It would make it easier to work with if you undid the nuts on the cat so then you can take the whole exhaust off in one go and get at it from any angle. Depending on how rusted on it is, trying to prise the joint apart from the slits might not work. I tried this once and it just ended up flaring the bits next to the slits and the rest was still stuck.

Yup it is a slide over join lol. Clean the pipes with some wire wool if you have any before putting your new back box on.

I'm not sure of how it's set up on a Corsa B but if it is a slide over join I normal put a screw driver in the slits on the exhaust and twist it to prize them open slightly.

When I was removing my exhaust before I nearly gave up. I found That It worked by constantly adding wd40 and moving it up/down and twisting it because the pipe is not a perfect circle so you have to keep twisting it. Place a wooden block on the exhaust and swing at it and then do the same for the other side.

Use a rubber hammer and wd40. Best tools for changing a Corsa or nova bb from underneath. :lol:

Ok, thanks for the replies. So it looks like I'll have to hit it a LOT harder!

But what about the bumper issue? How did you slide the backbox securing bits out from inside the bumper after you've taken the rubbers off??

[Edited on 29-09-2012 by Billy Dean]

As said, all you can really do is hit the back box to try and dislodge it and pull harder.

Beat the fuck out of the back box away from the system, you'll also need the twist it as well. But be carefull because you might break the flange on the cat. Which I've done in the past.

It always seems easy just changing the back box, but it's a right pain while on your back.

'm halfway through changing my backbox on my Corsa B 1.4 16v.
I have managed to take the backbox out of the securing rubbers. And I have taken the clamp off joining it to the centre section too.

2 problems seem to be facing me now though.

1. The backbox is not sliding off the centre pipe. I've sprayed it with Plus Gas to kill any rust. And I've wacked it gingerly a few times with a hammer. But it seems to be welded on!

2. The backbox 'securing lugs' (you know, the long metal bits that fit into the rubbers) are out of the rubbers but inside the bumper. I can't seem to yank the exhaust off because these lugs will just hit the inside of the bumper. Do you have to take the bumper off to make this job easier?


p.s. I am doing this job lying on my back with axle stands propping up the car.

Any help and advice much appreciated!