help, pre cat gutting on sat..

[Starry]

Any help on anything i may of forgotten?

Things i have-

WD40.
6 new Studs & bolts.
Lambda sensor remover tool.
Heat, plasma.
Spade headed drill bits.
Flexi head ratchet.
Exhaust putty/paste. To connect d/pipe to centre section which will be swopped to non res whilst its off.

As its my daily i can't have it stuck on the ramp... Any tips or advice would be good.

[Daytona]

First bit of advise, ignore what the S4 guide says it taking about half hour to 45 mins per side (once off)

[RichieRS]

My number 1 tip would be to give it to MRC or Unit 20 to do!!!.

Not much help I know but I attempted and failed to remove mine on axle stands!!!

Expect most of the studs to snap and then have hours of fun extracting the remenants. Unit 20 don't even both replacing the studs, they drill the broken ones out and replace with bolt and serated nuts!!!

[Daytona]

Get yourself one of these or similar and a course flap wheel:

http://www.screwfix.com/p/erbauer-flat- ... 00mm/11130

I'm sure there are better alternatives that fit the flap wheel shaft (6mm) better as I had to make a sleeve for it to sit centrally but I needed the car back on the road.

The S4 guide appears to show a mesh gauze that's retained with a ring, this is not the case with the RS4, it's bonded/welded to the inside of the casing hence the need to grind of the leftovers.

[Starry]

First bit of advise, ignore what the S4 guide says it taking about half hour to 45 mins per side (once off)

How long once off?

[Starry]

My number 1 tip would be to give it to MRC or Unit 20 to do!!!.

Not much help I know but I attempted and failed to remove mine on axle stands!!!

Expect most of the studs to snap and then have hours of fun extracting the remenants. Unit 20 don't even both replacing the studs, they drill the broken ones out and replace with bolt and serated nuts!!!

I've got nuts and bolts on stand by. If need be I'll drill it and use them.

[Starry]

Get yourself one of these or similar and a course flap wheel:

http://www.screwfix.com/p/erbauer-flat- ... 00mm/11130

I'm sure there are better alternatives that fit the flap wheel shaft (6mm) better as I had to make a sleeve for it to sit centrally but I needed the car back on the road.

The S4 guide appears to show a mesh gauze that's retained with a ring, this is not the case with the RS4, it's bonded/welded to the inside of the casing hence the need to grind of the leftovers.

How thick are the cats? Also how far down the pipe do you need to go before you get to it.?

[Daytona]

It's hard to say as I did it over three evenings after work experimenting with different flap wheels and extensions but probably a couple of hours each maybe less.

The cat material seemed (to me anyway) to be once piece from start to end, the end being roughly where the heat shield finishes:


This is what it looks like:


This is what you're left with after hacking:


After the flap wheel has seen it:


HTH

[Starry]

Wow! Didn't think it would take that long to gut them. Thought the time consuming part was getting the pipes off..
Oh well, challenge on!!!!!

[Daytona]

This is the flap wheel I used, just fits:

https://www.machinemart.co.uk/p/alumini ... 60x40x6mm/

[weekenny]

Top tip would be try and get the top nuts first, I broke the wobble extension that I could get to them with so gave up as I had other jobs to do. So it's going in to a local place to get the faulty lambda changed and I'm just going to leave the pre-cats intact.

[Starry]

Trip to b&q to get some more drill bits and abrasive wheels. Im lucky enough to have the use of full Audi dealer workshop and a mate of mine who works there is doing it with me.
Fingers crossed

[mobblers]

Apologies for resurrecting an old thread but my car is currently at my local dealer having a faulty cat replaced. When they tried to remove the old cat they snapped two of the bolts at the exhaust manifold end.

They have arranged for a mobile thread specialist to look at the car on Monday but they have warned that if the broken bolts can't be removed they will need to replace the exhaust manifold which is an engine out job at HUGE expense.

From previous posts in the thread it looks as though it is not unusual for the exhaust bolts to snap and require drilling out. I couldn't see any mention of that being particularly difficult to do so should I expect the thread specialist to be able to remove the snapped bolts without too many problems or should I start preparing for the possibility of a massive repair bill?

[ArthurPE]

There is no way I would pull the motor and buy new manifolds.
Drill them out and get some of these.
I've used them before on manifold flanges.
You can press in with a c-clamp and a socket over the threaded portion.

It may be exactly what Audi uses?

[Quango86]

If you can get the studs out the flange on the manifold is threaded. I replaced mines once I took the exhaust off to change the clutch. I welded a nut on to the bit off snapped stud then used some heat and they screwed out. Defo wouldn't be taking the engine out