Removing pre-cats (again,Sorry)
Discussion
Thanks once again for info (dai) but how the heck did you get the pre-cat out????? I have a 96 griff 500 and removed manifolds, but have been drilling 
in to the dam thing but it's still stuck solid..is there an easier way, or will i have to resort to cutting out and getting re-welded...If thats the case, what sort of weld will hold up, and what metal is the exhaust made of? Any help appreciated..
..Or can you buy, manifold with pre-cat removed, with lambda sensor hole and which bolt onto original y-piece....
in to the dam thing but it's still stuck solid..is there an easier way, or will i have to resort to cutting out and getting re-welded...If thats the case, what sort of weld will hold up, and what metal is the exhaust made of? Any help appreciated....Or can you buy, manifold with pre-cat removed, with lambda sensor hole and which bolt onto original y-piece....The best way is to cut the manifolds remove cats and fit a cone (reducer) in place, also if you want to de-cat the "Y" piece you may as well fit a proper catless part with a sensible bore, (£235)in stainless, and keep the original intact for future use, We can supply these if you require, and modify the manifolds for you, or supply new, as most other specialists can.
Tim
Tim
Mark,
I think I said it's a sod of a job!
The guy who wrote to me with the instructions said that is pretty much a matter of keeping going. His view ended up being that manifolds without cats were so expensive there was plenty of hours of labour left in the job, but it is time consuming...
I believe he reverted to something more substantial than a drill in the end but as always with these things keep the common sense theme going!
If all else fails I got a quote from Joospeed for £200 to remove them. They said that they cut the pipe and reweld.
I'll check my emails when I get home and see what else I can pull together for you
Cheers
DC
I think I said it's a sod of a job!
The guy who wrote to me with the instructions said that is pretty much a matter of keeping going. His view ended up being that manifolds without cats were so expensive there was plenty of hours of labour left in the job, but it is time consuming...
I believe he reverted to something more substantial than a drill in the end but as always with these things keep the common sense theme going!
If all else fails I got a quote from Joospeed for £200 to remove them. They said that they cut the pipe and reweld.
I'll check my emails when I get home and see what else I can pull together for you
Cheers
DC
Tools required;
Vice.
Hammer.
Long nosed pliers.
Drill and bits and one of those flexible extensions,
Crow bar(about 14")-flat end sharpened on grind wheel.
Chisel-long enough to reach cat-again sharpened.
Big crow bar-about 3ft-not sharpened.
Remove lambda sensors (i did'nt and they were'nt damaged-but it'll probably make access easier).
Secure mainfold in vice(using old chammios to prevent scoring outer surface).Position manifold in vice in such a way as to gain maximum access to cat.
Using flexi drill , drill series of holes in cat.
(not easy as your tryng to work round a corner,virtually).
On my car (98 Chim 500)the pre cats are'nt ceramic (they'd probably just fracture with one blow!)they're the stainless steel mesh type,consequently hitting them from above will just compact them further into the manifold.
Therefore,using the chisel and sharpened crow bar,work around the outside of the cat where its bonded to the inner wall of the manifold.
The aim is to separate the cat from its bonding ,and at the same time crush it inwards on its self (i.e from an O/D of about 5" to the point where its moving about in the manifold).
Use the large crow bar to compress the cats.
It is important whilst doing this to remember not to push the(now free)cat furher down into the manifold !!.
pt2 to follow
Vice.
Hammer.
Long nosed pliers.
Drill and bits and one of those flexible extensions,
Crow bar(about 14")-flat end sharpened on grind wheel.
Chisel-long enough to reach cat-again sharpened.
Big crow bar-about 3ft-not sharpened.
Remove lambda sensors (i did'nt and they were'nt damaged-but it'll probably make access easier).
Secure mainfold in vice(using old chammios to prevent scoring outer surface).Position manifold in vice in such a way as to gain maximum access to cat.
Using flexi drill , drill series of holes in cat.
(not easy as your tryng to work round a corner,virtually).
On my car (98 Chim 500)the pre cats are'nt ceramic (they'd probably just fracture with one blow!)they're the stainless steel mesh type,consequently hitting them from above will just compact them further into the manifold.
Therefore,using the chisel and sharpened crow bar,work around the outside of the cat where its bonded to the inner wall of the manifold.
The aim is to separate the cat from its bonding ,and at the same time crush it inwards on its self (i.e from an O/D of about 5" to the point where its moving about in the manifold).
Use the large crow bar to compress the cats.
It is important whilst doing this to remember not to push the(now free)cat furher down into the manifold !!.
pt2 to follow
Part2
Periodically, use pliers to fish out pieces of cat that work free.
Eventually you should have lumps of compressed pre-cat which is small enough to drop out when the manifold is upturned.
Then remove any pieces of cat which may still be bonded to the inner wall of the manifold.
Easy
.
Notes
.
1)If i knew then what i do now , i wouldnt have started.
2)Having said that im glad i did,sounds and runs better.
3)Use safety goggles,gloves and mask (lots of cat dust-cant be healthy).
4)The above took about 5 hours per manifold !
5)Be aware of not damaging the manifolds .ie crushing them in the vice or denting them.
6)Its not easy to remove the pre-cats this way but its not impossible.
Regards.
Darren.
Periodically, use pliers to fish out pieces of cat that work free.
Eventually you should have lumps of compressed pre-cat which is small enough to drop out when the manifold is upturned.
Then remove any pieces of cat which may still be bonded to the inner wall of the manifold.
Easy
. Notes
. 1)If i knew then what i do now , i wouldnt have started.
2)Having said that im glad i did,sounds and runs better.
3)Use safety goggles,gloves and mask (lots of cat dust-cant be healthy).
4)The above took about 5 hours per manifold !
5)Be aware of not damaging the manifolds .ie crushing them in the vice or denting them.
6)Its not easy to remove the pre-cats this way but its not impossible.
Regards.
Darren.
peninsula did mine as stated below - except they did them on the car. dont suppose they were too worried about replacing manifold gaskets(which they didn't have to)
took them about two hours to remove both precats, labour only as it was in for the 404 cam anyway. also has been piped! sounds great at 110db (goodwood marshalls)
go for it!
>> Edited by Guillotine on Friday 29th November 19:23
>> Edited by Guillotine on Friday 29th November 19:24
took them about two hours to remove both precats, labour only as it was in for the 404 cam anyway. also has been piped! sounds great at 110db (goodwood marshalls)
go for it!
>> Edited by Guillotine on Friday 29th November 19:23
>> Edited by Guillotine on Friday 29th November 19:24
Well have now done one side, took about 2hrs total. Used a big wooden mallet and a crow bar, perfect for reaching all sides of cat.
Re: MOT, i believe (from various sources) as 2sheds said, it will still pass with main cat in and will sound a bit sweeter also, maybe releasing some Bhp also?
Re: MOT, i believe (from various sources) as 2sheds said, it will still pass with main cat in and will sound a bit sweeter also, maybe releasing some Bhp also?
whitechimp500 said:
whitechimp500 said: Part2
4)The above took about 5 hours per manifold !
This included removing manifolds from engine bay,actual removing cats took about 3 hrs per side -dont want to discourage too many people from trying it !
Yes, sorry. My time was on actual removing cats, not manifold........But should be worth the effort!
Thanks for all the help chaps.......
Well at last, both pre-cats removed!!! Will bolt back on tomorrow...Just a quick checklist now?
1/ Leave lambda sensors in place
2/ No more mods reqd to fuelling?
3/ Will be fitting act plenum soon, with large cone filter...Guess then i will need a re-chip or rolling road at least???
Thanks Mark
PS:- Anyone know how much lambda sensors are from tvr?
As been quoted £120 from Lucas UK..(sound okay?)
1/ Leave lambda sensors in place
2/ No more mods reqd to fuelling?
3/ Will be fitting act plenum soon, with large cone filter...Guess then i will need a re-chip or rolling road at least???
Thanks Mark
PS:- Anyone know how much lambda sensors are from tvr?
As been quoted £120 from Lucas UK..(sound okay?)
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