Gutting the precats (how hard?)

[JCviggen]

Since my car is under the knife currently I wanted to gut the precats while the downpipes are off. Problem is the Shop is over 100 miles away from here so I've asked a friend ( a good mechanic ) who lives near there to pick up the pipes and gut them saving me half a day of driving.

He's a little worried about it. How hard is it? From what I read it's mostly a time consuming PITA but not technically that difficult? He'd be trying it without cutting and welding...backup plan I have him take them somewhere but though I'd ask here who's done it?

[chunky79]

i dont know how its done but have read that it takes a long time. Don't know if you can use a hammer and chizzel?

dunc

[JCviggen]

Well he sure can...but he's never seen one of our downpipes and is just worried he'll do something wrong lol

[Monaro-Azz]

It's not that hard just takes some time.
You need to mount it with the turbo end facing down in a vice & use a long shaft flat head screwdriver and a hammer/mallet.
You then have to free up the cat's cell substrate by tapping the screwdriver through the cells till it breaks free, then get a pair of pliers and try and wiggle/ crush the cell structure till it comes out the opening.
Finally you then have to scrape any remain substrate from the walls of the DP.

You can only use this method on the PRE cat as the second cat is too far in to reach.

It is really important you do it upside down as if you do it the other way round little bits of substrate will fall into the second cat clogging it up and undo all the work your doing by removing the precat

I did one DP in about 2.5-3 hours but I was drinking beers & mucking around with mates at the same time.

For the second cat you'll have to cut the DP at the front of the cat to remove the Cell Substrate then reweld it.

Hope that helps,

[JCviggen]

Thanks m8. Only interested in doing the precats and keep the main ones in there.