket which connects the front pipe to catback. Some people reuse the donut gasket and others change it

Sent from my SM-G973F using Tapatalk
 

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Discussion Starter · #3 ·
If you arent changing the manifold you dont need gaskets for em. You just need 2.5" exhaust gaskets; how many depends on what catback you get.
Yup, as I said, not touching the manifold, but that seemed to be the only gaskets I could find. I'll try searching for 2.5" gaskets then. Ta.

And itd be a good idea to get a new donut gasket which connects the front pipe to catback. Some people reuse the donut gasket and others change it
Noted. I assumed the gasket at this point was the same as the one between the mid pipe and the backbox.

Just found a handy diagram which supports this. For clarity, I'm just replacing the mid-pipe and backbox, so I just need the donut gasket and a 2.5" one then. Sorted.
 

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For the sake of a few quid, it might be worth replacing the rubber hangers? Even with liberal amounts of WD-40, they can be a pain to remove and cutting them off can save a fair bit of time.

Also having a spare jack/stand, something a scissor jack, would come in handy, to support the other end of the exhaust, while you mount it up?

Edit: These sould be the gaskets you need but double check as the are for the OEM sizing.
https://www.importcarparts.co.uk/parts-info?id=12011
https://www.importcarparts.co.uk/parts-info?id=12017
 

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Discussion Starter · #5 ·
For the sake of a few quid, it might be worth replacing the rubber hangers? Even with liberal amounts of WD-40, they can be a pain to remove and cutting them off can save a fair bit of time.

Also having a spare jack/stand, something a scissor jack, would come in handy, to support the other end of the exhaust, while you mount it up?

Edit: These sould be the gaskets you need but double check as the are for the OEM sizing.
https://www.importcarparts.co.uk/parts-info?id=12011
https://www.importcarparts.co.uk/parts-info?id=12017
I haven't looked at how the hangars are designed, but if they are hard to remove, won't they be just as tough to put back on? Or is it easier mounting them onto the new exhaust first or something?
And yes, I have a spare trolley jack. But I also have a pair of old fashioned metal ramps, so if I can get the back wheels up on those I should have both jacks and all axle stands available for supporting bits if needed.
 

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I bought a used exhaust off a club member. I took it to a local garage I use for servicing two of my other cars. They put it on a ramp removed the old exhaust and fitted the new cat back. Took them all of half an hour. They inspected all the gaskets and could if needed replace any as necessary. They charged me £25 and they even dropped off my old exhaust in their transit. Do yourself a favour and get it fitted by someone who can do it in their sleep. Who needs the agg.
 

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I haven't looked at how the hangars are designed, but if they are hard to remove, won't they be just as tough to put back on? Or is it easier mounting them onto the new exhaust first or something?
And yes, I have a spare trolley jack. But I also have a pair of old fashioned metal ramps, so if I can get the back wheels up on those I should have both jacks and all axle stands available for supporting bits if needed.
When the rubber gets old, it gets quite tough and hard to work with. It also tends to crack and it's easy to damage them when removing.
It's not a requirement, just once of those; while your at it / just in case jobs.

Nice! Sounds like it should be plain sailing for you :)
 

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Discussion Starter · #8 ·
I bought a used exhaust off a club member. I took it to a local garage I use for servicing two of my other cars. They put it on a ramp removed the old exhaust and fitted the new cat back. Took them all of half an hour. They inspected all the gaskets and could if needed replace any as necessary. They charged me £25 and they even dropped off my old exhaust in their transit. Do yourself a favour and get it fitted by someone who can do it in their sleep. Who needs the agg.
To be honest, if I've got the tools and the ability, I don't mind having a go at stuff like this. And it gives me a good opportunity to check under the car while I'm at it.
I'll see how I feel once I get the parts though.
 

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Discussion Starter · #9 ·
Did the install this morning. Physically, it went smoothly. I was got the car up on ramps and axle stands, so I was able to get under quite nicely. The exhaust hangars were a bit of a fiddle, but I found by sticking a flathead through them from behind, I was able to lever them off the car quite well. The bolts at the joint between backbox and centre section were just piles of rust - however, the sprung bolts at the cat were fine, so I undid these and withdrew the whole lot, backbox and centre pipe, in one. I can try and split them later if needs be.

Putting the new parts back in was fairly trouble free, right up until I needed to fit the cone gasket. The replacement I ordered came from japanparts.co.uk, and it seems to be a genuine Subaru item. However, I could not get it to fit over the exposed flange pipe of the cat. I tried everything and it would not fit. I measured the internal diameter of the gasket with a micrometer and found that it's too small - it came up at about 2.38 inches...the gasket that came off had the correct 2.54 inches. So over a tenth of an inch too small.

I tried everything to get the new gasket on. Tried greasing it, swearing at it, and heating it to see if would expand a little. I even tried filing away at the inside of it to increase the internal diameter enough for it to fit. But, even a tenth of an inch is a fair bit of material to remove with hand tools, and given that the gasket is made of metal gauze, it was coming apart a bit and getting pretty messy.

In the end I gave up, and resorted to using the cone gasket that came off the car. I'm guessing this is only a few years old as the cat was replaced with the header was changed. However, this is leaking a little (and I think had been before I started, noticed condensation at the join before I took the old exhaust off), so I need to find a solution. Could I just have been sent a duff gasket, or is there some reason they are smaller?

If I get a replacement that fits, hopefully changing it shouldn't be too much work. However at the moment, I'm not really getting a true idea of how the exhaust sounds if it's blowing.
 

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If I get a replacement that fits, hopefully changing it shouldn't be too much work. However at the moment, I'm not really getting a true idea of how the exhaust sounds if it's blowing.
Did you get the right part in the end? I'm also struggling a bit with this. The only OEM one I can find listed for a BRZ is this:


But searching using the part number (44022AA123) it's more commonly listed as an Impreza part, not BRZ. It doesn't say whether it's 60mm (2.36 inch) or 65mm (2.56 inch) internal diameter, which I believe are the 2 common options.

I can find generic 65mm ones, but they all look a bit carp.
 

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Discussion Starter · #11 ·
Did you get the right part in the end? I'm also struggling a bit with this. The only OEM one I can find listed for a BRZ is this:


But searching using the part number (44022AA123) it's more commonly listed as an Impreza part, not BRZ. It doesn't say whether it's 60mm (2.36 inch) or 65mm (2.56 inch) internal diameter, which I believe are the 2 common options.

I can find generic 65mm ones, but they all look a bit carp.
In in the end I just bought a generic 2.5" donut gasket. But that part number I think is the correct one if you have the OEM front pipe. The issue was that I had a Cobra front pipe which is a true 2.5", so the OEM gasket being slightly smaller wouldn't fit over it. I just bought a generic 2.5" gasket in the end. However I've since taken off the Cobra front pipe and reverted to OEM anyway.
 
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