I thought the cat was supposed to be expensive?

Richard53

AdrianC wrote: »

This is the cat from a 1.8 Astra G.
Cats used to be way down the exhaust pipe, but as emissions have become stricter, they've moved to nearer the engine - which means they get hot quicker, so start to function much faster.

Ah, right. The only ones I have looked at were tucked away well underneath the floor. Out of sight, out of mind, until it fails an MoT.

JustAnotherSaver

To the ones who ask why i thought that was a cat...

Richard53 wrote: »

Thanks for the explanations. I have never needed to take a cat off, but I have seen so-called 'sports cats' which looked similar to the one in the pic.

Maybe this is why.

I always thought (wrongly obviously) that the cat was shaped like that thing in the middle of the link i provided.

But after i kept reading that the listing does not contain the cat i figured that the cat was that cylindrical like thing that was posted by AdrianC.

Thanks for the confirmation. That explains why the part is so cheap then.

But for the record i wasn't pointing fingers & never thought there was anything 'suspicious' about the listing, as though the seller was up to no good.




As said, my back box & mid silencer are stainless (Cybox which i believe is rebranded Peco). This piece that's broken i'm not so sure.

I bought a 'catback' system so on that basis i would've thought that this pipe would be the same material as the other 2 pieces i just mentioned. It might be, but it's been 7-8 years since i bought the system & had it fitted and with my memory ............! I can't say for 100% whether that front piece came with it.


What's the purpose of that flexi part?

I'm just wondering whether it'd be 'worth' picking up that part in stainless - the same material as the other parts or just get the original part which i guess is mild steel & have it connected up to what's already there.

JustAnotherSaver

Plus then you get listings like this http://www.ebay.co.uk/itm/VAUXHALL-ASTRA-MK-4-G-IV-1-4-1-6-1-8-CAT-CATALYTIC-CONVERTER-FRONT-PIPE-FLEX-/272350427511?fits=Model%3AAstra%7CPlat_Gen%3AG&hash=item3f6959b977:g:9-gAAOSwIgNXvCV-


Which states cat. That's another reason i thought this front piece had a cat but looking at it now after what's been said here it seems to have another section which i guess is the cat, although i don't know then why you'd have 2 cats on this system!?

Mercdriver

JustAnotherSaver wrote: »

Plus then you get listings like this http://www.ebay.co.uk/itm/VAUXHALL-ASTRA-MK-4-G-IV-1-4-1-6-1-8-CAT-CATALYTIC-CONVERTER-FRONT-PIPE-FLEX-/272350427511?fits=Model%3AAstra%7CPlat_Gen%3AG&hash=item3f6959b977:g:9-gAAOSwIgNXvCV-


Which states cat. That's another reason i thought this front piece had a cat but looking at it now after what's been said here it seems to have another section which i guess is the cat, although i don't know then why you'd have 2 cats on this system!?

It can be read to mean front pipe and flex FOR a catalytic converter.

AdrianC

JustAnotherSaver wrote: »

What's the purpose of that flexi part?

The engine moves relative to the body, mostly around a transverse axis, both because of the orientation of the crankshaft and because of the orientation of the torque forces from the driveshafts and road.
The exhaust is flexibly mounted against the body, but if you think about what the tailpipe would be doing from engine movement...

JustAnotherSaver

AdrianC wrote: »

The engine moves relative to the body, mostly around a transverse axis, both because of the orientation of the crankshaft and because of the orientation of the torque forces from the driveshafts and road.
The exhaust is flexibly mounted against the body, but if you think about what the tailpipe would be doing from engine movement...

So you're saying it's sort of like a shock absorber then so that it doesn't just end up breaking off the underside of the car?

AdrianC

JustAnotherSaver wrote: »

So you're saying it's sort of like a shock absorber then so that it doesn't just end up breaking off the underside of the car?

Kinda, but not really if we're going to get techie...

The flexi simply allows for differences in movement, while a "shock absorber" doesn't actually absorb any shocks - that's what the springs are for - it damps the travel of the suspension, which is why it should be called a "damper"...

forgotmyname

As Adrian mentioned it allows the engine to move without bending the exhaust.

Open the bonnet and rev the engine it will move slightly. The flexi part will allow that movement without breaking. Similar to the rest of the exhaust being hung on rubbers to allow the exhaust to move slightly.